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17701. 题目: Sugarcane bagasse biochar modulates metal and salinity stresses on microbial functions and enzyme activities in saline co-contaminated soils
文章编号: N21042804
期刊: Applied Soil Ecology
作者: Nahid Azadi, Fayez Raiesi
更新时间: 2021-04-28
摘要: Biochar can reduce salinity stress and metal toxicity to soil microbial community and enzymatic activity, hence would improve soil biological fertility and quality. However, the effects of sugarcane bagasse biochar (SCB) on microbial and biochemical responses to salinity stress in metal co-contaminated soils still remain unknown. The aim of this study was to assess the impact of SCB application on microbial activity, biomass and enzymatic activities in a soil co-contaminated with cadmium (Cd) and lead (Pb) when simultaneously exposed to NaCl salinity stress during an incubation experiment. Soil samples were initially co-contaminated with cadmium (10 mg Cd kg−1) and lead (150 mg Pb kg−1) solutions, then pre-incubated for 30 days and finally salinized with three levels of NaCl solution (0, 20 and 40 mM NaCl). Two slow pyrolysis SCBs prepared at 400 and 600 °C were applied to the saline polluted soils at 1% (w/w) and the mixtures were incubated for 120 days under laboratory conditions. Soils amended with raw bagasse and without amendment were also used in the experiment. Results showed that soil amendment with SCBs decreased the availability of Cd by 17–19% and Pb by 11–18%, and increased the content of soil organic carbon (SOC) by 96–104% and dissolved organic carbon (DOC) by 14–164% under saline conditions. High-temperature SCB decreased metal availability and enhanced SOM content in the soil more than low-temperature SCB. Application of SCBs increased soil microbial and biochemical properties from 27 to 180%, depending on the pyrolysis temperature, salinity level and the assay itself. Biochar reduced the adverse influences of metal toxicity and salinity stresses on soil microbial and biochemical functions, most largely through immobilizing metals and improving SOC and DOC. Low-temperature SCB promoted soil microbial quality more than high-temperature SCB. This study indicated that low-temperature SCB could be used as an amendment in metal co-contaminated soils to alleviate the potential risks associated with the combined effects of metal pollution and salinity stresses on microbial and biochemical indicators of soil quality/health under arid and semi-arid conditions. The findings would have some useful implications for the soils co-contaminated with toxic metals under the stress of salinity and for rehabilitation of salt-affected soils using SCB as a cost-effective source of organic matter.

17702. 题目: Determining the origin and fate of nitrate in the Nanyang Basin, Central China, using environmental isotopes and the Bayesian mixing model
文章编号: N21042803
期刊: Environmental Science and Pollution Research
作者: Shengwei Cao, Yuhong Fei, Xia Tian, Xiangxiang Cui, Xueqing Zhang, Ruoxi Yuan, Yasong Li
更新时间: 2021-04-28
摘要: Identifying sources of nitrate contamination has been a long-term challenge in areas with different land uses. We investigated the biogeochemical processes and quantified the contribution of potential nitrate sources in the Nanyang Basin, the source area of the South to North Water Diversion Project in China. Hydrogeochemical characteristics, the dual-isotope method (δ15N-NO3− and δ18O-NO3−), and the Bayesian mixing model (SIAR) were combined. The results for 160 samples indicated that mean nitrate concentrations of residential area (162.83 mg L−1) and farmland (75.71 mg L−1) were higher compared with those of surface water (16.15 mg L−1) and forest (36.25 mg L−1). Hydrochemical facies and molar ratios of major ions indicated that the natural environment was greatly impacted by anthropogenic activities. Nitrification, ammonium volatilization, and mixing effects were the dominant processes in nitrogen transformation. The contributions of different sources to nitrate contamination were 45.41%, 35.81%, 17.87%, and 0.91% for sewage and manure, soil organic nitrogen, synthetic fertilizer, and atmospheric deposition, respectively. Undeveloped infrastructure and sewage disposal in rural areas were the main causes of nitrate contamination. Our results provide a theoretical basis for the development of measures to guarantee long-term water supply of the South to North Water Diversion Project.

