Soil quality assessment under emerging regulatory requirements

Best management practices for minimizing undesired effects of thermal remediation and soil washing on soil properties. A review

The use of remediated soils as end-of-life materials raises some challenges including policy and regulation, permits and specifications, technological limitations, knowledge and information, costs, as well as quality and performance associated with using them. Therefore, a set of procedures must be followed to preserve the quality and fundamental properties of soil during a remediation process. This study presented a comprehensive review regarding the fundamental impacts of thermal desorption (TD) and soil washing (SW) on soil characteristics. The effects of main operating parameters of TD and SW on the physical, chemical, and biological properties of soil were systematically reviewed. In TD, temperature has a more remarkable effect on physic-chemical and biological characteristics of soil than heating time. Therefore, decrease in temperature within a suitable range prevents unreversible changes on soil properties. In SW, more attention should be paid to extraction process of contaminants from soil particles. Using the right dosage and type of chelating agents, surfactants, solvents, and other additives can help to avoid problems with recovery or treatment using conventional methods. In addition, this review introduced a framework for implementing sustainable remediation approaches based on a holistic approach to best management practices (BMPs), which, besides reducing the risks associated with different pollutants, might provide new horizons for decreasing the unfavourable impacts of TD and SW on soil.

Assessment of the Driving Pollution Factors of Soil Environmental Quality Based on China's Risk Control Standard: Multiple Bigdata-Based Approaches with Intensive Sampling

Identifying the driving factors of soil environmental quality is critical in raising countermeasures for managing the soil environment efficiently and precisely. In 2018, China issued risk control standards to divide soil environmental quality into three classes to meet the demands of environment management. However, there is a lack of knowledge of this new standard. An intensive field-sampling research (2598 top-soil samples were analyzed) was conducted in the agricultural land of Hubei province, central China, to find the driving factors of pollutants based on this new standard. According to the standard, the proportion of classes 1, 2, and 3 in the overall quality grade was 57.3%, 41.7%, and 1%, respectively. The standardized index showed that the pollution levels of cadmium, arsenic, lead, and chromium were higher than that of mercury. The first component of the principal component analysis explained 56.4% of the total variance, and the loading of cadmium, arsenic and lead were -53.5%, -52.1%, and -51.2%, respectively. The general linear modeling found that cadmium and arsenic showed positive and significant effects (p < 0.001) on the grading results of soil environmental quality. Based on the random forest algorithm, cadmium showed the greatest importance on soil environmental quality (increase in mean squared error = 32.5%). Overall, this study revealed that cadmium, arsenic, and lead were driving pollutants affecting soil environment quality grade. The large data size increased the reliability and robustness of the study's conclusions, and it provided reference methods for future studies investigating China's new standard for assessing soil environmental quality.

Application of Soil Washing and Thermal Desorption for Sustainable Remediation and Reuse of Remediated Soil

Global governance of soil resources as well as revitalizations and remediation of degraded areas seem to be necessary actions for sustainable development. A great deal of effort has gone into developing remediation technologies to remove or reduce the impact of these contaminants in the environment. However, contaminated soil remediations in stringent conditions deteriorate soil properties and functions and create the need for efficient soil revitalization measures. Soil washing (SW) and thermal desorption (TD) are commonly used to remediate contaminated soil and can significantly reduce the contaminant, sometimes to safe levels where reuse can be considered; however, the effects of treatment on soil quality must be understood in order to support redevelopment after remediation. In this review, we discussed the effects of SW and TD on soil properties, including subsequent soil quality and health. Furthermore, the importance of these techniques for remediation and reclamation strategies was discussed. Some restoration strategies were also proposed for the recovery of soil quality. In addition, remediated and revitalized soil can be reused for various purposes, which can be accepted as an implementation of sustainable remediation. This review concludes with an outlook of future research efforts that will further shift SW and TD toward sustainable remediation.

Environmental Impact of the Presence, Distribution, and Use of Artificial Sweeteners as Emerging Sources of Pollution

Artificial sweeteners are posing a new threat to the environment. The water ecosystem is the primary recipient of these emerging contaminants. Once ingested, sufficient amount of these artificial sweeteners escape unchanged from the human body and are added to the environment. However, some are added in the form of their breakdown products through excretion. Artificial sweeteners are resistant to wastewater treatment processes and are therefore continuously introduced into the water environments. However, the environmental behavior, fate, and long-term ecotoxicological contributions of artificial sweeteners in our water resources still remain largely unknown. Some artificial sweeteners like saccharin are used as a food additive in animal feeds. It also forms the degradation product of the sulfonylurea herbicides. All artificial sweeteners enter into the wastewater treatment plants from the industries and households. From the effluents, they finally reside into the receiving environmental bodies including wastewaters, groundwaters, and surface waters. The global production of these sweeteners is several hundred tons annually and is continuously being added into the environment.

