Atmospheric deposition of hazardous elements and its accumulation in both soil and grain of winter wheat in a lead-zinc smelter contaminated area, Central China

Hazardous elements (HEs) and its deposition from atmosphere have become a major healthy and environmental concern worldwide, however, the risks to food safety of deposited HE are still largely unknown, especially for wheat grains (Triticum aestivum L.). This research was to characterize atmospheric deposition of high HEs [such as lead (Pb), cadmium (Cd) and arsenic (As)] at deposited site (TS) and assess its impacts on the soil and winter wheat accumulation in a lead‑zinc smelter contaminated area of Central China. Results indicated that deposited As, Cd and Pb at TS site were 31.15, 15.94 and 281.86 mg m^-2 during the winter wheat growing season, contributing 86.9%, 81.7% and 80.4% to the annual total, respectively. Most of deposited HEs were retained in top 35-cm soil, resulting in soil Cd concentration above the national soil regulatory limit (0.6 mg kg^-1; GB 15618-2018). The newly deposited HEs could contribute 57.7-88.2% and 16.2-29.1% to total HEs of wheat grains in clean soil based on a soil transplanted experiment and in contaminated soil based on a two-year in-situ experiment, respectively. Moreover, the newly deposited HEs significantly increased HE concentration of wheat grain by 22.9-57.5% in the contaminated soil when an immobilizing amendment were applied (p < 0.05), and grain Cd concentration exceeded the national grain limit (0.1 mg kg^-1; GB 2762-2017). Thus, deposited HE could be accumulated in soil and wheat grain and decrease the remediation effectiveness of passivation amendments in contaminated soils, which would raise a public awareness of HE deposition and provide a scientific data in support of environmental pollution control and remediation.

Cost-effective in-situ remediation technologies for complete mineralization of dyes contaminated soils

Dyes & dyes intermediates are one of the important and critically polluted industrial sectors, generating a large environmental liability. Therefore characterization of microbial community structure and diversity of contaminated soils helps to optimize the bioremediation strategies and performance. This study investigated the roles of environmental variables and contamination levels in shaping microbial community structure at an abandoned aged. In total, 20 bacterial and 4 fungal phyla were identified across soils with different physiochemical properties and concentration of the contaminants. Taxonomic analysis revealed the Proteobacteria, Firmicutes, Ascomycota and Basidiomycota represented the lineages and accounted for 49.5%-51.2%, 5.1%-15.3%, 2.5%-3.8% and 1.6%-2.1% of the total population, respectively. Microbial community (site 1) achieved decolorization rate of 972 ± 1.21 mg dyes kgsoil^-1d^-1 after 15d and 692 ± 1.4 mg kg-soil^-1d^-1 COD removal rate after 30 day of the experiment. Microbial community mineralized intermediates, 4-amino benzenesulfonate, 6-amino naphthalene sulfonate and benzene/naphthalene sulfonate in TCA cycle and stimulate the growth of selected soil bacteria, primary nutrient as well as plant growth of contaminated soil.

Evaluating vanadium bioavailability to cabbage in rural soils using geochemical and micro-spectroscopic techniques

Assessing the vanadium (V) fractionation and speciation to predict its bioavailability using a combined approach of geochemical extractions and micro-spectroscopic techniques is still not well studied. Therefore, we aimed to determine the bioavailability of V in rural soils using single extractants, sequential extraction procedure, and the X-ray absorption near edge structure (XANES) spectroscopy. We collected and characterized ninety four samples originated from horizons of seventeen soil profiles in Taiwan. We determined the total content of V and its geochemical fractions using the BCR sequential extraction procedure to predict its potential mobility. We also assessed the bioavailability of V in the soils using four availability indices i.e., CaCl₂, HCl, ethylenediaminetetraacetic acid (EDTA), and NaHCO₃ and related them to its uptake by Chinese cabbage (Brassica chinensis L.). Additionally, we determined the V speciation by vanadium K-edge XANES spectra. Moreover, we studied the elemental compositions of the soils using Electron Probe Micro Analysis (EPMA). Vanadium was mainly distributed in the residual fraction (81-98% of total V). Among the potential mobile fractions, V was mainly associated with Fe oxides, as identified by the BCR sequential extraction and EMPA. The XANES analysis indicated that V mainly existed in the soils as V(IV) and V(V). The EDTA and NaHCO₃ extracted more V than CaCl₂ and HCl, and both, particularly NaHCO₃ were positively and significantly correlated with the total soil content and plant shoot concentrations of V; therefore NaHCO₃ might be recommended as a bioavailability index for soil V. We hypothesize that the NaHCO₃ may extract vanadate from soil surfaces and also vanadate transformed from vanadyl at alkaline pH during the extraction. The NaHCO₃-extracted V can be predicted by a function of soil total V, CEC, and pH. Our results should be verified using different soils and plants in the future.

