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25261. 题目: Characteristics of organic material inputs affect soil microbial NO 3 − immobilization rates calculated using different methods
文章编号: N20033002
期刊: European Journal of Soil Science
作者: Zhao-Xiong Chen, Hui-Min Zhang, Xiao-Shun Tu, Xin Sun, Jing Wang, Yi Cheng, Jin-Bo Zhang, Zu-Cong Cai, Scott X. Chang
更新时间: 2020-03-30
摘要: Microbial immobilization of nitrate (NO3−) is considered as an important process in reducing NO3 − accumulation and regulating nitrogen (N) retention capacity in soils. Accurately quantifying the rate of microbial NO3− immobilization is therefore necessary to predict its role in lowering NO3− accumulation in soils. We compared microbial NO3− immobilization rates using a 15NO3− labelling technique in three different ways: (i) 15N pool dilution, (ii) organic 15N recovery and (iii) microbial biomass 15N recovery in a nitrate‐rich upland soil with and without amendment with organic materials with differing C/N ratios. The three methods generated similar NO3− immobilization rates, except when the soil was amended with easily decomposable organic materials (glucose and sucrose). We also developed a microbial NO3− immobilization‐specific quality index that incorporates C/N ratio, contents of lignin, cellulose and hemicellulose contents, and pH for slowly decomposing organic materials (plant residues). This study provides a direct empirical evidence that the results of different methods for calculating soil microbial NO3− immobilization rates are affected by the characteristics of organic materials amended to the soil.

25262. 题目: Recycling of powder coke to cost effective adsorbent material and its application for tertiary treatment of coking wastewater
文章编号: N20033001
期刊: Journal of Cleaner Production
作者: Chen Zhang, Jianfeng Li, Fangqin Cheng
更新时间: 2020-03-30
摘要: Rapid removal of recalcitrant organic contaminants from coking wastewater remains a challenge. Powder coke is a burden to coke plant and environment, has the potential as a cost-effective absorbent material. But its absorption capacity is limited by the dense crystalline carbon structure and low surface activity. This study proposes a facile method to fabricate powder coke-derived adsorbent by tuning the surface functional groups. Results revealed that the obtained powder coke-derived adsorbent presented a relatively smooth surface, worm-like pore structure and discernible graphitization degree. The O1S and N1S functional groups were increased from 27.7% to 52.2%. The adsorption of recalcitrant organic contaminants from coking wastewater was increased by 70%, implying significantly by the reduced UV254. The increased N and O-contained functional groups on the surface could introduce hydrophobic force and π-π EDA interactions, which are responsible to the enhanced interactions between powder coke-derived adsorbent and recalcitrant organic contaminants (PAHs and BAD, etc). The engineering aspect of the powder coke-derived adsorbent was discussed in the perspective of recent advances and challenges. This study provides scientific basis for its effective use of powder coke as an adsorbent for tertiary treatment of coke wastewater, so as to achieve the dual purposes of clean production and environmental protection.

