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This study focused on the study of earthworm survival, growth, reproduction, enzyme activities, and protein contents to evaluate and predict the effects of different soil pH levels and determine the optimal risk assessment indicators for the effects. Survival rate, growth rate, and cocoon number as well as four enzyme (glutathione peroxidase (GSH-PX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) activities and two proteins (total protein (TP) and metallothionein (MT)) contents in earthworms were determined to characterize the responses of earthworm activity to five soil pH levels. These biological datasets (survival, growth, and reproduction) were compared with biochemical indexes (GSH-PX, SOD, POD, CAT, TP, and MT), mainly using biphasic dose-response models. The results indicated that the soil pH value had significant inhibitory effects on the survival, growth, and reproduction of earthworms beginning with 3.0, 4.0, and 5.2, respectively. The dose-response models (J-shaped and inverted U-shaped curves) statistics indicated that the critical values (EC ZEP ) of the GSH-PX, SOD, POD, CAT, TP, and MT inhibited by soil acid stress were 3.46, 3.76, 3.35, 3.54, 3.50, and 3.96 (average 3.60), respectively. In the present study, the fitting curve analysis showed that the responses of the CAT activities and TP and MT contents in earthworm in response to soil pH have the behavior of hormesis.

Soil-exchangeable aluminum (Al) has toxic effects on living organisms in acidic soils. Earthworm presence and activity can alter soil pH, which has a significant influence on Al toxicity. However, the effects of earthworms on soil Al toxicity and fractions are still largely unknown. This laboratory study focused on the effects of three earthworm species (endogeics Pontoscolex corethrurus and Amynthas robustus, anecis Amynthas aspergillum) on soil acidification, Al fraction distribution, and base cation release. Three native earthworm species and a soil (latosolic red soil) collected from a botanical garden in South China were incubated under laboratory conditions. After 40 days of incubation, six Al fractions in soil, namely exchangeable (Al Ex ), weakly organically bound (Al Orw ), organically bound (Al Or ), amorphous (Al Amo ), Al occluded in crystalline iron oxides (Al Oxi ), and amorphous aluminosilicate and gibbsite (Al Aag ) fractions, were extracted using a sequential procedure. Soil pH; organic carbon; total nitrogen; total Al (Al Total ); exchangeable K, Na, Ca, Mg contents; and CEC were determined as well. Compared to control soil, pH values increased by 0.79, 0.41, and 0.57 units in casts in the presence of P. corethrurus, A. robustus, and A. aspergillum, and 0.70, 0.32, and 0.50 units in non-ingested soil, respectively. Compared to control soil, the 61.7%, 30.7%, and 36.1% of Al Ex contents in casts and 68.5%, 25.9%, and 39.0% of Al Ex in non-ingested soil significantly decreased with the addition of P. corethrurus, A. robustus, and A. aspergillum, respectively. Moreover, compared to control soil, the 78.7%, 37.7%, and 40.1% of exchangeable Ca 2+ and 12.3%, 24.7%, and 26.8% of exchangeable Mg 2+ contents in casts significantly increased with the presence of P. corethrurus, A. robustus, and A. aspergillum, respectively. Soil treated with P. corethrurus had higher soil pH values, exchangeable Ca 2+ contents, and lower Al Ex than those with A. robustus and A. aspergillum. Results of principal component analyses showed that P. corethrurus, A. robustus, and A. aspergillum casts and non-ingested soil differ for soil pH, Al fractions, and exchangeable base cations release. These results indicate that earthworms, especially P. corethrurus, can reduce soil Al toxicity, increase soil pH, and affect the release of exchangeable base cations.

This study investigates the spatiotemporal variability of major and trace elements, dissolved organic carbon (DOC), total dissolved solids (TDS), and suspended particulate matter (SPM) in surface waters of several hydrosystems of the Loire River watershed in France. In particular, this study aims to delineate the impact of the abovementioned water physicochemical parameters on natural iron and manganese physical speciation (homoaggregation/heteroaggregation) among fine colloidal and dissolved (< 10 nm), colloidal (10-450 nm) and particulate (> 450 nm) phases in Loire River watershed. Results show that the chemistry of the Loire River watershed is controlled by two end members: magmatic and metamorphic petrographic context on the upper part of the watershed; and sedimentary rocks for the middle and low part of the Loire. The percentage of particulate Fe and Mn increased downstream concurrent with the increase in SPM and major cations concentration, whereas the percentage of colloidal Fe and Mn decreased downstream. Transmission electron microscopy analyses of the colloidal and particulate fractions (from the non-filtered water sample) revealed that heteroaggregation of Fe and Mn rich natural nanoparticles and natural organic matter to the particulate phase is the dominant mechanism. The heteroaggregation controls the partitioning of Fe and Mn in the different fractions, potentially due to the increase in the ionic strength, and divalent cations concentration downstream, and SPM concentration. These findings imply that SPM concentration plays an important role in controlling the fate and behavior of Fe and Mn in various sized fractions. Graphical abstract Physical speciation by heteroaggregation of (Fe-Mn) compounds: high [SPM] → [Fe-Mn] particulate faction; low {SPM] → [Fe-Mn] colloid-dissolved fraction.