Influence of soil characteristics and leaching rate on copper migration: column test

Soil copper (Cu) supply is used to correct Cu deficiency in many crops grown in southern Mediterranean areas. Oversupply of this fertilizer may contaminate soil and groundwater. This study aims to assess Cu migration in different soils of Moroccan agricultural areas. Three soil samples were collected from different areas. For each soil, three annual leaching rates were tested: 35 mm, 237 mm, and 565 mm for a sandy soil; 35 mm, 70 mm, and 140 mm for a clay calcareous soil; and 35 mm, 103 mm, and 247 mm for silty clay soil. The leaching experiments were conducted in columns filled identically up to 30 cm with each soil sample. Then, 0.6 mg of Cu kg⁻¹ was added to the soil surface in the sulfate form (CuSO₄.5H₂O). The results showed that soil Cu loss increased mainly with leaching rate: y = 0.004 x – 0.10 (R² = 0.97) where y: soil Cu loss (10⁻⁴ meq 100 g⁻¹) and x: leaching rate (mm). The regression analysis did not reveal a significant influence of the soil properties on Cu leaching. However, the Cu loss seems insignificant regarding the no recurrence of high annual leaching rate (over 500 mm), in south Mediterranean areas. Also, soil Cu accumulation risk occurred in all studied soils. For sandy soil, available Cu content was 78% higher in the top layer (0–10 cm) than its content in the middle (10–20 cm) and lower (20–30 cm) layers. Furthermore, a release of bioavailable Cu was recorded in silty clay and clay calcareous soils at a leaching rate of over 70 mm.

Chickens bred extensively as sentinels from soil contamination by Toxocara

Environmental contamination by Toxocara spp eggs can be verified by parasitological techniques, which are mostly laborious, have low sensitivity, and may require repeated tests to establish the contamination status of a certain area. Given the significance of this parasite as an agent of infections in humans, that may cause blindness, especially in children, broilers chickens created extensively were evaluated as possible markers of parasite environmental contamination, through the detection of anti-Toxocara serum antibodies. Eighteen 15-day-old Label Rouge broilers were released on a farm with a history of dogs with Toxocara infection. At 0, 15 and 30 days after the release birds blood samples were taken, as well as soil samples. At the end of the experiment the birds were slaughtered, and the gastrointestinal tract was collected for coprological exams. The presence of anti-Toxocara antibodies resulted in increased reactivity indexes with time, and at 15 days five of the birds were positive and at 30 days, seven birds showed seroconversion. Examination of the soil samples by the centrifugation-flotation method in hyper saturated zinc sulfate solution revealed contamination by embryonated or infertile eggs of Toxocara at all times of collection, as well as the presence of Ascaridia eggs at 15 days after release of birds. Examination of bird's stool samples at the end of the experiment demonstrated 100% infection by Ascaridia galli, however there was no correlation between the counts of this parasite and the ELISA reactivity indices for anti-Toxocara antibodies. The results obtained allow us to infer the possibility of using anti-Toxocara spp-specific antibodies determination in birds raised extensively, which could then serve as sentinels of environmental contamination by this parasite.

Seasonal fluctuations of Zn, Pb, As and Cd contents in the biomass of selected grass species growing on contaminated soils: Implications for in situ phytostabilization

Phytostabilization aims to immobilize contaminants at the rhizosphere level using the root system of adapted plants. In order to exploit wild grasses with potential for phytostabilization, a screening throughout the year was conducted at a site contaminated by Pb and Zn. Three plant species were chosen: Agrostis capillaris, Arrhenatherum elatius and Calamagrostis epigeios. Rhizospheric soil and biomass was used for chemical characterization. Above- and below-ground was analyzed. For each sample, arbuscular mycorrhiza fungi colonization was determined. The highest concentrations of Pb were found in the A. capillaris rhizosphere (3417 mg kg^-1), and in A. elatius for Zn (3876 mg kg^-1). CaCl₂-extractable Zn in the rhizosphere of C. epigeios was the lowest and Pb was lower for A. elatius. CaCl₂-extractable Cd was neither species-dependent nor time-dependent. Arsenic was not species-dependent. The fractionation of target elements did not show differences between separate sampling campaigns and Pb was the only element that showed differences during the year. A. capillaris showed the best capacity to take up elements. The colonization by AMF did not show significant differences for different sampling times, or interactions between time and species, however differences were found for different species, i.e., C. epigeios showed significantly lower colonization by arbuscular mycorrhiza fungi. Our results indicate that A. capillaris appears to be a good indigenous candidate for phytostabilization.

