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Recent research has highlighted the ecological risk posed by microplastics (MPs) from mulching film and heavy metals to soil organisms. However, most studies overlooked real environmental levels of MPs and heavy metals. To address this gap, pristine and aged polyethylene (PE) mulching film-derived MPs (PMPs, 500 mg/kg; AMPs, 500 mg/kg) were combined with cadmium (Cd, 0.5 mg/kg) to assess the acute toxicity to earthworms and investigate associated molecular mechanisms (oxidative stress, osmoregulation pressure, gut microbiota, and metabolic responses) at environmentally relevant concentrations. Compared to Cd alone and Cd + PMPs treatments (11.15 ± 4.19 items/g), Cd + AMPs treatment resulted in higher MPs bioaccumulation (23.73 ± 13.14 items/g), more severe tissue lesions, and increased cell membrane osmotic pressure in earthworms' intestines. Cd + AMPs induced neurotoxicity through elevated levels of glutamate and acetylcholinesterase. Earthworm intestines (0.98 ± 0.49 to 3.33 ± 0.37 mg/kg) exhibited significantly higher Cd content than soils (0.19 ± 0.01 to 0.51 ± 0.06 mg/kg) and casts (0.15 ± 0.01 to 0.25 ± 0.05 mg/kg), indicating PE-MPs facilitated Cd transport in earthworms' bodies. Metabolomic analysis showed Cd + AMPs exposure depleted energy and nucleotide metabolites, disrupted cell homeostasis more profoundly than Cd and Cd + PMPs treatments. Overall, co-exposure to AMPs + Cd induced more severe neurotoxicity and disruption of homeostasis in earthworm than Cd and PMPs + Cd treatments. Our study, using Cd and MPs with environmental relevance, underscores MPs' role in amplifying Cd accumulation and toxicity in earthworms., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nanosized agrochemicals like nanofertilizers are being applied to soils. Adverse impacts of nanofertilizers on soil microflora were reported in past studies, but only considering a single application. Repeated applications are however more likely to occur in agriculture. We investigated effects of single versus repeated applications of a copper hydroxide nanofertilizer formulation (NFF) on soil enzyme activity and bacterial community. One or three applications were performed within 21 days to achieve same final level of Cu in soil (48 mg(Cu)/kg: the recommended dose of NFF). Besides, the active ingredient (i.e., copper hydroxide nanotubes (NT)) and dispersing agent (DA) of NFF, and an ionic fertilizer (i.e., CuSO 4 ) were examined. Fluorescein diacetate hydrolase (FDAse), N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and urease (URE) showed negligible changes in the activities between the control and DA treatment. Bacterial community abundance, composition and diversity exhibited similar phenomena. Exposures to copper hydroxide NFF and NT or CuSO 4 enhanced the activities of FDAse and NAG, weakened the activity of URE, and showed negligible changes in the LAP activity irrespective of single and repeated applications. Concentrations of NO 3 - -N and NH 4 + -N in soil were also affected by the application mode of NFF. More importantly, responses of soil bacterial community to copper hydroxide NFF were highly dependent on its application mode, whereas similar responses were observed in the CuSO 4 treatment regardless of single or repeated applications. This study provided new insights into environmental risk of copper hydroxide NFF that were ignored in previous studies using a single exposure., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Poly- and perfluoroalkyl substances (PFASs) are synthetic chemicals, which are introduced to the environment through anthropogenic activities. Aqueous film forming foam used in firefighting, wastewater effluent, landfill leachate, and biosolids are major sources of PFAS input to soil and groundwater. Remediation of PFAS contaminated solid and aqueous media is challenging, which is attributed to the chemical and thermal stability of PFAS and the complexity of PFAS mixtures. In this review, remediation of PFAS contaminated soils through manipulation of their bioavailability and destruction is presented. While the mobilizing amendments (e.g., surfactants) enhance the mobility and bioavailability of PFAS, the immobilizing amendments (e.g., activated carbon) decrease their bioavailability and mobility. Mobilizing amendments can be applied to facilitate the removal of PFAS though soil washing, phytoremediation, and complete destruction through thermal and chemical redox reactions. Immobilizing amendments are likely to reduce the transfer of PFAS to food chain through plant and biota (e.g., earthworm) uptake, and leaching to potable water sources. Future studies should focus on quantifying the potential leaching of the mobilized PFAS in the absence of removal by plant and biota uptake or soil washing, and regular monitoring of the long-term stability of the immobilized