Global assessment of soil pollution

Intergovernmental Technical Panel on Soils

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Home > Books > Biodegradation Technology of Organic and Inorganic Pollutants

Bioremediation Techniques for Soil Pollution: An Introduction

Submitted: 30 May 2021 Reviewed: 23 June 2021 Published: 14 September 2021

DOI: 10.5772/intechopen.99028

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Environmental pollution has been on the rise in the past few decades owing to increased human activities on energy reservoirs, unsafe agricultural practices and rapid industrialization. Soil pollution is one of the major worry among all because soil contamination can harm the humans by consumption of food grown in polluted soil or it can cause infertility to soil and lower the productivity, Among the pollutants that are of environmental and public health concerns due to their toxicities are: heavy metals, nuclear wastes, pesticides, greenhouse gases, and hydrocarbons. So this chapter will include; Sources of soil pollution and remediation of polluted sites using biological means has proven effective and reliable due to its eco-friendly features. Bio-remediation can either be carried out ex situ or in situ, depending on several factors, which include site characteristics, type and concentration of pollutants. It also seen as a solution for emerging contaminant problems.

  • soil pollution
  • bio-remediation
  • ex situ bio-remediation
  • in situ bio-remediation

Author Information

Anita verma *.

  • Department of Environmental Sciences, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh

*Address all correspondence to: [email protected]

1. Introduction

Soil is an essential a neighborhood of the common habitat. It’s pretty much as significant as plants, creatures, rocks, landforms, loch and waterways. It is a living space for a genuine scope of living beings. It goes about as stream control for water and synthetic substances between the environment and along these lines the world, and furthermore both as a source and store for gases (like oxygen and carbon dioxide) inside the climate. Soils do not simply influence characteristic cycles yet additionally record human exercises both at this and inside the past.

Soil is dynamic organically and a permeable medium that has created inside the highest layer of Earth’s covering. Soil is one of the corpus foundations of life on Earth, which might be a supply of water and supplements, as a mechanism for the filtration and breakdown of squanders, and as a functioning member inside the cycling of carbon and different components through the environment accessible universally. It’s gotten from enduring cycles driven by natural, climatic, geologic, and geographical impacts.

Soil is the linkage between the different ecosystems like biosphere, atmosphere, and hydrosphere. So, the soils are fundamental in the preservation of environmental quality at local, regional, and worldwide level. For example, its buffering capacity contributes to water quality, since the ability to act as a sink for contaminants can have an important role in controlling the negative impacts of pollution on other environment. Researchers are trying to develop and model different bioremediation techniques; however, there is no single bioremediation technique that treats all types of contamination and to restore polluted environments. Bioremediation is a natural process, which relies on bacteria, fungi, and plants to remove, reduce, degrade, or immobilize environmental pollutants from soil and water, thus restoring contaminated sites to a relatively clean nontoxic environment [ 1 ].

It is now recognized that, soil is considered a vital resource, and due to its slow formation, it can be considered nonrenewable. Moreover, it has impacts on environmental, economic, and cultural activities. These techniques are environmentally friendly and cost effective features are the major advantages of bioremediation compared to both chemical and physical methods of remediation. Thus far, several good definitions have been given to bioremediation, with particular emphasis on one of the processes.

2. Soil pollution

Soil contamination is that the decrease inside the efficiency of soil in light of the presence of soil toxins. Soil toxins adversely affect the actual substance and organic properties of the dirt and decrease its profitability. Pesticides, composts, natural excrement, synthetic substances, radioactive squanders, disposed of food, garments, cowhide merchandise, plastics, paper, bottles, tins-jars and cadavers all contribute towards causing soil contamination. Synthetic substances like iron lead mercury, copper, zinc, cadmium, aluminum, cyanides, acids and soluble bases and so on are available in modern squanders and arrive at the dirt either straightforwardly with water or in a roundabout way through air. (for example through corrosive downpour).

Soil contamination can cause contamination if harmful synthetics drain into groundwater, or whenever sullied spillover arrives at streams, lakes, or seas. Soil additionally normally adds to contamination by delivering unstable mixtures into the environment. Nitrogen escapes through alkali volatilization and denitrification. The disintegration of natural materials in soil can deliver sulfur dioxide and other sulfur compounds, causing corrosive downpour. Substantial metals and other possibly poisonous components are the principal genuine soil toxins in sewage. Sewage slop contains substantial metals and, whenever applied over and again or in huge sums, the treated soil may gather weighty metals and thus it become incapable to try and support blossoms.

soil pollution project work methodology pdf

3. Man made pollutants

3.1 agricultural pollution.

Agricultural processes contribute to soil pollution. For increasing increase crop yield fertilizers are used which also cause pollution that impacts soil quality. Use of pesticides also harms plants and animals by contaminating the soil, these chemicals get deep inside the soil and poison the ground water system and runoff of these chemicals by rain and irrigation also contaminate the local water system and causes eutrophication of fresh water body. Phosphate is the main contributor to eutrophication its high concentration promotes Cyanobacteria and Algae growth which ultimately reduces dissolved oxygen in water [ 2 ].

3.2 Industrial waste

Most of the pollution is caused by industrial waste products and improper disposal of waste contaminates the soil with harmful chemicals. These pollutants affect plant and animal species and local water supplies and drinking water. On the other hand toxic fumes from the regulated landfills contain chemicals that can fall back to the earth in the form of acid rain and can damage the soil profile. Industrial activities like leads to acidification of soil and contamination due to the disposal of industrial waste, heavy metals, toxic chemicals, dumping oil and fuel, etc.

3.3 Urban activities

Human activities can lead to soil pollution directly and indirectly. For example improper drainage and increase run-off contaminates the nearby land areas or streams. Unorganized disposal of trash breaks down into the soil and it deposits in a number of chemical and pollutants into the soil. These may again seep into groundwater or wash away in local water system and excess waste deposition increases the presence of bacteria in the soil which leads to the generation of methane gas from decomposition activities by bacteria contributing to global warming and poor air quality. It also creates foul odors and can impact quality of life [ 3 ].

3.4 Acid rain

Acid rain primarily caused by Sulfur dioxide (SO2), oxides of nitrogen and ozone to some extent. Acid rain is caused when pollutants present in the air mixes up with the rain and fall back on the ground. Sulfuric and nitric acid solutions cause acidity in rainwater. Acid rain decreases the pH of the soil, causing its acidity to increase, which decreases the level of important nutrients found in the soil [ 4 ]. Soils low in cation exchange capacity and base saturation are the most sensitive to acid precipitation [ 5 ].

4. Natural source of soil pollution

Some of natural event also can be the cause of soil pollution like earthquakes, landslides, hurricanes, and flood. These natural disasters cause transpose to the composition of soil which leads to the contamination. For example weathering of naturally occurring sulphide-bearing rock make mineralized zones of arsenopyrite (gossans), Most of these minerals present a high spatial variability and many of them can be found in higher concentrations in deeper layers. However, As is slightly bioaccessible if getting from natural sources [ 6 ]. Soils and rocks are also natural sources of the radioactive gas Radon (Rn). High natural radioactivity is common in acidic igneous rocks, mainly in feldspar-rich rocks and illite-rich rocks.

However, There are other numerous of ways of soil contamination, for example, • Seepage from a landfill • Discharge of mechanical waste into the dirt • Percolation of defiled water into the dirt • Rupture of underground stockpiling tanks • Excess utilization of pesticides, herbicides or compost • Solid waste drainage • The most well-known synthetics associated with causing soil contamination are: • Petroleum hydrocarbons • Heavy metals • Solvents Soil contamination happens when these synthetic substances hold fast to the dirt, either from being straightforwardly spilled onto the dirt or through contact with soil that has effectively been tainted.