25263. 题目: Root cellulose drives soil fulvic acid carbon sequestration in the grassland restoration process
文章编号: N20032911
期刊: Catena
作者: Xuejuan Bai, Zehui Guo, Yimei Huang, Shaoshan An
更新时间: 2020-03-29
摘要: Revegetation is an effective means to increase the soil organic carbon (SOC) stock and reverse SOC loss worldwide. Restoration through grasslands has great potential primarily due to the contribution of the root system. However, the impacts of grassland restoration remain uncertain, as current understandings of the direction and magnitude of changes in different SOC fractions and the influence of root properties on SOC are still unclear. To address this problem, we conducted a field study to investigate variations in SOC fractions and root properties under different grassland restoration times (1, 5, 10, 15, 25 and 30 years following restoration) in the Loess Plateau, China. Specifically, we measured fractions of soil labile organic carbon including microbial biomass carbon (MBC) and dissolved organic carbon (DOC) and fractions of soil stable organic C including humus carbon (HS), fulvic acid carbon (FA) and humic acid carbon (HA) in the 1 m soil profile. Furthermore, we evaluated root biomass, root C, root lignin and cellulose as potential drivers of SOC patterns. We found that SOC, soil labile organic C and soil stable organic C fractions generally increased with the revegetation time, except for brief decreases at the 5- and 15-year marks. Across the entire period (year 1 to 30), the proportions of HS and FA to SOC increased by 10.64% and 14.72% at 30 years, respectively, while the ratios of MBC and DOC to SOC were relatively stable. The average SOC accumulation rate was 0.72 Mg ha−1 yr−1 in the 1 m soil profile over the 30-year grassland revegetation period. The average rate of change of FA (0.67 Mg ha−1 yr−1) was higher than that of the HA, HS and soil labile organic C fractions, which indicated that SOC stability increased and SOC accumulation was mainly derived from the enhancement of FA. Decreases in root biomass and cellulose storage drove reductions in SOC fraction stores with soil depth. The root cellulose exerted significant influences on the SOC and SOC fractions, especially on FA (R2 = 0.82, p < 0.01). These findings show that grassland restoration plays an important role in improving and increasing SOC; in particular, the increase of FA results from the augmentations of root cellulose.

25264. 题目: Effects of land use on the characteristics and composition of fluvial chromophoric dissolved organic matter (CDOM) in the Yiluo River watershed, China
文章编号: N20032910
期刊: Ecological Indicators
作者: Tiantian Shao, Tao Wang
更新时间: 2020-03-29
摘要: Chromophoric dissolved organic matter (CDOM) is a key indicator of water quality, biogeochemical state and nutrient content in freshwaters. Land use affects the concentration, quality, source, and age of CDOM in rivers. To investigate the characteristics and composition of fluvial CDOM and the effects of land use on carbon components, 37 sites were sampled during May 2017 in the Yiluo River watershed, China. In addition, water parameters, absorption and fluorescence spectral parameters of CDOM were measured in situ and in the lab. Some samples showed atypical CDOM absorption curves with an absorption shoulder at 390 nm. CDOM absorption at 440 nm [aCDOM(440)] was positively correlated with dissolved organic carbon (DOC) and fluorescence intensity (Fn). Fluorescence excitation-emission spectra indicated the presence of strong humic-like and tryptophan-like fluorophores revealing terrestrial, anthropogenic influence. Low recent autochthonous contribution index (BIX) and humification index (HIX) values indicated that autochthonous production was an important contributor to CDOM levels. Cropland-dominated subwatersheds (SWs) exhibited high aCDOM(440), Fn and DOC and forest-dominated SWs showed low CDOM concentration. At the riparian buffer scale, CDOM in the built-up-dominated areas showed the highest CDOM concentration. Moreover, built-up areas greatly influenced the concentrations of DOC and CDOM quantificationally at both the SW and riparian buffer scales; more than 64% of the overall variation in carbon components at the SW scale and 46% of DOC variation at the riparian buffer scale was explained by built-up areas. Overall, the results of our study showed that the properties of fluvial CDOM are dependent on the surrounding land use, further highlighting the importance of land use for CDOM photoreactivity in SWs and riparian buffer zones.

25265. 题目: Quantifying the contributions of surface area and redox-active moieties to electron exchange capacities of biochar
文章编号: N20032909
期刊: Journal of Hazardous Materials
作者: Shasha Li, Liming Shao, Hua Zhang, Pinjing He, Fan Lü
更新时间: 2020-03-29
摘要: Redox properties play a critical part in enabling biochar to participate in geochemical redox cycles. To manufacture biochar with targeted redox properties, it is essential to define the correlation of redox properties with the structure and moieties of biochar. However, previous studies focused on moieties, while structural parameters were overlooked. Furthermore, most publications used a single-factor analysis for certain types of moieties with other moieties possibly ignored. Herein, four kinds of representative biomass components, cellulose, lignin, casein, and starch, were pyrolyzed at low, intermediate, and high temperatures to obtain biochar with distinct structures and moieties. Then, the partial least-squares modeling was implemented to evaluate the quantitative contributions of structure and moieties to redox properties with the results obtained by characterizing the biochar. In addition to redox-active moieties, specific surface area was also found to be critical to the redox properties. The cellulose-derived chars exhibited better electron-donating capacities, while the lignin-derived chars exhibited better electron-accepting capacities. The starch-derived chars pyrolyzed at 700℃ possessed both high electron-donating and electron-accepting capacities. The casein-derived biochar exhibited weak redox capacities. These findings show the importance of structural influences on the redox properties and provide feedstock choices when applying and producing biochar with targeted redox properties.