Biochar is a potential candidate for the remediation of metal(loid)-contaminated soils. However, the mechanisms of contaminant-biochar retention and release depend on the amount of soil contaminants and physicochemical characteristics, as well as the durability of the biochar contaminant complex, which may be related to the pyrolysis process parameters. The objective of the present study was to evaluate, in a former contaminated smelting site, the impact of two doses of wood biochar (2 and 5% w/w) on metal immobilization and/or phytoavailability and their effectiveness in promoting plant growth in mesocosm experiments. Different soil mixtures were investigated. The main physicochemical parameters and the Cd, Pb, and Zn contents were determined in soil and in soil pore water. Additionally, the growth, dry weight, and metal concentrations were analyzed in the different dwarf bean plant (Phaseolus vulgaris L.) organs tested. Results showed that the addition of biochar at two doses (2 and 5%) improved soil conditions by increasing soil pH, electrical conductivity, and water holding capacity. Furthermore, the application of biochar (5%) to metal-contaminated soil reduced Cd, Pb, and Zn mobility and availability, and hence their accumulation in the different P. vulgaris L. organs. In conclusion, the data clearly demonstrated that biochar application can be effectively used for Cd, Pb, and Zn immobilization, thereby reducing their bioavailability and phytotoxicity.

The phytoavailabilities and potential remobilization of potentially toxic elements (PTEs) such as Zn, Pb, Cd, As, and Sb were assessed in contaminated technosols from former mining and smelting sites. The PTE concentrations in soil pore water (SPW) and diffusive gradients in thin films (DGT)-measured concentration (C DGT) methods were used to assess the bioavailabilities of PTE and their remobilization in this study. Together with classical Chelex-100 DGT probes to measure Zn, Cd, and Pb, novel ferrihydrite-backed DGT were used for As and Sb measurements alongside with Rhizon soil moisture sampler method for SPW sampling. To assess the phytoavailabilities of PTE, a germination test with dwarf beans as a plant indicator was used for this purpose. Dwarf bean primary leaves showed high Zn concentrations in contrast to Pb and Cd which showed low phytoavailabilities. Despite As and Sb are present in high concentrations in the mine tailings, their phytoavailabilities indicate very low bioavailabilities. The amounts of Zn, Pb, Cd, As, and Sb extracted with DGT devices correlated well with the total dissolved PTE concentrations in the SPW. The highest R values were observed for Zn, followed by Cd and Pb, indicating the ability of the soil to sustain SPW concentrations, which decreased in that order. Good correlations were also observed between each of dissolved PTE concentrations in SPW, DGT-measured PTE concentrations (C DGT), and the accumulation of PTE in dwarf bean primary leaves. It could be concluded that the use of Rhizon soil moisture samplers and DGT methods may be considered to be a good methods to predict the PTE bioavailabilities in contaminated technosols.

This study aimed at assessing the effect of nitrogen addition under two forms, nitrate and ammonium, on the stabilization of Zn, Pb, and Cd by Populus euramericana Dorskamp grown in contaminated soils for 35 days under controlled conditions. Temporal changes in the soil pore water (SPW) were monitored for pH, dissolved organic carbon (DOC), and total dissolved concentrations of metals in the soils rhizosphere. Rhizospheric SPW pH decreased gradually with NH4(+) addition and increased with NO3(-) addition up to one unit, while it slightly decreased initially then increased for the untreated control soil DOC increased with time up to six times, the highest increase occurring with NH4(+) fertilization. An increase in the metal concentrations in the rhizospheric SPW was observed for NH4(+) addition associated with the lowest rhizospheric SPW pH, whereas the opposite was observed for the control soil and NO3(-) fertilization. Fertilization did not affect plant shoots or roots biomass development compared to the untreated control (without N addition). Metals were mostly accumulated in the rhizosphere and N fertilization increased the accumulation for Zn and Pb while Cd accumulation was enhanced for NH4(+) addition. Collectively, our results suggest metal stabilization by P. euramericana Dorskamp rhizosphere with nitrogen fertilization and are potential for phytostabilization of contaminated technosol.

