Spatial distribution of mercury in topsoil from five regions of China

The concentrations and distributions of mercury (Hg) in topsoil from four provinces and one municipality in China were investigated. A total of 1,254 samples were collected and analyzed. The average concentrations of Hg were 0.064 mg kg^?1 for Liaoning Province, 0.100 mg kg^?1 for Jiangsu Province, 0.110 mg kg^?1 for Zhejiang Province, 0.154 mg kg^?1 for Sichuan Province, and 0.098 mg kg^?1 for Chongqing Municipality. Although differences were found among the ranges of Hg concentrations, the average values for each region were similar with other published data. The concentrations of Hg in topsoil varied largely upon the sampling locations. More than 80 % of the soil samples from Liaoning Province, Jiangsu Province, Zhejiang Province, and Chongqing Municipality, were ranked Grade I by the China Environmental Quality Standard for Soils, which can be considered as not contaminated by Hg. The concentrations of Hg in 0.3–0.4 % of soils collected from Jiangsu Province, Zhejiang Province and Chongqing Municipality exceeded the limitation for Grade III, indicating the contamination of Hg in these sites. The sources and potential risks of Hg in these sites should be brought to attention and further investigated.     

Distribution of potentially toxic elements (PTEs) in tailings,soils, and plants around Gol-E-Gohar iron mine,a case study in Iran

This study investigated the concentration of potentially toxic elements (PTEs) including Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, V, and Zn in 102 soils (in the Near and Far areas of the mine), 7 tailings, and 60 plant samples (shoots and roots of Artemisia sieberi and Zygophylum species) collected at the Gol-E-Gohar iron ore mine in Iran. The elemental concentrations in tailings and soil samples (in Near and Far areas) varied between 7.4 and 35.8 mg kg^?1 for As (with a mean of 25.39 mg kg^?1 for tailings), 7.9 and 261.5 mg kg^?1 (mean 189.83 mg kg^?1 for tailings) for Co, 17.7 and 885.03 mg kg^?1 (mean 472.77 mg kg^?1 for tailings) for Cu, 12,500 and 400,000 mg kg^?1 (mean 120,642.86 mg kg^?1 for tailings) for Fe, and 28.1 and 278.1 mg kg^?1 (mean 150.29 mg kg^?1 for tailings) for Ni. A number of physicochemical parameters and pollution index for soils were determined around the mine. Sequential extractions of tailings and soil samples indicated that Fe, Cr, and Co were the least mobile and that Mn, Zn, Cu, and As were potentially available for plants uptake. Similar to soil, the concentration of Al, As, Co, Cr, Cu, Fe, Mn, Mo, Ni, and Zn in plant samples decreased with the distance from the mining/processing areas. Data on plants showed that metal concentrations in shoots usually exceeded those in roots and varied significantly between the two investigated species (Artemisia sieberi > Zygophylum). All the reported results suggest that the soil and plants near the iron ore mine are contaminated with PTEs and that they can be potentially dispersed in the environment via aerosol transport and deposition.     

Local deposition of mercury in topsoils around coal-fired power plants: is it always true?

Mercury (Hg) is a toxic element that is emitted to the atmosphere through human activities, mainly fossil fuel combustion. Hg accumulations in soil are associated with atmospheric deposition, while coal-burning power plants remain the most important source of anthropogenic mercury emissions. In this study, we analyzed the Hg concentration in the topsoil of the Kozani–Ptolemais basin where four coal-fired power plants (4,065 MW) run to provide 50 % of electricity in Greece. The study aimed to investigate the extent of soil contamination by Hg using geostatistical techniques to evaluate the presumed Hg enrichment around the four power plants. Hg variability in agricultural soils was evaluated using 276 soil samples from 92 locations covering an area of 1,000 km². We were surprised to find a low Hg content in soil (range 1–59 μg kg^?1) and 50 % of samples with a concentration lower than 6 μg kg^?1. The influence of mercury emissions from the four coal-fired power plants on soil was poor or virtually nil. We associate this effect with low Hg contents in the coal (1.5–24.5 μg kg^?1) used in the combustion of these power plants (one of the most Hg-poor in the world). Despite anthropic activity in the area, we conclude that Hg content in the agricultural soils of the Kozani–Ptolemais basin is present in low concentrations.     