4.1 Effects of soil pollution

Human health

Growth of plants

Air pollution

Diminished Soil Fertility:

Impact on scene and Odor contamination:

Changes in Soil Structure:

Impact on Ecosystem and Biodiversity:

Tainting of Water Sources:

When it downpours, surface run-off conveys debased soil into water sources causing water contamination. Toxins can likewise penetrate down to debase ground water. The defiled water is subsequently unsuitable for both creature and human utilization. It will likewise influence amphibian daily routine since the living beings that experience in these water bodies will discover their living spaces inhabitable.

5. Bioremediation

Remediation means to get rid of an issue and if it is associated with taking care of an ecological issue like soil and groundwater contamination is called bio-remediation. Bioremediation is a mechanism which utilizes the living microorganisms to reduce natural contaminations or to anticipate contamination [ 9 ]. It is an evolution towards elimination of toxins from the climate in this way reestablishing the first characteristic environmental factors and forestalling further contamination. Bioremediation also can be a permanent in situ solution for contamination instead of simply translocating the problem. Remediation of heavy metals, metalloids, or other inorganic pollutants from soil or water can be done by this technique [ 10 ]. It is a cost-effective, efficient, novel, eco-friendly, and solar-driven technology with good public acceptance as compared with other engineering techniques.

soil pollution project work methodology pdf

A. Based on applied strategies : bioremediation techniques applied on the basis of strategies can be classified in two categories.

Ex-situ bioremediation.

In-situ bioremediation.

5.1 Ex-situ bioremediation

Ex-situ as name suggests its mean to remove contamination mat to a remote treatment location. This classification is not much popular because it involves the big task of excavating polluted soil and transports it to offsite. The basic principal of ex situ remediation is to introducing the correct soil oxygen, moisture and nutrient conditions on offsite [ 11 ]. However, Ex situ bioremediation process poses a hazard to spreading contamination or risking an accidental spill during transport [ 12 ]. There are two technique classes can be applied explained bellow.

5.1.1 Slurry phase

This technique involves the process of combining contaminated soil with water and other additives in a large bio-reactor and mixed to keep the indigenous micro-organisms in contact with the contaminants. Essential nutrients, oxygen are added and the conditions in the bio-reactor are ensured at optimum environment for the micro-organisms to degrade the contaminants. After completion of the treatment, the water is removed from the solids -wastewater is disposed and further treated if still contaminated. Slurry-phase is a relatively rapid process compared to other biological treatment processes specifically for contaminated clays [ 13 ].

5.1.2 Solid phase

Solid phase treatment use to treats soils in above-ground treatment area. This area equipped with collection systems to check the contaminants from escaping the treatment. The parameters like moisture, heat, nutrients, and oxygen are controlled to enhance rate of degradation. Solid-phase systems are simple to process and maintain in spite of, it require a large amount of space and more time of treatment than slurry-phase processes. This treatment can be achieved by following techniques [ 14 ]. Land farming

This technique basically stimulates biodegradation through indigenous microorganisms and facilitate aerobic degradation of contaminates. It is done by a simple methodology technique in which contaminated soil is excavated and spread over a prepared bed and regularly until pollutants are degraded. For promoting the growth of the indigenous species some nutrients and minerals are also added. Soil biopiles

This biodegradation technique used for the remediation of excavated soil contaminated with petroleum contents. Soil biopiles also known as biocells. This technology involves the accumulation of contaminated soil into piles and the stimulation of microbial activity either aerobically or by adding nutrients, minerals or moisture [ 13 ]. A typical height of biopiles can be three and ten feet. This technology also uses oxygen as a method to stimulate bacterial growth. Biopiles are aerated by forcing air to move by injection through perforated piping placed throughout the pile [ 14 ]. Composting

Composting involves mixing the contaminated soil with a biomass such as straw, hay, or corncobs which make it suitable to deliver the optimum levels of air and water to the microorganisms. Composting involves the locating of the contaminated soil in treatment vessels and it is mixed there for aeration. Window composting a type of composting process in which the soil is placed in long piles named as windows and mixed by tractors regularly. A ratio of 75% contaminated soil to 25% compost use for composting. This ratio is depending on the variability of soil type, contaminants level and characteristics. Compost remediation is known as a faster remediation because it can remediate in weeks [ 15 ].

5.2 In-situ bioremediation

Bioremediation process is done at the contamination site defines the in-situ method. In situ is the preferred bioremediation method, as it requires less mechanical efforts to eliminates spreading contaminants and prevent the spread of pollutant through transportation or pumping away to other treatment locations.

In situ bioremediation are biological processes which include microorganisms metabolize organic contaminants to inorganic material, such as carbon dioxide, methane, water and inorganic salts. This process can be achieved either in natural or engineered conditions [ 16 ].

5.2.1 Types of In situ bioremediation intrinsic bioremediation.

Intrinsic bioremediation is a process for converting environmental pollutants degrades to non-toxic forms through the immanent abilities of naturally occurring microbial population at the site. This process is usually employed in underground places as such underground petroleum tanks. Intrinsic bioremediation manages the innate capabilities of naturally occurring microbial communities to degrade environmental pollutants without modified or taking any engineering steps to accelerate the process [ 11 ]. This technique deals with stimulation of indigenous microbial population by feeding them nutrients and oxygen to increase their metabolic activity. Enhanced (engineered) In situ bioremediation


Bio-venting is an in situ remediation technique that uses microorganisms to degrade organic constituents adsorbed on soils [ 17 ]. This technique involves regulated stimulation of airflow for increasing oxygen to unsaturated zone for enhances the bioremediation, by increasing activities of indigenous microbes. In the process of bio-venting, amendments are done by adding nutrients and moisture to increase bioremediation to achieve microbial transformation of pollutants to a nontoxic state. This technique has gained popularity among other in situ bioremediation techniques especially in restoring sites polluted with light spilled petroleum products. Bioventing primarily use for the degradation of adsorbed fuel residuals, and also can use in the degradation of volatile organic compounds (VOCs) through biologically active soil.


Bioslurping technique is the combination of bioventing and vacuum-enhanced pumping of soil and groundwater remediation by indirect provision of oxygen and stimulation of contaminant biodegradation [ 18 ]. This technique uses a “slurp” that extends into the free product layer, which draws up liquids (free products and soil gas) from this layer in a manner similar to that of how a straw draws liquid from any vessel. The bioslurping system is constituted by a well connected to an adjustable length called “slurp tube” is installed, and this slurp tube, connected to a vacuum pump, which is lowered into the light non-aqueous phase liquids (LNAPL) layer, and pumping begins to remove free product along with some groundwater. The vacuum-induced negative pressure zone in the well promotes LNAPL flow towards the well and also draws LNAPL trapped in small pore spaces above the water table. This technique used to remediate soils contaminated with volatile and semi-volatile organic compounds


Soil permeability (which determines pollutant bioavailability to microorganisms)

Pollutant biodegradability


Bioaugmentation is arrangement to enrich the existing microorganism population and make it more effective in reducing the level of contamination. This technique refers to the addition of organic culture to the contaminated soil and make environment of the site similar to a bioreactor. There are two common options can be used one is addition of a pre-adapted pure bacterial strain and second is addition of a pre-adapted consortium to the contaminated site. Bioaugmentation is mainly used in oil contaminated site for bioremediation. Bioaugmentation is a low-cost method in comparision of other methods of treating wastewater and soil contamination [ 20 ].