Tillage Impacts on Initial Soil Erosion in Wheat and Sainfoin Fields under Simulated Extreme Rainfall Treatments

The main aim of this research was to determine the potential effects of different tillage systems (TT: traditional tillage and RT: reduced tillage) on runoff and erosion at two different locations (Kahramanmaras and Tarsus, Southern Turkey) under (i) fallow, (ii) wheat (Triticumaestivum L.), and (iii) sainfoin (Onobrychissativa L.) crops. Rainfall simulations with intensity of 120 mm h−1 and 30-min duration, representing a typical extreme thunderstorm in this area, were used. We quantified the elapsed time to runoff generation (ET), total runoff volume (R), soil loss (SL), sediment concentration (SC), and runoff coefficient (RC). At both locations, the fallow plots indicated the first runoff response ranging between 1.2 and 3.1 min, while the range was between 9.4 and 8.9 min for the sainfoin plots. The highest runoff coefficient was recorded for the fallow parcel in Tarsus (57.7%), and the lowest runoff coefficient was recorded for the sainfoin parcel in Kahramanmaras (4%). For both study sites, the fallow plots showed higher soil erosion rates (871 and 29.21 g m−2) compared with the wheat plots (307 and 11.25 g m−2), while sainfoin recorded the lowest soil losses (93.68 and 3.45 g m−2), for Tarsus and Kahramanmaras, respectively. Runoff and sediment yield generated from sainfoin and wheat parcels under the RT system were less than under the TT system at the Kahramanmaras location. At the Tarsus location, the effect of soil tillage on soil and water losses was insignificant on the sainfoin planted plots. The reduced tillage system was successful in reducing sediment yield and runoff generated from parcels growing wheat and sainfoin compared to traditional tillage in Tarsus location, but runoff and soil loss were found to be very high compared to parcels constructed in the Kahramanmaras location.

Use of Zinc Carbonate Spiking to Obtain Phytotoxicity Thresholds Comparable to Those in Field-Collected Soils

Several studies have reported the presence of smithsonite (ZnCO₃ ) in soils polluted by zinc mining. The present study aimed to determine upper critical threshold values of Zn phytotoxicity in a substrate spiked with ZnCO₃ and to compare them with those obtained in field-collected soils. We studied Zn toxicity to perennial ryegrass (Lolium perenne L.) grown in pots with unpolluted peat treated with increasing concentrations of ZnCO₃ that produced nominal total Zn concentrations of 0, 0.7, 1.3, 2.0, 2.6, and 3.3%. To keep constant near-neutral pH value in all the treatments, we used decreasing concentrations of dolomitic lime. In the treatment with total soil Zn of 3.3% (pH 6.8), the foliar Zn concentration of L. perenne was 1914 ± 211 mg kg^-1 , falling into the range of 2400 ± 300 mg kg^-1 reported for Lolium species grown under similar laboratory conditions in a polluted soil (total soil Zn 5.4%, pH 7.3) collected near a Zn smelter. The value of 92 ± 98 mg kg^-1 was obtained for the median effective concentration (EC50) values of 0.01 M KNO₃ -extractable Zn using the responses of shoot dry biomass, shoot length, and total pigments. This value falls within the range of 95 ± 46 mg kg^-1 reported in other studies for the EC50 values of salt-extractable Zn using field-collected soils. The application of ZnCO₃ for spiking was able to mimic foliar Zn concentrations of Lolium species observed in field-collected soils. The effective concentrations of soil Zn obtained in the present study are comparable to those obtained in field-collected soils. Future research should determine effective concentrations of metals using soils spiked with metal-containing compounds that mimic a real source of contamination. Environ Toxicol Chem 2020;39:1790-1796. © 2020 SETAC.