PFAS., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Nanopesticides are being introduced in agriculture, and the associated environmental risks and benefits must be carefully assessed before their widespread agricultural applications. We investigated the impacts of a commercial Cu(OH) 2 nanopesticide formulation (NPF) at different agricultural application doses (e.g., 0.5, 5, and 50 mg of Cu kg -1 ) on enzyme activities and bacterial communities of loamy soil (organic matter content of 3.61%) over 21 days. Results were compared to its ionic analogue (i.e., CuSO 4 ) and nano-Cu(OH) 2 , including both the commercial unformulated active ingredient of NPF (AI-NPF) and synthesized Cu(OH) 2 nanorods (NR). There were negligible changes in the activity of acid phosphatase, regardless of exposure dose, whereas significant ( p < 0.05) variations in activities of invertase, urease, and catalase were observed at a dose of 5 mg kg -1 or higher. Invertase activity decreased with an increasing bioavailable Cu concentration in soil under various treatments. In comparison to CuSO 4 , both Cu(OH) 2 nanopesticide (i.e., NPF) and nano-Cu(OH) 2 (i.e., AI-NPF and NR) caused a significant ( p < 0.05) inhibition of urease activity, wherein a significant ( p < 0.05) increase in the activity of catalase was observed, representing serious oxidative stress. Accordingly, NPF, AI-NPF, and NR differently affected soil bacterial abundance, diversity, and community compared to CuSO 4 , which could have resulted from the changes in the bioavailable Cu concentration as a result of the distinct nature of copper spiked (i.e., nano form versus salt). Moreover, minor differences in the soil enzyme activity and bacterial community were observed between NPF and AI-NPF, reflecting that the impact of the Cu(OH) 2 nanopesticide was primarily attributed to the presence of nano-Cu(OH) 2 . In total, the impacts of nano-Cu(OH) 2 on the soil bacterial community and enzyme activity tested in this study differed from CuSO 4 , shedding light on the environmental risks of the Cu(OH) 2 nanopesticide in the long run.

Diffusely contaminated soils often remain untreated as classical remediation approaches would be disproportionately expensive. Adding compost can accelerate the biodegradation of organic contaminants and adding biochar can immobilize contaminants through sorption. The combined use of compost and biochar to reduce polycyclic aromatic hydrocarbon (PAH) and NSO-substituted PAH contamination has, however, not previously been systematically investigated. We have therefore investigated the processes involved (i) through sorption batch experiments, (ii) by monitoring changes in bacterial, fungal and archaeal communities using denaturing gradient gel electrophoresis, and (iii) through degradation experiments with fluorene, phenanthrene, pyrene, carbazole, dibenzothiophene, and dibenzofuran. Sorption coefficients for organic contaminants in soils increased tenfold following 10% compost addition and up to a hundredfold with further addition of 5% biochar. The rate of PAH and NSO-PAH degradation increased up to twofold following compost addition despite increased sorption, probably due to the introduction of additional microbial species into the autochthonous soil communities. In contrast, degradation of PAHs and NSO-PAHs in soil-compost-biochar mixtures slowed down up to tenfold due to the additional sorption, although some degradation still occurred. The combined use of biochar and compost may therefore provide a strategy for immobilizing PAHs and NSO-PAHs and facilitating degradation of remaining accessible contaminant fractions., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The study investigates the role of biochar and/or compost in mitigating the toxic effects of pyrene in soils using reproduction of nematodes and porewater concentration as measures of pyrene toxicity and bioavailability, respectively. Two soils were spiked with increasing levels of pyrene to achieve a concentration-response relationship for the reproduction of Caenorhabditis elegans. The observed EC50 values (pyrene concentration causing 50% inhibition of reproduction) were 14mg/kg and 31mg/kg (dry mass) for these soils, corresponding to equilibrium porewater concentrations of 37μg/L and 47μg/L, respectively. Differences in organic carbon content were not sufficient to explain the variability in toxicity between the different soils. Soils causing a significant inhibition of reproduction were further amended with 10%-compost, 5%-biochar, or both, and the effects on reproduction and porewater concentration determined. Combined addition of compost and biochar was identified as the most effective strategy in reducing pyrene concentration in soil porewater, which was also partly reflected in soil toxicity. However, porewater concentrations predicted only 52% of pyrene toxicity to nematodes, pointing to particle-bound or dietary exposure pathways. Capsule: Amending pyrene-spiked soil with biochar and compost effectively reduced pyrene porewater concentrations and toxicity to nematodes, which were significantly related., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The influence of ageing on biochar properties has been investigated by comparing three fresh biochars with biochars artificially aged by either H 2 O 2 thermal oxidation or horseradish peroxidase enzymatic oxidation. In addition, a field-aged counterpart for one of the biochars was recovered from an agricultural field site, four years after application. Biochar properties, including surface areas and pore volumes (derived by N 2 and CO 2 physisorption) and elemental compositions, showed only minor changes following both artificial and field ageing, indicating high biochar stability. Concentrations of the 16 US EPA PAHs were measured in all of the biochars and a contaminant trap was used to investigate the effect of ageing on their bioaccessibility. The concentrations of total and bioaccessible PAHs ranged from 4.4 to 22.6 mg kg -1 and 0.0 to 9.7 mg kg -1 , respectively. Concentrations of the 16 US EPA PAHs decreased following field ageing, but the proportion of low molecular weight PAHs increased. The observed changes in PAH composition with field ageing can be explained by uptake from the surrounding soil and intra-biochar transfer processes. To better understand changes in PAH composition with ageing, an additional broad range of alkylated PAHs was also analyzed in selected samples. Our results show that the tested artificial ageing protocols are unable to approximate the changes in PAH composition resulting from field ageing. Nevertheless, total and bioaccessible PAH concentrations decreased for both artificially and field-aged biochars, indicating that biochars release PAHs when they are freshly produced and that the risk of PAH release decreases with ageing.

For the first time, regulatory protocols defined in the OECD guidelines were applied to determine the fate properties of a nanopesticide in two agricultural soils with contrasting characteristics. The nanoformulation studied had no effect on the degradation kinetics of atrazine indicating that (1) the release of atrazine from the polymer nanocarriers occurred rapidly relative to the degradation kinetics (half-lives 36-53 days) and/or that (2) atrazine associated with the nanocarriers was subject to biotic or abiotic degradation. Sorption coefficients, derived from a batch and a centrifugation technique at a realistic soil-to-solution ratio, were higher for the nanoformulated atrazine than for the pure active ingredient. Results indicate that the nanoformulation had an effect on the fate of atrazine. However, since the protocols applied were designed to assess solutes, conclusions about the transport of atrazine loaded onto the nanocarriers should be made extremely cautiously. The centrifugation method applied over time (here over 7 days) appears to be a useful tool to indirectly assess the durability of nanopesticides under realistic soil-to-solution ratios and estimate the period of time during which an influence on the fate of the active ingredient may be expected. More detailed investigations into the bioavailability and durability of nanopesticides are necessary and will require the development of novel methods suitable to address both the "nano" and "organic" characteristics of polymer-based nanopesticides.

This review of the epidemiological literature shows that evidence for negative impacts of land contaminated by waste disposal on human health is limited. However, the potential for health impacts cannot be dismissed. The link between residence close to hazardous waste disposal sites and heightened levels of stress and anxiety is relatively well established. However, studies on self-reported outcomes generally suffer from interpretational problems, as subjective symptoms may be due to increased perception and recall. Several recent multiple-site studies support a plausible linkage between residence near waste disposal sites and reproductive effects (including congenital anomalies and low birth weight). There is some conflict in the literature investigating links between land contamination and cancers; the evidence for and against a link is equally balanced and is insufficient to make causal inferences. These are difficult to establish because of lack of data on individual exposures, and other socioeconomic and lifestyle factors that may confound a relationship with area of residence. There is no consistently occurring risk for any specific tumor across multiple studies on sites expected to contain similar contaminants. Further insights on health effects of land contamination are likely to be gained from studies that consider exposure pathways and biomarkers of exposure and effect, similar to those deployed with some success in investigating impacts of cadmium on human health.