Soil pH and Anion Abundance Affects on Copper Adsorption

Abstract

Copper (Cu) input to agricultural soils results from Cu containing pesticides and/or that in soil amendments, such as manure or sewage sludge. Soil and soil solution properties influence the adsorption and desorption of Cu by the soil, which in turn determines its plant availability and/or phytotoxicities. Effects of different anion enrichment in the equilibrium solution on Cu adsorption by different soils (pH range of 6.2–9.9) were investigated in this study over a range of Cu concentrations. With Cu concentrations in the range of 0–100 mg L^?1 in the equilibration solution, 95–99% of applied Cu was adsorbed by all three soils. The adsorption of Cu was similar regardless of using either 0.01 M CaCl₂ or Ca(NO₃)₂ as the equilibration solution. When the Cu concentration in the equilibration solution was further increased in the range of 500–2000 mg L^?1, the adsorption of Cu decreased from 60 to 24% of applied Cu in two soils with pH 6.2–7.9. In a high pH soil (pH = 9.9), the Cu adsorption decreased from 77 to 34%. Addition of incinerated sewage sludge (ISS) to a Palouse silt loam soil (pH = 6.2) increased the Cu adsorption as compared to that by unamended soil. This was, in part, due to an increase in the soil suspension pH with ISS amendment.     

Half a century of changing mercury levels in Swedish freshwater fish

The variability of mercury (Hg) levels in Swedish freshwater fish during almost 50 years was assessed based on a compilation of 44 927 observations from 2881 waters. To obtain comparable values, individual Hg concentrations of fish from any species and of any size were normalized to correspond to a standard 1-kg pike [median: 0.69 mg kg^?1 wet weight (ww), mean ± SD: 0.84 ± 0.67 mg kg^?1 ww]. The EU Environmental Quality Standard of 0.02 mg kg^?1 was exceeded in all waters, while the guideline set by FAO/WHO for Hg levels in fish used for human consumption (0.5–1.0 mg kg^?1) was exceeded in 52.5 % of Swedish waters after 2000. Different trend analysis approaches indicated an overall long-term decline of at least 20 % during 1965–2012 but trends did not follow any consistent regional pattern. During the latest decade (2003–2012), however, a spatial gradient has emerged with decreasing trends predominating in southwestern Sweden.     

Phytoremediation for co-contaminated soils of chromium and benzo[a]pyrene using Zea mays L.

A greenhouse experiment was carried out to investigate the single effect of benzo[a]pyrene (B[a]P) or chromium (Cr) and the joint effect of Cr–B[a]P on the growth of Zea mays, its uptake and accumulation of Cr, and the dissipation of B[a]P over 60 days. Results showed that single or joint contamination of Cr and B[a]P did not affect the plant growth relative to control treatments. However, the occurrence of B[a]P had an enhancing effect on the accumulation and translocation of Cr. The accumulation of Cr in shoot of plant significantly increased by?≥?79 % in 50 mg kg^?1 Cr–B[a]P (1, 5, and 10 mg kg^?1) treatments and by?≥?86 % in 100 mg kg^?1 Cr–B[a]P (1, 5, and 10 mg kg^?1) treatments relative to control treatments. The presence of plants did not enhance the dissipation of B[a]P in lower (1and 5 mg kg^?1) B[a]P contaminated soils; however, over 60 days of planting Z. mays seemed to enhance the dissipation of B[a]P by over 60 % in 10 mg kg^?1 single contaminated soil and by 28 to 41 % in 10 mg kg^?1B[a]P co-contaminated soil. This suggests that Z. mays might be a useful plant for the remediation of Cr–B[a]P co-contaminated soil.     