The spatio-temporal trend of trace metals (Cd, Co, Cr, Cu, Ni, Pb, and Zn) in a tropical urban estuary under the influence of monsoon was determined using diffusive gradient in thin films (DGT) in situ samplers. Three different climatic periods were observed: period 1, dry with dredging activity; period 2, intermediate meaning from dry to wet event; and period 3, wet having continuous rainfall. Conforming to monsoon regimes, these periods correspond to the following: transition from winter to summer, winter, and summer monsoons, respectively. The distinction of each period is defined by their specific hydrological and physico-chemical conditions. Substantial concentrations of the trace metals were detected. The distribution and trend of the trace metals under the challenge of a tropical climate were able to follow using DGT as a sensitive in situ sampler. In order to identify the differences among periods, statistical analyses were performed. This allowed discriminating period 2 (oxic water) as significantly different compared to other periods. The spatio-temporal analysis was then applied in order to distinguish the trend of the trace metals. Results showed that the trend of trace metals can be described according to their response to (i) seasonal variations (Cd and Cr), (ii) spatio-temporal conditions (Co, Cu, Ni, and Pb), and (iii) neither (i) nor (ii) meaning exhibiting no response or having constant change (Zn). The correlation of the trace metals and the physico-chemical parameters reveals that Cd, Co, Cu, and Cr are proportional to the dissolved oxygen (DO), Cd and Ni are correlated pH, and Zn lightly influenced by salinity.

The aim of this paper was to estimate the potential leakage of acrylamide monomer, used for flocculation in a settling basin, towards the groundwaters. Surface-groundwater interactions were conceptualized with a groundwater transport model, using a transfer rate to describe the clogged properties of the interface. The change in the transfer rate as a function of the spreading of the clogged layer in the settling basin was characterized with respect to time. It is shown that the water and the Acrylamide transfer rate are not controlled by the spreading of the clogged layer until this layer fully covers the interface. When the clogged layer spreads out, the transfer rate remains in the same order of magnitude until the area covered reaches 80 %. The main flux takes place through bank seepage. In these early stage conditions of a working settling basin, the acrylamide flux towards groundwaters remains constant, at close to 10 g/year (±5).

The aim of this review was to summarize information and scientific data from the literature dedicated to the fate of polyacrylamide (PAM)-based flocculants in hydrosystems. Flocculants, usually composed of PAMs, are widely used in several industrial fields, particularly in minerals extraction, to enhance solid/liquid separation in water containing suspended matter. These polymers can contain residual monomer of acrylamide (AMD), which is known to be a toxic compound. This review focuses on the mechanisms of transfer and degradation, which can affect both PAM and residual AMD, with a special attention given to the potential release of AMD during PAM degradation. Due to the ability of PAM to adsorb onto mineral particles, its transport in surface water, groundwater, and soils is rather limited and restricted to specific conditions. PAM can also be a subject of biodegradation, photodegradation, and mechanical degradation, but most of the studies report slow degradation rates without AMD release. On the contrary, the adsorption of AMD onto particles is very low, which could favor its transfer in surface waters and groundwater. However, AMD transfer is likely to be limited by quick microbial degradation.

This study reports the chemical bioavailability of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated Technosols from two former smelting and mining areas. Though these elements have long been recognized as potentially harmful elements, understanding of their toxicity and environmental behavior in Technosols developed on former mining and smelting sites are more limited, particularly for As and Sb. Surface soils were sampled from metallophyte grassland contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (North France) and from a former mining settling basin contaminated with As, Pb, and Sb located at la Petite Faye (Limoges, France). Various selective single extraction procedures (CaCl2, NaNO3, NH4NO3, DTPA, and EDTA) were used together with germination tests with dwarf beans whose shoots were analyzed for their potentially toxic element concentrations after 21 days of growth. The extraction capacity of the potentially toxic elements followed the order EDTA > DTPA > NH4NO3 > CaCl2 > NaNO3 for both studied areas. Pearson's correlation coefficient analysis between the concentrations of potentially toxic elements accumulated in bean primary leaves or their mineral mass with their extractable concentrations showed a positive significant correlation with dilute CaCl2 and nitrate solutions extraction procedures. In contrast, for all studied elements, except Pb, the complexing and chelating extractants (EDTA and DTPA) exhibited poor correlation with the dwarf bean leaves concentrations. Moreover, results showed that the 0.01 M CaCl2 extraction procedure was the most suitable and provided the most useful indications of metal phytoavailability for studied elements.

