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121. 题目: Factors controlling the competition between <i>Phaeocystis</i> and diatoms in the Southern Ocean and implications for carbon export fluxes
文章编号: N21011516
期刊: Biogeosciences
作者: Cara Nissen, Meike Vogt
更新时间: 2021-01-15
摘要: The high-latitude Southern Ocean phytoplankton community is shaped by the competition between Phaeocystis and silicifying diatoms, with the relative abundance of these two groups controlling primary and export production, the production of dimethylsulfide, the ratio of silicic acid and nitrate available in the water column, and the structure of the food web. Here, we investigate this competition using a regional physical–biogeochemical–ecological model (ROMS-BEC) configured at eddy-permitting resolution for the Southern Ocean south of 35∘ S. We improved ROMS-BEC by adding an explicit parameterization of Phaeocystis colonies so that the model, together with the previous addition of an explicit coccolithophore type, now includes all biogeochemically relevant Southern Ocean phytoplankton types. We find that Phaeocystis contribute 46±21 % (1σ in space) and 40±20 % to annual net primary production (NPP) and particulate organic carbon (POC) export south of 60∘ S, respectively, making them an important contributor to high-latitude carbon cycling. In our simulation, the relative importance of Phaeocystis and diatoms is mainly controlled by spatiotemporal variability in temperature and iron availability. In addition, in more coastal areas, such as the Ross Sea, the higher light sensitivity of Phaeocystis at low irradiances promotes the succession from Phaeocystis to diatoms. Differences in the biomass loss rates, such as aggregation or grazing by zooplankton, need to be considered to explain the simulated seasonal biomass evolution and carbon export fluxes.

122. 题目: Paper Birch (Betula papyrifera) Nutrient Resorption Rates on Nutrient-Poor Metal-Contaminated Soils and Mine Tailings
文章编号: N21011515
期刊: Water, Air, & Soil Pollution
作者: Kimber E. Munford, Maria Casamatta, Nathan Basiliko, Susan Glasauer, Nadia C. S. Mykytczuk, Shaun A. Watmough
更新时间: 2021-01-15
摘要: Acidic, metalliferous mine tailings are hostile environments for vegetation growth. Despite this, Betula papyrifera (paper birch) has emerged as a primary colonizer in metal contaminated areas. This study assessed foliar nutrient resorption efficiency and proficiency in B. papyrifera growing on two Ni-Cu (nickel-copper) tailings sites and two smelter-impacted sites near Sudbury, Ontario, in Canada. Soils at the smelter-impacted sites were more acidic, with significantly higher OM (organic matter) and P (phosphorus), whereas soil at the tailings sites had much higher concentrations of many metals. The primary limiting nutrients in the tailings were P and K (potassium), which were below reported foliar critical thresholds for paper birch, whereas foliar nitrogen (N) concentrations indicated sufficiency. Despite much lower pre-senescence foliar P and K concentrations, trees growing on tailings did not resorb nutrients more effectively than those at smelter-impacted sites. Wide within-site variation in foliar nutrient resorption efficiency and proficiency may indicate that there are physiological constraints to nutrient resorption in contaminated sites, preventing trees from fully resorbing foliar P and K. The similarities in P resorption proficiency despite large differences in pre-senescence chemistry indicate that there may be critical physiological limits below which paper birch are incapable of resorbing nutrients.

123. 题目: Identification of sources, characteristics and photochemical transformations of dissolved organic matter with EEM-PARAFAC in the Wei River of China
文章编号: N21011514
期刊: Frontiers of Environmental Science & Engineering
作者: Yuanyuan Luo, Yangyang Zhang, Mengfan Lang, Xuetao Guo, Tianjiao Xia, Tiecheng Wang, Hanzhong Jia, Lingyan Zhu
更新时间: 2021-01-15
摘要: Dissolved organic matter (DOM) in rivers is a critical regulator of the cycling and toxicity of pollutants and the behavior of DOM is a key indicator for the health of the environment. We investigated the sources and characteristics of DOM in surface water and sediment samples of the Wei River, China. Dissolved organic carbon (DOC) concentration and ultraviolet absorbance at 254 nm (UV254) increased in the surface water and were decreased in the sediment downstream, indicating that the source of DOM in the water differed from the sediment. Parallel factor (PARAFAC) analysis of the excitation-emission matrices (EEM) revealed the presence of terrestrial humus-like, microbial humus-like and tryptophan-like proteins in the surface water, whereas the sediment contained UVA humic-like, UVC humic-like and fulvic-like in the sediment. The DOM in the surface water and sediment were mainly derived from microbial metabolic activity and the surrounding soil. Surface water DOM displayed greater photodegradation potential than sediment DOM. PARAFAC analysis indicated that the terrestrial humic-like substance in the water and the fulvic-like component in the sediment decomposed more rapidly. These data describe the characteristics of DOM in the Wei River and are crucial to understanding the fluctuations in environmental patterns.