25266. 题目: Organic carbon storage and its influencing factors under climate warming of sediments in steppe wetland, China
文章编号: N20032908
期刊: Environmental Science and Pollution Research
作者: Shihai Lyu
更新时间: 2020-03-29
摘要: The effect of climate warming on soil organic carbon (SOC) of sediment in wetlands is important for accurately projecting SOC content. Thus, understanding the mechanism influencing SOC content under climate warming is necessary. Field investigation and a laboratory incubation experiment were conducted in Hulunbeier steppe wetland during 2016 and 2017. Four types of wetland were selected to incubate with ambient temperature and temperature increased by 2.5 °C. The results showed that SOC content was negatively affected by temperature warming. The SOC content reduction in sediment caused by increasing temperature was ranged from − 2.34 to 39.52%. In addition, the content of sand, silt, total phosphorus (TP), calcium phosphate tribasic (Ca-P), total nitrogen (TN), and sediment moisture (MC) should be considered in models of SOC content in steppe wetland. However, it requires further validation, in particular how SOC content varies with warming temperatures, the duration of incubation, and other abiotic and biotic factors. These findings provide evidence that both climate warming and original characteristics of sediment can control the SOC storage dynamics in the steppe wetland.

25267. 题目: Enhanced formation of carbonaceous and nitrogenous disinfection byproducts from biofilm extracellular polymeric substances undercatalysis of copper corrosion products
文章编号: N20032907
期刊: Science of the Total Environment
作者: Jun Hu, Chen Wang, Bijuan Shao, Lingxiao Fu, Jianming Yu, Zhimin Qiang, Jianmeng Chen
更新时间: 2020-03-29
摘要: Biofilm formation is ubiquitous on the corroded inner surface of water distribution pipes. Extracellular polymeric substances (EPS) secreted by biofilm microorganisms are nonnegligible precursors of disinfection byproducts (DBPs). The aim was to study the catalysis of copper corrosion products (CCPs, CuO and Cu2+) on the formation of carbonaceous and nitrogenous DBPs (C-DBPs and N-DBPs) with EPS as a precursor. Results indicate that CCPs had a remarkable enhancement on the formation of DBPs, especially N-DBPs. The enhancement by Cu2+ was mainly via homogeneous catalysis initiating from its complexation with EPS, while that by CuO was primarily through heterogeneous catalysis initiating from the polarization of Cl atom in HOCl/OCl−. The enhancement was more evident as pH increased because an alkaline condition favored the electrostatic interactions of CCPs with EPS and HOCl/OCl−. The presence of Br− weakened the enhancement, which may be attributed to that HOBr/OBr− had a much higher reaction rate than HOCl/OCl− towards the low reactive moieties in EPS. Due to more phenolic or unsaturated/conjugated groups, EPS proteins had a higher catalytic formation of DBPs than EPS polysaccharides. Among the major amino acids in EPS proteins for DBPs formation, tyrosine had the highest enhancement on the formation of trihalomethanes, while histidine had the highest catalytic formation of halogenated acetic acids, acetonitriles and acetamides. The study helps to understand the formation of DBPs by the joint actions of EPS and CCPs in drinking water distribution systems.

