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Effects of the long-term application of atrazine on soil enzyme activity and bacterial community structure in farmlands in China Full text
2020
Liu, Yufei | Fan, Xiaoxu | Zhang, Tong | He, Wenyuan | Song, Fuqiang
Atrazine has been used on Chinese farmlands for a long time and over a wide range. The concentration of atrazine (1.86–1100 mg kg⁻¹) has exceeded the allowable limit in the soil (1.0 mg kg⁻¹), and concern is increasing about the potential harm to farmland soil. Four treatments (AT₀, AT₆, AT₁₀, AT₁₆) were established to reveal the effects of the long-term application of atrazine on soil health. The results showed a nonlinear regulation of the atrazine residue concentrations in the four treatments. The highest concentration of atrazine residue was in AT₆, at 167 mg kg⁻¹, and the lowest concentration of atrazine residue was in AT₁₆, at 102 mg kg⁻¹, but there was no significant difference between AT₁₀ and AT₁₆. The soil urease activity decreased significantly with the increase in the years of atrazine application, the saccharase and cellulase activities in the AT₆ were significantly higher than those observed in the other three treatments, the catalase activity gradually decreased with the increase in atrazine application years, and the activity in AT₆ was significantly higher than that in AT₁₆. A total of 238 genera were identified by Illumina MiSeq sequencing, and 28 dominant genera were screened. Atrazine significantly increased the relative abundance of Actinobacteria and contributed to the relative abundance of Rubrobacter, Blastococcus, Promicromonospora, Jiangella, Psychroglaciecola and Acetobacteraceae_uncultured, which exhibited significantly higher abundance in AT₁₆ than in AT₀. Although there were atrazine-degrading bacteria in the soil, and the atrazine residue decreased with the increase in application years, the concentration of the atrazine residue was still nearly 100 times higher than the allowable limit in the soil, which is a great threat to the soil health.
Show more [+] Less [-]Nitrogen and sulfur co-doped biochar derived from peanut shell with enhanced adsorption capacity for diethyl phthalate Full text
2020
Guo, Ruishui | Yan, Lili | Rao, Pinhua | Wang, Runkai | Guo, Xin
Doping of nitrogen and sulfur on biochar (NS-B) was investigated by a novel and improved method for diethyl phthalate (DEP) removal. The preparation parameters including pyrolysis temperature and size of peanut shell biochar as well as thiourea/biochar mass ratio were selected as independent variables at three levels by applying the Box-Behnken design. The ANOVA results indicated that thiourea/biochar mass ratio exhibited the most significant effect. The comprehensive effects of the three factors on DEP removal efficiency were further elaborated, combining with the characterization results of the obtained NS-B materials. The formation of the pyridinic N and oxidized S groups examined by XPS was responsible for enhancing the DEP removal efficiency. The adsorption kinetic model fitting illustrated that large micropores and numerous adsorption sites improved the adsorption capacity of NS-B. According to the adsorption isotherm model fitting, NS-B (temperature 375 °C, size 300 mesh and thiourea/biochar mass ratio 0.1) possessed much higher maximum adsorption capacity for DEP (14.34 mg g⁻¹) than biochar (6.57 mg g⁻¹). NS-B exhibited excellent reusability towards DEP removal after five times recycling. Moreover, NS-B also had the potential in peroxydisulfate activation. These findings provide new insights into the environmental implications of NS-B.