124. 题目: Metal contaminations in sediment and associated ecological risk assessment of river Mahanadi, India
文章编号: N21011513
期刊: Environmental Monitoring and Assessment
作者: S. Samanta, Vikas Kumar, S. K. Nag, R. K. Raman, K. Saha, S. Bandyopadhyay, B. P. Mohanty, B. K. Das
更新时间: 2021-01-15
摘要: Mahanadi is one of the major rivers of peninsular India. Like other Indian rivers, it is contaminated with sewages, industrial discharges, and agricultural runoff. Thus, necessity was felt to monitor its pollution status. Present work was part of that program and aimed to assess the sediment contamination due to the trace metals Cd, Cr, Cu, Mn, Pb, and Zn during 2012–2015. Sediment pollution status and ecological risks were evaluated calculating contamination factor (CF), geo-accumulation (Igeo), pollution load index (PLI), potential ecological risk (EiR), etc. The recorded metal concentrations were Cd BDL of flame mode of AAS; Cr BDL - 73.9; Cu BDL - 44.4; Mn 37.2 - 1887.0; Pb BDL - 29.5; and Zn BDL - 92.5 mg kg−1. As per US EPA guidelines, Cr concentrations at many locations were in the moderately polluted range. Igeo, CF, mCd, PLI, and EiR indicated low pollution levels and low ecological risks due to the trace metals assessed. The sediment quality guidelines (SQGs) indicated that Cr and Cu concentrations exceeded (16% sample) the threshold effect concentrations and may occasionally exhibit adverse biological effects. The association of sediment organic matter, conductivity and content of Cu, and their grouping in component 1 of PCA revealed that the anthropogenic input was dominant and so also the component 2 where Cr exhibited moderately good correlation with organic matter. Cluster analysis of the sampling sites based on pollution status yielded 3 groups: relatively uncontaminated (S3, S4), low to moderately contaminated (S2), and moderately contaminated (S1, S5, S6) stretches.

125. 题目: Sediment trap-derived particulate matter fluxes in the oligotrophic subtropical gyre of the South Indian Ocean
文章编号: N21011512
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: Natalie C. Harms, Niko Lahajnar, Birgit Gaye, Tim Rixen, Ulrich Schwarz-Schampera, Kay-Christian Emeis
更新时间: 2021-01-15
摘要: Oligotrophic areas cover about 75% of the ocean's surface, and these ocean regions are predicted to expand under global warming scenarios. To evaluate impacts on global marine biogeochemical cycles and changes in ocean-atmosphere carbon fluxes, it is essential to understand particulate matter fluxes and determine the amount of organic carbon that is exported to the ocean's interior. The oligotrophic Indian Ocean subtropical gyre (IOSG) is one of the least explored ocean regions in terms of particulate matter fluxes. Sediment trap-based particulate matter fluxes determined during a 4-year time series provide new information on the nature of export fluxes, their controlling factors, and on the spatial and temporal variability of oceanic processes in the IOSG. Trap-averaged total mass fluxes (∼9.8 ± 3.7 mg m-2 day-1), as well as particulate organic carbon (POC) fluxes (0.50 ± 0.15 mg m-2 day-1) measured at 500–600 m above bottom (2600–3500 m water depth) are among the lowest fluxes recorded worldwide. These low flux values are a result of strongly stratified and nutrient-depleted upper waters in the gyre. Such oligotrophic conditions lead to low primary production rates in a relatively homogeneous and isolated ocean region. Consequently, we observe an almost constant rain of POC fluxes in space and time, although minor variations in the net primary production (NPP) and in the sea surface temperature (SST) are seen in satellite surveys and model estimations. Factors contributing to the lack of seasonality in the POC fluxes are intense organic matter degradation, variations in the ocean mixed layer depth (OMLD), and impacts of physical mixing (surface wind stress, cyclonic eddies). Preliminary estimates indicate that the average POC export efficiency (ε = 0.03 ± 0.01) is extremely low in the IOSG. Assuming that the IOSG, as well as comparable ocean regions, will expand under climate warming conditions, it is of major importance to investigate POC export fluxes to the deep ocean in order to predict changes in the global carbon cycle during the next decades.