17703. 题目: Integrated approach for quantitative estimation of particulate organic carbon sources in a complex river system
文章编号: N21042802
期刊: Water Research
作者: Dong-Hun Lee, Seung-Hee Kim, Eun-Ji Won, Min-Seob Kim, Jin Hur, Kyung-Hoon Shin
更新时间: 2021-04-28
摘要: Despite receiving a considerable amount of attention in the past, quantitative and systematic estimation of the source contributions for different organic carbons (OCs) in complex river systems is still challenging. In this study, we tested an integrated framework using field data of bulk elements and lipid biomarkers and hydrological modeling (hydrological simulation program FORTRAN, HSPF) for the quantitative estimation of OC loads along different land-use types of a watershed (Geumho River watershed in South Korea). Based on the specific source assignments identified from the lipid biomarker patterns in particulate organic carbon (POC) such as short/long chains of alkanes, fatty acids and alcohols, and coprostanol/cholesterol, spatial variations of the diagnostic lipids could be used as an indicator to discriminate between the contributions of natural (algae, bacteria, and terrestrial plants) and anthropogenic sources (fecal). Based on the integration of HSPF modeling, it was also found that various POC loads might be partially controlled by different water discharges within watersheds. With the increase in POC fluxes, the increase in fecal loads was also noticed, as reflected by the predominant lipid (especially coprostanol normalized by water discharges). As a straightforward approach, we developed a set of indices including fecal index-1, ratios of coprostanol, fatty acids, and alkanes, which strengthened the sensitivity for fecal contamination. Compared with the conventional HSPF results, the variations of these proposed indices were more influenced by the broadened watershed extents with increasing downstream distance, which provided a more accurate estimation of the quantitative contributions of POC loadings in the complex river system.

17704. 题目: Insight into cesium immobilization in contaminated soil amended with biochar, incinerated sewage sludge ash and zeolite
文章编号: N21042801
期刊: Environmental Technology & Innovation
作者: Huijuan Shao, Yongfen Wei, Changjie Wei, Fuping Zhang, Fusheng Li
更新时间: 2021-04-28
摘要: Radioactive cesium (Cs) in the soil represents a severe threat to human health and the environment. Plant uptake is an important pathway for the migration of Cs to the human food chain. It is therefore essential to find effective amendments for reducing the phytoavailability of Cs. In this study, we aimed to evaluate the effectiveness and possible mechanisms of biochar (BC), incinerated sewage sludge ash (ISSA) and zeolite (ZL) on the immobilization of Cs in the contaminated soil. Greenhouse pot experiment was conducted using Napier grass (Pennisetum purpureum) to investigate the effects of BC, ISSA and ZL (10% application rate, w/w) on the soil properties, plant biomass, the accumulation and distribution of Cs in the grass grown on the contaminated soil added with Cs as a rate of 100 mg kg −1. The results showed that all amendments enhanced the grass growth, with the maximum biomass recorded in the ISSA treatment. The concentrations of Cs in the leaf blade, leaf sheath and root of grass significantly decreased with all amendment applications. Especially the BC application showed the lowest Cs concentration in grass, decreased by up to 95% compared to control (no amended soil). Moreover, the obtained results in terms of pH, cation exchange capacity, surface charge, specific surface area and potassium concentration of amendments and potting soils highlighted the remarkable efficiency of biochar to adsorb Cs and reduce the plant uptake of Cs providing key evidences for Cs immobilization.

17705. 题目: Reduction in Riverine Freshwater Supply Changes Inorganic and Organic Carbon Dynamics and Air–water CO 2 Fluxes in a Tropical Mangrove Dominated Estuary
文章编号: N21042709
期刊: Journal of Geophysical Research: Biogeosciences
作者: Anirban Akhand, Abhra Chanda, Kenta Watanabe, Sourav Das, Tatsuki Tokoro, Sugata Hazra, Tomohiro Kuwae
更新时间: 2021-04-27
摘要: Reduction in riverine freshwater supply due to climate change as well as anthropogenic activities are documented throughout the globe. How river discontinuity in upstream reaches and the subsequent reduction in freshwater influx alter inorganic and organic carbon dynamics in downstream estuaries adjacent to mangroves has been rarely reported. We investigated the dynamics of the inorganic carbon system and organic matter (OM) in two Indian estuaries near mangroves; riverine freshwater supply to the Matla Estuary was reduced and that to the Dhamra Estuary was uninterrupted. Seasonal sampling was conducted over an annual cycle. We used elemental and stable isotope signatures to delineate the sources of OM and dissolved inorganic carbon (DIC). We found that compared to the Dhamra, the reduced riverine freshwater supply to the Matla increased the marine influence in the estuary on the OM degradation pathways and decreased CO2 emissions to the atmosphere. In the Dhamra, higher seasonal variability in biogeochemical pathways, including carbonate dissolution, facilitated high internal carbonate buffering capacity; in contrast in the Matla, the greater marine influence increased the carbonate buffering capacity, resulting in retention of higher DIC concentrations and low CO2 emissions. Dissolved and particulate organic carbon concentrations were higher in the Dhamra than the Matla, indicating higher riverine supply of these. The present study can contribute an overlooked effect of long‐term changes in riverine freshwater supply on the carbon dynamics of mangrove‐dominated estuaries, which might help to improve the understanding of coastal carbon budgets in a changing world.