Responses of earthworm to aluminum toxicity in latosol

Excess aluminum (Al) in soils due to acid rain leaching is toxic to water resources and harmful to soil organisms and plants. This study investigated adverse impacts of Al levels upon earthworms (Eisenia fetida) from the latosol (acidic red soil). Laboratory experiments were performed to examine the survival and avoidance of earthworms from high Al concentrations and investigate the response of earthworms upon Al toxicity at seven different Al concentrations that ranged from 0 to 300 mg kg^?1 over a 28-day period. Our study showed that the rate of the earthworm survival was 100 % within the first 7 days and decreased as time elapsed, especially for the Al concentrations at 200 and 300 mg kg^?1. A very good linear correlation existed between the earthworm avoidance and the soil Al concentration. There was no Al toxicity to earthworms with the Al concentration ≤50 mg kg^?1, and the toxicity started with the Al concentration ≥100 mg kg^?1. Low Al concentration (i.e., <50 mg kg^?1) enhanced the growth of the earthworms, while high Al concentration (>100 mg kg^?1) retarded the growth of the earthworms. The weight of earthworms and the uptake of Al by earthworms increased with the Al concentrations from 0 to 50 mg kg^?1 and decreased with the Al concentrations from 50 to 300 mg kg^?1. The protein content in the earthworms decreased with the Al concentrations from 0 to 100 mg kg^?1 and increased from 100 to 300 mg kg^?1. In contrast, the catalase (CAT) and superoxide dismutase (SOD) activities in the earthworms increased with the Al concentrations from 0 to 100 mg kg^?1 and decreased from 100 to 300 mg kg^?1. The highest CAT and SOD activities and lowest protein content were found at the Al concentration of 100 mg kg^?1. Results suggest that a high level of Al content in latosol was harmful to earthworms.     

Chemical properties of dissolved organic matter derived from sugarcane rind and the impacts on copper adsorption onto red soil

Dissolved organic matter (DOM), as the most active organic carbon in the soil, has a coherent affinity with heavy metals from inherent and exogenous sources. Although the important roles of DOM in the adsorption of heavy metals in soil have previously been demonstrated, the heterogeneity and variability of the chemical constitution of DOM impede the investigation of its effects on heavy metal adsorption onto soil under natural conditions. Fresh DOM (FDOM) and degraded DOM (DDOM) from sugarcane rind were prepared, and their chemical properties were measured by Fourier-transform infrared spectrometry (FTIR), excitation-emission matrix (EEM) fluorescence spectroscopes, nuclear magnetic resonance (NMR), and molecular weight distribution (MWD). They were also used in batch experiments to evaluate their effects on the adsorption of Cu(II) onto farmland red soil. Based on our results, the chemical structure and composition of DDOM greatly varied; compared with FDOM, the C/O ratio (from 24.0 to 9.6%) and fluorescence index (FI) (from 1.4 to 1.0) decreased, and high molecular weight (>10 kDa) compounds increased from 23.18 to 70.51%, while low molecular weight (<3 kDa) compounds decreased from 56.13 to 12.13%; aromaticity and humification degree were markedly enhanced. The discrepancy of FDOM and DDOM in terms of chemical properties greatly influenced Cu(II) adsorption onto red soil by affecting DOM-Cu(II) complex capacity. The FDOM inhibited the adsorption of Cu(II), while DDOM promoted adsorption, which was significantly influenced by soil pH. Maximum adsorption capacity (Q _m) was 0.92 and 5.76 mg g^?1 in the presence of FDOM and DDOM, respectively. The adsorption process with DDOM could be better described by the Langmuir model, while that with FDOM was better described by the Freundlich model. The impacts caused by the dynamic changes of the chemical properties of DOM under natural conditions should therefore be considered in the risk assessment and remediation of soils contaminated with heavy metals.     

Dissipation of spiromesifen and spiromesifen-enol on tomato fruit,tomato leaf,and soil under field and controlled environmental conditions