The direct use of green plants and their associated microorganisms to stabilize or reduce contamination in soils, sludges, sediments, surface water, or ground water is defined as Phytoremediation. This technique depends on the use of plant interactions (physical, biochemical, biological, chemical and microbiological) to contaminated sites to mitigate the toxic effects of pollutants. It is an alternative technology that can be used along with or in place of mechanical conventional clean-up technologies that often require high capital inputs and are energy intensive. Area with low concentrations of contaminants over large cleanup areas and at shallow depths presents especially favorable conditions for phytoremediation. Depending on pollutant type (elemental or organic), there are several mechanisms (accumulation or extraction, degradation, filtration, stabilization and volatilization) involved in phytoremediation [ 21 ]. Elemental pollutants (toxic heavy metals and radionuclides) are mostly removed by extraction, transformation and sequestration.

Phytostabilization - using plants to reduce heavy metal bioavailability in soil.

Phytoextraction — using plants to extract and remove heavy metals from soil.

Phytovolatilization — using plants to absorb heavy metal from soil and release into the atmosphere as volatile compounds.

Phytofiltration — using hydroponically cultured plants to absorb or adsorb heavy metal ions from groundwater and aqueous waste.


The phytostabilization process involves plants which established and function primarily to accumulate metals into tissues of root or aid in their precipitation in the root zone. This technique is based on the chemical stabilization of heavy metals using various non-organic and/or organic soil additives in connection with adequately chosen plant species [ 22 ]. Species which will be resistant to specific conditions present in the soil, such as low pH and high concentrations of heavy metals, ought to be selecting. Phytostabilization reduces the mobility of contaminants, and help to minimize the risk, of inorganic contaminants within the site. This technology does not generate contaminated secondary waste that needs further treatment. This technique basically limits the bioavailability of heavy metals and to restore adequate soil quality.


Phytoextraction is a phytoremediation technique that uses plants to uptake and removes metals and other contaminants from soil or water [ 22 ]. This technology can be used to reduce both organic and inorganic pollutants from the soil, water and the air as well. This technology seems to be similar as solar driven pumps which can extract and concentrate certain elements from their environment. This should be achieved at a lower cost than any alternate technology as it only requires the identification and planting of such plant which possess the ability of hyperaccumulation. The ability to accumulate heavy metals varies significantly between species and between cultivars within a species [ 23 ].


Phytovolatilization, employs the plant-mediated uptake of contaminants and transforms them into volatile compounds, and subsequently releases these compounds in the atmosphere. In this technique plant absorbs organic pollutants an water while growing it travels from root to other parts of the plants as same or in an altered form due to its metabolic and transpiration pull.


Phytofiltration technique is manly use to treat contaminated water. This technique involves, high metal-accumulating plants which function as biofilters, and it can be also effective in sequestering metals from polluted waters [ 24 ]. In this technique the polluteded water is either collected from a waste site or brought to the plants, or the plants are planted in the contaminated area, where the roots take up the waste water and the dissolved contaminants [ 25 ]. Many plant species naturally uptake heavy metals and other contaminant due to this it is a cost effective procedure for remediation.


Phytodegradation technique refers to the degradation of organic contaminants through the enzymatic activates of plants. The plant releases enzymes from roots, or through metabolic activities within plant tissues. In phytodegradation organic contaminants are taken up by roots and metabolized in plant tissues to less toxic substances [ 26 ]. Phytodegradation process can degrade hydrophobic organic contaminants more efficiently.


Mycoremediation is a technique of using fungus as a bioremediator. This biotechniques uses particular fungi that release enzymes which can degrade several pollutants and found to be promising strategies in the removal of contaminant with in a site. Mycoremediation is an efficient and economical technique as well [ 27 ].

6. Conclusion

Bioremediation is an effective technique available to clean up contaminated sites. The idea of bioremediation has a long history. However, other applications are relatively new and many other applications are emerging or being developed. This process can be aerobic or anaerobic depending on the microorganisms and the electron acceptors available. This process may be natural (intrinsic bioremediation) or it may be enhanced by man (engineered bioremediation). Several remediation approaches, particularly physical systems, involve the treatment of aqueous phase pollutants and, here, the distinction between soil and groundwater is of limited practical significance. Remediation approaches aimed primarily at treating or containing groundwater within ‘geological’ materials will be mentioned only briefly, whereas those commonly used for dual purposes will be considered in more detail. These technologies offer an efficient and cost effective way to treat contaminated ground water and soil.

There are other common methods of preventing soil pollution include reforestation and recycling of waste materials. De forestation often leads to erosion of the soil, which leads to soil pollution due to the loss of fertility of the soil. Thus, reforestation is an effective method of preventing soil pollution. In addition, reducing the volume of refuse or waste in landfills by recycling materials such as plastics, papers and various other materials is another effective and common method of preventing the phenomenon of soil pollution.

Overall study suggested that Pollution is a threat to our health and damages the environment and damage to soils which affects the ability to grow crops. Bioremediation can help to reduce and remove the pollution and to provide clean water, air and healthy soils for future generations. The bioremediation process is completely natural process with very less harmful side effects. It carried out in situ for most applications which do not require dangerous transport. It creates relatively few harmful byproducts. Bioremediation is way cheaper than most remediation methods because it does not require substantial equipment or labor.

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Method for Assessing the Integrated Risk of Soil Pollution in Industrial and Mining Gathering Areas

1 College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China; E-Mails: ten.haey@devdenarik (Y.G.); nc.ude.iaknan@tiemuj (M.J.)

Chaofeng Shao

2 Department of Soil Pollution and Control, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; E-Mails: nc.gro.searc@bqug (Q.G.); nc.gro.searc@naiqgnahz (Q.Z.)

Industrial and mining activities are recognized as major sources of soil pollution. This study proposes an index system for evaluating the inherent risk level of polluting factories and introduces an integrated risk assessment method based on human health risk. As a case study, the health risk, polluting factories and integrated risks were analyzed in a typical industrial and mining gathering area in China, namely, Binhai New Area. The spatial distribution of the risk level was determined using a Geographic Information System. The results confirmed the following: (1) Human health risk in the study area is moderate to extreme, with heavy metals posing the greatest threat; (2) Polluting factories pose a moderate to extreme inherent risk in the study area. Such factories are concentrated in industrial and urban areas, but are irregularly distributed and also occupy agricultural land, showing a lack of proper planning and management; (3) The integrated risks of soil are moderate to high in the study area.

1. Introduction

Industrial and mining activities have always been leading sources of soil pollution [ 1 , 2 ]. In China, mining and industrial gathering areas have been established and rapidly developed across the country. According to several studies [ 3 , 4 , 5 ] and the National Soil Pollution Survey Bulletin [ 6 ], over ten million hectares of land in China have been threatened by soil pollution. Among these, two million hectares are threatened by mining and five million are threatened by petroleum pollution. Moreover, because of irrational planning and rough development in the initial construction stage, types, range and potential risks of the pollutants in soil of industrial and mining gathering areas are intricate and should not be underestimated.

In the interests of preventing and controlling soil pollution caused by industrial and mining activities, several studies have conducted ecological and health risk assessments, evaluation criteria grading, and spatial distributions of pollutants in different regions of China. Since the 1990s, China has developed quality standards for general soil environments [ 7 ] and for soils allocated to specific land usages [ 8 , 9 , 10 , 11 ]. Li et al. [ 12 ] summarized the published data (2005–2012) on soils polluted with heavy metals originating from mining areas in China, and then comprehensively assessed the heavy metal pollution derived from these mines based on soil pollution levels and human health risks. In previous studies, the mines and surrounding areas were identified as sources and heavy metals were considered the most serious pollutants. The spatial distribution [ 2 , 13 , 14 , 15 ], risk assessment [ 2 , 13 , 16 , 17 , 18 ], and mobility [ 19 , 20 ] of pollutants in soils also provided important information.