17706. 题目: Porewater Lead Concentrations Limited by Particulate Organic Matter Coupled With Ephemeral Iron(III) and Sulfide Phases during Redox Cycles Within Contaminated Floodplain Soils
文章编号: N21042708
期刊: Environmental Science & Technology
作者: Christian Dewey, John R. Bargar, Scott Fendorf
更新时间: 2021-04-27
摘要: Lead contamination in soils and sediments is a major threat to water quality. In surface and near-surface environments, Pb is not redox active; however, common Pb hosts, including Fe(III)-(hydr)oxides and sulfides, dissolve and precipitate as redox conditions change. Dissolution of Pb hosts may release Pb to porewater, leading to spikes in dissolved Pb concentrations and potential transport into surface or groundwater. Here, we examine the impacts of hydrologically coupled redox transitions on Pb partitioning in contaminated floodplain soils. We find that the affinity of Pb for particulate organic matter (POM), inclusive of mineral-associated organic matter, ensures that across redox transitions Pb is retained in the solid phase, despite host-phase (Fe(III)-(hydr)oxide and sulfide) dissolution. As seasonal hydrologic dynamics shift porewater redox conditions, Pb-bearing Fe(III)-(hydr)oxides (Pb-HFO) and sulfides (PbS) are dissolved and (re)precipitated. However, despite these shifts in redox conditions and associated host-phase transformations, Pb retention on POM, coupled with the formation of PbS and Pb-HFO, maintains dissolved Pb concentrations below 17 μg L–1. Importantly, the predominance of Pb adsorbed on POM alongside low dissolved Pb concentrations indicates that Pb released from HFO and PbS is retained by POM. Thus, despite host-phase dissolution during redox transitions, partitioning of Pb to the aqueous phase is minimal and, therefore, transport of dissolved Pb is unlikely.

17707. 题目: Molecular Determination of Organic Adsorption Sites on Smectite during Fe Redox Processes Using ToF-SIMS Analysis
文章编号: N21042707
期刊: Environmental Science & Technology
作者: Liuqin Huang, Qun Yu, Wen Liu, Jungang Wang, Wenxiao Guo, Endong Jia, Qiang Zeng, Ruijun Qin, Jianqiu Zheng, Kirsten S. Hofmockel, Hailiang Dong, Hongchen Jiang, Zihua Zhu
更新时间: 2021-04-27
摘要: Turnover of soil organic carbon (SOC) is strongly affected by a balance between mineral protection and microbial degradation. However, the mechanisms controlling the heterogeneous and preferential adsorption of different types of SOC remain elusive. In this work, the heterogeneous adsorption of humic substances (HSs) and microbial carbon (MC) on a clay mineral (nontronite NAu-2) during microbial-mediated Fe redox cycling was determined using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results revealed that HSs pre-adsorbed on NAu-2 would partially inhibit structural modification of NAu-2 by microbial Fe(III) reduction, thus retarding the subsequent adsorption of MC. In contrast, NAu-2 without precoated HSs adsorbed a significant amount of MC from microbial polysaccharides as a result of Fe(III) reduction. This was attributed to the deposition of a thin Al-rich layer on the clay surface, which provided active sites for MC adsorption. This study provides direct and detailed molecular evidence for the first time to explain the preferential adsorption of MC over HSs on the surface of clay minerals in iron redox processes, which could be critical for the preservation of MC in soil. The results also indicate that ToF-SIMS is a unique tool for understanding complex organic–mineral–microbe interactions.