Dissipation of spiromesifen and its metabolite, spiromesifen-enol, on tomato fruit, tomato leaf, and soil was studied in the open field and controlled environmental conditions. Sample preparation was carried out by QuEChERS method and analysis using LC-MS/MS. Method validation for analysis of the compounds was carried out as per “single laboratory method validation guidelines.” Method validation studies gave satisfactory recoveries for spiromesifen and spiromesifen-enol (71.59–105.3%) with relative standard deviation (RSD) < 20%. LOD and LOQ of the method were 0.0015 μg mL^?1 and 0.005 mg kg^?1, respectively. Spiromesifen residues on tomato fruits were 0.855 and 1.545 mg kg^?1 in open field and 0.976 and 1.670 mg kg^?1 under polyhouse condition, from treatments at the standard and double doses of 125 and 250 g a.i. ha^?1, respectively. On tomato leaves, the residues were 5.64 and 8.226 mg kg^?1 in open field and 6.874 and 10.187 mg kg^?1 in the polyhouse. In soil, the residues were 0.532 and 1.032 mg kg^?1 and 0.486 and 0.925 mg kg^?1 under open field and polyhouse conditions, respectively. The half-life of degradation of spiromesifen on tomato fruit was 6–6.5 days in the open field and 8.1–9.3 days in the polyhouse. On tomato leaves, it was 7–7.6 and 17.6–18.4 days and in soil 5.6–7.4 and 8.4–9.5 days, respectively. Metabolite, spiromesifen-enol, was not detected in any of the sample throughout the study period. Photodegradation could be the major route for dissipation of spiromesifen in the tomato leaves, whereas in the fruits, it may be the combination of photodegradation and dilution due to fruit growth. The results of the study can be utilized for application of spiromesifen in plant protection of tomato crop under protected environmental conditions.     

Influence of ciprofloxacin on the microbial catabolic diversity in soil

In this study, the effect of ciprofloxacin (CIP) on the catabolic diversity of soil microbial communities was evaluated. Soil samples were spiked with ciprofloxacin (0, 1, 5 and 50 mg?kg^?1) and were incubated for 1, 3, 9, 22 and 40 days. Untreated controls received only water. The functional diversity of the microbial community studied was characterized using a catabolic response profile (CRP). Six substrate groups were tested: carbohydrates, amino acids, carboxylic acids, aromatic chemicals, alcohols and polymers. After 40 days, the CIP concentrations in the soil samples ranged from 25% to 58% of the initial concentrations. Soil respiratory responses to the individual substrates D-glucose, lactose, D-mannose, L-glutamic, Na-citrate, malic acid and inosine were inhibited at the high CIP concentrations (5 and 50 mg·kg^?1) in the soils and were increased at the lowest CIP concentration (1 mg·kg^?1). Soil respiration was inhibited at all of the CIP concentrations after the addition of D-galactose and glycerol. The CIP concentration and incubation time explained 45.3% of the variance of the catabolic responses. The CRP analysis clearly discriminated among the different CIP concentrations. The results suggest that CIP strongly affects the catabolic diversities of soil microbial communities and that its effect is more significant than that of incubation time.     

Adsorption of lambda-cyhalothrin and cypermethrin on two typical Chinese soils as affected by copper