25268. 题目: Food waste composting - Is it really so simple as stated in scientific literature? – A case study
文章编号: N20032906
期刊: Science of the Total Environment
作者: Stanislava Voběrková, Alžbeta Maxianová, Nikola Schlosserová, Dana Adamcová, Martina Vršanská, Lukáš Richtera, Milica Gagić, Jan Zloch, Magdalena Daria Vaverková
更新时间: 2020-03-29
摘要: Food waste has recently gained much worldwide interest due to its influence on the environment, economy and society. Gathering and recycling of food waste is the essential issue in the waste management and the interest in processing food waste arises mainly out of influence of the processes of food putrefaction on the environment. Composting of food waste encounters a number of technical challenges, arising weak physical structure of food waste with weak porosity, high content of water, low carbon-to-nitrogen relation and fast hydrolysis and accumulation of organic acids during composting. Therefore, the aim of this study was to investigate the challenges facing installations intended for food waste composting, with the purpose to their optimization with use of appropriate additives. Physico-chemical, biochemical characteristics and phytotoxicity of the produced compost has been measured. Two additives (20% biochar and 20% sawdust) were chosen from experimental variants I-XII containing different additives (biochar, Devonian sand, sawdust) in diverse concentration. The use of selected additives seems to slightly increase potential of hydrogen value and carbon-to-nitrogen ratio, while decreasing electrical conductivity in comparison with control sample. The results obtained also show that the addition of biochar leads to an increase dehydrogenase, phosphatase and arylsulphatase activities and addition of sawdust has a positive effect on beta-D-glucosidase, protease, phosphatase and arylsulphatase activities. The phytotoxicity test shows that the compost made of food waste (control sample) and with addition of biochar is toxic to plants. By contrast, the addition of sawdust shows that the compost was not phytotoxic. In conclusion, the addition of additives does not provide unambiguous results in terms of the quality of the final product in all monitored parameters. Therefore, we can state that food waste was reduced and hygienized, and that the final product does not meet conditions for mature compost.

25269. 题目: Transport and transformation of Cd between biochar and soil under combined dry-wet and freeze-thaw aging
文章编号: N20032905
期刊: Environmental Pollution
作者: Zhuowen Meng, Shuang Huang, Ting Xu, Yiyi Deng, Zhongbing Lin, Xiugui Wang
更新时间: 2020-03-29
摘要: We quantified the transport and transformation of Cd in historically contaminated soil (OS) and artificially contaminated soil (NS), treated with 3% (w/w) rice straw biochar prepared at 400 °C (BC400) and 700 °C (BC700) under combined dry-wet and freeze-thaw cycles for 72 days simulating the natural aging process of 8 years. An improved three-layer mesh experiment was developed to simulate the natural situation in field. The result showed that the total Cd concentration increased in the biochar but decreased in the soil, suggesting that Cd was transported from the soil into the biochar during the aging process. The total Cd concentration in BC400 treated with both soils was higher than that in BC700 treated with both soils, however, BC700 displayed stronger ability on immobilizing Cd than BC400 because the Tessier exchangeable Cd fraction in BC700 treated both soils was lower than that in BC400 treated with both soils. The average Tessier exchangeable Cd fraction in the soil and biochar decreased in all treatments during the aging process, indicating that Cd tended to be more stable in the soil for a long term. The result also showed that biochar could immobilizate Cd by decreasing the Tessier exchangeable Cd fraction of soil and biochar, and the quantitative contributions of biochar and soil to Cd immobilization were different in OS and NS treated with BC400 and BC700. The biochar contribution to the reduction in Tessier exchangeable Cd fraction accounted for 40–85% in NS treated with BC400 and 54–82% in NS treated with BC700. However, in OS treated with biochar, the biochar contribution accounted for nearly 100%, and soil had almost no contribution. In summary, OS did not contribute to Cd immobilization, while NS contributed nearly 50% to Cd immobilization, and BC700 was more effective in immobilizing Cd than BC400.