Application of a soil quality assessment system using ecotoxicological indicators to evaluate contaminated and remediated soils

The deterioration of soil quality owing to human activities results in adverse effects on the soil ecosystem. This study developed a systematic method to quantitatively evaluate soil quality based on physical, chemical, biological, and ecotoxicological indicators and proposed the soil quality assessment and management system. This system consists of step-by-step processes, including indicator classification, indicator measurement, scoring and weighting, and soil quality index (SQI) calculation. The novel strategy included the usage of authentic ecotoxicological indicators for realistically interpreting soil quality assessment results. This study used five ecotoxicological indicators, including earthworm survival, enzyme activities, nematode reproduction, plant germination and growth, soil algal biomass, and soil algal photosynthetic capacity. Relatively higher SQI values than those corresponding to the actual soil quality status would be obtained without considering the ecotoxicological indicators. We conclude that the use of ecotoxicological indicator can help in soil quality assessment even under extreme soil quality conditions, such as highly contaminated or physically and chemically remediated soils.

Integrated use of straw mulch with nitrogen fertilizer improves soil functionality and soybean production

Mulching can effectively maintain and improve soil health and functionality. The mechanisms, however, have not been fully elucidated. Therefore, the effects of temperature on the biogeochemical properties of soil were investigated in the present study in relation to nitrogen management and soil functionality. The results of the 3-year field experiments showed that integrated straw mulch (S) and nitrogen fertilizer (N) treatments enhanced the activities of soil urease, invertase, alkaline phosphatase, and catalase by >1.8, 2.1, 2.0 and 1.4 fold, respectively, compared with the control treatment. Furthermore, these treatments increased soil available N by 28%, phosphorus by 45%, and potassium by 55%. In general, the soil organic carbon, dissolved carbon and labile organic carbon content in the treated plot were approximately 1.2-2.9 folds greater than in the control plot. These improvements in soil fertility and carbon indices increased the biomass and grain yield of soybean (67 and 75%, respectively) during the three-year study period. During 2015-2017, the straw mulch and nitrogen fertilizer treatment increased the soil moisture (23%) and decreased the soil temperature (8%) in comparison to the control in the 0-0.2 m soil depth and, therefore, improved soil enzyme activities, nutrient availability, and carbon stocks, and ultimately, soil functionality and sustainability, in the semiarid region.

Legal measures to prevent and manage soil contamination and to increase food safety for consumer health: The case of Spain

This article contains a brief overview of the European and Spanish environmental law framework for the prevention of soil contamination, for the management of contaminated soils and for consumers health protection in relation to agricultural crops. Some important aspects of the legislative framework for the prevention and management of soil contamination include recognising the possible risk to both human health and ecosystems that certain agricultural and industrial activities pose given the use of organic and inorganic chemical substances of a hazardous nature and pathogenic microorganisms. It is worth highlighting the milestone that many national constitutions include about the right to the environment. This right entails the obligation to protect it and to, therefore, protect soil from any degradation, including contamination. Legislation that protects soil from contamination and, consequently human health and ecosystems, is related mainly to agricultural activities (use of sewage sludge on farmlands, use of wastewater for irrigation, use of organic fertilisers and pesticides), and to industrial and commercial soil-contaminating activities. Consumer protection may be achieved through a legal system of environmental liability, specific measures to prevent contaminants entering soil, managing contaminated soils and a food traceability system. It is crucial to make the penalties for soil contamination offenses, and for violators of protective prohibitions, effective, proportionate and dissuasive. Global standards and guidelines on soil contamination could provide national legislative systems with substantive and procedural legal mechanisms to help prevent and manage soil contamination.

Thermal remediation alters soil properties - a review

Contaminated soils pose a risk to human and ecological health, and thermal remediation is an efficient and reliable way to reduce soil contaminant concentration in a range of situations. A primary benefit of thermal treatment is the speed at which remediation can occur, allowing the return of treated soils to a desired land use as quickly as possible. However, this treatment also alters many soil properties that affect the capacity of the soil to function. While extensive research addresses contaminant reduction, the range and magnitude of effects to soil properties have not been explored. Understanding the effects of thermal remediation on soil properties is vital to successful reclamation, as drastic effects may preclude certain post-treatment land uses. This review highlights thermal remediation studies that have quantified alterations to soil properties, and it supplements that information with laboratory heating studies to further elucidate the effects of thermal treatment of soil. Notably, both heating temperature and heating time affect i) soil organic matter; ii) soil texture and mineralogy; iii) soil pH; iv) plant available nutrients and heavy metals; v) soil biological communities; and iv) the ability of the soil to sustain vegetation. Broadly, increasing either temperature or time results in greater contaminant reduction efficiency, but it also causes more severe impacts to soil characteristics. Thus, project managers must balance the need for contaminant reduction with the deterioration of soil function for each specific remediation project.