The remediation of copper-contaminated soils by aided phytostabilisation in 16 field plots at a wood preservation site was investigated. The mobility and bioavailability of four potentially toxic trace elements (PTTE), i.e., Cu, Zn, Cr, and As, were investigated in these soils 4 years after the incorporation of compost (OM, 5 % w/w) and dolomite limestone (DL, 0.2 % w/w), singly and in combination (OMDL), and the transplantation of mycorrhizal poplar and willows. Topsoil samples were collected in all field plots and potted in the laboratory. Total PTTE concentrations were determined in soil pore water (SPW) collected by Rhizon soil moisture samplers. Soil exposure intensity was assessed by Chelex100-DGT (diffusive gradient in thin films) probes. The PTTE phytoavailability was characterized by growing dwarf beans on potted soils and analyzing their foliar PTTE concentrations. OM and DL, singly and in combination (OMDL), were effective to decrease foliar Cu, Cr, Zn, and As concentrations of beans, the lowest values being numerically for the OM plants. The soil treatments did not reduce the Cu and Zn mineral masses of the bean primary leaves, but those of Cr and As decreased for the OM and DL plants. The Cu concentration in SPW was increased in the OM soil and remained unchanged in the DL and OMDL soils. The available Cu measured by DGT used to assess the soil exposure intensity correlated with the foliar Cu concentration. The Zn concentrations in SPW were reduced in the DL soil. All amendments increased As in the SPW. Based on DGT data, Cu availability was reduced in both OM and OMDL soils, while DL was the most effective to decrease soil Zn availability.

The efficiency of aided phytostabilization using organic amendments such as ramial chipped wood (RCW) and composted sewage sludge (CSS) was studied on contaminated techno-soils, on nine experimental plots. The objective was to characterize the role of fulvic (FA) and humic acids (HA) on the mobilization of trace elements, specifically As, Cu, Mo, Pb and Zn. Results showed that the addition of CSS increased the total organic carbon and nitrogen content more than with RCW and as a result, the C/N ratio in the CSS soil was higher than in the RCW and non-amended (NE) soil, reflecting the high decomposition of soil organic matter in the CSS soil compared with the other soils. The RCW and CSS amendments increased the hydrogen index (HI) values and the oxygen index (OI) values compared with the NE soil, especially for the soil treated with CSS which contained more aliphatic than aromatic compounds. The addition of CSS to the techno-soil significantly increased the percentage of C org associated with the HA fractions compared with the RCW and NE soils. The soil amended with CSS showed the highest E 4/E 6 ratio and the lowest E 2/E 3 ratio of FA. Zn and As were more abundant in the FA fraction than in the HA fraction, whereas Pb, Cu and Mo were more associated to HA than to FA in the treated and untreated soils, which may explain the difference in their mobility and availability.

This study reports the chemical fractionation of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated technosoils of two former smelting and mining areas using two sequential extraction schemes. The extraction schemes used in this study were the Tessier's scheme and a modified BCR scheme. The fractions were rearranged into four equivalent fractions defined as acid soluble, reducible, oxidizable, and residual to compare the results obtained from two sequential extraction schemes. Surface soils were samples from a waste landfill contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (MDN; North France) and from a settling basin contaminated with PTE such as As, Pb, and Sb located at La Petite Faye (LPF; Limoges, France). The study of the Zn, Pb, Cd, As, and Sb partitioning in the acid soluble, reducible, oxidizable, and residual fractions of the technosoils revealed that Zn, Cd, and Pb were mainly associated with the acid soluble and reducible fractions for MDN site, while As, Sb, and Pb were associated with residual fraction for LPF site. Fractionation results indicate that the percentages of Zn, Pb, Cd, As, and Sb extracted in Fe-Mn oxide bound fraction of Tessier's scheme were always higher than those extracted by modified BCR scheme. This may be attributed to the stronger Tessier's scheme conditions used to extract this fraction. In contrast the percentages of Zn, Pb, Cd, As, and Sb extracted in the organic fraction of the modified BCR scheme were always higher than those of the Tessier's scheme. The order of mobility of PTE was as follows: Cd > Zn > Pb in MDN site and As > Sb > Pb in LPF site. PTE were distributed in all soil fractions, with the most relevant enrichments in extractable and residual fractions. A significant amount of Cd, Pb, and Zn were rather mobile, which suggests that these elements can be readily available to plants and soil organisms.