17708. 题目: A review on mechanism of biomineralization using microbial-induced precipitation for immobilizing lead ions
文章编号: N21042706
期刊: Environmental Science and Pollution Research
作者: Bing Shan, Ruixia Hao, Hui Xu, Jiani Li, Yinhuang Li, Xiyang Xu, Junman Zhang
更新时间: 2021-04-27
摘要: Lead (Pb) is a toxic metal originating from natural processes and anthropogenic activities such as coal power plants, mining, waste gas fuel, leather whipping, paint, and battery factories, which has adverse effects on the ecosystem and the health of human beings. Hence, the studies about investigating the remediation of Pb pollution have aroused extensive attention. Microbial remediation has the advantages of lower cost, higher efficiency, and less impact on the environment. This paper represented a review on the mechanism of biomineralization using microbial-induced precipitation for immobilizing Pb(II), including microbial-induced carbonate precipitation (MICP), microbial-induced phosphate precipitation (MIPP), and direct mineralization. The main mechanisms including biosorption, bioaccumulation, complexation, and biomineralization could decrease Pb(II) concentrations and convert exchangeable state into less toxic residual state. We also discuss the factors that govern methods for the bioremediation of Pb such as microbe characteristics, pH, temperature, and humic substances. Based on the above reviews, we provide a scientific basis for the remediation performance of microbial-induced precipitation technique and theoretical guidance for the application of Pb(II) remediation in soils and wastewater.

17709. 题目: Effect of inorganic carbonate and organic matter in thermal treatment of mercury-contaminated soil
文章编号: N21042705
期刊: Environmental Science and Pollution Research
作者: Kanghee Cho, Jinkyu Kang, Songbae Kim, Oyunbileg Purev, Eunji Myung, Hyunsoo Kim, Nagchoul Choi
更新时间: 2021-04-27
摘要: Thermal treatment of mercury (Hg)-contaminated soil was studied to investigate the desorption behavior of Hg at different temperatures. The soil samples were collected from two locations with different land uses around the mine and industrial site. The effect of soil properties such as inorganic carbonate minerals and organic matter content on Hg desorption was investigated to understand the thermal desorption process. The effect of soil composition on Hg desorption showed that behavior at 100 °C was similar, but a different behavior could be found at 300 °C. The thermal desorption efficiency at 300 °C is affected by the thermal properties of soils and the Hg desorption capacity of the soils. The Hg from both soil types was removed above 300 °C, and Hg was effectively removed from mine soil due to the partial decomposition of carbonate in the soil composition, while industrial soil showed that desorption would be restrained by Hg organic matter complexes due to organic matter content. Despite a relatively higher concentration of Hg in the mine soil, Hg removal efficiency was greater than that in the industrial soil. Sequential extraction results showed that only the Hg fractions (residual fractions, step 6) in mine soil changed, while the industrial soil was affected by changes in Hg fractions (step 3 to step 6) at 300 °C. Changes in soil pH during thermal desorption are also influenced by heating time and temperature. Therefore, the mechanisms of Hg desorption during thermal treatment were observed by soil properties. The volatilization of Hg in the soil is induced by organic carbon, while soil Hg release is controlled by organic matter complexes.

17710. 题目: Controls on Organic Carbon Burial in the Eastern China Marginal Seas: A Regional Synthesis
文章编号: N21042704
期刊: Global Biogeochemical Cycles
作者: B. Zhao, P. Yao, T. S. Bianchi, Z. G. Yu
更新时间: 2021-04-27
摘要: A regional synthesis of organic carbon (OC) burial was conducted using a comprehensive data set to reveal some of the key drivers and human multi‐stressors controlling OC burial and transport in the Eastern China Marginal Seas (ECMS). Both OC and Δ14C values of suspended particulate matter (SPM) in the Changjiang River, were significantly higher than estuarine mobile‐muds, suggesting selective decay of more labile younger OC from both marine and terrestrial sources and the accumulation of more recalcitrant older OC. Some of this decay is likely to be associated with iron‐redox cycling in mobile‐muds. In contrast, OC, δ13C, and Δ14C values increased along the Yellow River sediment dispersal pathway, indicating adding of young marine OC and less decay of terrestrial OC. OC burial efficiency in mud areas in the Bohai Sea (∼43%) was significantly higher than those in the Yellow (∼11%) and East China Seas (∼16%), owing to rapid deposition. Burial flux of biospheric OC in mud areas of the ECMS is 7.00 ± 0.79 Mt yr−1, corresponding to atmospheric CO2 drawdown by silicate weathering in major river drainage basins of mainland China. The burial flux of petrogenic OC was estimated to be 0.81 ± 0.25 Mt yr−1, accounting for >1.9% of total burial in the global ocean. While the ECMS is an important OC sink, river damming has greatly reduced OC burial. Thus, the overall impact on anthropogenically altered river‐dominated marginal seas remains an important and rapidly changing component of the coastal ocean carbon budget.