Background, aim, and scope  Pesticides and heavy metals pollution in soil environment has become a serious problem in many countries including China. Repeated applications of bordeaux mixture (a blend of copper sulfate and calcium hydroxide) and pyrethroid (Pys) insecticides have led to elevated copper (Cu) and Pys concentrations in vineyard surface soils. However, few studies focused on the interaction of Pys and heavy metals in the soil environment. Our previous studies had indicated the combined effect of cypermethrin (CPM) and Cu on soil catalase activity. Also, we had suggested that the addition of Cu could catalyze photo-degradation of CPM and lambda-cyhalothrin (λ-CHT) in aqueous solution and restrain their degradation in soil. To better understand the potential influence of Cu on the fate of Pys in the soil environment, the aim of the present work was to examine the effect of Cu on the adsorption of λ-CHT and CPM on two typical Chinese soils with different soil characteristics, which was one of the key processes controlling the fate of Pys, and to provide more information about the potential ecological risk of chemicals on the soil ecosystem. Fourier transform infrared and point charges analysis using the MOPAC program of the Gaussian system were also used to reveal the probable adsorption mechanism of λ-CHT and CPM on soils. Materials and methods  Two vineyard soils with different properties were chosen as experimental samples. They were sampled from 0 to 10 cm, dried, and sieved to 2 mm. Each soil was spiked with copper sulfate solution to obtain the following total soil Cu concentrations: 100, 200, 400, 800, and 1,600 mg·kg⁻¹. The treated soils were incubated for 2 weeks and then dried at 20°C. For each soil sample and at each soil Cu concentration, the adsorption of λ-CHT and CPM was measured using a batch equilibrium method. The concentration of λ-CHT was determined by HPLC, and the amount of λ-CHT and CPM adsorbed by the soil sample at equilibrium was determined by the difference between the initial and equilibrium concentrations in solution corrected by the blank adsorption measurement. Results  Without the addition of Cu, the adsorption of λ-CHT and CPM on Black soil is greater than that on Red soil, while the adsorption of λ-CHT on both soils is significantly stronger than that of CPM. As the soil Cu concentration increased from 19 (or 18; background) to 1,600 mg·kg⁻¹, the adsorption coefficient (K _d) of λ-CHT decreased from 12.2 to 5.9 L·kg⁻¹ for Red soil, and from 26.1 to 16.8 L·kg⁻¹ for Black soil, whereas the CPM adsorption coefficient in both soils decreased nearly by 100% (K _d decreased from 9.4 to 0.2 L·kg⁻¹ for Red soil and from 16.2 to 0.5 L·kg⁻¹ for Black soil). Discussion  Pys adsorption is a surface phenomenon which depends on the surface area and the organic matter content. Thus, the Black soil, having higher organic matter and greater surface area than that of the Red soil, show greater adsorption affinity to λ-CHT and CPM. In our study, the different adsorption affinity of the two Pys was obtained, which was probably attributed to differences with respect to their physical–chemical properties. Further comparison upon the two Pys was conducted. The point charges of halogen atoms in the λ-CHT and CPM were calculated, the differences of which probably lead to the fact that λ-CHT has a stronger binding capacity to soils than CPM. Also, FTIR spectra show that competitive adsorption occurs between CPM and Cu for the same adsorption sites, which is responsible for the obtained suppression of CPM adsorption affected by Cu. Conclusions  Lambda-cyhalothrin shows a significantly stronger adsorption than cypermethrin on both soils. This phenomenon may be due to several reasons: (1) λ-CHT has lower solubility and a higher octanol–water partition coefficient value than CPM; (2) λ-CHT consists of specific isomers, whereas CPM is mixtures of eight different isomers; (3) the chlorine and fluorine atoms in the λ-CHT have a negative point charge, whereas the chlorine atoms in the CPM have a positive point charge. As the soil Cu concentrations increased from 19 (or 18) mg·kg⁻¹ to 1,600 mg·kg⁻¹, the adsorption coefficient of λ-CHT and CPM decreased on both soils. This is mainly due to a competition between Cu and Pys for occupying the adsorption sites on soils. The information from this study have important implications for vineyard and orchard soils, which often contain elevated levels of Cu and Pys. These results are also useful in assessing the environmental fate and health effect of λ-CHT and CPM. Recommendations and perspectives  It is important for environmental scientists and engineers to get a better understanding of soil–metal–organic contaminant interactions. However, pesticide adsorption involves complex processes, and shortcomings in understanding them still restrict the ability to predict the fate and behavior of pesticide. Therefore, considerable research should be carried out to understand the mechanism of interaction between Pys and heavy metal on soils clearly.     

Detection and quantification of chlordecone in contaminated soils from the French West Indies by GC-MS using the 13C10-chlordecone stable isotope as a tracer

Chlordecone is an organochlorine insecticide that has been widely used to control banana weevil in the French West Indies. As a result of this intense use, up to 20,000 ha are contaminated by this insecticide in the French West Indies, and this causes environmental damage and health problems. A scenario of exposure was drawn by French authorities, based on land usage records. Many efforts have been made to monitor the occurrence of chlordecone and its main metabolites using different analytical methods, including GC, GC/MS, LC/MS, and NIRS. Although these different methods allow for the detection and quantification of chlordecone from soils, none of them estimate the bottleneck caused by extraction of this organochlorine from soils with high adsorption ability. In this study, we used ¹³C₁₀-chlordecone as a tracer to estimate chlordecone extraction yield and to quantify chlordecone in soil extracts based on the ¹³C/¹²C isotope dilution. We report the optimization of ¹³C₁₀-chlordecone extraction from an Andosol. The method was found to be linear from 0.118 to 43 mg kg^?1 in the Andosol, with an instrumental detection limit estimated at 8.84 μg kg^?1. This method showed that chlordecone ranged from 35.4 down to 0.18 mg kg^?1 in Andosol, Nitisol, Ferralsol, and Fluvisol soil types. Traces of the metabolite β-monohydrochlordecone were detected in the Andosol, Nitisol, and Ferralsol soil samples. This last result indicates that this method could be useful to monitor the fate of chlordecone in soils of the French West Indies.     