However, the risk assessment of soil pollutants has focused almost exclusively on heavy metal pollution. Organic pollution, especially the organic pollutants generated by the petrochemical industries, is largely ignored, despite its strong presence in the industrial and mining gathering areas and its potential for serious harm. Moreover, although most researchers have analyzed the risk sources, the survey, classification, grading, and management methods of polluting factories (the main sources of pollution in industrial and mining gathering areas) are relatively simple and not associated with the risk analysis. Finally, the difficulty of investigation and data collection has precluded a spatial analysis that combines a soil pollution study with an evaluation of the inherent risk level of polluting factories. Therefore, to understand the overall status of the soil environment in industrial and mining gathering areas, a comprehensive method that considers the soil risk caused by complex pollutants and pollution sources is necessary.

The present study proposes a comprehensive method for evaluating soil risk status. It includes the human health risk, the inherent risk level of the polluting factories and evaluated risk regionalization and characteristics of pollution sources. The method was piloted in Binhai New Area, Tianjin, China, a typical area of high mining and industrial activity.

2. Methodology

This study assesses human health risk and the inherent risk levels of polluting factories. From these results, a comprehensive method for assessing hazardous soil environments in industrial and mining gathering areas is developed.

2.1. Human Health Risk Assessment

By assessing human health risk, we can characterize the potential health hazards imposed by environmental pollution and elucidate the impacts and damage to human health [ 21 , 22 ]. The latter (including the carcinogenic and non-carcinogenic health risks of soil contamination) are revealed by the land use patterns and exposure pathways. Appendix A describes the assessment of human health risk on both organic pollutants and heavy metal contaminants. This assessment provides a scientific basis and technical support for comprehensive risk management.

2.2. Inherent Risk Assessment of Polluting Factories

Polluting factories, refer to factories engaged in industrial production or other industries, which may directly or indirectly cause large-scale environmental or ecological pollution. As mentioned in the Introduction, mining and industrial activities are major sources of soil contamination in industrial and mining gathering area. The operating conditions, pollutant emission levels, environmental management, and risk prevention levels of polluting factories are all important affecters of soil environmental risks. Therefore, to guide the soil environmental management in industrial and mining gathering areas, the risk assessment of polluting factories should be included in the soil environmental risk assessment.

2.2.1. Evaluation Index System

The polluting factories in industrial and mining gathering areas significantly differ in type, pollutant emission characteristics, and risk supervision level. Therefore, the environmental risks also differ among factories. The evaluation system is divided into three levels. The first layer, referred to as the target layer, measures the overall level of soil environmental risk posed by polluting factories. The second layer, the criteria layer, includes the inherent degree of sudden environmental risks, degree of cumulative environmental risk, and degree of environmental risk supervision by factories. The third level includes the assessment indicators. Appendix B described the construction of indicator system and the weight distribution of indicators, the results are listed in Table 1 .

Risk assessment indicators of polluting factories.

2.2.2. Scoring of Indicators and Comprehensive Assessment

Because the dimensions of each index in the index system are variable, these indices cannot be directly calculated and must instead be standardized. In this study, the indicators were scored and standardized by referencing the national standards and evaluation guidelines of related industries. The standardized indicators and calculation method of parameters are presented in Appendix C .

2.3. Spatial Analysis

To guide the functional zoning of contaminated soil environment and identify the primary areas of soil contamination management, we require spatial analysis, risk regionalization, and a comprehensive risk partitioning method. In the current study, the human health risks were quantified by sampling, surveying, and analyzing the soil pollutants, soil environment, and the integrated status of the industrial and mining gathering areas. The assessment methods are described in Section 2.1 . The results were then spatially interpolated using the inverse distance weighted (IDW) method, implemented in the ArcGis 9.3 software environment (Spatial Analyst module, ESRI, Beijing, China).

Compared with the IDW interpolation, other commonly employed methods such as Kriging and Spline interpolation also have strong ability to predict the overall trend of soil pollution. However, in purpose of identifying of the polluted areas, it is necessary to require the interpolation method to predict the local feature of soil pollution. In industrial and mining gathering areas, the concentration of pollutants in soil showed a high spatial variability, but the local maxima of soil pollution (concentration or risk value) is likely to be smoothed out by Kriging or Spline interpolation. Therefore, to reserve the local maxima and minima of soil pollution in industrial and mining gathering areas, IDW interpolation is an appropriate choice. Moreover, relevant study [ 23 ] indicated that, according to the root mean square error (RMSE) for cross validation, although Kriging and Spline interpolation are more accurate than other methods, the interpolation results of soils in polluted area estimated by Kriging are significantly smaller than the results by actual statistical results. Therefore, as a measure of overall sample prediction accuracy, RMSE cannot describe the estimated error of local extreme values.

From the interpolation results, the spatial distribution maps of human health risk were derived. Again, using the spatial interpolation, the assessment results of the polluting factories were embedded in an integrated risk regionalization map. In this way, the soil environment risks and inherent risks of the polluting factories were combined into a comprehensively partitioned classification of the soil environmental risks in the study area.

2.4. Comprehensive Analysis

The classification of land use in industrial and mining gathering areas was performed based on landscape, distribution and characteristics of population, functional requirements of lands, and protection requirements of ecological sensitive targets. Different types of land are divided into four classes: industrial land, including industrial land and mining sites, storage land, supply facilities area and so on; agriculture land, including farmland, orchards, aquaculture bases and so on; residential land, including residential areas, living areas, culture and entertainment land, education and health land, business area and so on; conservation land, including nature conservation objectives, coastal waters, wetlands and so on.

The regionalization results of human health risk ( TCR value) and the land use class of the study area were incorporated into a matrix assessment method. This method uses the comprehensive risk classifications in Table 2 to evaluate the risk status of the industrial and mining gathering areas. From the classification results, risk management and control measures can be designated.

Classification method of soil integrated risk.

2.5. Site Description

The selected study area is a typical mining and industrial gathering area in the Binhai New Area, Tianjin, China, located southeast of Tianjin, China. The study area, shown in Figure 1 , mainly covers the southern region of this area. Established in 1994, the Binhai New Area has become an important industrial and economic center in Tianjin, one of China’s largest industrial cities. The area is also the third zone especially designated for industrial economy development in China [ 24 ]. Unfortunately, industrial economic expansion and progress of the mining industry has been accompanied by increased soil contamination (mainly heavy metals). The study area covers approximately 1200 km 2 and experiences a warm temperate, semihumid continental monsoon climate. Its average annual temperature and precipitation levels are 14 °C and 600 mm, respectively [ 25 ]. As noted in reports on National Major Function-oriented Zoning, China has invested heavily in developing this international port city as an eco-city and in enhancing the northern economic center of Tianjin. Owing to its rich reserves of oil and metal resources near Bohai Bay, the Binhai New Area is of significant strategic interest. The main industries are located in the northeastern and eastern parts of the region and include petrochemical, metallurgical, and mining industries. In particular, this area is becoming an important petrochemical industry base in northern China, as outlined in the Overall Plan for the New Town in Tianjin (2006–2020).

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Location and scope of the study area.

The ecological environment of this area is extremely sensitive and fragile because it borders the river, sea, and land. The pollution problem is exacerbated by the uneven distributions of the residential and industrial regions. Heavy metals introduced to the soil by human activity have contaminated large portions of this area and its vicinities [ 26 , 27 , 28 ]. Specifically, rivers, farmlands, and coastal waters have been polluted to varying extents by heavy metals discharging into water bodies over long periods.