Review of the ecotoxicological effects of emerging contaminants to soil biota

In recent years, emerging contaminants (e.g. pesticides and their metabolites, pharmaceuticals, personal and house care products, life-style compounds, food additives, industrial products and wastes, as well as nanomaterials) have become a problem to the environment. In fact, the cumulative use of a panoply of chemical substances in agriculture, industrial activities, in our homes and in health care services has led to their recent appearance in detectable levels in soils, surface, and groundwater resources, with unpredictable consequences for these ecosystems. Few data exist regarding the toxicity and potential for bioaccumulation in biota. When available, data were obtained only for some representatives of the main groups of chemical substances, and for a limited number of species, following non-standard protocols. This makes difficult the calculation of predicted no effect concentrations (PNEC) and the existence of sufficient data to set limits for their release into the environment. This is particularly concerning for the soil compartment, since only recently the scientific community, regulators, and the public have realised the importance of protecting this natural resource and its services to guarantee the sustainability of terrestrial ecosystems and human well-being. In this context, this review paper aims to identify the major groups of soil emerging contaminants, their sources, pathways and receptors, and in parallel to analyse existing ecotoxicological data for soil biota.

Advances on the determination of thresholds of Cu phytotoxicity in field-contaminated soils in central Chile

To better determine phytotoxicity thresholds for metals in the soil, studies should use actual field-contaminated soil samples rather than metal-spiked soil preparations. However, there are surprisingly few such data available for Cu phytotoxicity in field-contaminated soils. Moreover, these studies differ from each other with regards to soil characteristics and experimental setups. This study aimed at more accurately estimating Cu phytotoxicity thresholds using field-collected agricultural soils (Entisols) from areas exposed to contamination from Cu mining. For this purpose, the exposure to Cu was assessed by measuring total soil Cu, soluble Cu, free Cu²⁺ activity, and Cu in the plant aerial tissues. On the other hand, two bioassay durations (short-term and long-term), three plant species (Avena sativa L., Brassica rapa CrGC syn. Rbr, and Lolium perenne L.), and five biometric endpoints (shoot length and weight, root length and weight, and number of seed pods) were considered. Overall plant growth was best predicted by total Cu content of the soil. Despite some confounding factors, it was possible to determine EC₁₀, EC₂₅ and EC₅₀ of total Cu in the soil. Brassica rapa was more sensitive than Avena sativa for all endpoints, while Lolium perenne was of intermediate sensitivity. For the short-term bioassay (21 days for all three species), the averaged EC₁₀, EC₂₅ and EC₅₀ values of total soil Cu (in mg kg^-1) were 356, 621, and 904, respectively. For the long-term bioassay (62 days for oat and 42 days for turnip), the averaged EC₁₀, EC₂₅ and EC₅₀ values of total soil Cu (in mg kg^-1) were 355, 513, and 688, respectively. The obtained results indicate that chronic test is a suitable method for assessing Cu phytotoxicity in field-contaminated soils.

Detection, production, and application of microbial arylsulfatases

Arylsulfatases are enzymes which catalyze the hydrolysis of arylsulfate ester bonds to release a free sulfonate. They are widespread in nature and are found in microorganisms, most animal and human tissues, and plant seeds. However, this review focuses on arylsulfatases from microbial origin and gives an overview of different assays and substrates used to determine the arylsulfatase activity. Furthermore, the production of microbial arylsulfatases using wild-type organisms as well as the recombinant production using Escherichia coli and Kluyveromyces lactis as expression hosts is discussed. Finally, various potential applications of these enzymes are reviewed.

Contribution for the derivation of a soil screening value (SSV) for uranium, using a natural reference soil