Heavy metal accumulation by poplar in calcareous soil with various degrees of multi-metal contamination: implications for phytoextraction and phytostabilization

The object of this study was to assess the capacity of Populus alba L. var. pyramidalis Bunge for phytoremediation of heavy metals on calcareous soils contaminated with multiple metals. In a pot culture experiment, a multi-metal-contaminated calcareous soil was mixed at different ratios with an uncontaminated, but otherwise similar soil, to establish a gradient of soil metal contamination levels. In a field experiment, poplars with different stand ages (3, 5, and 7 years) were sampled randomly in a wastewater-irrigated field. The concentrations of cadmium (Cd), Cu, lead (Pb), and zinc (Zn) in the poplar tissues and soil were determined. The accumulation of Cd and Zn was greatest in the leaves of P. pyramidalis, while Cu and Pb mainly accumulated in the roots. In the pot experiment, the highest tissue concentrations of Cd (40.76 mg kg^?1), Cu (8.21 mg kg^?1), Pb (41.62 mg kg^?1), and Zn (696 mg kg^?1) were all noted in the multi-metal-contaminated soil. Although extremely high levels of Cd and Zn accumulated in the leaves, phytoextraction using P. pyramidalis may take at least 24 and 16 years for Cd and Zn, respectively. The foliar concentrations of Cu and Pb were always within the normal ranges and were never higher than 8 and 5 mg kg^?1, respectively. The field experiment also revealed that the concentrations of all four metals in the bark were significantly higher than that in the wood. In addition, the tissue metal concentrations, together with the NH₄NO₃-extractable concentrations of metals in the root zone, decreased as the stand age increased. P. pyramidalis is suitable for phytostabilization of calcareous soils contaminated with multiple metals, but collection of the litter fall would be necessary due to the relatively high foliar concentrations of Cd and Zn.     

Ecotoxicological effects on the earthworm Eisenia fetida following exposure to soil contaminated with imidacloprid

Imidacloprid, a neonicotinoid insecticide, has been used widely in agriculture worldwide. The adverse effects of imidacloprid on exposed biota have brought it increasing attention. However, knowledge about the effects of imidacloprid on antioxidant defense systems and digestive systems in the earthworm is vague and not comprehensive. In the present study, the changes in the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), cellulase, reactive oxygen species (ROS), and malondialdehyde (MDA) in the earthworm Eisenia fetida exposed to artificial soil treated with imidacloprid were examined systematically. The results showed that the activity of these biomarkers was closely related to the dose and duration of the exposure to imidacloprid. The activity of SOD was stimulated significantly at doses of 0.66 and 2 mg kg^?1 imidacloprid but markedly inhibited at a dose of 4 mg kg^?1 imidacloprid with prolonged exposure. The activities of CAT and POD increased irregularly at 0.2–4 mg kg^?1 imidacloprid over different exposure times. The level of ROS at a dose of 2 or 4 mg kg^?1 imidacloprid was significantly increased over the entire exposure period. When the concentration of imidacloprid was above 0.66 mg kg^?1, the balance of the activity of the antioxidant enzymes and ROS level was interrupted. The activity of cellulase decreased significantly with prolonged exposure. At the stress of 4 mg kg^?1 imidacloprid, the content of MDA was significantly increased with increasing exposure time. The results of the present study suggest that imidacloprid has a potentially harmful effect on E. fetida and may be helpful for assessment of the risk of imidacloprid to the soil ecosystem environment. However, to obtain more comprehensive toxicity data, it is necessary to investigate the effects of imidacloprid on earthworm using native soils in the future work.     