2.6. Sampling and Analysis

Soil samples were collected from the study area in 2013. Forty-six census points were selected by systematic random grid sampling, the grid spacing of census points was 3 km. These points were separated by soil type, topographic characteristics, and the distribution of their contamination sources by a grid laying method. Moreover, to fully reflect the impact of highly aggregated mining industries on the quality of the soil environment, 68 encrypted points were selected in densely mined areas and areas with industrial activity ( Figure 2 ), the grid spacing of encrypted points was 1 km. The large empty area in the sampling point map is occupied by a water reservoir.

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Soil sampling bitmaps. Note: the blank area is the North Dagang Reservoir.

The selected monitoring targets were eight common heavy metals, namely, As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg; two common pollutants of mining industries, Co and V; and eight organic pollutants including Pyrene, Carbon tetrachloride, Dichloroethane, 1,2-, Trichlorothane, 1,1,1-, Benzene, Ethylbenzene, Fluoranthene, and Xylenes. The soil samples were pretreated by air-drying at room temperature. Plant roots, organic residues, and visible intrusions were removed from the samples. Finally, the samples were crushed, ground, and passed through a 0.85-mm sieve. The samples were suspended in deionized water (1:2.5 v / v ), agitated for 1 h using a Sartorius PB-10 (Sartorius, Beijing, China), and subjected to pH measurements. The concentrations of the monitoring targets (except As and Hg) were determined by inductively coupled plasma-atomic emission spectrometry. The As and Hg concentrations were measured by atomic fluorescence spectrometry (AFS-2202, Haiguang Company, Beijing, China). Volatile and semivolatile organic compounds, polycyclic aromatic hydrocarbon substances, and other organic pollutants were monitored by gas chromatography mass spectrometry.

3.1. Overview of Soil Pollutants

Table 3 showed the basic situation of various pollutants in soil. The detection rate of nine kinds of heavy metals reached 100%, and the detection rate of Hg and eight kinds of organic pollutants was less than 10%, indicating that heavy metal pollution was more serious in soil environment of the study area. Moreover, coefficients of variation of nine kinds of heavy metals except Hg were relative low, indicating that the nine kinds of heavy metals were widely distributed in the study area and the content difference of the nine heavy metals at different sampling points were relatively small.

Overview of soil pollutants.

3.2. Human Health Risk

3.2.1. overview.

The TCR and THI values of heavy metal contaminants and organic pollutants were separately calculated, as described in Section 2.1 . The THI values of organic pollutants were below 1 at all sampling points, and the total TCR values were lower than 10 −6 . Therefore, the health hazards posed by organic pollutants in the study area were generally acceptable. The THI values of heavy metals were also below 1 at all sampling points, indicating that heavy metals pose acceptable non-carcinogenic risk. However, in the carcinogenic risk category, the TCR values of Cd, As, and Cr 6+ at many of the sampling points exceeded 10 −6 . The results confirmed that heavy metals are the most important risk factors in the study area, especially considering their bioaccumulative character and non-biodegradability. Therefore, heavy metal pollution should continue to be targeted in industrial and mining gathering areas.

3.2.2. Human Health Risk of Heavy Metals

The TCR ranges of Cd, Cr 6+ and As were 1.6 × 10 −6 to 3.8 × 10 −4 , 2.2 × 10 −8 to 8.3 × 10 −6 , and 6.0 × 10 −6 to 7.6 × 10 −3 , respectively, indicating that the carcinogenic risks of these three heavy metals exceeded the acceptable level by varying degrees. At 114 of the sampling points, the TCR of Cr 6+ was lower than 1 × 10 −5 , indicating that Cr 6+ poses a low carcinogenic risk. The TCR s of As and Cd exceeded 1 × 10 −4 at 47 and 37 of the sampling points, respectively. Therefore, these heavy metals pose high or extreme carcinogenic risk at more than 30% of the sampling points.

Figure 3 showed the spatial distribution of carcinogenic risks of Cd, As and Cr 6+ . It is clear that the carcinogenic risk of Cr 6+ is low to moderate across most of the study area, the carcinogenic risk of As is high to extreme, and the carcinogenic risk of Cd is moderate to high. The overall level of carcinogenic risk of As is high, indicating that As is the main contributor of carcinogenic risk in the study area. Extreme risk areas of As are mainly concentrated in the north and east of the reservoir. Similarly, high risk areas of Cd and moderate risk areas of Cr 6+ are mainly concentrated in the north and east of the reservoir, indicating that carcinogenic risk in such areas is more serious. Extreme risk areas of Cd are mainly concentrated in the northeast and southwest of the study area.

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Spatial distribution map of the human health risks of three heavy metals posed by contaminated soil.

The spatial distribution of the integrated human health risk (carcinogenic), obtained by IDW interpolation of the calculated TCR values, is shown in Figure 4 . The human health risk regionalization results revealed the following: (1) The carcinogenic risk is moderate to high risk across most of the study area; low-risk sites are minimal. (2) Extreme risk areas are mainly concentrated in the northeast of the study area and south of the reservoir. (3) Looking at the land use patterns ( Figure 5 ), high-risk areas are found to be concentrated in the Sanjiaodi industrial area located northeast of the reservoir and in the oilfield industrial zone, with its surroundings (including residential areas). (4) Extreme risk areas are concentrated in the Dagang urban area in the northeast of the study area, the Guangang forest park in the northeast corner, and residential areas affiliated with the oilfield industrial zone. The industrial land uses of these three regions share several common characteristics; complex population composition, frequent living activities, proximity to conservation projects (reservoirs and forest parks), and high vulnerability of receptors. Risk management and pollution prevention in such areas, especially in residential lands, is essential.

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Spatial distribution map of the human health risks posed by contaminated soil.

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Land use of study area.

3.3. Inherent Risk of Polluting Factories

According to the Census of Pollution Sources conducted by local environmental protection departments and statistical agencies in 2010, 150 polluting factories exist in the study area. The offending industries include electrical power, metallurgy, non-ferrous metals, petrochemicals, manufacturing (brick, paper, and textiles), and a small number of food production industries. The inherent risk of these polluting factories was calculated by the abovementioned risk evaluation method.

The calculated risks of the 150 polluting factories are summarized in Table 4 . As shown in this table, none of the factories incurred no or low risk, indicating that the polluting factories pose a serious threat in the study area. Half (75) of the factories, especially those involved in smelting, forging, production and processing of non-ferrous and ferrous metals, and some petrochemical factories, posed moderate risk. These industries are the leading industries in typical industrial and mining gathering areas. However, some of the large-scale metal production and processing factories achieved low scores in environmental management system and risk prevention measures. This indicates that after 30 years of development and construction, some leading industries had gradually developed and improved their risk monitoring and prevention systems. On the other hand, a large proportion of the 150 factories were assessed as high-risk. Among the 69 factories in this category, the vast majority was brick production and thermoelectric industries; the remainder included chemical industrial factories and metal production and processing factories. Therefore, large state-owned factories remain important sources of pollution in the study area. However, note that a significant number of small-scale factories involved in property management, food production, and light industry were also high-risk. These results highlight the importance of reasonable risk control measures and risk prevention awareness. Among the six extreme risk factories, four were large state-owned petrochemical factories; the remaining two were the largest brick factory in the study area and a glass factory. The pollutant emission levels of these six factories were also high.

Overview of polluting factory risk in the study area.

3.4. Integrated Risk

The classification and spatial distribution of integrated risk of soil environment in the study area is presented in Figure 6 . The integrated risk of soil in the study area was moderate to high. Furthermore, in Dagang urban area that located in the northeast of the study area, living areas affiliated to oilfield industrial zone that located in the southeast of the reservoir, wetland and forest park in the northeast of the study area, the integrated risk of soil was high to extreme, indicating that the integrated risks of residential land and conservation land were relative high. In most areas in the west and south of the study area, the integrated risk of soil was generally moderate. In Sanjiaodi industrial area and industrial production area of oilfield industrial zone, the integrated risk of soil was generally low.