A review of the epidemiological literature on the potential effects of land contamination shows that the largest body of contaminant-specific research relates to cadmium (Cd). First, a brief outline of the key issues related to the study of health impact of land contamination is presented. The recent literature is then reviewed for evidence of associations and possible causal relationships between exposure to Cd from land contamination and health impact. A large number of studies focusing on Cd arise because of the ready availability of biomarkers of exposure and effect and the demonstrated link between soil Cd and itai-itai disease (severe renal and bone disorders) via dietary exposure in Japan and China. Where dietary differences yield lower exposures, links have been established between Cd in soil and biomarkers of renal or bone dysfunctions, but not to health impacts per se. Potential effects of Cd exposure were also investigated for other health outcomes, including hypertension, cancer incidence, preterm delivery, and semen parameters. In contrast to renal and bone disorders, results are generally inconsistent and require further lines of evidence. Residence in locations with elevated concentrations of Cd in soil is a poor surrogate for exposure, and there are examples where residents in locations with elevated concentrations of Cd in soil did not appear to suffer serious health consequences.

Background: Pesticide degradation and adsorption in soils are key processes determining whether pesticide use will have any impact on environmental quality. Pesticide degradation in soil generally results in a reduction in toxicity, but some pesticides have breakdown products that are more toxic than the parent compound. Adsorption to soil particles ensures that herbicide is retained in the place where its biological activity is expressed and also determines potential for transportation away from the site of action. Degradation and adsorption are complex processes, and shortcomings in understanding them still restrict the ability to predict the fate and behaviour of ionisable pesticides. This paper reports the sorption and degradation behaviour of four acidic pesticides in five soils from southern Spain. Results are used to investigate the influence of soil and pesticide properties on adsorption and degradation as well as the potential link between the two processes., Results: Adsorption and degradation of four acidic pesticides were measured in four soils from Spain characterised by small organic matter (OM) contents (0.3-1.0%) and varying clay contents (3-66%). In general, sorption increased in the order dicamba < metsulfuron-methyl < 2,4-D < flupyrsulfuron-methyl-sodium. Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for these soils. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. A clear positive correlation was observed for degradation rate with clay and OM content (P < 0.01), and a negative correlation was observed with pH (P < 0.01). The exception was metsulfuron-methyl, for which degradation was found to be significantly correlated only with soil bioactivity (P < 0.05)., Conclusions: Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for soils of this type. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. The contrasting behaviour shown for these four acidic pesticides indicates that chemical degradation in soil is more difficult to predict than adsorption. Most of the variables measured were interrelated, and different behaviours were observed even for compounds from the same chemical class and with similar structures.

Degradation and sorption of six acidic pesticides (2,4-D, dicamba, fluroxypyr, fluazifop-P, metsulfuron-methyl, and flupyrsulfuron-methyl) and four basic pesticides (metribuzin, terbutryn, pirimicarb, and fenpropimorph) were determined in nine temperate soils. Results were submitted to statistical analyses against a wide range of soil and pesticide properties to (i) identify any commonalities in factors influencing rate of degradation and (ii) determine whether there was any link between sorption and degradation processes for the compounds and soils studied. There were some marked differences between the soils in their ability to degrade the different pesticides. The parameters selected to explain variations in degradation rates depended on the soil-pesticide combination. The lack of consistent behavior renders a global approach to prediction of degradation unrealistic. The soil organic carbon content generally had a positive influence on degradation. The relationship between pH and degradation rates depended on the dominant mode of degradation for each pesticide. There were positive relationships between sorption and rate of degradation for metsulfuron-methyl, pirimicarb, and all acidic pesticides considered together (all P < 0.001) and for dicamba and all bases considered together (P < 0.05). No relationship between these processes was observed for the remaining seven individual pesticides.