Residual soil pollution from the Aznalcóllar mine spill is still a problem in some parts of the affected area, today converted in the Guadiamar Green Corridor. Dispersed spots of polluted soils, ...identified by the absence of vegetation, are characterized by soil acid pH and high concentrations of As, Pb, Cu and Zn. Ex situ remediation techniques were performed with unrecovered soil samples. Landfarming, Composting and Biopiles techniques were tested in order to immobilize pollutants, to improve soil properties and to promote vegetation recovery. The effectiveness of these techniques was assessed by toxicity bioassays: Lactuca sativa L. root elongation test, Vibrio fischeri bioluminescence reduction test, soil induced respiration test, and Eisenia andrei survival and metal bioaccumulation tests. Landfarming and Composting were not effective techniques, mainly due to the poor improvement of soil properties which maintained high soluble concentrations of Zn and Cu after treatments. Biopile technique, using adjacent recovered soils in the area, was the most effective action in the reduction of soil toxicity; the improvement of soil properties and the reduction in pollutants solubility were key to improve the response of the tested organisms. Therefore, the mixture of recovered soils with polluted soils in the areas affected by residual contamination is considered a more suitable technique to reduce the residual pollution and to promote the complete soil recovery in the Guadiamar Green Corridor.
•Residual soil pollution in Guadiamar Green Corridor is still a problem 18 years after contamination.•Soil toxicity bioassays were key tools for the assessment of remediation techniques applied.•Landfarming and Composting were not effective due to the high soluble concentrations of Zn and Cu after treatment.•Biopiles, using recovered soils in the area, were the most effective treatment for soil remediation.
This study aimed at assessing the influence of soil properties on the uptake and toxicity effects of arsenic in the earthworm
Eisenia andrei
exposed for 4 weeks to seven natural soils spiked with ...different arsenic concentrations. Water-soluble soil concentrations (AsW) and internal As concentrations in the earthworms (AsE) were greatly different between soils. These two variables were highly correlated and were key factors in earthworm toxicity response. AsW was explained by some soil properties, such as the pH, calcium carbonate content, ionic strength, texture or oxide forms. Toxicity showed a clear variation between soils, in some cases without achieving 50 % adverse effect at the highest As concentration added (600 mg kg
−1
). Nevertheless, soil properties did not show, in general, a high relation with studied toxicity endpoints, although the high correlation with AsW could greatly reduce indirectly As bioavailability and toxicity risk for earthworms. Obtained results suggest that soil properties should be part of the criteria to establishing thresholds for contaminated soils because they will be key in controlling As availability and thus result in different degrees of toxicity.
The present work assesses the residual pollution in the Guadiamar Green Corridor (SW, Spain) after a long-term aging process (18 years) since the accident of the Aznalcóllar pyrite mine. We have ...focused on the study of trace elements (Cu, Zn, Cd, As and Pb) in soils, their fractionation and the transference to the surrounding vegetation. The residual polluted areas are characterized by scattered plots with absence of vegetation, presenting high concentrations of trace elements, acidic pH and low organic carbon content. Surrounding these polluted plots, two vegetation gradient belts are clearly identified by changes in plant cover and richness. The inhibition of plant growth in the bare soils is related to the highest mobility of soluble and exchangeable Cu, Zn and Cd forms, which significantly decrease with the distance to the polluted plots.
Plant richness and cover show differences between belts; bioaccumulation of trace elements in plants also differs, with a preferential accumulation in roots. Despite the low bioavailability of As and Pb in soils, bioaccumulation factors in plants for these elements are significantly higher in belt 1 in relation to belt 2. High Cu and Cd potential toxic concentrations in aerial parts of vegetation are found, posing a risk for livestock and a potential entrance to the food-chain. On the other hand, Lamarckia aurea (L.) Moench (in belt1) and Trifolium campestre Schreb. (in belt2) were the most dominant species in severely polluted soils. Elevated concentrations of trace elements in the vegetation growing in the area indicate plant adaptation mechanisms to live in these severely polluted soils, which can be used as a good bioindicator of pollution in similar polluted areas.
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•Areas with residual polluted soils persist in the Guadiamar Green Corridor 18 years after the recovery.•High concentrations of potentially bioavailable metal(loid)s were found in some soils in the area.•Plant richness and vegetation cover shows small-scale differences in spatial distribution.•Transfer of trace elements to plants poses a risk of pollution for the ecosystem and livestock.
•Pb bioavailability was assessed in 7 soils with different properties.•Pb toxicity measured in aqueous extracts (plants, bacteria) and with soil respiration.•Pb toxicity was affected by pH, carbonate ...content and organic carbon content.•L. sativa root elongation was more sensitive to Pb than microbial parameters.•Current regulatory guideline values can underestimate or overestimate Pb toxicity.