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Spatial distribution map of the integrated risk.

More than half of the polluting factories were located in the northeast of the study area, and nearly 20 of these were located in residential areas, posing high to extreme threats to human health. Five of the polluting factories assessed as extreme risk were located in the Sanjiaodi industrial area; the remaining one was surrounded by several polluting factories of different sizes in the southwest of the study area. Polluting factories tended to be distributed throughout green spaces or agricultural lands in the western parts. Such occupancy of non-industrial land by factories typifies industrial and mining gathering areas throughout China, indicating unreasonable planning of land layout and a disordered distribution of factories in the initial stage of regional development. Polluting factories posing high and moderate risks were cluttered and many were located in non-industrial areas. In Figure 6 , we can see that most of the polluting factories are centralized in the three industrial zones, but some are scattered outside of these zones, indicating a need for rational planning and management. Finally, although few of the polluting factories posed extreme risk to human health, their presence around densely populated areas and conservation regions such as reservoirs and forest parks presents a high inherent risk.

4. Discussion

The results revealed that the integrated risk status of residential lands and conservation projects were relatively high and should be improved to ensure that residents are not exposed to contaminated soil and to ensure ecological security. The rational planning of industrial and mining factories is the most important measure against soil environmental risk. In addition, polluting factories near residential lands and conservation areas should maintain their inherent risk below moderate levels. To achieve this goal, they require more comprehensive risk management plans and control measures.

The areas situated northeast to the study area, where polluting factories are largely intermingled with the population and the land use is mainly residential, were assessed as high to extreme integrated risk. Due to the high population density, such areas should be treated as the primary targets for soil risk management and control. A buffer zone should be erected between the urban and industrial areas and the emissions of polluting factories should be monitored.

Polluting factories, especially industrial and mining factories with high or extreme levels of inherent risk, should be relocated to the three major industrial areas to centralize their management and control. Industrial and mining factories located in the southwest of the study area should be shut down or relocated; alternatively, a new industrial zone should be established in this region and the residents should migrate to other residential areas. The non-negligible risks posed by other factories, including brick, food production, papermaking, and property management companies, require special attention. Such factories share common features such as cluttered distribution, lack of proper planning, and poor management. However, the production conditions and requirements and product flow of these industries largely differs from those in the heavy industrial and mining category. Therefore, relocating these factories to the three major industrial zones is neither practical nor wise. One possible solution is to establish specialized industrial areas for light industry and food production and processing in suitable locations. Moreover, these factories require guidance and supervision of their production processes, pollution monitoring systems, and environmental management measures.

From the distribution of industrial land and polluting factories in the southwest of the study area, the staggered distribution of industrial and residential lands was a prominent feature of China’s old industrial areas, and may have derived from the expansion of residential areas and functional areas of factory employees. Such intermingling reflects a lack of overall planning and long-term consideration of risk prevention. To protect residential lands, the long-term planning of industrial and mining gathering areas should separate residential and industrial lands as much as possible. Efficient transportation systems and risk isolation measures would ensure the normal operation of industrial and mining factories without posing risks to the nearby inhabitants.

5. Conclusions

This study established a method for assessing the soil environment risk in industrial and mining gathering areas. To this end, the pollutants and their sources were monitored and investigated. Moreover, the soil environmental risks in a typical industrial and mining gathering area were systematically analyzed. The main contributions of the study are summarized below.

(1) To assess the impacts and damage to human health by soil environmental pollution, a human health risk of heavy metal contaminants and organic pollutants was conducted. Similar to previous studies, heavy metals were identified as the most serious contaminants in the study area. High and extreme risk was found mainly in industrial and residential areas.

(2) The inherent risk level of polluting factories, which pose the main risks in industrial and mining gathering areas, was evaluated. The evaluation system was designed to optimize the layout of the regional environmental risk sources while protecting the residential population and the most sensitive conservation targets.

(3) A comprehensive analysis of soil environmental risk was conducted using a matrix overlay. By this method, the integrated risk in a typical industrial and mining gathering area was assessed. The integrated risk includes the risk level of the soil environment and inherent risk level of the polluting factories.

In industrial and mining gathering areas, the theories and methods of risk assessment and management of the regional soil environment remain at the developmental stage. In particular, the spatial and temporal zoning of environmental risk, multi-risk coupling and risk-field superimposition, and the allocation capacities of regional environmental risk are still being explored. Industrial and mining gathering areas have already implemented technologies and management systems to alleviate their integrated risk to the soil environment. However, further tests, optimization, and upgraded and improved application practices are needed, which should be based on the investigation and evaluation of risk sources.


The study was supported by “Funding Project of Environmental Nonprofit Industry Research and Special of China” (NO. 201309032) and “National Natural Science Foundation of China” (No. 41301579).

Appendix A. Assessment of Human Health Risk

Soil contaminants enter the human body mainly via the food chain, oral ingestion, skin contact, and breathing [ 12 , 29 ]. The health impacts of soil pollutants predominantly arise by the distribution and migration of soils, crops, and food. Therefore, in industrial and mining gathering areas, where soil environments are largely contaminated by heavy metals, the oral intake of such pollutants poses the most serious threat. Among the pollutants investigated in the current study, three heavy metals (Cr 6+ , Cd, and As) and seven organics (listed in Table A1 ) were identified as carcinogenic by the Integrated Risk Information System (IRIS) of US Environmental Protection Agency (EPA) [ 30 ] and the Technical Guidelines for Risk Assessment of Contaminated Sites (HJ 25.3-2014) [ 31 ] issued by China’s Ministry of Environmental Protection. The non-carcinogenic contaminants are ten heavy metals and eight organics (listed in Table A2 ).

The oral intakes of carcinogenic and non-carcinogenic pollutants in residential land are calculated by Equations (A1) and (A2), respectively:

Similarly, the oral intakes of carcinogenic and non-carcinogenic pollutants in farmland and industrial land are calculated by Equations (A3) and (A4), respectively:

In the above expressions, CDI car and CDI ncr , respectively, denote the oral intakes (mg/kg·d) of carcinogenic and non-carcinogenic pollutants from residential land, and CDI cafi and CDI ncfi are the corresponding intakes from farmland and industrial land, respectively. The subscripts a and c refer to adults and children, respectively. IR c and IR a denote the daily intake from soil (mg/d), and ED c and ED a are the periods of exposure duration (year) (the corresponding frequencies (d/year) are EF c and EF a ). BW c and BW a denote average body weights (kg), ABS o is the oral intake absorption efficiency factor, and AT ca and AT nc are the average times of the carcinogenic and non-carcinogenic effects, respectively (d). CS is the pollutant content in the soil (mg/kg), and CF is a conversion factor.

Total carcinogenic and non-carcinogenic risks of various soil pollutants are calculated by formulas (A5) and (A6), respectively:

In these formulas, TCR and THI denote the total carcinogenic and non-carcinogenic risks, respectively, CDI cai and CDI nci are the oral intakes (mg/kg·d) of a single pollutant and non-carcinogenic pollutant, respectively, i denotes an individual pollutant, SF oi is the carcinogenic slope factor of the i -th pollutant (kg·d/mg) (listed in Table A1 ), and RfD oi is the reference oral intake dose of the i -th pollutant (mg/kg·d) (listed in Table A2 ).

The parameter values in the above formulas are listed in Table A1 , Table A2 and Table A3 , the values were extracted from the Technical Guidelines for Risk Assessment of Contaminated Sites (HJ 25.3-2014) [ 31 ], issued by China’s Ministry of Environmental Protection.