17711. 题目: Study on the new dynamics and driving factors of soil pH in the red soil, hilly region of South China
文章编号: N21042703
期刊: Environmental Monitoring and Assessment
作者: Yuye Shen, Zhongqi Zhang, Yue Xue
更新时间: 2021-04-27
摘要: Soil acidification has always been a substantial eco-environmental problem restricting agricultural development in the red soil region of southern China. It is necessary to determine the dynamic change in soil pH in this area to formulate regional agricultural and environmental management measures. Yujiang County, a typical county with red soil acidification in southern China, was selected as the study area. Based on soil data from 1982, 2007, and 2018, the spatiotemporal variation characteristics and the latest changes in soil pH in the county were analyzed. The results show that the soil pH in Yujiang County decreased from 5.66 to 4.74 and then increased to 4.96 from 1982 to 2018, showing a trend of first decreasing and then increasing. According to the spatial distribution characteristics of soil pH, the low soil pH values in the three periods were mainly distributed in the northern mountainous areas with more forestland and dry land area and some southern hilly areas, while the paddy soil pH values in the middle low hilly areas were relatively higher. The soil pH decreased rapidly from 1982 to 2007, showing a large area of acidification. In 2007, the proportions of acidic (4.5 < pH < 5.5) and strongly acidic (pH < 4.5) soils increased by 67.37% and 10.6%, respectively, compared with that in 1982. However, from 2007 to 2018, the soil pH of the whole county increased, and the acidification trend was alleviated, which is of great significance to the regional red soil ecological environment. Through the analysis of the main factors affecting the change in soil pH, it was found that the sharp decline in soil pH in Yujiang County during 1982–2007 was mainly caused by acid rain and excessive nitrogen application. From 2007 to 2018, no significant reduction in nitrogen fertilizer in this area occurred, and although the increase in soil organic matter contributed to alleviating soil acidification, the analysis showed that the decrease in acid rain was the main reason for the rise in soil pH in Yujiang County. At the same time, notably, there is a large area of soil in the area that is still acidic, and effective control of soil acidification is still an important ecological and environmental issue in this area. In order to further improve the pH value of soil in red soil region, it is suggested that on the basis of continuous improvement of acid rain, in addition to increasing soil organic matter by returning straw to field and other measures, appropriate amount of lime or alkaline biochar can be applied to better improve the soil ecological environment in red soil hilly region.

17712. 题目: Quantifying microbial control of soil organic matter dynamics at macrosystem scales
文章编号: N21042702
期刊: Biogeochemistry
作者: Mark A. Bradford, Stephen A. Wood, Ethan T. Addicott, Eli P. Fenichel, Nicholas Fields, Javier González-Rivero, Fiona V. Jevon, Daniel S. Maynard, Emily E. Oldfield, Alexander Polussa, Elisabeth B. Ward, William R. Wieder
更新时间: 2021-04-27
摘要: Soil organic matter (SOM) stocks, decomposition and persistence are largely the product of controls that act locally. Yet the controls are shaped and interact at multiple spatiotemporal scales, from which macrosystem patterns in SOM emerge. Theory on SOM turnover recognizes the resulting spatial and temporal conditionality in the effect sizes of controls that play out across macrosystems, and couples them through evolutionary and community assembly processes. For example, climate history shapes plant functional traits, which in turn interact with contemporary climate to influence SOM dynamics. Selection and assembly also shape the functional traits of soil decomposer communities, but it is less clear how in turn these traits influence temporal macrosystem patterns in SOM turnover. Here, we review evidence that establishes the expectation that selection and assembly should generate decomposer communities across macrosystems that have distinct functional effects on SOM dynamics. Representation of this knowledge in soil biogeochemical models affects the magnitude and direction of projected SOM responses under global change. Yet there is high uncertainty and low confidence in these projections. To address these issues, we make the case that a coordinated set of empirical practices are required which necessitate (1) greater use of statistical approaches in biogeochemistry that are suited to causative inference; (2) long-term, macrosystem-scale, observational and experimental networks to reveal conditionality in effect sizes, and embedded correlation, in controls on SOM turnover; and (3) use of multiple measurement grains to capture local- and macroscale variation in controls and outcomes, to avoid obscuring causative understanding through data aggregation. When employed together, along with process-based models to synthesize knowledge and guide further empirical work, we believe these practices will rapidly advance understanding of microbial controls on SOM and improve carbon cycle projections that guide policies on climate adaptation and mitigation.