Petroleum hydrocarbons degradation in contaminated soil using the plants of the Aster family

Oil extraction is one of the causes of soil contamination with the total petroleum hydrocarbons. The objective of this study was to clarify the effect of Asteraceae plants on the degradation of petroleum hydrocarbon in contaminated soil. Initial soils with 40 and 90 g kg^-1 of total petroleum hydrocarbon (TPH) were prepared. There were three treatments: (1) no addition, (2) addition of FeCl₃ and nitrilotriacetic acid (NTA) solution, and (3) addition of FeCl₃ + NTA and the cultivation of nine Asteraceae plants. The concentration of TPH was measured using infrared spectrophotometer, 2 and 3 months after transplanting (MAT). Shoot and root dry weights were measured 3 MAT. The concentration of TPH in soil cultivated with Cosmos caudatus was lower than that of the initial soil (40 g kg^-1 TPH), 2 MAT. The concentrations of TPH in soils cultivated with Calendula officinalis, Callistephus chinensis, C. caudatus, and Tagetes sp. were also lower than that in the initial soil, 3 MAT. The concentrations of TPH in soils cultivated with Achillea filipendulina, Anthemis tinctoria, Tagetes erecta, Chrysanthemum coronarium, C. officinalis, C. chinensis, and C. caudatus were lower than that in the initial soil (90 g kg^-1 TPH), 2 MAT. The concentrations of TPH in soils cultivated with T. erecta, A. tinctoria, Zinnia elegans, C. chinensis, C. caudatus, and Tagetes sp. were lower than that in the initial soil, 3 MAT. A. filipendulina and C. coronarium died at both 40 and 90 kg^-1 TPH soils. These results suggest that the roots of Asteraceae plants degrade petroleum hydrocarbon in contaminated soil and C. chinensis and Z. elegans are more suitable for using TPH remediation. Plant survival and extensive root system are important factors for the remediation of TPH in contaminated soil.

Sensitivity to Copper and Development of Culturing and Toxicity Test Procedures for the Antarctic Terrestrial Nematode Plectus murrayi

Environmental quality guideline values and remediation targets, specific to Antarctic ecosystems, are required for the risk assessment and remediation of contaminated sites in Antarctica. Ecotoxicological testing with Antarctic soil organisms is fundamental in determining reliable contaminant effect threshold concentrations. The present study describes the development of optimal culturing techniques and aqueous toxicity test procedures for an endemic Antarctic soil nematode, Plectus murrayi, which lives within interstitial waters between soil particles. Toxicity tests were of extended duration to account for the species' physiology and life-history characteristics. Plectus murrayi was sensitive to aqueous copper with a 50% effective concentration for egg-hatching success of 139 µg/L. Hatched juveniles that were first exposed to copper as eggs appeared to be less sensitive than those first exposed at the hatched J2 stage, indicating a potential protective effect of the egg. Sensitivity of juveniles to copper increased with exposure duration, with 50% lethal concentrations of 478 and 117 µg/L at 21 and 28 d, respectively. The present study describes new methods for the application of an environmentally relevant test species to the risk assessment of contaminants in Antarctic soil and provides the first estimates of sensitivity to a toxicant for an Antarctic terrestrial microinvertebrate. Environ Toxicol Chem 2020;39:482-491. © 2019 SETAC.

Prevalence, risk factors and genotype distribution of Toxoplasma gondii DNA in soil in China

In the present study, we performed a cross-sectional survey to determine the occurrence and genotype distribution of T. gondii DNA in soil samples collected from different sources from six geographic regions in China. Between March 2015 and June 2017, 2100 soil samples were collected from schools, parks, farms and coastal beaches, and examined for T. gondii DNA using three PCR assays targeting 529-bp repeat element (RE) sequence, B1 gene and ITS-1 gene sequences. Also, we investigated whether geographic region, soil source and type, and sampling season can influence the prevalence of T. gondii DNA in the soil. Soil samples collected from farms and parks had the highest prevalence, whereas samples collected from school playgrounds and coastal beaches had the lowest prevalence. PCR assays targeting 529-bp RE and ITS-1 gene sequences were more sensitive than the B1 gene-based assay. Positive PCR products were genotyped using multi-locus PCR-RFLP, and ToxoDB #9 was the predominant genotype found in the contaminated soil samples. Multiple logistic regression identified factors correlated significantly with the presence of T. gondii DNA in the soil to be the source of the soil, including farms (odds ratio 3.10; 95% confidence interval [CI], 1.52 to 6.29; p = 0.002) and parks (2.59; 95% CI 1.28 to 5.27; p = 0.009). These results show that Chinese soil hosts T. gondii of the most prevalent genotype in China (ToxoDB#9) and that the soil type influences infection patterns.