Carcinogenic slope factor (SF o ) of carcinogenic pollutants (From the Technical Guidelines for Risk Assessment of Contaminated Sites HJ 25.3-2014 ).

Reference oral intake dose (RfD o ) of non-carcinogenic pollutants (From the Technical Guidelines for Risk Assessment of Contaminated Sites HJ 25.3-2014 ).

Exposure assessment parameters (From the Technical Guidelines for Risk Assessment of Contaminated Sites HJ 25.3-2014 ).

In general, acceptable values of the total carcinogenic risk range from 1 × 10 −6 to 1 × 10 −4 , and the total non-carcinogenic risk value ( THI ) should not exceed 1. Therefore, on the basis of the calculation of the total carcinogenic risk, 1 × 10 −5 was selected as an acceptable level of carcinogenic risk in the present study. The adjusted valuation criteria for the TCR are as follows: TCR ≤ 1 × 10 −5 (low risk), 1 × 10 −5 < TCR ≤ 1 × 10 −4 (moderate risk), 1 × 10 −4 < TCR ≤ 5 × 10 −4 (high risk), and TCR > 5 × 10 −4 (extreme risk). The THI was divided into two risk levels: THI < 1 (no risk) and THI ≥ 1 (non-carcinogenic risk).

Appendix B. Evaluation Index System and Weight Distribution

The polluting enterprises in industrial and mining gathering areas significantly differ in type, pollutant emission characteristics, and risk supervision level. Therefore, the environmental risks also differ among enterprises. To comprehensively assess the inherent risk level of polluting enterprises, this study applies an evaluation index system comprising sudden risk, cumulative risk, and risk supervision. Sudden risk refers to the risks on soil environment and human health posed by unexpected environmental accidents, natural disasters, and other transient factors. The sudden risk might reflect the degree to which various factors of polluting enterprises affect the environment. These factors include design layout, technology, management skills, and quality of personnel. Cumulative risk refers to the potential damage to human health and ecological environments by long-term, non-accidental discharge of pollutants during human production and development activities. The cumulative risk could reflect the risk imposed on soils during normal operation of polluting enterprises. Risk supervision focuses on the production safety, elimination of hazards, and treatment of contaminants. Risk supervision reflects the ability of the polluting enterprise to effectively control and prevent risks, and indirectly reflects the enterprises’ handling of production processing, equipment, management, and safety hazards.

To comprehensively assess the risk of polluting enterprises, each index must be weighted to reflect its contribution to the evaluated risk. Indices are commonly weighted by their entropy, Delphi method, the analytic hierarchy process (AHP), or principal component analysis (PCA). The present study adopts a mix of qualitative and quantitative methods. Advice was sought from 20 experts (including five environmental regulators, five engineers specializing in environmental impact assessment, and ten professors engaged in soil environmental protection). The indicator weights of the three evaluations in the criteria layer were then distributed by the AHP and Delphi methods on the basis of the characteristics of the soil environment and the indicators’ individual contributions to the soil quality in the area. The judgment matrix was constructed as S = ( u ij ) m×n (A7):

where u ij denotes the importance of indicator i to indicator j .

The consistency of the judgment matrix can be tested through calculation. The consistency is acceptable when the consistency proportion < 0.1. The feature vector A = (w 1 ,w 2 ,…,w n ) indicates that the largest eigenvalue of the judgment matrix corresponds to the weight distribution. The weight distribution results are presented in Table A3 .

Appendix C. Standardized Indicators and Calculation Method

Grading standards of the assessment indicators.

In Table A4 , the inventory level Q of hazardous substances is determined by Equation (A8):

where Q i and qi denote the inventory and critical value, respectively, of hazardous substance i , and n is the number of different hazardous substances. The critical values of hazardous substances are listed in Enterprise Environmental Risk Level Assessment Method [ 32 ]. Industrial output value refers to the total value of the products of the industrial enterprises within a certain period. Industrial policy requirements are accessible through the Industrial Restructuring Catalog issued by the National Development and Reform Commission [ 33 ]. Soot denotes the smoke and dust generated by industrial production process that performed in industrial furnaces using gas, liquid and solid fuels. According to the National Industrial Soot Emission Standards (GB T9078-1996), soot is an important indicator to measure the pollutant emission level of industrial factories in China. Indicator values were acquired mainly from pollution census, completion acceptance reports of enterprises, statistical yearbooks, and departmental rules and regulations from China’s State Council.

The comprehensive risk levels of polluting enterprises in mining and industrial gathering areas were characterized by comprehensive risk indexing ( CRI ) on the basis of the weight distributions and classification standards. The CRI is calculated by Equation (A9):

where CRI represents the inherent risk level of an enterprise, and w i and I i represent the weight and score of indicator i , respectively. The CRI lies within [0, 3] and is divided into four ranks; a score of [0, 1] indicates a healthy state of all indicators and a low risk level, (1, 2] denotes an alert state with moderate risk level, (2, 2.5] indicates a poor state with high risk level, and (2.5, 3] suggests extreme risk to human and environmental health.

Author Contributions

Yang Guan, Chaofeng Shao, Qingbao Gu, Meiting Ju and Qian Zhang work together. Specifically, Chaofeng Shao brings the idea, provides insight for literature guidance and choice of evaluation model. Yang Guan conducts all simulations and interprets the results. Qingbao Gu, Meiting Ju and Qian Zhang involve in the thesis structure, and provides a large number of basic data that are necessary for doing an assessment.

Conflicts of Interest

The authors declare no conflict of interest.

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Soil Pollution - Causes and Effects

Suaad Hadi Hassan Al-Taai 1

Published under licence by IOP Publishing Ltd IOP Conference Series: Earth and Environmental Science , Volume 790 , First International Virtual Conference on Environment & Natural Resources 24-25 March 2021, College of Science, University of Al-Qadisiyah, Iraq Citation Suaad Hadi Hassan Al-Taai 2021 IOP Conf. Ser.: Earth Environ. Sci. 790 012009 DOI 10.1088/1755-1315/790/1/012009

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The study of soil pollution has occupied the attention of a large number of researchers because of its continuity and effect on humans, animals and plants alike. Soil pollution occurs as a result of the entry of elements that change the composition and organism of the soil, and reduce its fertility, making it more vulnerable to drought, and unsuitable for agriculture. The research addresses the most important soil pollutants before radioactive uranium pollution, pollution by industrial and household waste, volcanic eruptions, forest fires, and others. Most of the agricultural lands are irrigated by rivers polluted with factory wastewater. Also, the research discusses the most important sources of pollution represented by pesticides and chemical fertilizers that contain toxic substances and seep into the soil to remain for a long time, and contribute to eliminate soil fertility. The research deals with the impact of logging the desertification of agricultural areas and their transformation into a vast desert that is unsuitable for agriculture, and pollutes the soil with hydrocarbons. The research refers to the method of soil protection and agricultural lands from pollution by using organic agriculture, fertilizers, organic and bio-pesticides, and forest planting..