Dissipation of available benzo[a]pyrene in aging soil co-contaminated with cadmium and pyrene

A microcosm experiment was conducted to investigate the dissipation of available benzo[a]pyrene (BaP) in soils co-contaminated with cadmium (Cd) and pyrene (PYR) during aging process. The available residue of BaP in soil was separated into desorbing and non-desorbing fractions. The desorbing fraction contributed more to the dissipation of available BaP than the non-desorbing fraction did. The concentration of bound-residue fraction of BaP was quite low across all treatments. Within the duration of this study (250 days), transformation of BaP from available fractions to bound-residue fraction was not observed. Microbial degradation was the dominant mechanism of the dissipation of available BaP in the soil. The dissipation of available BaP was significantly inhibited with the increment in Cd level in the soil. The addition of PYR (250 mg kg^?1) remarkably promoted the dissipation of available BaP without reducing Cd availability in the soil. The calculated half-life of available BaP in the soil prolonged with the increment in Cd level; however, the addition of PYR shortened the half-life of available BaP by 13.1, 12.7, and 32.8 % in 0.44, 2.56, and 22 mg Cd kg^?1 soils, respectively. These results demonstrated that the inhibiting effect of Cd and the promoting effect of PYR on the dissipation of available BaP were competitive. Therefore, this study shows that the bioremediation process of BaP can be more complicated in co-contaminated soils.     

Bioremediation of Cd and carbendazim co-contaminated soil by Cd-hyperaccumulator Sedum alfredii associated with carbendazim-degrading bacterial strains

The objective of this study was to develop a bioremediation strategy for cadmium (Cd) and carbendazim co-contaminated soil using a hyperaccumulator plant (Sedum alfredii) combined with carbendazim-degrading bacterial strains (Bacillus subtilis, Paracoccus sp., Flavobacterium and Pseudomonas sp.). A pot experiment was conducted under greenhouse conditions for 180 days with S. alfredii and/or carbendazim-degrading strains grown in soil artificially polluted with two levels of contaminants (low level, 1 mg kg^?1 Cd and 21 mg kg^?1 carbendazim; high level, 6 mg kg^?1 Cd and 117 mg kg^?1 carbendazim). Cd removal efficiencies were 32.3–35.1 % and 7.8–8.2 % for the low and high contaminant level, respectively. Inoculation with carbendazim-degrading bacterial strains significantly (P?<?0.05) increased Cd removal efficiencies at the low level. The carbendazim removal efficiencies increased by 32.1–42.5 % by the association of S. alfredii with carbendazim-degrading bacterial strains, as compared to control, regardless of contaminant level. Cultivation with S. alfredii and inoculation of carbendazim-degrading bacterial strains increased soil microbial biomass, dehydrogenase activities and microbial diversities by 46.2–121.3 %, 64.2–143.4 %, and 2.4–24.7 %, respectively. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis revealed that S. alfredii stimulated the activities of Flavobacteria and Bradyrhizobiaceae. The association of S. alfredii with carbendazim-degrading bacterial strains enhanced the degradation of carbendazim by changing microbial activity and community structure in the soil. The results demonstrated that association of S. alfredii with carbendazim-degrading bacterial strains is promising for remediation of Cd and carbendazim co-contaminated soil.     

Iron improving bio-char derived from microalgae on removal of tetracycline from aqueous system

Novel magnetic carbonaceous bio-char was hydrothermal prepared from microalgae under different loadings of iron and its structures and surface chemistry were characterized with Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and nitrogen adsorption-desorption isotherm (BET). The morphology of bio-char changed from sheet to particle as iron loading increased and its surface area also increased. When 3.0 g of dried microalgae and 6.0 mmol iron salt ((NH₄)₂SO₄·FeSO₄·6H₂O) were mixed and treated, the obtained bio-char possessing the highest amount of oxygen-containing functional groups resulted in the best adsorption performance on tetracycline (TC). This adsorption process was fitted to Langmuir adsorption isotherm and the maximum adsorption capacity was 95.86 mg/g, which is higher than other bio-char reported. The iron loading contributed to the higher adsorption capacity of bio-char, which may be due to three factors, the high surface area, more hydrogen bonding, and bridging effects of the structural Fe for TC. Our data suggest that bio-char may have more important role in stabilization of pollutants in the environment.     