Potential of asphalt concrete as a source of trace metals

Asphalt concrete is one of the most important building materials in the modern world, but the leaching potential of metals from this composite material to the environment is poorly understood. In this study, metals leaching from four hot-mix asphalt samples were analyzed: two fresh samples of low-traffic and high-traffic composition and their weathered equivalents collected from roads in the city of Edmonton, Alberta, Canada. A sequential extraction, based on the Community Bureau of Reference method, was applied to study the speciation and potential mobility of metals and metalloids in those samples. Major trace metals identified in all four samples were Mn, P, Ba, Sr, Zn, V, and Ni, with the highest metals concentrations generally found in weathered asphalt concrete. Of the major trace metals, P, Mn, Sr, and Zn were relatively mobile, having large portions of their total concentrations in the exchangeable/acid-soluble and reducible fractions. When considering the most mobile fraction (exchangeable/acid soluble) and using Canada as a model country, up to 180 t P, 440 t Mn, 50 t Ba, 36 t Sr, 11 t Zn, and 0.11-3.2 t of other metals and metalloids (including Cr, Ni, Cu, As, and Pb) could potentially leach from the top layer of Canada's total of paved public roads. To place these amounts into perspective, they were estimated to make up to 22‰ of Canada's annual release numbers into soil, water and air for these same metals and metalloids. However, they are concentrated in a small area around roads and highways, creating the potential for localized soil and groundwater contamination.

Impact of bonfires on soil properties in an urban park in Vilnius (Lithuania)

Lighting bonfires in urban parks is a widespread practice. However, few studies have examined their impact on soil properties. The aim of this study was to analyze the impact of bonfires on the soil properties of an urban park in Vilnius, Lithuania. The properties studied were soil water repellency (SWR), aggregate stability (AS), soil organic matter (SOM) content, total nitrogen (TN), inorganic carbon (IC), pH, electrical conductivity (EC), extractable calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), aluminum (Al), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), boron (B), chromium (Cr), available phosphorus (P), silicon (Si) and sulfur (S). Soil ratios calculated were carbon/nitrogen ratio (C/N), Ca + Mg/(Na + K)^1/2 (SPAR), Ca:Al and Ca:Mg. Three areas were studied: Site 1) Pinus sylvestris L. and Quercus robur L.; Site 2) Aesculus glabra Wild.; and Site 3) Pinus sylvestris L. and Acer plantanoides L. At each site, 20 samples were collected (10 within the bonfire area, 10 from a control area). The results showed significantly higher values of SOM, IC, pH, EC, Ca, Mg, Na, K, P, Al, Zn, Cu, Cr, S, C/N ratio, Ca:Al ratio and Ca:Mg ratio in bonfire soils than in control unburned soils. In bonfire soils, significantly lower values were recorded of SWR, AS, TN, SOM, Al, Mn, Fe, Cr, S and SPAR comparing to control soils. Most affected area by the bonfire was Site 1, which presented a marked increase in heavy metal content comparing to the control. The impact of soil heating was evident in AS, IC, pH, extractable Ca, Mg, Na, K, P, Al, Zn, Cu, Cr, S, and in its ratios. Protective measures are needed to limit bonfires and prohibit the burning of hazardous materials.

Quantitative assessment of exposure of heavy metals in groundwater and soil on human health in Reasi district, Jammu and Kashmir

The assessment of heavy metal contents in environmental sectors is important to estimate the carcinogenic and non-carcinogenic doses and risks for the mankind associated with it. The present work deals with the assessment of the risk exposure related to heavy metal contents in groundwater and soil samples to two different age groups via three different transits, i.e., ingestion, inhalation and dermal. The concentrations of heavy metals (Zn, Cd, Cu, Pb and Cr) were measured in the villages of lower Himalayas of Reasi district by using microwave plasma atomic emission spectrometer. The calculated mean contamination factors of heavy metals in soil samples were as: Zn, 0.73; Cu, 0.70; Pb, 0.74; and Cr, 0.33; which led to pollution load index less than unity. The overall carcinogenic risks have been varied from 6.4E-08 to 5.1E-07 in soil samples and from 7.3E-06 to 1.1E-04 in ground water samples and were found to be well within the range prescribed by USEPA (Screening level ecological risk assessment protocol for hazardous waste combustion facilities, appendix E: toxicity reference values, US Environmental Protection Agency, Washington, D.C., 1999). The mean values of heavy metal contents except lead and chromium in water samples were found to be less than the values prescribed by various agencies. Geo-accumulation Index showed that Pb contribute to the highest contamination (0 < I_geo < 1) among the other heavy metals. Cluster analysis and principal component analysis identified that Zn, Cu, Pb and Cr had a relationship and the presence of these heavy metals could be related to vehicle emissions, traffic sources and industrial sources. The overall mean values of the non-carcinogenic doses and associated hazard risks in soil and water samples calculated for children were found to be higher than the adults which may be due to hand to mouth activities.