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Assessing the environmental risk and pollution status of soil and water resources in the vicinity of municipal solid waste dumpsites

  • Published: 02 December 2021
  • Volume 193 , article number  857 , ( 2021 )

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soil pollution project work methodology pdf

  • Ghida Soubra 1 ,
  • May A. Massoud   ORCID: 1 ,
  • Ibrahim Alameddine 2 ,
  • Mahmoud Al Hindi 3 &
  • Carol Sukhn 4  

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Municipal solid waste management remains a major challenge for many developing countries where unsanitary and environmentally damaging practices, such as open dumping and burning of wastes, are consistently utilized as means of waste disposal. This study aimed to assess the impact of local dumpsites in a region in Southern Lebanon and to assess/determine the level of pollution they cause on local ecosystems and the concomitant risks to public health. Accordingly, soil and water samples were collected from the seven dumpsites that were investigated over the course of two seasons. Several biological, chemical, and physical parameters were examined, with the results being utilized to calculate a number of environmental indices. Results indicated that several soil parameters including TN (700–2400 mg/kg), pH (8.3–8.7), COD (39–1995 mg/kg), and sulfate levels (17.8–301.6 mg/kg) were altered by the dumpsites. Heavy metal concentrations varied between dumpsites; however, the most commonly prevalent metals across all dumps were Fe (992–41,500 mg/kg), Cr (17.4–139.5 mg/kg), Zn (24.1–177.4 mg/kg), Cu (9.42–148.2 mg/kg), and Mn (25.2–776.5 mg/kg), though recorded concentrations exceeded permissible limits only in certain instances. Evidently, soil samples collected at dumpsites had higher concentrations compared to the samples collected away from dumpsites reaching 27 times more in certain locations. The altered parameters have a direct effect on soil fertility and, if biomagnified, could disrupt crop yields and impact human health. Physiochemical properties and heavy metal concentrations in water samples were not significantly altered and were found to be within permissible limits. However, it is crucial to develop a monitoring and remediation plan to decrease the percolation of leachate to water resources.

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Assessing the Ecological Risks and Spatial Distribution of Heavy Metal Contamination at Solid Waste Dumpsites

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Evaluation of the contamination of the soil and water of an open dump in the Amazon Region, Brazil

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The authors would like to extend their appreciation and gratitude to the European Commission (Grant #: ENI/2018/398–061; Starting date: 2018) for funding this research project.

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Soubra, G., Massoud, M.A., Alameddine, I. et al. Assessing the environmental risk and pollution status of soil and water resources in the vicinity of municipal solid waste dumpsites. Environ Monit Assess 193 , 857 (2021).

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What are leaking underground storage tanks and how are they being cleaned up?

FILE - Workers remove a 10,000-gallon underground gasoline storage tank to be replaced with a new tank at a gas station in Sacramento, Calif., May 23, 2003. Nearly half of Americans depend on groundwater for their drinking water, according to the Environmental Protection Agency. Environmental experts say even a pinprick-size hole in an underground tank can send 400 gallons of fuel a year into the ground, polluting soil and water. (AP Photo/Rich Pedroncelli, File)

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For more than a decade, some residents of the tiny Richmond, Rhode Island, neighborhood of Canob Park drank and bathed using tap water that had been tainted by gasoline that leaked from storage tanks buried under service stations a few hundred yards from their homes. They spent years battling oil companies, dealing with the daily misery of boiling most of their water and wondering about lasting damage to themselves and their children.

The Canob Park disaster sparked a national outcry in the 1980s to clean up and regulate the thousands of underground tanks storing petroleum, heating oil and other hazardous chemicals across the United States. It’s a program that continues today, where the tanks are a leading cause of groundwater pollution even after more than a half-million sites have been cleaned up.

EDITOR’S NOTE: This article is a collaboration between The Associated Press and The Uproot Project.

Nearly half of Americans depend on groundwater for their drinking water, according to the Environmental Protection Agency, and it’s not just well water that is threatened. A city’s water supply, while treated and processed to make sure it meets federal standards, may still collect contaminants from gas leaks on its way to the tap. In some cases, this can happen when the water originates from an unregulated well — some cities get their drinking water from a mix of surface and groundwater — or through cracked pipes.

For privately owned wells, which aren’t regulated by the government, the homeowner has the responsibility to treat and filter the water.

HOW LEAKS HAPPEN Environmental experts say even a pinprick-size hole in an underground tank can send 400 gallons of fuel a year into the ground, polluting soil and water. Spills can also destroy habitat and kill wildlife. Roughly 81 million people live within a quarter-mile of an underground storage tank that’s experienced at least one leak, based on the latest EPA data .

Most tanks were made of steel in the mid-1980s and likely to corrode over time. Modern tanks are fiberglass, which is more resistant to corrosion, but all tanks begin to leak sooner or later, said Dr. Kelly Pennell, a professor of environmental engineering and water resources at the University of Kentucky. The cylindrical tanks typically hold tens of thousands of gallons of fuel.

Detecting leaks is not easy, she said.

“If a gasoline station operated for 10 or 15 years, you may not be able to detect those small leaks,” said Dr. Pennell. “You wouldn’t be losing 1,000 gallons a day – you’re losing drips – but over time those matter.”

Leaks can form chemical plumes that move through groundwater and turn into vapor that rises up through cracks in the foundations of homes and businesses. Those fumes can contain cancer-causing chemicals including benzene, an ingredient in gasoline. And they carry a risk of fire and explosion. When contamination was found in Canob Park, the local fire chief sampled drinking water at one of the service stations and said it was “almost ignitable.”

Cleaning up groundwater pollution is costly, said Anne Rabe, environmental policy director at the New York Public Interest Research Group, a non-profit that works on environmental issues, including leaking underground storage tanks.

“You really have to do extensive testing to determine when these underground storage tanks are leaking and take immediate action or every week it spreads and spreads, and that increases the cost of remediation,” Rabe said.

More than 516,000 leaks have been cleaned up since Congress directed EPA to begin regulating underground tanks in 1984, but more than 57,000 known sites still await a full cleanup, the EPA said.

COSTS OF CLEANUP The average cost to clean up a site is $154,000, according to the Association of State and Territorial Solid Waste Management Officials, an organization that acts as a liaison between state and territorial leaking underground storage tank programs and the EPA. But that cost can be much higher or lower depending on how much work is needed.

The owners of tanks are supposed to carry insurance and pay for cleanup, but that doesn’t always happen. A trust fund that gets money from a gas tax helps — it currently holds about $1.5 billion — but the program costs states and the federal government about $1 billion a year beyond the fund.

While leaking underground storage tanks are located in nearly every town in the U.S., those who live closest to these sites tend to be in communities that are lower income with a higher proportion of minorities, according to the EPA.

The EPA requires owners and operators of underground storage tanks to install approved leak detection equipment and to regularly test these systems. But they aren’t foolproof. There are different types of systems, and any one type can miss a leak or its magnitude. Trade associations suggest building a system that uses more than one leak detection method, but that doesn’t always happen, and sometimes the one chosen may not be the best one for a particular tank. And owners may not maintain them properly.

Complying with the regulations, the EPA estimated in 2015, would cost tank owners and operators a total of $160 million a year — or about $715 per facility per year. But it would mean less taxpayer money needed for cleanups, the agency said.

Some of the properties cleaned up since the program began got funding from federal and state brownfields programs, which encourage the cleanup and reuse of contaminated or potentially contaminated sites.

The EPA last year announced a $315 million historic investment in the brownfields program, with most of the money coming from the bipartisan infrastructure deal President Joe Biden signed into law more than two years ago.

The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at .

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Authorities say a human skull found padlocked to an exercise dumbbell has been fished out of a New Orleans waterway, leaving police with a mystery on their hands

Missouri fifth grade student Daken Kramer, 11, holds an award at Blue Springs High School in Blue Springs, Kansas. Kramer was concerned about children who owed money for meals at his school. So the enterprising fifth-grader decided to do something about it. Daken posted a video challenging friends, family, even strangers and businesses to pay off the meal debt at the school. The 11-year-old was apparently pretty convincing: He raised more than double the original $3,500 goal — all told, $7,370 — enough money to also cut into the debt. (Vanessa Kramer via AP)

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