126. 题目: Oxidation of black shale and its deterioration mechanism in the slip zone of the Xujiaping landslide in Sichuan Province, Southwestern China
文章编号: N21011511
期刊: CATENA
作者: Chunwei Sun, Sixiang Ling, Xiyong Wu, Xiaoning Li, Jiannan Chen, Wencai Jiang
更新时间: 2021-01-15
摘要: This work investigated the chemical water–rock interaction of black shale interbedded with limestone along a bedding slip zone and how its deterioration affects the surrounding rock mass in the Xujiaping (XJP) landslide. Many dissolved pits were found on the limestone, and geochemical phenomena were investigated. Rock and water samples from the site were analysed for mineralogy, chemical composition and hydrochemistry. In slip zones, water–rock chemical processes occur in the bedding fractures of interface between black shale and limestone. Thus, a bedding water–rock cyclic reaction experiment was designed with limestone, black shale and black shale interbedded with limestone. Many major elements and heavy elements (Fe, Mn, Si, Zn, Ni, Al, S, Mg, Ca, Na, K, Co and Sr) dissolved out, demonstrating that strong dissolution occurred because of the acidic water during the black shale water–rock interaction. The limestone neutralized the acidic water through black shale oxidation in the interfacial fractures between black shale and limestone, causing deterioration of the slip zone. The acidic water from the fissure network inside the black shale strata migrated along the bedding to the exposed surfaces of cliffs and rock fractures, then evaporated to form secondary mineral phases, including melanterite, rozenite, szomolnokite, and gypsum. The water–rock chemical interaction in the XJP landslide included dissolution, oxidation, dehydration, and neutralization reactions. The accumulation trends and hydrochemical properties at different reaction stages of ions dissolved from the surrounding rock mass in the bedding direction were revealed. The deterioration mechanism was expanded: (i) rock-forming and carbonate minerals were especially prone to dissolution by sulfuric acid from black shale oxidation in the slip zone, and (ii) volume expansion due to the crystallization force of precipitated minerals caused further fracture expansion and deformation. Therefore, geochemical analyses can effectively elucidate the long-term development and nature of slip zones in landslide investigations.

127. 题目: Use of polyacrylamide modified biochar coupled with organic and chemical fertilizers for reducing phosphorus loss under different cropping systems
文章编号: N21011510
期刊: Agriculture, Ecosystems & Environment
作者: Fayong Li, Yingbing Jin, Shuang He, Junwei Jin, Ziwan Wang, Sangar Khan, Guangming Tian, Xinqiang Liang
更新时间: 2021-01-15
摘要: Agricultural cropping systems involve the application of high fertilizer rates, which lead to phosphorus (P) losses via surface runoff to the aquatic environment, thereby resulting in severe eutrophication. Here, to evaluate the nutrient loss, we established three monitoring stations in Zhejiang Province, China, in each of which the crop types were double cropping rice, rice–wheat rotation, and vegetable cultivation. Field experiments were conducted with four treatments and three replications over a whole planting year. The four treatments at the same P application rate were: 1) no fertilization (control; CK), 2) chemical fertilization (CF), 3) substitution of 30 % chemical P in CF by organic P in solid sheep manure (OF) or in liquid biogas slurry (BS), and 4) substitution of 30 % chemical P in CF by organic P fertilizers (solid sheep manure or liquid biogas slurry) +1.5 t ha−1 polyacrylamide modified BC (PSB). The runoff losses of various P forms, that is, the total P, total dissolved P, particulate P, and colloidal P losses were analyzed. The total P concentration varied greatly with the crop growth stages. Compared with CF treatment, PSB treatment significantly reduced the concentration of P fractions in the runoff in all three cropping systems, while the OF treatment significantly reduced the particulate P and colloidal P concentrations by coating colloidal particles with organic carbon. However, BS treatment increased particulate P and colloidal P concentrations. Compared with CF treatment, PSB treatment reduced total P loss by 41.1 %, 29.7 %, and 37.8 % in the double cropping rice, rice–wheat, and vegetable systems, respectively. The PSB and OF treatments significantly reduced the particulate P and colloidal P losses, while BS treatment increased the loss of various P forms. Compared with the CF treatment, the PSB treatment significantly increased the available P contents by 12.7–85.4 mg kg-1, and decreased the colloidal P contents by 26.7 %–51.4 % in the soils examined. The results of the redundancy analysis confirmed that P loss via runoff was mainly caused by differences in the P inputs and crop types. The results of this study highlight the important role of PSB in reducing P loss via runoff from agricultural cropping systems.