17713. 题目: Kinetics and efficacy of membrane/DNA damage to Bacillus subtilis and autochthonous bacteria during UV/chlorine treatment under different pH and irradiation wavelengths
文章编号: N21042701
期刊: Chemical Engineering Journal
作者: Ji Wu, Shi Cheng, Yuan-Zhi Duan, Shan-Qi Shen, Bi-Cun Jiang, Yan Li, Peng Shi, Wen-Tao Li, Quan-Xing Zhang, Ai-Min Li
更新时间: 2021-04-27
摘要: The UV photolysis of chlorine (UV/chlorine) produces a suite of radical species and has been proposed as a novel water treatment process for advanced oxidation and enhanced disinfection purposes. In this study, the kinetics and efficacy of membrane/DNA damage to B. subtilis and autochthonous bacteria during UV/chlorine treatment were investigated under different pH and irradiation wavelengths (254 nm Hg lamp vs 275 nm LEDs) with flow cytometer analysis. Compared to UV irradiation or chlorination alone, the UV/chlorine showed the enhanced kinetics and efficacy of cell membrane or DNA damage to B. subtilis. These enhancements by UV/chlorine might be primarily attributed to the in-situ generation of radical species HO• and Cl• around intracellular DNA. With pH increasing from acidic to alkaline, the UV254/chlorine showed the decreased kinetics of cell membrane or DNA damage to B. subtilis while the UV275/chlorine exhibited the increased cell membrane and DNA damage kinetics due to the higher chlorine photolysis rates. When the chlorine dose was not excess, the DNA damage of B. subtilis were highly depended on the cumulative exposures of free available chlorine (CTFAC). During UV275/chlorine in the presence of natural organic matter, the cell membrane damage also showed linear correlations with the decreases of UV absorbance at 254 nm (UVA254), and about 20−25% decrease of UVA254 indicates a sufficient cell membrane damage. Using the CTFAC values and decrease of UVA254, this study has provided the surrogate indicators for fast determining the minimal chlorine dose for sufficient inactivation of bacteria by UV/chlorine treatment.

17714. 题目: Enhanced complexation of humic acids: Homogenization of protonated groups in the hybrid ozonation-coagulation process
文章编号: N21042612
期刊: Chemosphere
作者: Shiyi Hu, Xin Jin, Chao Yang, Yong Wang, Xinyue Xie, Shaohua Zhang, Pengkang Jin, Xiaochang C. Wang
更新时间: 2021-04-26
摘要: In this study, we compared dissolved organic carbon (DOC) and UV254 removal efficiencies of the hybrid ozonation-coagulation (HOC) and pre-ozonation-coagulation (POC) processes for humic acid (HA) at pH 5 with AlCl3•6H2O as the coagulant. The DOC and UV254 removal efficiencies of the HOC process were higher than those of the POC process at ozone dosages less than 2.0 mg O3 (mg DOC)-1. The ozone dosage was optimized at 0.3 and 0.1 mg O3 (mg DOC)-1 for the HOC and POC processes, respectively, implying a more rigorous ozone dosage for the POC process. During the POC process, pre-ozonation was observed to increase the binding sites of HA (e.g., hydroxyl and carboxyl groups), improving the complexation of dissolved organic matter. For the HOC process, in addition to its role in the oxidation of organic matter, ozone also reacted with coagulants. The reaction between ozone and coagulants can facilitate the formation of Al13. Moreover, the oxidation of •OH and ozone can increase the charge density of the HA binding sites, homogenizing the binding sites of HA and enhancing the complexation with Al13.

17715. 题目: The influences of illite/smectite clay on lignocellulose decomposition and humification process revealed by metagenomics analysis during cattle manure composting
文章编号: N21042611
期刊: Waste Management
作者: Qingran Meng, Susu Wang, Qiuqi Niu, Hailong Yan, Qunliang Li
更新时间: 2021-04-26
摘要: The purpose of this study was to analyze the effects of illite/smectite clay (I/S) on lignocellulosic degradation and humification process via metagenomics during cattle manure composting. The test group (TG) with 10% I/S and the reference group (RG) were established. The results indicated that the addition of I/S made the degradation rate of lignocellulose in TG (1.56%, 29.01%, 17.96%) was higher than that in RG (1.16%, 17.24%, 13.14%). Compared with RG, the abundance values of AA2, AA10, GH1, GH10 in TG increased by 15.18%, 29.28%, 31.08%, 21.65%, respectively. Meanwhile, humic substance (HS) content was increased by 3.49% and 7.16% during RG and TG composting. Furthermore, the microbial community in TG changed, in which the relative abundance of Actinobacteria increased and the relative abundance of Proteobacteria decreased. Redundancy analysis (RDA) showed that the temperature was positively correlated with the abundance of the four enzymes, whereas the organic matter (OM) content was negatively correlated with them. Overall, adding I/S to the compost could stimulate microbial activity, promote the degradation of lignocellulose and humification process.