Soil contamination with lead is a worldwide problem. Pb can cause adverse effects, but its mobility and availability in the terrestrial environment are strongly controlled by soil properties. The present study investigated the influence of different soil properties on the solubility of lead in laboratory spiked soils, and its toxicity in three bioassays, including Lactuca sativa root elongation and Vibrio fischeri illumination tests applied to aqueous extracts and basal soil respiration assays. Final aim was to compare soil-dependent toxicity with guideline values. The L. sativa bioassay proved to be more sensitive to Pb toxicity than the V. fischeri and soil respiration tests. Toxicity was significantly correlated with soil properties, with soil pH, carbonate and organic carbon content being the most important factors. Therefore, these variables should be considered when defining guideline values.
Soil pollution from the spill of Aznalcóllar mine (S Spain) was monitored by analysing polluted soils in 1998, 1999, and 2004. Following the methodology used in previous studies, in 2013 we conducted ...a new sampling and analysis of the soils affected by the spill and the data were compared with those of 2004. The results confirm that the pH tended to rise and concentration of pollutants tended to diminish over time. In 2013, the total concentration of pollutants was within the normal range for uncontaminated soils and close to the background concentration of the soils prior to the spill; while the soluble concentration of pollutants was clearly below the toxic level. These results indicate that remediation measures implemented have been effective. However, the removal of tailings (first remediation measure applied) was deficient and in many places the tailings were mixed with the soil. The high concentration of sulphides and metal(loid)s in the tailings gave rise to spots with very acidic and highly polluted soils devoid of vegetation. In 2013, fifteen years after the spill, these spots of bare soils remain a major source of pollution from which pollutants are scattered through the solid and liquid phases of runoff water, requiring action to immobilize pollutants and encourage the restoration of vegetation on these soils. In this type of pollution in a Mediterranean environment, the complete removal of tailings is more important than the speed at which they are removed.
•15 years after the accident around 7% of the affected soils remain unrecovered.•Soils with acidic pH and high As and Pb total concentrations are still detected.•Soil remediation actions are required to remove these sources of pollution.
In this work, the potential soil contamination in the abandoned mining area of Rodalquilar (SE, Spain) is studied using portable X-ray fluorescence (PXRF). Measurements were made
in situ, and data ...were statistically treated to study the spatial distribution of the anomalous values of trace elements. The elements exceeding the background values of the soils in the area were As, Pb, Zn, and Cu. Intervention levels both for agricultural as well as natural use in the area were exceeded by As concentrations, with 89% and 67% of the samples above these limits, respectively. The field observations and the spatial distribution of the data after the statistical treatment imply that the main mechanism of dispersion of the trace elements in soils of the area were water and wind erosion. PXRF is a useful tool for screening and assessing contaminated areas for quick and easy
in situ determination of trace-element concentrations. After this study, the mobility and bioavailability of main potentially pollutant element (As) together with toxicity bioassays are necessary to estimate the potential environmental risk of the soils of the area.
►The use of PXRF was used in an abandoned mining area. ►The spatial distribution of pollutants and background values was determined. ►The element exceeding the intervention levels in the area was arsenic. ►Toxicity assessments are necessary to estimate the potential environmental risk.
Residual pollution in the Guadiamar Green Corridor still remains after Aználcollar mine spill in 1998. The polluted areas are identified by the absence of vegetation, soil acidic pH and high ...concentrations of As, Pb, Zn and Cu. Soil toxicity was assessed by lettuce root elongation and induced soil respiration bioassays. In bare soils, total As and Pb concentrations and water-extractable levels for As, Zn and Cu exceeded the toxicity guidelines. Pollutants responsible for toxicity were different depending on the tested organism, with arsenic being most toxic for lettuce and the metal mixture to soil respiration. Soil properties, such as pH or organic carbon content, are key factors to control metal availability and toxicity in the area. According to our results, there is a risk of pollution to living organisms and the soil quality criteria established in the area should be revised to reduce the risk of toxicity.
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•15 years after the Aznalcóllar mine spill residual pollution remains in some areas.•Toxic levels were exceeded for total As and Pb and for soluble As, Zn and Cu.•Metals responsible for soil toxicity are different depending on the tested organism.•pH and organic carbon content reduce metal availability and therefore soil toxicity.•Regulatory guidelines in the area should be revised to reduce the risk of toxicity.
Residual pollution in the Guadiamar Green Corridor remains in some areas after long-term stabilization, with some risk of pollution according to toxicity bioassays.