128. 题目: Post-agricultural restoration of soil organic carbon pools across a climate gradient
文章编号: N21011509
期刊: CATENA
作者: Yidong Wang, Dongmei Xue, Ning Hu, Yilai Lou, Qingzhong Zhang, Limin Zhang, Ping Zhu, Hongjun Gao, Shuiqing Zhang, Huimin Zhang, Dongchu Li, Zhaoliang Song, Irina Kurganova, Yakov Kuzyakov, Zhong-Liang Wang
更新时间: 2021-01-15
摘要: Post-agricultural natural restoration is a worldwide strategy for eco-environmental sustainability. However, it is unclear how it affects soil organic carbon (SOC) pools and composition among soil types across climate gradient. Here, we investigated 23-year post-agricultural restorations of SOC in three soils: Luvic Phaeozem, Calcaric Cambisol and Ferralic Cambisol typical for mid-temperate, warm-temperate and subtropical zones, respectively. Six SOC fractions with different protection mechanisms (non-protected, physically, chemically, biochemically, physico-chemically and physico-biochemically) were separated. Compared with pre-restoration in 1990, post-agricultural restoration rebuilt SOC similarly (+68–+91%) among the three soils despite of different SOC background. Compared with continuous cultivation, post-agricultural restoration increased total SOC pools in all the three soils (+33–+60%) mainly because of the increments of non-protected pool (coarse particulate organic C, cPOC). However, the pure physically, chemically, and biochemically protected SOC fractions were less sensitive to post-agricultural restoration. The physico-biochemically protected SOC was hampered by restoration in the two temperate soils but remained stable in the subtropical soil, suggesting a divergent self-restoring trend. Positive correlations of the total SOC and most fractions with wetness (precipitation/temperature ratio) demonstrated the climate dependency of SOC. In conclusion, post-agricultural natural restoration builds up SOC pool mainly due to the cPOC increment and shifts SOC composition towards more easily available C in three soils across the climatic gradient.

129. 题目: How much carbon input is required to preserve or increase projected soil organic carbon stocks in German croplands under climate change?
文章编号: N21011508
期刊: Plant and Soil
作者: Catharina Riggers, Christopher Poeplau, Axel Don, Cathleen Frühauf, René Dechow
更新时间: 2021-01-15
摘要: Increasing soil organic carbon (SOC) stocks is discussed as negative emission technology with the potential to remove relevant amounts of carbon from the atmosphere. At the same time, climate change-driven losses of SOC to the atmosphere might impede such goals.