17716. 题目: Spatial and environmental characteristics of colloidal trace Cu in the surface water of the Yellow River Estuary, China
文章编号: N21042610
期刊: Marine Pollution Bulletin
作者: Yuxi Lu, Dawei Pan, Tingting Yang, Chenchen Wang
更新时间: 2021-04-26
摘要: Dynamic variations in chemical composition and size distribution of dissolved copper (Cu) along the river-sea interface in the Yellow River Estuary (China) were investigated. On average, ~64% and ~8% of bulk dissolved Cu (<0.45 μm) were partitioned in the <1 kDa fraction and 1–100 kDa, respectively. The other 28% were in the 100 kDa–0.45 μm colloids, which indicates that this fraction may dominate the overall morphology of colloidal Cu. The <3 kDa Cu fraction was susceptible to environmental parameters and the >3 kDa fraction was related to the behavior of dissolved organic carbon. 1–100 kDa Cu migrated more violently than >100 kDa Cu and tended to be a stable polymer, with stability increasing towards the sea. The source of <1 kDa Cu was complex and may be supplemented by the decomposition of small molecular colloids and the addition of the sediments or particles ligands.

17717. 题目: Particulate organic matter dynamics and its isotopic signatures (δ13CPOC and δ15NPN) in relation to physical forcing in the central Arabian Sea during SW monsoon (2017-2018)
文章编号: N21042609
期刊: Science of The Total Environment
作者: Saumya Silori, Diksha Sharma, Mintu Chowdhury, Haimanti Biswas, Damien Cardinal, M. Mandeng-Yogo
更新时间: 2021-04-26
摘要: Monsoonal changes in particulate organic matter (POM) and its isotopic signatures (δ13CPOC and δ15NPN) were studied (Aug 2017 and 2018) in the central Arabian Sea (21-11°N 64°E) . A low-level atmospheric jet (Findlater Jet) forms during the south-west (SW) monsoon and results in open ocean upwelling to the north of the jet’s axis. Higher wind speed and jet-induced wind stress curl coupled with low sea surface temperature (SST) and higher nutrients were noticed in 2018 than in 2017. The region to the north of the jet was characterized by substantially shallower Mixed Layers Depths (MLDs) and higher POM contents relative to the jet’s axis and southern stations. The molar ratio between particulate organic carbon (POC) and nitrogen (PN) (6.2±1.9in 2017; 6.4±0.9 in 2018) was very close to the canonical Redfield ratio (6.63). The δ13CPOC values (-26.3±1.4 ‰ in 2017; 25.5±1.4 ‰ in 2018) exhibited typical marine signature reported from this area and revealed a noticeable inter-annual difference. Relatively higher δ15NPN values noticed in the north (7.68±2.6 ‰ in 2017; 9.24±3 ‰ in 2018) indicated regenerated dissolved inorganic nitrogen coming from the oxygen minimum zone (OMZ) into the well-lit zone. The lower δ15NPN values along the jet axis and south of it were attributed to lateral advection of nitrogen from the Somali upwelling. Despite the higher nutrient availability, POC contents in 2018 did not exceed the values in 2017. Considering the total consumption of nitrogen (according to C:N: P=106:16:1), the potential POC development in 2018 could be double the value in 2017. The interannual differences in SW monsoon onset and wind speed seem to directly control the nutrient supply, affecting plankton community structure and POM variability. Thus, any future change in the physical forcing may directly influence the POC pool and consequent export flux to the mesopelagic.