Show more [+] Less [-]Co-effect of minerals and Cd(II) promoted the formation of bacterial biofilm and consequently enhanced the sorption of Cd(II) Full text
2020
Xu, Shaozu | Xing, Yonghui | Liu, Song | Luo, Xuesong | Chen, Wenli | Huang, Qiaoyun
Heavy metal pollution is very common in soils. Soils are complex systems including minerals, bacteria, and various other substances. In Cd(II) contaminated soil, the combined effects of clay minerals and heavy metals on bacterial biofilm and Cd(II) adsorption are unappreciated. Our study showed that the combination of clay minerals (goethite, kaolinite, and montmorillonite) and heavy metals promoted Serratia marcescens S14 biofilm development significantly more than clay minerals or Cd(II) alone. The amount of biofilm after binary treatment with clay minerals and Cd(II) was 2.3–7.3 times than that in control. Mineral-induced cell death and the expression of the fimA, bsmA, and eps were key players in biofilm formation. Binary treatment with montmorillonite and Cd(II) significantly enhanced biofilm development and consequently increased the adsorption of Cd(II). Cd(II) removal is the result of co-adsorption of bacteria and minerals. Bacterial biofilm played an important role in Cd(II) adsorption. FTIR spectroscopy showed the components of biofilm were not affected by minerals and revealed the functional groups –OH, –NH, –CH₂, –SH, –COO participated in Cd(II) immobilization. Our findings are of fundamental significance for understanding how minerals and Cd(II) affect biofilms and thereby enhance Cd(II) adsorption and predicting the mobility and fate of heavy metals in heavy metal-contaminated soil.
Show more [+] Less [-]Effective degradation of phenol via catalytic wet peroxide oxidation over N, S, and Fe-tridoped activated carbon Full text
2020
Yang, Guo | Mo, Sha | Xing, Bo | Dong, Jingwen | Song, Xiang | Liu, Xingyong | Yuan, Jigang
The N, S, and Fe-tridoped carbon catalysts (NSFe-Cs), Fe/ACNS1 and Fe/ACNS2, were synthesized by wet impregnation with different concentration of ammonium ferrous sulfate solution. The prepared catalysts have a similar textural structure. The N species, S species, Feᴵᴵ and Feᴵᴵᴵ were simultaneously introduced onto the surface of catalysts. Comparison with the only Fe doped catalyst, NSFe-Cs showed greater stability and higher phenol removal in catalytic wet peroxide oxidation at different reaction condition. The main intermediates including p-hydroxybenzoic acid, formic acid, and maleic acid were determined in the treated wastewater. The high catalytic activity for NSFe-C was related to the ability of H₂O₂ decomposition. NSFe-Cs have more amount of Feᴵᴵ partially due to the formation of FeS₂, which promoted the decomposition of H₂O₂ on Fe/ACNS1 and Fe/ACNS2 surface. The generation of ·OH and ·HO₂/·O₂⁻ radicals in the bulk solution was crucial to phenol degradation, and the decomposition of H₂O₂ complied with the pseudo-first-order kinetics. The highly linear relationship between decomposition kinetic constant for H₂O₂ and the amount of surface groups suggested, including Feᴵᴵ species, pyridinic N/Fe-bonded N, pyrrolic N as well as graphitic N were responsible to the high activity of NSFe-Cs.
Show more [+] Less [-]Carotenoid- but not melanin-based plumage coloration is negatively related to metal exposure and proximity to the road in an urban songbird Full text
2020
Grunst, Melissa L. | Grunst, Andrea S. | Pinxten, Rianne | Bervoets, Lieven | Eens, Marcel
Rapid urbanization is a global phenomenon that is increasingly exposing organisms to novel stressors. These novel stressors can affect diverse aspects of organismal function, including development of condition-dependent ornaments, which play critical roles in social and sexual selection. We investigated the relationship between metal pollution, proximity to roads, and carotenoid- and melanin-based plumage coloration in a common songbird, the great tit (Parus major). We studied populations located across a well-characterized metal pollution gradient and surrounded by roadway networks. Metal exposure and road-associated pollution could reduce carotenoid-based pigmentation by inducing oxidative stress or affecting habitat quality, but metals could also enhance melanin-based pigmentation, through effects on melanogenesis and testosterone concentrations. Using a large sample size (N > 500), we found that birds residing close to a point source for metals had reduced ultraviolet chroma, a component of carotenoid-based pigmentation. Moreover, birds with high feather metal concentrations had lower carotenoid chroma, hue, and ultraviolet chroma, with effects modified by age class. Birds residing closer to roads also had lower carotenoid chroma and hue. Melanin-based pigmentation showed high between-year repeatability, and no association with anthropogenic pollution. Results suggest that carotenoid-, but not melanin-, based pigmentation is negatively affected by multiple anthropogenic stressors. We are the first to demonstrate a negative association between roads and a plumage-based signaling trait, which could have important implications for sexual signaling dynamics in urban landscapes.