In order to regulate the management of contaminated land, many countries have been deriving soil screening values (SSV). However, the ecotoxicological data available for uranium is still insufficient and incapable to generate SSVs for European soils. In this sense, and so as to make up for this shortcoming, a battery of ecotoxicological assays focusing on soil functions and organisms, and a wide range of endpoints was carried out, using a natural soil artificially spiked with uranium. In terrestrial ecotoxicology, it is widely recognized that soils have different properties that can influence the bioavailability and the toxicity of chemicals. In this context, SSVs derived for artificial soils or for other types of natural soils, may lead to unfeasible environmental risk assessment. Hence, the use of natural regional representative soils is of great importance in the derivation of SSVs. A Portuguese natural reference soil PTRS1, from a granitic region, was thereby applied as test substrate. This study allowed the determination of NOEC, LOEC, EC₂₀ and EC₅₀ values for uranium. Dehydrogenase and urease enzymes displayed the lowest values (34.9 and <134.5 mg U Kg, respectively). Eisenia andrei and Enchytraeus crypticus revealed to be more sensitive to uranium than Folsomia candida. EC₅₀ values of 631.00, 518.65 and 851.64 mg U Kg were recorded for the three species, respectively. Concerning plants, only Lactuca sativa was affected by U at concentrations up to 1000 mg U kg¹. The outcomes of the study may in part be constrained by physical and chemical characteristics of soils, hence contributing to the discrepancy between the toxicity data generated in this study and that available in the literature. Following the assessment factor method, a predicted no effect concentration (PNEC) value of 15.5 mg kg⁻¹_dw was obtained for U. This PNEC value is proposed as a SSV for soils similar to the PTRS1.

SF Box--a tool for evaluating the effects on soil functions in remediation projects

Although remediation is usually aimed at reducing the risks posed by contaminants to human health and the environment, it is also desirable that the remediated soil within future green spaces is capable of providing relevant ecological functions, e.g., basis for primary production. Yet while addressing a contamination problem by reducing contaminant concentration and/or amounts in the soil, the remedial action itself can lead to soil structure disturbances, decline in organic matter and nutrient deficiencies, and in turn affect a soil's capacity to carry out its ecological soil functions. This article presents the Soil Function Box (SF Box) tool that is aimed to facilitate integration of information from suggested soil quality indicators (SQIs) into a management process in remediation using a scoring method. The scored SQIs are integrated into a soil quality index corresponding to 1 of 5 classes. SF Box is applied to 2 cases from Sweden (Kvillebäcken and Hexion), explicitly taking into consideration uncertainties in the results by means of Monte Carlo simulations. At both sites the generated soil quality indices corresponded to a medium soil performance (soil class 3) with a high certainty. The main soil constraints at both Kvillebäcken and Hexion were associated with biological activity in the soil, as soil organisms were unable to supply plant-available N. At the Kvillebäcken site the top layer had a content of coarse fragment (ø > 2 mm) higher than 35%, indicating plant rooting limitations. At the Hexion site, the soil had limited amount of organic matter, thus poor aggregate stability and nutrient cycling potential. In contrast, the soil at Kvillebäcken was rich in organic matter. The soils at both sites were capable of storing a sufficient amount of water for soil organisms between precipitation events.

Soil and soil environmental quality monitoring in China: a review

Over the past few decades, numerous concerns have been raised in China over the issue of environmental sustainability. Various soil survey and monitoring programs have been carried out in China to study soil quality, and to provide a scientific basis for environment policy making. This paper provides an overview of past and current soil quality surveys and monitoring activities in China. This paper includes a summary of concerns over background concentrations of elements in soil, and soil environmental standards and guidelines in China. Levels of pollution in urban soil, agricultural soil, and soil in mining and smelting areas were compared using the concentrations and pollution indexes. In addition to soil surveys, soil monitoring is essential to study the data and to examine the effects of contaminants in soils. However, the current soil quality monitoring system was insufficient to accurately determine the soil quality status of soils across China. For accurate soil monitoring in China, it will be necessary to set up routine monitoring systems at various scales (national, provincial, and local scales), taking into consideration monitoring indicators and quality assurance. This is currently an important priority for the environmental protection administration of China.

Using soil function evaluation in multi-criteria decision analysis for sustainability appraisal of remediation alternatives

Soil contamination is one of the major threats constraining proper functioning of the soil and thus provision of ecosystem services. Remedial actions typically only address the chemical soil quality by reducing total contaminant concentrations to acceptable levels guided by land use. However, emerging regulatory requirements on soil protection demand a holistic view on soil assessment in remediation projects thus accounting for a variety of soil functions. Such a view would require not only that the contamination concentrations are assessed and attended to, but also that other aspects are taking into account, thus addressing also physical and biological as well as other chemical soil quality indicators (SQIs). This study outlines how soil function assessment can be a part of a holistic sustainability appraisal of remediation alternatives using multi-criteria decision analysis (MCDA). The paper presents a method for practitioners for evaluating the effects of remediation alternatives on selected ecological soil functions using a suggested minimum data set (MDS) containing physical, biological and chemical SQIs. The measured SQIs are transformed into sub-scores by the use of scoring curves, which allows interpretation and the integration of soil quality data into the MCDA framework. The method is demonstrated at a study site (Marieberg, Sweden) and the results give an example of how soil analyses using the suggested MDS can be used for soil function assessment and subsequent input to the MCDA framework.