Comparable effects of manure and its biochar on reducing soil Cr bioavailability and narrowing the rhizosphere extent of enzyme activities

Chromium (Cr) contamination is especially hazardous to soil biota. Application of manure and biochar has been frequently proposed to remediate Cr-contaminated soil. However, the understanding of mechanisms behind manure and biochar impacts on soil enzyme activities requires advanced visualization technologies. For the first time, we compared manure and its biochar influence on the spatial distribution of β-glucosidase, N-acetyl-glucosaminidase and phosphomonoesterase activities in Cr-contaminated soil using direct zymography. Maize was planted for 45 days in (a) soil mixed with manure, (b) soil mixed with manure-derived biochar and (c) soil without any addition. Soil pH decreased over 45 days, inducing an increase in acid soluble Cr. The concomitant decrease in β-glucosidase and N-acetyl-glucosaminidase activities explained the narrowing rhizosphere extent of enzyme activities by 13-44%, indicating that increased Cr bioavailability decreases microbial activities. A larger maize performance index and the greatest plant shoot/root ratio after biochar application suggested enhanced maize growth (p < 0.05). In contrast, manure induced the narrowest extent of β-glucosidase and phosphomonoesterase activities due to the addition of labile organic compounds and nutrients following its application. Our study emphasizes the importance of pH on Cr bioavailability and enzyme activities and demonstrates that biochar application is more ideally suited for remediating Cr-contaminated soil.

Geochemical fractionation of thallium in contaminated soils near a large-scale Hg-Tl mineralised area

Enriched levels of thallium (Tl) in the environment are not only derived from anthropogenic sources but also have potential natural origins owing to Tl-rich sulphide mineralization. However, little is known regarding the geochemical fractionations of Tl in contaminated soils from geogenic sources. This study aims to reveal the Tl geochemical fractionations in different types of soils from a large-scale independent Tl mine in southwestern China, via a modified Institute for Reference Materials and Measurement (IRMM) sequential extraction (four-step) scheme. The results revealed that a large percentage of Tl was related to the labile portions (including reducible, weak-acid-exchangeable, and oxidizable fraction) of the soils (68.8-367 mg kg^-1). Further analyses by Scanning Transmission Electron Microscopy-Energy Dispersive X-ray Spectrometer (STEM-EDS) found that Tl mainly existed in the Fe-containing minerals (such as jarosite and hematite) with fine particles (∼1 μm). These results highlight that, apart from the anthropogenically induced Tl pollution, the naturally occurring Tl contamination in soils may also pose significant risks to human health and ecological safety. Owing to the relatively high mobility and bioavailability of Tl in the labile fractions, it is important to understand geochemical fractionations of this element for alleviating Tl pollution and effective management of naturally occurring Tl contaminated soils.

Ecological risk assessment of mercury and chromium in greenhouse soils

Very little information is available about Hg and Cr evolution in greenhouse soils. This paper presents the results of determining Hg and Cr in greenhouse soils in a semi-arid region in the southern Iberian Peninsula (Almería, Spain), and assessing the enrichment level and the Potential Ecological Risk Index (PERI) according to crop age. Hakanson's approach was used to evaluate the PERI. To investigate the behaviour of Hg and Cr in greenhouse soils over time, samples were grouped into values in soils for blocks according to crop age: 0 years, 5-10 years, 10-20 years, more than 20 years. The results showed that 74% of GS exceeded the obtained background level (37.1 μg kg^-1) for Hg, with 43% (48.9 mg kg^-1) for Cr. Temporal patterns indicated that these elements are accumulating in greenhouse soils and this trend was very significant for Hg. After more than 20 intensive crop-farming years, concentrations and the PERI had clearly increased. Although the ecological risk was moderate, our observations suggest that the farming practices performed in the last 35 years have allowed these metals to accumulate. In fact, the 15% of the studied soils presented a considerable potential risk and were the soils that had been used longer.

Assessment of sunflower germplasm for phytoremediation of lead-polluted soil and production of seed oil and seed meal for human and animal consumption

Phytoremediation is a valuable technology for mitigating soil contamination in agricultural lands, but phytoremediation without economic revenue is unfeasible for land owners and farmers. The use of crops with high biomass and bioenergy for phytoremediation is a unique strategy to derive supplementary benefits along with remediation activities. Sunflower (Helianthus annuus L.) is a high-biomass crop that can be used for the phytoremediation of polluted lands with additional advantages (biomass and oil). In this study, 40 germplasms of sunflower were screened in field conditions for phytoremediation with the possibility for oil and meal production. The study was carried out to the physiological maturity stage. All studied germplasms mopped up substantial concentrations of Pb, with maximum amounts in shoot > root > seed respectively. The phytoextraction efficiency of the germplasm was assessed in terms of the Transfer factor (TF), Metal removal efficiency (MRE) and Metal extraction ratio (MER). Among all assessed criteria, GP.8585 was found to be most appropriate for restoring moderately Pb-contaminated soil accompanied with providing high biomass and high yield production. The Pb content in the oil of GP.8585 was below the Food safety standard of China, with 59.5% oleic acid and 32.1% linoleic acid. Moreover, amino acid analysis in meal illustrated significant differences among essential and non-essential amino acids. Glutamic acid was found in the highest percentage (22.4%), whereas cysteine in the lowest percentage (1.3%). Therefore, its efficient phytoextraction ability and good quality edible oil and meal production makes GP.8585 the most convenient sunflower germplasm for phytoremediation of moderately Pb-contaminated soil, with fringe benefits to farmers and landowners.