25270. 题目: Aqueous Cr(VI) removal by biochar derived from waste mangosteen shells: Role of pyrolysis and modification on its absorption process
文章编号: N20032904
期刊: Journal of Environmental Chemical Engineering
作者: Rui Shan, Yueyue Shi, Jing Gu, Jingwang Bi, Haoran Yuan, Bo Luo, Yong Chen
更新时间: 2020-03-29
摘要: A series of mangosteen-derived biochars were produced by several modifiers (HCl, KOH and ZnCl2), in different preparation conditions (i.e. pyrolysis temperature, pyrolysis process and impregnation ratio). It indicated that the Z2PT350-700 presented excellent ability for Cr(VI) removal. The physical/chemical properties of the prepared biochar are reflected by the electrostatic interaction, surface complexation, ion exchange occupied primary position in the process of adsorbing Cr(VI). Besides, the effects of reaction time, pH, adsorbent dosage and initial adsorbate concentration on Cr(VI) removal were evaluated. The sorption process of Cr(VI) could be described by the pseudo-second order (PSO) kinetic model and Sips isotherm model. In optimal reaction condition, the surface of Zn2MB350-700 was composed of homogeneous and heterogeneous adsorption and the chemical adsorption dominated in the adsorption process. Therefore, the results suggested that Zn2MB350-700 could be used as an inexpensive and highly efficient adsorbent for Cr removal from water environment.

25271. 题目: Seasonality of Hg dynamics in the Ebrié Lagoon (Côte d’Ivoire) ecosystem: influence of biogeochemical factors
文章编号: N20032903
期刊: Environmental Science and Pollution Research
作者: Lou Brou Cécile Kouame, Emile B. Bolou Bi, Natchia Aka, Vanessa Alphonse, Bi Tié Albert Goula, Clarisse Balland-Bolou-Bi
更新时间: 2020-03-29
摘要: This study addresses the different biogeochemical parameters that control the dynamics of Hg, which is a less-studied metal in the Ebrié Lagoon. During two hydrological seasons, the dry season and the rainy season, we regularly sampled and analysed various compartments (e.g. sediments and fishes (Tilapia sp.)) of the lagoon. Thus, the physicochemical parameters were measured in situ (e.g. temperature, pH, salinity, redox potential and dissolved oxygen, total dissolved organic carbon, nitrates and sulphates), and the microbiological parameters (e.g. cultivable cells, total enzymatic activity and catabolic activity) were measured to establish the seasonal variations in the links between Hg and biogeochemical parameters through multivariate statistical analyses. The bioavailability of Hg from an unpolluted site was studied by comparing the ratios of fish and sediment. The results indicated that the seasons influenced the different biogeochemical factors, although for some factors, the variations were not significant. This influence was more pronounced in the dry season than in the rainy season. The impact of microbial activities and organic matter on Hg dynamics was observed in all seasons. However, other factors, such as pH, temperature, salinity, Eh and sulphates, influenced the dynamics of Hg only in the dry season.

25272. 题目: A quantitative assessment of organic carbon content as a regional sediment-condition indicator
文章编号: N20032902
期刊: Ecological Indicators
作者: Walter G. Nelson
更新时间: 2020-03-29
摘要: Organic carbon content of sediments, whether directly or indirectly assessed, has often been used as an indicator of marine benthic community condition both in site-specific and regional scale condition assessment studies. The conceptual framework underlying use of this indicator was developed based primarily on site-specific studies. A quantitative analysis of literature data on sediment organic matter impacts in marine systems was conducted to determine whether biotic metrics respond to abiotic indicators of sediment organic content, as predicted by conceptual models, at larger spatial scales. The ability to detect predicted decreases in community metrics (abundance, species richness, species diversity index H', biomass) varied among metrics, with best performance by species richness and H'. There was significant added variation both between and within analytical approaches (loss on ignition, total organic carbon methods), emphasizing the need for careful cross calibration and quality control in studies with multiple laboratory partners. High levels of variability for biotic metrics versus organic carbon metrics appear typical for large scale studies, and organic matter source, site depth, and individual estuarine system differences were important sources of variation. Covariation of organic matter content with percent fine sediments is another known source of variation, but various normalization methods may be inadequate due to inherent sources of variation at estuary level. While likely still useful for point-source studies, multiple major sources of variation appear to limit the usefulness of sediment organic content as a benthic condition indicator at larger spatial scales.