Efficiency of soil organic and inorganic amendments on the remediation of a contaminated mine soil: II. Biological and ecotoxicological evaluation

The feasibility of two organic materials (pig slurry and compost) in combination with hydrated lime for the remediation of a highly acidic trace elements (TEs) contaminated mine soil was assessed in a mesocosm experiment. The effects of the amendments on soil biochemical and ecotoxicological properties were evaluated and related with the main physicochemical characteristics of soil and soil solution. The original soil showed impaired basic ecological functions due to the high availability of TEs, its acidic pH and high salinity. The three amendments slightly reduced the direct and indirect soil toxicity to plants, invertebrates and microorganisms as a consequence of the TEs' mobility decrease in topsoil, reducing therefore the soil associated risks. The organic amendments, especially compost, thanks to the supply of essential nutrients, were able to improve soil health, as they stimulated plant growth and significantly increased enzyme activities related with the key nutrients in soil. Therefore, the use of compost or pig slurry, in combination with hydrated lime, decreased soil ecotoxicity and seems to be a suitable management strategy for the remediation of highly acidic TEs contaminated soils.

Evaluation of the phytostabilisation efficiency in a trace elements contaminated soil using soil health indicators

The efficiency of a remediation strategy was evaluated in a mine soil highly contaminated with trace elements (TEs) by microbiological, ecotoxicological and physicochemical parameters of the soil and soil solution (extracted in situ), as a novel and integrative methodology for assessing recovery of soil health. A 2.5-year field phytostabilisation experiment was carried out using olive mill-waste compost, pig slurry and hydrated lime as amendments, and a native halophytic shrub (Atriplex halimus L.). Comparing with non-treated soil, the addition of the amendments increased soil pH and reduced TEs availability, favoured the development of a sustainable vegetation cover (especially the organic materials), stimulated soil microorganisms (increasing microbial biomass, activity and functional diversity, and reducing stress) and reduced direct and indirect soil toxicity (i.e., its potential associated risks). Therefore, under semi-arid conditions, the use of compost and pig slurry with A. halimus is an effective phytostabilisation strategy to improve soil health of nutrient-poor soils with high TEs concentrations, by improving the habitat function of the soil ecosystem, the reactivation of the biogeochemical cycles of essential nutrients, and the reduction of TEs dissemination and their environmental impact.

The effects of pipeline construction disturbance on soil properties and restoration cycle

Disturbance to the physical-chemical properties of soil caused by pipeline installation was evaluated using two soil quality indices to identify the scale of disturbance and the restoration cycle. The integrated soil quality index (SQI) was used to evaluate soil property changes in different pipeline zones (0, 10, 20, and 50 m from the pipeline) at sites 1 and 2. The soil restoration index (SRI) was used to estimate soil recovery from three pipelines with different recovery periods (2, 6, and 8 years) at site 3. The results showed that the adverse effects of pipeline construction on soil properties mainly occurred in the right-of-way (ROW) areas and the impaired zones were in the order trench > piling and working areas > 20 and 50 m. The soil restoration cycle may be complete within 6 years of construction. At site 3, the SRI in the ROW area of a pipeline after 6 years of restoration was close to 100 %, showing full soil recovery. However, the SRI in the disturbed areas of a pipeline after 2 years of restoration was much lower than that after 6 years of restoration, indicating that the soil was still recovering from the disturbance. The topography may change the intensity of disturbance in different areas due to the movement patterns of heavy machinery and traffic routes. There were local variations in the SQI within the pipeline zones, with flat areas suffering greater disturbance than hilly areas, indicating that topography should be considered in a pipeline's environmental impact assessment.