130. 题目: Sources and light absorption characteristics of water-soluble organic carbon (WSOC) of atmospheric particles at a remote area in inner Himalayas and Tibetan Plateau
文章编号: N21011507
期刊: Atmospheric Research
作者: Yawei Li, Fangping Yan, Shichang Kang, Chao Zhang, Pengfei Chen, Zhaofu Hu, Chaoliu Li
更新时间: 2021-01-15
摘要: Water-soluble organic carbon (WSOC) is an important component of carbonaceous aerosols. Increasing evidences show that WSOC absorbs and scatters sunlight in the atmosphere, which is one of the key components of climate change. Despite numbers of related studies, understanding of basic characteristics of WSOC is limited at remote region, such as the Himalayas and Tibetan Plateau (HTP), one of the remotest regions in the world with weak local anthropogenic activities. In this study, we conducted a year-round investigation of multiple aerosol species at Nam Co, a pristine station in inner part of the HTP. The results showed that the annual mean concentrations of PM2.5 and its WSOC were 8.9 ± 5.4 μg m−3 and 249 ± 111 ng m−3, respectively, which was among the lowest values in the HTP, representing a clean environment. WSOC of PM2.5 and total suspended particle (TSP) samples were mainly derived from combustion emissions and fine particle of local surface soil, respectively, indicating significant contribution of local sources of the HTP to TSP samples. Similarly, due to the influence of surface soil, respective absorption per mass of WSOC at 365 nm (α/ρWSOC) of TSP (1.74 ± 0.94 m2 g−1) was significantly higher than that of PM2.5 (1.22 ± 0.43 m2 g−1). Seasonally, high and low WSOC concentrations and α/ρWSOC values appeared at non-monsoon and monsoon periods, respectively. This study provides observational constraints for related researches such as modelling of the environmental impact of WSOC in the HTP.

131. 题目: The joint effect of ammonium and pH on the growth of Chlorella vulgaris and ammonium removal in artificial liquid digestate
文章编号: N21011506
期刊: Bioresource Technology
作者: Renyuan Jiang, Lei Qin, Siran Feng, Dalong Huang, Zhongming Wang, Shunni Zhu
更新时间: 2021-01-15
摘要: Although ammonium containing digestate is an ideal alternative medium for microalgae cultivation, high ammonium or unfavorable pH may inhibit microalgal growth. In this study, the joint effect of ammonium and pH on the growth of C. vulgaris and nutrient removal in artificial digestate was investigated. Our results show that ammonium and pH both affected algal growth, but free ammonia (FA) was the main actual inhibitory factor. Algal specific growth rate presented a negative correlation with FA and their relationship was well fitted by a linear regression model. Microalgal growth was little affected below 36.8 mg L-1 FA, while the obvious inhibition occurred at 184 mg L-1 FA (EC50), indicating a high tolerance to FA. Ammonium removal was well described by a first-order kinetics model. FA stress stimulated the production of extracellular organic matters (EOMs), which was good for microalgae adaptation but adverse to pollutant removal.

132. 题目: Improving anaerobic digestion of chicken manure under optimized biochar supplementation strategies
文章编号: N21011505
期刊: Bioresource Technology
作者: Junyi Ma, Fengfen Chen, Shuaixing Xue, Junting Pan, Benyamin Khoshnevisan, Yadong Yang, Hongbin Liu, Ling Qiu
更新时间: 2021-01-15
摘要: Anaerobic digestion of chicken manure was carried out in this study basing on central composite design to identify the most optimal strategy for biochar supplementation. Model of cumulative methane production (CMP) was established by using response surface methodology. The optimal conditions predicted accordingly, including manure loading of 51.8 g VS/L, biochar dosage of 3.3% VSmanure, and cellulose loading of 98.0 g VS/L, were expected to maximize CMP, i.e., 294 mL/g VSmanure. The results also demonstrated that biochar dosage and its interaction with manure loading were key factors with significant impact on CMP. Biochar dosage higher than 3.5% VSmanure was observed to weaken the transformation of organic substances to methane. Higher dosage of biochar could considerably reduce concentration of organic acids, total ammonia nitrogen, as well as soluble salts. Verification experiment supported validity of the optimal strategy and provided data for cost assessment, which showed positive cost balances from biochar supplementation.

133. 题目: Effects of microplastic accumulation on floc characteristics and fouling behavior in a membrane bioreactor
文章编号: N21011504
期刊: Journal of Hazardous Materials
作者: Thitiwut Maliwan, Wiboonluk Pungrasmi, Jenyuk Lohwacharin
更新时间: 2021-01-15
摘要: Issues associated with accumulating microplastic (MP) in sewage sludge during wastewater treatment in a membrane bioreactor (MBR) system have not been studied in detail. Here, we investigated the microplastic’s effects on floc characteristics, microbial community compositions, and fouling behavior inside sequencing-batch MBRs. MBRs were operated with 0, 7, 15, and 75 MPs/L of feed for 124-days. Results indicated that MP presence decreased sludge floc size, floc hydrophobicity, and extracellular polymeric substance (EPS) molecular size, and increased EPS concentration and the floc’s negative zeta potential. These results were attributed to the facilitation of divalent cation (Ca2+ and Mg2+) uptake by MPs that weakened ion-bridging interactions within the sludge flocs. MPs accumulation slightly affected microbial structure and diversity. Relative abundances of dominant phyla, Actinobacteria, also decreased substantially. MPs also acted like a scouring material on membrane surfaces, inducing transformation of matured biofilm structures where protein content was substantially lower than nucleic acid content, in contrast to the control. Overall, MPs’ negative effects on sludge flocs were counteracted by their scouring effect; consequently, SB-MBRs operated up to 4 months did not suffer from severe cake fouling, compared to control.