Adsorption characteristics of Cu(II) from aqueous solution onto biochar derived from swine manure

The purpose of this study was to investigate adsorption characteristic of swine manure biochars pyrolyzed at 400 °C and 700 °C for the removal of Cu(II) ions from aqueous solutions. The biochars were characterized using BET surface area, Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy/energy dispersive spectrometer (SEM–EDS), and X-ray diffraction (XRD). The adsorption of Cu(II) ions by batch method was carried out and the optimum conditions were investigated. The adsorption processes of these biochars are well described by a pseudo-second-order kinetic model, and the adsorption isotherm closely fitted the Sips model. Thermodynamic analysis suggested that the adsorption was endothermic. The maximum Cu(II) adsorption capacities of biochars derived from fresh and composted swine manure at 400 °C were 17.71 and 21.94 mg g^?1, respectively, which were higher than those at 700 °C. XRD patterns indicated that the silicate and phosphate particles within the biochars served as adsorption sites for Cu(II). The removal of Cu(II) ions from industrial effluent indicated that the fresh swine manure biochar pyrolyzed at 400 °C can be considered as an effective adsorbent.     

Effect of deposit age on adsorption and desorption behaviors of ammonia nitrogen on municipal solid waste

Ammonia nitrogen pollution control is an urgent issue of landfill. This research aims to select an optimal refuse for ammonia nitrogen removal in landfill from the point of view of adsorption and desorption behavior. MSW (municipal solid waste) samples which deposit ages were in the range of 5 to 15 years (named as R₁₅, R₁₁, R₇, and R₅) were collected from real landfill site. The ammonia nitrogen adsorption behaviors of MSW including equilibrium time, adsorption isotherms, and desorption behaviors including equilibrium time were determined. Furthermore, the effects of pH, OM, Cu(II), Zn(II), and Pb(II) on adsorption and desorption behavior of ammonia nitrogen were conducted by orthogonal experiment. The equilibrium time of ammonia nitrogen adsorption by each tested MSW was very short, i.e., 20 min, whereas desorption process needed 24 h and the ammonia nitrogen released from refuses was much lesser than that adsorbed, i.e., accounted for 3.20 % (R₁₅), 14.32 % (R₁₁), 20.59 % (R₇), and 20.50 % (R₅) of each adsorption quantity, respectively. The maximum adsorption capacity estimated from Langmuir isotherm appeared in R₁₅-KCl, i.e., 25,000 mg kg^?1. The best condition for ammonia nitrogen removal from leachate was pH >7.5, OM 23.58 %, Cu(II) <5 mg L^?1, Zn(II) <10 mg L^?1, and Pb(II) <1 mg L^?1. Ammonia nitrogen in landfill leachate could be quickly and largely absorbed by MSW but slowly and infrequently released. The refuse deposited for 15 years could be a suitable material for ammonia nitrogen removal.     

Mercury in the Grisette,Amanita vaginata Fr. and soil below the fruiting bodies

This study examined the mercury concentration in the Grisette Amanita vaginata Fr. and soil below the fruiting bodies collected between 2000 and 2008 from the wild at seven distant sites across Poland. The Hg content in samples was determined by cold atomic absorption method (CV-AAS) at a wavelength of 253.7 nm. Mean Hg contents varied from 0.096 ± 0.052 to 0.48 ± 0.13 mg kg^?1 dry matter (dm) in caps (range, 0.043–0.73 mg kg^?1), from 0.047 ± 0.02 to 0.23 ± 0.07 mg kg^?1 dm (range, 0.028–0.47 mg kg^?1) in stipes, and in underlying soil were from 0.035 ± 0.018 to 0.096 ± 0.036 mg kg^?1 dm (range, 0.017 to 0.16 mg kg^?1). The median Qc/s values ranged from 1.2 to 2.2 (mean 1.2 ± 0.4 to 2.1 ± 0.5) indicating that Hg content in stipes was generally lower than in caps. This mushroom species has some potential to bioconcentrate Hg in the fruiting bodies, as the values of the bioconcentration factor (BCF) varied for the sites between 1.2 ± 0.6 to 11 ± 5 for caps and 0.61 ± 0.26 to 7.4 ± 3.9 for stipes. Also available literature data on Hg in A. vaginata are reviewed and discussed.