Show more [+] Less [-]Analysis of 58 poly-/perfluoroalkyl substances and their occurrence in surface water in a high-technology industrial park Full text
2020
Zheng, Pingping | Liu, Min | Yin, Haowen | Shen, Lu | Wang, Yingzhi | Wu, Qiang
Poly/perfluoroalkyl substances (PFASs) have some water solubility so that they are more liable to enter surface water. A comprehensive analysis method was established to analyze 17 classes of 58 PFASs in surface water by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) after automated solid phase extraction (SPE). The method showed acceptable recoveries and precision with recoveries of 60%–130% and RSD less than 30% with a few exceptions, and method detection limits (MDLs) of 0.004 ng/L-2.0 ng/L. It was investigated the surface water around Zhangjiang High-Technology Park in Shanghai. The concentration of ∑PFASs ranged from 115 ng/L to 600 ng/L. The main pollutant was perfluoro-3-methylheptanoic acid (P3MHpA), which is isopropyl isomer of perfluorooctanoic acid (PFOA), accounting 41.6% of ∑PFASs. It was detected in all samples and its level was far higher than that of PFOA with the maximum of 432 ng/L determined surrounding integrated circuits company. Short-chain perfluorocarboxylic acids (PFCAs) and PFOA were also major constituents accounting for 39.9% of ∑PFASs. Perfluorosulfonic acid (PFSAs (C₄, ₆, ₈)) were detected in all samples, while most concentrations were below 10 ng/L. In addition, 1H,1H,2H,2H-perfluorooctane sulfonate (6:2) (6:2 FTS), 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid (HFPO-DA) and 9-chlorohexadecafluoro-3-oxanonane-sulfonate (9Cl-PF3ONS) were also detected in all samples at low level. Long chain PFCAs and PFSAs and other classes of PFASs were also detected with low levels and/or low frequencies. The level of PFASs shows an increasing trend in surface water in Shanghai. The whole risk is low for residents from water exposure, while it should cautious to the emission of P3MHpA from integrated circuits and its potential risk.
Show more [+] Less [-]The mechanism for inhibiting acidification of variable charge soils by adhered Pseudomonas fluorescens Full text
2020
Nkoh, Jackson Nkoh | Yan, Jing | Xu, Ren-Kou | Shi, Ren-yong | Hong, Zhi-neng
Acidification in variable charge soils is on the rise due to increased acid deposition and use of nitrogenous fertilizers. The associated low pH and cation exchange capacity make the soils prone to depleted base cations and increased levels of Al³⁺. Consequently, Al toxicity to plants and soil infertility decrease crop yield. This study was designed to investigate the effect of Pseudomonas fluorescens on the acidification of two Ultisols. The simulated acidification experiment demonstrated that the pH of bacteria-treated soil was higher than that of control under similar conditions, suggesting that the adhered bacteria inhibited soil acidification. This observation was attributed to the association of organic anions (RCOO⁻ or RO⁻) on bacteria with H⁺ to form neutral molecules (RCOOH or ROH) and reducing the activity of H⁺ in solution. The bacteria also inhibited the increase in soil soluble Al and exchangeable Al during soil acidification. The adhesion of bacteria on the soils increased soil effective cation exchange capacity (ECEC) and exchangeable base cations at each pH compared to control. The release of exchangeable base cations from bacteria-treated soil, and the decrease in soil ECEC and exchangeable base cations with decreasing pH confirmed that protonation of organic anions on adhered bacteria was mainly responsible for the inhibition of soil acidification. The change of zeta potential of the bacteria with pH and the ART-FTIR analysis at various pH provided more evidence for this mechanism. Therefore, the bacteria in variable charge soils played an important role in retarding soil acidification.