134. 题目: A predictive model for arsenic accumulation in rice grains based on bioavailable arsenic and soil characteristics
文章编号: N21011503
期刊: Journal of Hazardous Materials
作者: Bao-Min Yao, Peng Chen, Hong-Mei Zhang, Guo-Xin Sun
更新时间: 2021-01-15
摘要: Arsenic (As) is a well-known human carcinogen, and rice consumption is the main way Chinese people are exposed to As. In this study, 14 kinds of paddy soils were collected from the main rice-producing areas in China. The results showed that rice roots and leaves accumulated more As than stems and grains in the following sequence: Asroot > Asleaf > Asstem > Asgrain. The accumulation of As by rice grains mainly depends on the total As and bioavailable As (0.43 mol/L HNO3 extractable As), which explained 32.2% and 22.2% of the variation in the grain As, respectively. In addition, soil pH, organic matter (OM) and clay contents were the major factors affecting grain As, explaining 13.1%, 7.9% and 5.3% of the variation, respectively. An effective prediction model was established via multiple linear regression as Asgrain = 0.024 BAs - 0.225 pH + 0.013 OM + 0.648 EC - 0.320 TN - 0.088 TP - 0.002 AS + 2.157 (R2 = 0.68, P < 0.01). Through the verification of the samples from both pot experiments and paddy fields, the model successfully provided accurate predictions for rice grain As.

135. 题目: Study of soil microorganisms modified wheat straw and biochar for reducing cadmium leaching potential and bioavailability
文章编号: N21011502
期刊: Chemosphere
作者: Haris. Muhammad, Ting. Wei, Geng. Cao, ShengHui. Yu, XinHao. Ren, HongLei. Jia, Atif. Saleem, Li. Hua, JunKang. Guo, Yongtao. Li
更新时间: 2021-01-15
摘要: The application of crops straw and biochar in trace metals remediation from the contaminated environment attracted more and more attention during the past decade. Although there has been some review work on the mechanism of trace metals stabilization by crops straw, the effects and mechanisms of interaction among soil indigenous-microbes and crops-straw for trace metal adsorption and stabilization is still unclear. In this study, the dynamic effects along with potential mechanisms of wheat-straw (WS), wheat-straw biochar (WBC) and biologically modified wheat-straw (BMWS) were conducted to investigate the adsorption, leaching behaviour, chemical fractions and bioavailability of cadmium (Cd). The results showed that the biosorption capacity (qe) was most elevated in the BMWS treatment (14.42 mg g-1) as compared to WBC (6.28 mg g-1) and WS (4.20 mg g-1). The application of BMWS, WBC and WS at the rate of 3% significantly reduced Cd concentration in leachate to 53, 45 and 21% respectively, as compared to control. The addition of BMWS reduced the exchangeable Cd fraction resulted an increase in organic matter and carbonate bound Cd fraction in the soil. The DTPA extractable Cd was significantly decreased by 31.2 and 28.6% with the application of BMWS and WBC at 3% w/w respectively as compared to control. The research results may provide a novel perceptive for the development of functional materials and strategies for eco-friendly and sustainable trace metal remediation in contaminated soil and water by combination of straw and soil-indigenous microorganisms.