17718. 题目: Shrub encroachment balances soil organic carbon pool by increasing carbon recalcitrance in a temperate herbaceous wetland
文章编号: N21042608
期刊: Plant and Soil
作者: Xinhou Zhang, Shuangshuang Jiang, Wei Jiang, Wenwen Tan, Rong Mao
更新时间: 2021-04-26
摘要: Background and aims In recent decades, temperate herbaceous wetlands have been widely experiencing shrub encroachment. By now, little has been known about whether such alteration in plant community would generate updated soil organic carbon (SOC) conservation strategies, and thus alter SOC dynamics. Methods To assess the temporal dynamics of SOC stock and fractions after shrub encroachment into temperate herbaceous wetlands, we measured floor litter mass, fine root biomass, and SOC stock and fractions (i.e. labile C pool I, labile C pool II, and recalcitrant C pool) across the 0–50 cm soil profile in the open wetlands and shrub islands (Betula fruticose and Salix floderusii) with different basal diameter sizes (small, 10 ~ 15 cm; medium, 15 ~ 20 cm; and large, 20 ~ 30 cm) in the Sanjiang Plain of Northeast China. Results Regardless of shrub species, SOC stock initially decreased after shrub expansion, but gradually recovered to the initial level of herbaceous wetlands. Moreover, SOC stock correlated positively with fine root biomass, but showed no significant relationship with floor litter mass. The responses of SOC fractions to shrub expansion mainly occurred in the surface soils (0–15 cm), despite a slight change in recalcitrant C pool in 15–50 cm layer. In the surface soils, labile C pool decreased substantially, whereas recalcitrant C pool and recalcitrant index of SOC elevated with increasing shrub sizes. Conclusions Shrub encroachment can recover SOC pool and enhance SOC recalcitrance in temperate herbaceous wetlands, and altered fine root biomass would account for shrub encroachment-induced SOC dynamics.

17719. 题目: Improvement of anaerobic co-digestion of plant waste and excess sludge using calcium peroxide
文章编号: N21042607
期刊: Environmental Science and Pollution Research
作者: Yongliang Wang, Xiaohui Zhou, Bin Dai, Xiaoqiang Zhu
更新时间: 2021-04-26
摘要: Plant waste (PW) and excess sludge (ES) are two main organic matters of municipal solid waste. However, there are few reports on their anaerobic co-digestion. In this work, the mixed proportion of PW and ES anaerobic co-digestion was first optimized at mesophilic temperature, and then the anaerobic co-digestion of PW and ES was enhanced with strong oxidant calcium peroxide (CP). The results showed that the optimal mixing ratio of PW and ES was 1/1 (in terms of volatile solids), the C/N of mixed digestion substrate was 23.5/1, and the maximum methane production was 172.6 mL/g (in terms of volatile solids). CP could enhance methane production from anaerobic co-digestion of PW and ES. When the content of CP was 0.2 g/g (in terms of total suspended solids), the maximum methane production was 234.8 mL/g, about 1.4 times of the blank. The mechanism investigation showed that CP promoted the release of organic matter during the co-digestion, and the higher the content of CP, the greater the release of soluble chemical oxygen demand. The presence of appropriate amount of CP promoted the activities of key enzymes in anaerobic fermentation process, and then increased the efficiency of methane production. The results of this work provide an alternative strategy for the resource utilization of PW and ES.

17720. 题目: Influence of rice husk addition on phosphorus fractions and heavy metals risk of biochar derived from sewage sludge
文章编号: N21042606
期刊: Chemosphere
作者: Qiao Xiong, Xiang Wu, Hang Lv, Shuhua Liu, Haobo Hou, Xu Wu
更新时间: 2021-04-26
摘要: This study investigated the effects of rice husk dose and pyrolysis temperature on the phosphorus (P) fractions and environmental risk of heavy metals in biochar co-pyrolyzed from sewage sludge and rice husk. Biochar properties were analyzed, and the transformation of P and heavy metals speciation during co-pyrolysis were also discussed. Co-pyrolysis of raw sludge and rice husk (10-50 wt%) could increase the carbonization degree and stability of biochar at 500 °C. The organic P (OP) in raw sludge (68 wt%) was transformed to inorganic P (IP) during co-pyrolysis, indicating that the addition of rice husk could improve biochar-P bioavailability by promoting the transformation of IP. The IP content increased from 71.5 wt% of sludge biochar to 92 wt% of blended biochar (50 wt% sludge and 50 wt% rice husk) at a pyrolysis temperature of 500 °C. With the mass ratio of sludge to rice husk of 5:5, the OP content decreased from 3 mg g-1 to 0.75 mg g-1 as the pyrolysis temperature increased from 300 °C to 700 °C. The 31P nuclear magnetic resonance spectra and X-ray photoelectron spectroscopy results showed that P species in biochar mainly existed as orthophosphate, which can be directly taken up by plants. After co-pyrolysis, the toxicity and mobility of heavy metals gradually decreased with increasing rice husk dose and pyrolysis temperature. The study indicates that co-pyrolysis of sewage sludge and rice husk could be a promising P reuse strategy.