Show more [+] Less [-]Effect of aquaculture on mercury and polyunsaturated fatty acids in fishes from reservoirs in Southwest China Full text
2020
Jing, Min | Lin, Dan | Wu, Pianpian | Kainz, Martin J. | Bishop, Kevin | Yan, Haiyu | Wang, Rui | Wang, Qing | Li, Qiuhua
Aquaculture can affect the polyunsaturated fatty acids (PUFA) and mercury (Hg) in fish by altering their diet. Here, planktivorous (silver carp and bighead carp), omnivorous and carnivorous fish with different dietary strategies were selected from two reservoirs, one with on-going aquaculture (WJD) and another without aquaculture (HF) in Southwest China. We compared the total mercury (THg), methylmercury (MeHg) contents and PUFA profiles of fish and their potential diets in these two reservoirs. THg and MeHg contents in omnivorous and carnivorous fish were lower from the WJD Reservoir, which is related to the lower THg and MeHg contents in the artificial fish food. THg and MeHg contents in silver carp from the WJD Reservoir were lower than those from the HF Reservoir, while they were similar in bighead carps from the two reservoirs. The Hg variation in planktivorous fish were inconsistent with that in plankton. THg contents in phyto- and zooplankton from the HF Reservoir were higher than those from the WJD Reservoir, yet their MeHg contents were similar. Artificial fish food which contained higher total PUFA eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), significantly increased the total PUFA and EPA + DHA contents in carnivorous fish, but had less effect on that in omnivorous fish from the WJD Reservoir. Eutrophication caused by aquaculture reduced total PUFA and EPA + DHA contents of plankton in WJD, yet did not reduce those in planktivorous fish. The impacts of aquaculture on Hg and PUFA accumulated in fish were varied among different fish species, and the mechanism needs further exploration.
Show more [+] Less [-]Occurrence of organic plastic additives in surface waters of the Rhône River (France) Full text
2020
Schmidt, Natascha | Castro-Jiménez, Javier | Fauvelle, Vincent | Ourgaud, Mélanie | Sempéré, Richard
We present here a comprehensive study (1-year regular sampling) on the occurrence of major families of organic plastic additives in the Rhône River surface waters. Potential sources and contaminant export are also discussed. A total of 22 dissolved phase samples were analyzed for 22 organic additives mainly used in the plastic industry, including organophosphate esters (OPEs), phthalates (PAEs) and bisphenols (BPs). Our results indicate that PAEs were the most abundant class, with concentrations ranging from 97 to 541 ng L⁻¹, followed by OPEs (85–265 ng L⁻¹) and BPs (4–21 ng L⁻¹). Among PAEs, diethylhexyl phthalate (DEHP) was the most abundant compound, whereas TCPP (Tris(1-chloro-2-propyl) phosphate) and TnBP (Tri(n-butyl)phosphate) were the predominant OPEs. Bisphenol S was the only BP detected. 5–54 metric tons year⁻¹ of dissolved organic plastic additives of emerging concern are estimated to be exported to the Gulf of Lion by the Rhône River, which is the main freshwater source of the Mediterranean Sea.
Show more [+] Less [-]Details of plastic ingestion and fibre contamination in North Sea fishes Full text
2020
Kuhn, Susanne | van Franeker, Jan A. | O’Donoghue, Anastasia M. | Swiers, Ailynn | Starkenburg, Marrit | van Werven, Bernike | Foekema, Edwin | Hermsen, Enya | Egelkraut-Holtus, Marion | Lindeboom, Han
This study combines published datasets with unpublished data on plastic ingestion in several North Sea fish species. The combined dataset of 4389 individuals from 15 species allows the analysis of spatial distribution and temporal variability of plastic uptake in fish. Airborne fibre contamination was observed to be the main contributor to fibres encountered in the samples. The number of fibres in samples was strongly related to the time needed to process a sample, not to the number of individual fishes in the sample. Accurate correction for secondary fibre contamination was not possible, but corrections required would be similar to fibre numbers observed in the samples. Consequently, all fibres were omitted from further analysis. The frequency of occurrence and the average number of plastics in fish is generally low (1.8% and 0.022 pieces per organism respectively), with only cod having a higher prevalence (12.3%). While latitude of catch locations influences plastic uptake in fish, no correlation with the distance to the coast was found. Slightly less plastics were ingested in winter, and a decrease in plastics ingested was observed between 2009 and 2018. These factors should be considered when fish species, catch location and time are discussed as indicators for plastic pollution in the European Marine Strategy Framework Directive. We recommend considering demersal cod and pelagic sprat as two species suitable for monitoring plastic ingestion in biota, both on the seafloor and in the water column.
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