136. 题目: Magnetic biochars have lower adsorption but higher separation effectiveness for Cd2+ from aqueous solution compared to nonmagnetic biochars
文章编号: N21011501
期刊: Environmental Pollution
作者: Fei Huang, Si-Ming Zhang, Ren-Ren Wu, Lu Zhang, Peng Wang, Rong-Bo Xiao
更新时间: 2021-01-15
摘要: Magnetic biochars were prepared by chemical co-precipitation of Fe3+/Fe2+ onto rice straw (M-RSB) and sewage sludge (M-SSB), followed by pyrolysis treatment, which was also used to prepare the corresponding nonmagnetic biochars (RSB and SSB). The comparison of adsorption characteristics between magnetic and nonmagnetic biochars was investigated as a function of pH, contact time, and initial Cd2+ concentration. The adsorption of nonmagnetic biochars was better described by pseudo-second-order kinetic model, and the adsorption of RSB and SSB was better described by Langmuir and Freundlich models, respectively. Magnetization of the biochars did not change the applicability of their respective adsorption models, but reduced their adsorption capabilities. The maximum capacities were 42.48 and 4.64 mg/g for M-RSB and M-SSB, respectively, underperforming their nonmagnetic counterparts of 58.65 and 7.22 mg/g for RSB and SSB. Such a reduction was fundamentally caused by the decreases in the importance of cation-exchange and Cπ-coordination after magnetization, but the Fe-oxides contributed to the precipitation-dependent adsorption capacity for Cd2+ on magnetic biochars. The qualitative and quantitative characterization of adsorption mechanisms were further analyzed, in which the contribution proportions of cation-exchange after magnetization were reduced by 31.9% and 12.1% for M-RSB and M-SSB, respectively, whereas that of Cπ-coordination were reduced by 3.4% and 31.1% for M-RSB and M-SSB, respectively. These reductions suggest that for adsorbing Cd2+ the choice of conventional biochar was more relevant than whether the biochar was magnetized. However, magnetic biochars are easily separated from treated solutions, depending largely on initial pH. Their easy of separation suggests that magnetic biochars hold promise as more sustainable alternatives for the remediation of moderately Cd-contaminated environments, such as surface water and agriculture soil, and that magnetic biochars should be studied further.

137. 题目: Metaproteomics reveals the molecular mechanism underlying bloom maintenance of a marine dinoflagellate under low ambient CO2 and inorganic nutrients
文章编号: N21011416
期刊: Science of The Total Environment
作者: Hao Zhang, Hong-Kai Xu, Shu-Feng Zhang, Youping Zhou, Yan-Bin He, Shady Amin, Jian-Wei Chen, Ke-Qiang Yan, Lin Lin, Si-Qi Liu, Da-Zhi Wang
更新时间: 2021-01-14
摘要: Dinoflagellate blooming periods are paradoxically characterized by high biomass growth rate and low ambient dissolved CO2 and inorganic nutrients, however, the underlying mechanisms linking cell growth and nutrient acquisition are poorly understood. Here, we compared metaproteomes of non-bloom, mid-blooming and late-blooming cells of a marine dinoflagellate Prorocentrum donghaiense. Cell division, metabolism of carbon, nitrogen, phosphorus, lipid, porphyrin and chlorophyll were more active in blooming cells than in non-bloom cells. Up-regulation of carbonic anhydrase, ribulose-1,5-bisphosphate carboxylase/oxygenase II, and C4-cycle proteins enhanced CO2 assimilation of P. donghaiense. Proteins participating in external organic nutrient acquisition and conversion, such as transporters for fatty acids, peptides and amino acids, external- and internal-phosphomonoester hydrolase, and diverse peptidases and amino acid transaminases, exhibited higher expression in blooming cells relative to non-bloom cells. Interestingly, dissolved organic nitrogen (DON) such as urea and aspartate significantly down-regulated expression and activity of carbon assimilation proteins except for RuBisCO form II, suggesting that DON provided sufficient carbon source which reduced the need to concentrate internal CO2. This study demonstrates that coupling of efficient CO2 assimilation with DON utilization are essential for bloom maintenance of P. donghaiense, and future efforts should be devoted to dissolved organic nutrients for prevention and management of dinoflagelllate blooms.