The risk assessment of pollution associated with metal extraction process is a social responsibility. The initial goal of this type of assessment should be the use of a methodology able to combine ...the use of easy application, low cost and high efficiency-techniques to provide the necessary information with the least amount of investment in time and money as possible. A suitable option maybe a combination of a simple, quick and reliable analytical technique such as PXRF with bioassays and chemometric tools like HCA, PCA or LDA as a viable approach to carrying out a preliminary estimation of phytotoxicity levels associated to the soil sampled in a metal-contaminated area. The method we propose has been shown to be a quick, economical and reliable tool for use in the first stages of environmental risk characterization in mining areas. Particularly, the use of root elongation (RE) as the classification criteria provides a viable approach for selecting the final samples (or zones) in which an “in-depth” investigation plan will be designed as part of a future remediation strategy.
•Quick/reliable methodology for initial environmental risk characterization.•PXRF-quantification of metal (oid)s associated to soil samples in mining areas.•Preliminary phytotoxicity estimation of soil samples in a metal-contaminated area.•HCA/PCA/LDA as a viable approach to carry out an estimation of contaminated soils.
Urinary concentrations of non-persistent environmental pollutants (npEPs) are widely assessed in biomonitoring studies under the assumption that they are metabolised and eliminated in urine. However, ...some of these chemicals are moderately lipophilic, and their presence in other biological matrices should also be evaluated to estimate mid/long-term exposure to npEPs and its impact on human health. The present study aims to explore concentrations and potential determinants of npEPs in adipose tissue from a hospital-based adult cohort (GraMo cohort, Southern Spain).
Concentrations of bisphenol-A (BPA), benzophenone-3 (BP-3), triclosan (TCS), three chlorophenols (2,4-DCP, 2,5-DCP and 2,4,5-TCP) and two phenylphenols (2-PP and 4-PP), triclocarban (TCCB) and parabens methyl- (MeP), ethyl- (EtP), propyl- (n-PrP and i-PrP), butyl- (n-BuP and i-BuP) and benzyl-paraben (BzP) were analysed in adipose tissue samples from a subcohort of 144 participants. Spearman correlation tests were performed, followed by stepwise multivariable linear regression analyses to assess determinants of the exposure.
Detection frequencies and median concentrations were: BPA (86.8%, 0.54 ng/g tissue), BP-3 (79.2%, 0.60 ng/g tissue), TCS (45.8%, <LOD), 2-PP (18.8%, <LOD), MeP (100.0%, 0.40 ng/g tissue), EtP (20.1%, <LOD) and n-PrP (54.2%, 0.06 ng/g tissue). The remaining npEPs were detected in <10% of the samples. BPA, MeP, EtP and n-PrP levels were significantly and positively correlated, while BP-3 showed a positive correlation with TCS and 2-PP. Older participants showed higher concentrations of TCS and MeP, while BMI was inversely associated with most of the analysed compounds and perceived recent weight loss was inversely associated with 2-PP. Female participants and residents of rural areas had increased BP-3 concentrations. npEP concentrations were positively associated with the consumption of fatty food but negatively associated with the consumption of vegetables and fruit.
This study reveals the widespread presence of numerous npEPs in adipose tissue from adults in southern Spain, suggesting a generalized distribution of these environmental compounds in fatty tissues. In these adults, many of the determinants of npEP concentrations in adipose tissue were similar to those of more lipophilic and persistent compounds.
•We analysed levels and determinants of non-persistent pollutants in adipose tissue.•BPA, BP-3, TCS, MeP, EtP, and n-PrP were detected in >10% of the samples.•Main determinants included age, gender, BMI, residence, recent weight loss, and diet.•Many determinants were similar to those of more lipophilic and persistent compounds.
Zinc (Zn) and copper (Cu) are essential elements for living organisms, but they are also among the most frequent soils pollutants. Toxicity of these elements is difficult to assess and often shows ...contradictory results among authors due to the great complexity of the interactions with soil properties and constituents. The study of the individual metal behaviour will help provide a complete overview of the metal patterns in field pollution processes. Here, the influence of different soil properties on the mobility of Zn and Cu is studied in laboratory spiked soil samples by assessing metal toxicity from three different toxicity tests: root elongation, heterotrophic soil respiration and Microtox® toxicity tests. The results indicate that toxicity is significantly correlated with soil properties, calcium carbonate and organic carbon being the variables with highest influence in the reduction of Zn and Cu toxicity. However, large differences among soil samples in the toxicity results are observed. Thus, endpoints measured differ strongly in each soil sample because of the different sensibility of the organisms used in the toxicity tests and the high variability in soil properties. In addition, the results indicate differences between the soil toxicity depending on whether total or bioavailable metal concentrations are taken into account. Therefore, the current threshold concentrations usually selected for determining soil toxicity are not realistic, and a new approach is necessary taking into account the soil properties and the metal availability as well as using different toxicity tests to assess the toxic risk of metal-polluted soils.
•Copper showed lower water-solubility than Zn in soils.•Carbonates content in soils is a good buffer for Zn and Cu retention.•Toxicity thresholds strongly difference among toxicity test.•Soil properties and constituents are key factors for assessing metal pollution.
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