Contamination by As, Hg, and Sb in a region with geogenic As anomaly and subsequent human health risk characterization

Arsenic (As) is among the most harmful toxic elements to human health with severe carcinogenic and non-carcinogenic effects. The present study aims to (1) characterize a site with geogenic As anomaly (Emet basin) in Kutahya, Turkey via soil (urban, agriculture, forest; n = 53 total), water (n = 11), and agricultural product (n = 19) samples; and, (2) characterize human health risks for different receptors under specific exposure scenarios. Soil As levels were very high (range, 22.4-765 mg kg^-1). Previous literature suggested some evidence of Sb and Hg combined with As in mineral forms in the region; the present study found elevated Sb (up to 76.0 mg kg^-1) in two regions with very high As levels, but Hg concentrations were low in the region. Soils from urban/agricultural zones (representing anthropogenic impact) did not have statistically different As levels compared with forest soils (representing low/no human impact). As water concentrations were also very high (range, 14.0-729 μg L^-1), however, uptake by agricultural products was low, mostly limited to wheat (up to 0.7 mg kg^-1). Exposure assessment/risk characterization showed that non-carcinogenic risk following exposure to soils was very high for children (hazard index up to 37 under reasonable maximum exposure) as well as carcinogenic risk (probability up to 1.19E-3). The risk was even higher considering intake of water, and in this case, both for children and adults (HI, 4.0-66.6; cancer risk, 1.29E-4-1.84E-2). The potential adverse outcomes of the As anomaly in the region may be grave, thus further geochemical investigation of As speciation and mobile fractions as well as gastrointestinal As bioaccessibility supplementing probabilistic human health risk characterization are recommended.

Environmental impacts of abrasive blasting of transmission towers in protected areas

In Australia, and other parts of the world, tower infrastructure in electricity transmission networks are nearing the end of their asset life. In changing economic, political and regulatory environments Transmission Network Service Providers are implementing new approaches to asset management and reinvestment, such as refurbishment to extend the life of existing assets, instead of replacement. As part of these refurbishment efforts, abrasive blasting and recoating is being employed to remove corrosion and extend the life of steel electricity transmission towers. New controls and procedures have been developed to manage the most likely impacts associated with the abrasive blasting of transmission towers. However, little or no data have been available on the environmental impacts of abrasive blasting or the effectiveness of management procedures currently being used to mitigate potential adverse environmental impacts.We conducted an integrated study on the impacts of abrasive blasting, which brought together on-site research; modelling; and controlled laboratory trials. The study was undertaken during a transmission tower refurbishment project within the World Heritage listed Wet Tropics Region in Queensland, Australia. Measured metal deposition around towers due to blasting, was primarily as large particles (>PM10) at 12-30 m from the tower. Soil concentrations of metals were highest under towers, with a small number of samples showing elevated zinc at 12-30 m. The presence of spent abrasive media and dust on the geofabric material used under the towers and up to 15 m from the tower base, as part of control measures used to contain the abrasive products, indicates that deposition also occurs between 0 and 12 m from the tower.The potential impacts of the abrasive blasting technique on plants and invertebrates appear to be low. Five species of tropical rainforest tree seedlings exposed to abrasive blasting dust at worst-case levels had no negative impact on physiological performance or plant health. This research will assist Transmission Network Service Providers and other operators of corroded linear infrastructure to plan and implement mitigating management actions and procedures during abrasive blasting projects and assist regulators and the community to better understand the impacts of the practice.

Evaluation on the risk controlling value of urban soil organic pollutants based on land-use planning in China

Land left after urban industrial enterprises relocate is usually planned for various land-use types that can influence human health risks. In China, urban development consists of at least eight land uses: urban residential (UR), public administration/service (PA/S), commercial/service (C/S), industrial, logistics storage, transportation (TR), public utility, and park green space. The (PA/S) type has two classes: PA/S1 includes administrative, cultural relics and historic, foreign affairs, and religious facility lands, with adults the sensitive recipients. Class PA/S2 includes lands related to cultural facilities, education and scientific research, sports, medical, and social welfare facilities, in which children are the sensitive recipients. The UR type has UR 1 and UR 2 classes with and without underground space, respectively. The C/S type has C/S1 and C/S2 classes with and without underground space, respectively. The TR type has TR1, TR2, and TR3 classes which indicate urban road, subway, and traffic hub land, respectively. To the above, we applied conceptual models and exposure pathways of volatile organic compounds and semi-volatile organic compounds. Exposure parameters were investigated for six regions and above eight land uses featuring different soil, climate, and population behavior characteristics: north, east, south, northwest, northeast, and southwest (covering China entirely). Risk controlling values (RCVs) corresponding to a lifetime cancer risk of 10^-6 in this paper were calculated using the C-GAC model introduced by 'Chinese Technical Guidelines for Risk Assessment of Contaminated Sites' with above exposure parameters to determine whether it has potentially significant levels of contamination that may warrant further investigation. Our results revealed two main patterns: (1) our soil risk controlling values for the six regions-north, east, south, northwest, northeast, and southwest-revealed some between-region variability (up to 28%). Hence, for urban contaminated sites in different regions of China, different RCVs should be considered when evaluating possible health risks. (2) The results for the organic pollutants tested across the eight types of land use showed maximum values up to 90 times the minimum value. The greater the risk controlling value of the same pollutant, the less sensitive the site is to that pollutant. Urban road land, traffic hub land, and park green space land are not sensitive to volatile organic pollutants.