Incorporating the soil function concept into sustainability appraisal of remediation alternatives

Soil functions are critical for ecosystem survival and thus for an ecosystem's provision of services to humans. This is recognized in the proposed EU Soil Framework Directive from 2006, which lists seven important soil functions and services to be considered in a soil management practice. Emerging regulatory requirements demand a holistic view on soil evaluation in remediation projects. This paper presents a multi-scale, structured and transparent approach for incorporating the soil function concept into sustainability appraisal of remediation alternatives using a set of ecological, socio-cultural and economic criteria. The basis for the presented approach is a conceptualization of the linkages between soil functions and ecosystem services connected to with the sustainability paradigm. The approach suggests using (1) soil quality indicators (i.e. physical, chemical and biological soil properties) for exploring the performance of soil functions at the site level, and (2) soil service indicators (i.e. value-related measurements) for evaluating the performance of services resulting from soil functions across all levels of the spatial scale. The suggested approach is demonstrated by application in a Multi-Criteria Decision Analysis (MCDA) framework for sustainability appraisals of remediation alternatives. Further, the possibilities of using soil quality indicators for soil function evaluation are explored by reviewing existing literature on potential negative and positive effects of remediation technologies on the functionality of the treated soil. The suggested approach for including the soil function concept in remediation projects is believed to provide a basis for better informed decisions that will facilitate efficient management of contaminated land and to meet emerging regulatory requirements on soil protection.

Long-term biomonitoring of soil contamination using poplar trees: accumulation of trace elements in leaves and fruits

Phytostabilization aims to immobilize soil contaminants using higher plants. The accumulation of trace elements in Populus alba leaves was monitored for 12 years after a mine spill. Concentrations of As and Pb significantly decreased, while concentrations of Cd and Zn did not significantly over time. Soil concentrations extracted by CaCl2 were measured by ICP-OES and results of As and Pb were below the detection limit. Long-term biomonitoring of soil contamination using poplar leaves was proven to be better suited for the study of trace elements. Plants suitable for phytostabilization must also be able to survive and reproduce in contaminated soils. Concentrations of trace elements were also measured in P. alba fruiting catkins to determine the effect on its reproduction potential. Cadmium and Zn were found to accumulate in fruiting catkins, with the transfer coefficient for Cd significantly greater than Zn. It is possible for trace elements to translocate to seed, which presents a concern for seed germination, establishment and colonization. We conclude that white poplar is a suitable tree for long-term monitoring of soil contaminated with Cd and Zn, and for phytostabilization in riparian habitats, although some caution should be taken with the possible effects on the food web. Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.

Effect of different soil layers on porewater to remediate acidic surface environment at a close mine site

This paper describes the chemistry of porewater when constructing different soil layers on acidic weathered rock of a closed mine to remediate the surface environment. Three cases were set on a flat surface of the site, all under different layer systems. Case 1 was only composed of weathered rocks. A top neutralization layer was constructed on the weathered rocks in case 2, whereas both an upper low-permeable and middle neutralization layers were constructed on the weathered rocks in case 3. The low-permeable layer of 30 cm thick consists of clay, and the neutralization layer of 30 cm thick consists of the mixture of the weathered rock and calcium carbonate as a neutralizer. Porewater sampling systems and soil sensors to measure temperature, water content, and electrical conductivity were set at different depths. In case 1, steadily high concentrations of heavy metals were observed regardless of the depth, and the pH ranged from 2 to 4. In cases 2 and 3, a dramatic decrease in concentrations of heavy metals was observed, even below the neutralization layer. For both cases, pH values were circumneutral. There were no significant seasonable changes in heavy metals concentrations and pH of porewater by considering the temperature and precipitation. In addition, the water content of the layers in case 3 fluctuated more mildly than that in cases 1 and 2, indicating that the low-permeable layer reduced the rate of infiltration. Therefore, a significant reduction in the load of heavy metals released from the site can be achieved by both implementing neutralization and low-permeable layers.

Gradient analysis reveals a copper paradox on floodplain soils under long-term pollution by mining waste

Arable alluvial soils are a globally important resource under increasing pressure from both industrial pollution and intensified agricultural land use. Quality of agricultural soils is ultimately defined by crop yields; it is however seldom feasible to study the consequences of complex soil pollution on crops under field conditions. This work analyses the long term effects of two gradients: spatial (relative distance from the water channel) and land use intensity (cropping frequency) on soil properties and model crop (barley) response. On an exceptional model locality in Eastern Serbia, degraded by fluvial deposition of sulphidic copper tailings during 50 years, multivariate analysis shows that land use accelerates the substitution of high plant available Cu by nutrient deficiency (primarily P and microelements) and excessive exchangeable Al. Though agronomic soil quality might not differ along the land use gradient, the environmental consequences do drastically change. The observed apparent "paradoxes" (e.g. soil Cu decreases towards the pollution source; higher yields might coincide with higher soil and leaf Cu concentrations; and leaching of Cu does not restore soils agronomic quality) can be explained by a) the Cu retention patterns along the transects, b) importance of higher SOM and nutrient availability for modifications of Cu toxicity, and c) the existence of plant adaptation mechanisms which can considerably counteract the adverse soil conditions. Land use-induced nutrient deficiency can counteract the positive effects of decreased Cu levels. In a long run, accelerated Cu mobilisation is likely to increase vulnerability of these soils to further environmental hazards. This study demonstrates the clear and consistent patterns in soil properties and plant response along the gradients and points out the probable long-term environmental trends in a "would be" scenario for agricultural use of similar polluted soils.