The aim of this study was to obtain saccharide (dextran and sucrose)-coated maghemite nanoparticles with antibacterial activity. The polysaccharide-coated maghemite nanoparticles were synthesized by an adapted coprecipitation method. X-ray diffraction (XRD) studies demonstrate that the obtained polysaccharide-coated maghemite nanoparticles can be indexed into the spinel cubic lattice with a lattice parameter of 8.35 Å. The refinement of XRD spectra indicated that no other phases except the maghemite are detectable. The characterization of the polysaccharide-coated maghemite nanoparticles by various techniques is described. The antibacterial activity of these polysaccharide-coated maghemite nanoparticles (NPs) was tested against Pseudomonas aeruginosa 1397, Enterococcus faecalis ATCC 29212, Candida krusei 963, and Escherichia coli ATCC 25922 and was found to be dependent on the polysaccharide type. The antibacterial activity of dextran-coated maghemite was significantly higher than that of sucrose-coated maghemite. The antibacterial studies showed the potential of dextran-coated iron oxide NPs to be used in a wide range of medical infections.

Purpose: A former wood exploitation revealing high Cu and As concentration of the soils served as a case study for assisted phytoextraction., Method: P-spiked Linz-Donawitz (LD) slag was used as a soil additive to improve physico-chemical soil properties and in situ stabilize Cu and other trace metals in a sandy Cu-contaminated soil (630 mg kg⁻¹ soil). The LD slag was incorporated into the contaminated soil to consist four treatments: 0% (T1), 1% (T2), 2% (T3), and 4% (T4). A similar uncontaminated soil was used as a control (CTRL). After a 1-month reaction period, potted soils were used for a 2-week growth experiment with dwarf beans., Results: Soil pH increased with the incorporation rate of LD slag. Similarly the soil electrical conductivity (EC, in millisiemens per centimetre) is ameliorated. Bean plants grown on the untreated soil (T1) showed a high phytotoxicity. All incorporation rates of LD slag increased the root and shoot dry weight yields compared to the T1. The foliar Ca concentration of beans was enhanced for all LD slag-amended soil, while the foliar Mg, K, and P concentrations were not increased. Foliar Cu, Zn, and Cr concentrations of beans decreased with the LD slag incorporation rate., Conclusions: P-spiked LD slag incorporation into polluted soil allow the bean growth and foliar Ca concentration, but also to reduce foliar Cu concentration below its upper critical value avoiding an excessive soil EC and Zn deficiency. This dual effect can be of interest for soil remediation at larger scale.

It is commonly assumed that iteroparous fish, once mature, normally reproduce in all consecutive seasons. Recent work has suggested, however, that in Norwegian spring-spawning herring-a population that undertakes extensive spawning migrations-almost one in two adults may skip their second spawning migration. Why should herring not return to spawn the year after first spawning, but instead wait an extra year? For herring, participation in distant, energetically costly, and risky spawning migrations will only pay off in terms of fitness if individuals are sufficiently large, and in sufficient condition, to both successfully migrate and spawn. Changes in the environment and individual condition should therefore affect the likelihood of skipped spawning. This paper describes long-term changes in the extent to which the second reproductive season is skipped in this herring population. These are shown to be linked to the size and condition of herring as first-time spawners, and to climatic factors possibly related to food availability. The findings corroborate the hypothesis that skipped reproduction results from trade-offs between current and future reproduction, growth and survival.

We explore evolutionarily stable co-evolution of host-macroparasite++ interactions in a discrete-time two-species population dynamics model, in which the dynamics may be stable, cyclic or chaotic. The macroparasites are assumed to harm host individuals through decreased reproductive output. Hosts may develop costly immune responses to defend themselves against parasites. Parasites compete with conspecifics by adjusting their fecundities. Overall, the presence of both parasites and the immune response in hosts produces more stable dynamics and lower host population sizes than that observed in the absence of the parasites. In our evolutionary analyses, we show that maximum parasite fecundity is always an evolutionarily stable strategy (ESS), irrespective of the type of population interaction, and that maximum parasite fecundity generally induces a minimum parasite population size through over-exploitation of the host. Phenotypic polymorphisms with respect to immunity in the host species are common and expected in ESS host strategies: the benefits of immunication depend on the frequency of the immune hosts in the population. In particular, the steady-state proportions of immune hosts depend, in addition to all the parameters of the parasite dynamics only on the cost of immunity and on the virulence of parasites in susceptible hosts. The implicit ecological dynamics of the host-parasite interaction affect the proportion of immune host individuals in the population. Furthermore, when changes in certain population parameters cause the dynamics of the host-parasite interaction to move from stability to cyclicity and then to chaos, the proportion of immune hosts tend to decrease; however, we also detected counter-examples to this result. As a whole, incorporating immunological and genetic aspects, as well as life-history trade-offs, into host-macroparasite dynamics produces a rich extension to the patterns observed in the models of ecological interactions and epidemics, and deserves more attention than is currently the case.