138. 题目: Adsorption and Regeneration on Iron-Activated Biochar for Removal of Microcystin-LR
文章编号: N21011415
期刊: Chemosphere
作者: Shengquan Zeng, Eunsung Kan
更新时间: 2021-01-14
摘要: Novel iron activated biochars (FA-BCs) were prepared via simultaneous pyrolysis and activation of FeCl3-pretreated bermudagrass (BG) for removing microcystin-LR (MC-LR) in aqueous solution. Compared to the raw BC (without activation), the surface area and adsorption capacity of FA-BC at iron impregnation ratio of 2 (2 g FeCl3/g BG) were enhanced from 86 m2/g and 0.76 mg/g to 835 m2/g and 9.00 mg/g. Moreover, FA-BC possessed various iron oxides at its surface which provided the catalytic capacity for regeneration of MC-LR spent FA-BC and magnetic separation after the MC-LR adsorption. Possible mechanisms for the MC-LR adsorption onto FA-BC would include electrostatic attraction, π+-π, hydrogen bond, and hydrophobic interactions. The detailed adsorption studies indicated mainly chemisorption and intra-particle diffusion limitation would participate in the adsorption process. The thermal regeneration at 300 °C kept high regeneration efficiency (99-100%) for the MC-LR spent FA-BC during four cycles of adsorption-regeneration. In addition, the high regeneration efficiency (close to 100%) was also achieved by persulfate oxidation-driven regeneration. FA-BC also exhibited high adsorption capacity for the MC-LR from the real lake water to meet the M C-L R concentration below 1 μg/L as a safe guideline suggested by WHO.

139. 题目: Increase in arsenic methylation and volatilization during manure composting with biochar amendment in an aeration bioreactor
文章编号: N21011414
期刊: Journal of Hazardous Materials
作者: Weiwei Zhai, Ting Guo, Su Yang, Williamson Gustave, Muhammad Zaffar Hashmi, Xianjin Tang, Weimin Wu, Lena Q. Ma, Jianming Xu
更新时间: 2021-01-14
摘要: Biochar is widely used as an amendment to optimize the composting process. In this study, we firstly investigated the effects of biochar amendment on methylation and volatilization of arsenic (As), and the microbial communities during manure composting. Biochar amendment was found to increase the concentrations of monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) during mesophilic (days 0–10) and early thermophilic (days 11–15) phases, and promote As volatilization during the maturing phase (days 60–80) of composting. In addition, the abundances of As(V) reductase (arsC) and As(III) S-adenosyl-L-methionine methyltransferase (arsM) genes were higher in the biochar treatment than that in the control. Moreover, biochar amendment influenced the microbial communities by promoting As methylation and volatilization via Ensifer and Sphingobium carrying arsC genes, and Rhodopseudomonas and Pseudomonas carrying arsM genes. This study emphasized the considerable role of biochar on methylation and volatilization of As during manure composting and provided an overall characterization of the community compositions of arsC and arsM genes during manure composting. It will broaden our insights in As biogeochemical cycle during manure composting with biochar amendment, which will facilitate the regulation of As during manure composting and its application in agricultural soil.

140. 题目: Potential linkage between sedimentary oxygen consumption and benthic flux of biogenic elements in a coastal scallop farming area, North Yellow Sea
文章编号: N21011413
期刊: Chemosphere
作者: Bo Yang, Xuelu Gao, Jianmin Zhao, Yongliang Liu, Lei Xie, Xiaoqing Lv, Qianguo Xing
更新时间: 2021-01-14
摘要: Surface sediments were collected from a mariculture area adjacent to the Yangma Island suffering from hypoxia in summer, and a laboratory static incubation was conducted to study the sedimentary oxygen consumption (SOC) and the benthic fluxes of nutrients and fluorescent dissolved organic matter (FDOM). Compared with some coastal areas, the SOC of the studied area was relatively low in summer with the value of 2.34-6.03 mmol m-2 d-1. Sediment acted as an important source of nutrients (except for nitrate) and FDOM for the overlying water. Dissolved oxygen (DO) in the overlying water could affect the decomposition mode of sedimentary organic matter (SOM), i.e. aerobic and anaerobic decomposition and subsequently dominated the release of nutrients and FDOM. When DO > 50 μmol l-1, it was beneficial to the release of ammonium, silicate and FDOM. In contrast, low oxygen conditions, i.e. DO < 100 μmol l-1, stimulated sediment phosphate efflux. In addition, scallop farming activities also affected the SOC and benthic flux of nutrients and FDOM mainly through biological deposition.

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