Public participation in soil surveys: lessons from a pilot study in England

In many countries there are policies in place that impact on soils, but very few legislative or policy tools specifically for the protection of soil. Recent EU legislative proposals on soil protection have been met with opposition on the grounds of excessive cost and resource demands. With the need for evidence based policy, and recognition that involving the public in environmental monitoring is an effective way of increasing understanding and commitment, there has been growing interest in soil surveys. In addition, it is accepted that the success of environmental policies depends greatly on how effectively scientists, regulators, stakeholders, and society communicate. This paper presents the Open Air Laboratories (OPAL) Soil and Earthworm Survey as an example of public participation in soil surveys that aims to integrate the above. It is demonstrated how such surveys generate data that can be used to prioritise soil assessment, in order to address some of the concerns and objections to soil protection policies. Lessons from this pilot study in England highlight that with strategic planning of civic participation activities, this approach can deliver improvements in the quality of the evidence collected and allow for effective public involvement in policymaking and implementation, on top of direct educational benefits.

Gene expression analysis of 4 biomarker candidates in Eisenia fetida exposed to an environmental metallic trace elements gradient: a microcosm study

Past activities of 2 smelters (Metaleurop Nord and Nyrstar) led to the accumulation of high amounts of Metal Trace Elements (TEs) in top soils of the Noyelles-Godault/Auby area, Northern France. Earthworms were exposed to polluted soils collected in this area to study and better understand the physiological changes, the mechanisms of acclimation, and detoxification resulting from TE exposure. Previously we have cloned and transcriptionally characterized potential biomarkers from immune cells of the ecotoxicologically important earthworm species Eisenia fetida exposed in vivo to TE-spiked standard soils. In the present study, analysis of expression kinetics of four candidate indicator genes (Cadmium-metallothionein, coactosin like protein, phytochelatin synthase and lysenin) was performed in E. fetida after microcosm exposures to natural soils exhibiting an environmental cadmium (Cd) gradient in a kinetic manner. TE body burdens were also measured. This microcosm study provided insights into: (1) the ability of the 4 tested genes to serve as expression biomarkers, (2) detoxification processes through the expression analysis of selected genes, and (3) influence of land uses on the response of potential biomarkers (gene expression or TE uptake).

Open Air Laboratories (OPAL): a community-driven research programme

OPAL is an English national programme that takes scientists into the community to investigate environmental issues. Biological monitoring plays a pivotal role covering topics of: i) soil and earthworms; ii) air, lichens and tar spot on sycamore; iii) water and aquatic invertebrates; iv) biodiversity and hedgerows; v) climate, clouds and thermal comfort. Each survey has been developed by an inter-disciplinary team and tested by voluntary, statutory and community sectors. Data are submitted via the web and instantly mapped. Preliminary results are presented, together with a discussion on data quality and uncertainty. Communities also investigate local pollution issues, ranging from nitrogen deposition on heathlands to traffic emissions on roadside vegetation. Over 200,000 people have participated so far, including over 1000 schools and 1000 voluntary groups. Benefits include a substantial, growing database on biodiversity and habitat condition, much from previously unsampled sites particularly in urban areas, and a more engaged public.

From chemical risk assessment to environmental quality management: the challenge for soil protection

The 40 years that have passed since the beginning of the 'environmental revolution' has seen a large increase in development of policies for the protection of environmental media and a recognition by the public of the importance of environmental quality. There has been a shift from policy in reaction to high profile events, then to control of releases to single environmental media, and to the present position of moving toward integrated management of all environmental media at present. This development has moved away from classical chemical risk assessment toward environmental holism, including recognition of the ecological value of these media. This work details how policy developments have taken place for air and water, with examples from the USA and EU, in order to compare this with policy development regarding soil. Soil, with quite different policy frameworks and distinct uses, understanding, and threats compared to other environmental media, is currently attracting attention regarding the need for its protection independent of use. Challenges for soil policy are identified and evaluated, and recommendations on how these challenges can be overcome are discussed with relevance to water and air protection policy.