Soil contamination in China: Current priorities, defining background levels and standards for heavy metals

The Chinese Government is working to establish an effective framework in managing soil contamination. Heavy metal contamination is key to the discussion about soil quality, health and remediation in China. Soil heavy metal contamination in China is briefly reviewed and the concepts of background values and standards discussed. The importance of contaminated land and its management for China food security and urbanization are discussed. Priorities for China's next steps in developing an effective research and management regime are presented. We propose that critically important to the science-based risk assessment of contaminants in soils is the incorporation of speciation and bioavailability into the measurement and evaluation criteria. Consideration of soil biology/ecological endpoints will be necessary to protect ecosystem health. National and regional/local scenarios of land use type/usage will address residential/urban re-use of industrial land as well as varying agricultural scenarios.

Transport, retention, and release of Escherichia coli and Rhodococcus erythropolis through dry natural soils as affected by water repellency

Microbial transport in soil affects pathogen retention, colonization, and innoculant delivery in bioremediating agricultural soils. Various bacteria strains residing in the fluid phases of soils are potential contaminants affecting human health. We measured the transport of hydrophilic Escherichia coli (E. coli) and hydrophobic Rhodococcus erythropolis (R. erythropolis) bacteria through initially air-dried wettable or water-repellent soil columns to understand the effect of water repellency and the hydrophobicity of the organism on its retention, release, and transport properties. Bacteria suspensions infiltrated the top of the columns under saturated (0 cm) and unsaturated (-5 cm) flows in the air-dried (pulse 1) and rewetting (pulse 2) conditions. Cells were recovered from the leachates and the soil extracts by the viable counts. Wettable soil efficiently retained both hydrophobic and hydrophilic bacteria (>80%) in initial air-dried conditions (pulse 1). Even after rewetting, and the formation and expansion of water films and corresponding reduction of the air-water interfacial area (pulse 2), few bacteria were released (maximum 31.5% and 10.1% for saturated and unsaturated flows, respectively), whereas more cells were released from the water-repellent counterpart (more that 72%). The smaller size of hydrophobic R. erythropolis made cell transport possible within the thinner water films of both soils compared to hydrophilic E. coli through pulses 1 and 2. The shape of each strain's retention profiles was uniform and exponential as influenced by soil, strain, and water flow conditions. The results suggest that hydrophobic bacteria will disperse readily when leached into initially dry soil, while hydrophilic bacteria are more susceptible to leaching, posing a risk of pathogen contamination. Clearly the wettability of soil and organisms affects fate and transport.

Estimating persistent oil contamination in tropical region using vegetation indices and random forest regression

The persistence of soil contamination after cessation of oil activities remains a major environmental issue in tropical regions. The assessment of the contamination is particularly difficult on vegetated sites, but promising advances in reflectance spectroscopy have recently emerged for this purpose. This study aimed to exploit vegetation reflectance for estimating low concentrations of Total Petroleum Hydrocarbons (TPH) in soils. A greenhouse experiment was carried out for 42 days on Cenchrus alopecuroides (L.) under realistic tropical conditions. The species was grown on oil-contaminated mud pit soils from industrial sites, with various concentrations of TPH. After 42 days, a significant decrease in plant growth and leaf chlorophyll and carotenoid contents was observed for plants exposed to 5-19 g kg^-1 TPH in comparison to the controls (p < 0.05). Conversely, pigment contents were higher for plants exposed to 1 g kg^-1 TPH (hormesis phenomenon). These modifications proportionally affected the reflectance of C. alopecuroides at leaf and plant scales, especially in the visible region around 550 and 700 nm. 33 vegetation indices were used for linking the biochemical and spectral responses of the species to oil using elastic net regressions. The established models indicated that chlorophylls a and b and β-carotene were the main pigments involved in the modifications of reflectance (R² > 0.7). The same indices also succeeded in estimating the concentrations of TPH using random forest regression, at leaf and plant scales (RMSE = 1.46 and 1.63 g kg^-1 and RPD = 5.09 and 4.44, respectively). Four out of the 33 indices contributed the most to the models (>75%). This study opens up encouraging perspectives for monitoring the cessation of oil activities in tropical regions. Further researches will focus on the application of our approach at larger scale, on airborne and satellite imagery.

Human health risk from consumption of two common crops grown in polluted soils

Contamination of agricultural soils by trace elements is a recurrent hazard for human health because of the possibility of pollutants entering the food chain. Aim of this study was to assess the human health risk from consumption of the common leafy (Lactuca sativa L.) and fruit (Cucurbita pepo L.) crops, in an agricultural area of Southern Italy. Along with agricultural practices, a major pollutant source is recurrent flooding from the highly polluted Solofrana river. Soil samples and edible parts of crops from 14 sites (10 flooded and 4 not flooded) were analyzed for total amounts of As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn. The bio-accumulation factor (BAF) and Health Risk Index (HRI) were calculated for each element, crop and site and as average values of all sites (BAF_mean and HRI_mean). Moreover, the Hazard Index (HI) was determined for each site, as the sum of HRI for all elements. Cr and Cu, mostly derived from river flooding and agricultural practices, respectively, were the only elements whose levels exceeded law thresholds and/or the natural background of the study area. Of the two considered crops, L. sativa accumulated more Cd, Cr and Ni, whereas C. pepo was a more effective bioaccumulator of Zn. Both HRI_mean (for As, Cd, Cr and Ni) and HI were higher for L. sativa than for C. pepo. A low health risk was associated to major soil pollutants (Cr and Cu) found in the study area; in contrast, combined data on soil pollution and plant bio-accumulation points to accumulation of Cd and As, mainly in lettuce, as a potential risk for human health. The results suggest that soil pollution data alone is not sufficient to assess health risk.

Soil infiltration capacity of chemical oxidants used for risk reduction of soil contamination

Chemical oxidation has been applied to remove soil contaminants and thereby reduce human and ecological risks from contaminated sites. However, few studies have been conducted on the natural infiltration of oxidant solutions into unsaturated soil. Moreover, the infiltration capacity of oxidant solutions at various concentrations in unsaturated soil has not yet been studied. This study investigated the natural infiltration tendency of oxidant solutions like hydrogen peroxide (H₂O₂), potassium permanganate (KMnO₄), and sodium persulfate (Na₂S₂O₈), in sand and sandy loam. Cumulative infiltration was recorded from a soil column equipped with a Mariotte reservoir. The infiltration rate, sorptivity, and unsaturated hydraulic conductivity were obtained from the cumulative infiltration results. Na₂S₂O₈ showed the highest infiltration rate in both sand and sandy loam, and the infiltration of Na₂S₂O₈ increased as the concentration was increased from 0.05 to 1%. However, the infiltration of KMnO₄ and H₂O₂ solutions was governed more by chemical reaction behavior than by liquid physical properties or soil hydraulic properties. The production of oxides and gas due to reaction induced clogging in flow paths, resulting in less infiltration. Infiltration of H₂O₂ at concentrations greater than 0.5% was not observed in sand or sandy loam due to gas formation and swelling.

Decision Framework for the environmental management of explosive contaminated land

The environmental risks from explosive manufacturing and testing activities are usually evaluated using a qualitative process such as environmental impact prioritisation as recommended by legislation and guidance. However, standard environmental management system (EMS) guidance rarely provides detailed information on how to objectively assess the significance of the environmental impacts based on a rational scientific evidence. Quantitative exposure and eco-toxicity assessments are frequently used in combination with environmental threshold limit guidelines, but these omit important environmental impacts such as physical damage to land, nuisance and contribution to climate change. These impacts are particularly relevant to the explosives industry where noise nuisance and physical damage are given high priority. In addition, contamination from explosive compositions may comprise mixtures of multiple legacy and new generation explosives such as 1,3,5-trinitro-1,3,5-triazinane (RDX), 2,4,6-trinitrotoluene (TNT), 5-nitro-1,2,4-triazol-3-one (NTO), 2,4-dinitroanisole (DNAN) and nitroguandine (NQ), which may have combined impacts not captured by conventional eco-toxicity assessments. Further, threshold limits for energetic materials in soil and water have not been established for most nations. Additionally, in the explosive industry wider concerns such as legislative compliance and stakeholder concerns may help to provide a more broadly applicable assessment of environmental impact. Therefore in this study a novel decision framework was developed to integrate empirical data with business risks to enable rational decision making for the environmental management of explosive manufacturing facilities. The application of the framework was illustrated using three case studies from the explosive manufacturing industry to demonstrate how the framework can be used to justify environmental management decision making. By linking the environmental impacts to business risks, we demonstrate that manufacturers are able to assess a wide spectrum of issues that might not be identified in the initial environmental assessment such as non-toxic pollution incidents, breaches in legislation and stakeholder perceptions.