25273. 题目: Deep Learning Neural Network Approach for Predicting the Sorption of Ionizable and Polar Organic Pollutants to a Wide Range of Carbonaceous Materials
文章编号: N20032901
期刊: Environmental Science & Technology
作者: Gabriel Sigmund, Mehdi Gharasoo, Thorsten Hüffer, Thilo Hofmann
更新时间: 2020-03-29
摘要: Most contaminants of emerging concern are polar and/or ionizable organic compounds, whose removal from engineered and environmental systems is difficult. Carbonaceous sorbents include activated carbon, biochar, fullerenes, and carbon nanotubes, with applications such as drinking water filtration, wastewater treatment, and contaminant remediation. Tools for predicting sorption of many emerging contaminants to these sorbents are lacking because existing models were developed for neutral compounds. A method to select the appropriate sorbent for a given contaminant based on the ability to predict sorption is required by researchers and practitioners alike. Here, we present a widely applicable deep learning neural network approach that excellently predicted the conventionally used Freundlich isotherm fitting parameters log KF and n (R2 > 0.98 for log KF, and R2 > 0.91 for n). The neural network models are based on parameters generally available for carbonaceous sorbents and/or parameters freely available from online databases. A freely accessible graphical user interface is provided.

25274. 题目: Protein to carbohydrate (P/C) ratio changes in microbial extracellular polymeric substances induced by oil and Corexit
文章编号: N20032805
期刊: Marine Chemistry
作者: Ruei-Feng Shiu, Meng-Hsuen Chiu, Carlos I. Vazquez, Yi-Yen Tsai, Andre Le, Agnes Kagiri, Chen Xu, Manoj Kamalanathan, Hernando Bacosa, Shawn Doyle, Jason Sylvan, Peter H. Santschi, Antonietta Quigg, Wei-Chun Chin
更新时间: 2020-03-28
摘要: Extracellular polymeric substances (EPS) released from marine microbial cells is a major response to stress. Most previous studies focus on the quantity of EPS released from microbes; however, the critical characteristic of EPS composition receive much less attention. Considering the complex nature and diversity of microbes in the marine system also impart distinct behaviors and reactions when exposed to stressful conditions, we cultured four phytoplankton and five bacterial species, to investigate the changes of the chemical composition of EPS under stress from a water-accommodated fraction (WAF) of oil or a chemically-enhanced WAF (CEWAF). Remaining viable cells (DNA amount) of nine marine microbes showed a higher linear negative correlation with increasing protein to carbohydrate (P/C) ratio under CEWAF than WAF treatments. The data also show that EPS with higher protein ratio was released under higher cellular stress levels induced by CEWAF, suggesting that higher protein ratio EPS, which is more hydrophobic, is secreted to physically or chemically ameliorate the hazardous agents. Our findings provide evidence that microbes can actively modify their EPS release and composition in responses to various adverse stress. Collectively, the results support the hypothesis that higher stress not only can trigger more EPS release, but also induce changes in its composition (P/C), thereby affecting environmental processes such as marine oil snow formation and the characteristic of marine organic matter.

25275. 题目: Processes controlling spatial and temporal dynamics of spring water chemistry in the Black Forest National Park
文章编号: N20032804
期刊: Science of the Total Environment
作者: Markus Merk, Nadine Goeppert, Nico Goldscheider
更新时间: 2020-03-28
摘要: Spring water chemistry is influenced by many factors, including geology, climate, vegetation and land use, which determine groundwater residence times and water–rock interaction. Changes in water chemistry can have a profound impact on their associated ecosystems. To protect these ecosystems and to evaluate possible changes, knowledge of the underlying processes and dynamics is important. We collected water samples at 20 locations during 5 campaigns within the water catchment area of the upper Schönmünz river in the Black Forest National Park, Southwest Germany and analyzed them hydro-chemically for their contents of inorganic constituents, organic carbon content, fluorescence properties as well as several physico chemical field parameters and spring discharge. Results show that water chemistry is strongly dependent on geology and that the response of dissolved organic carbon to changes in hydraulic conditions is highly dynamic. Due to increased flow through the upper soil layer during and after rain events, more organic carbon is extracted from the soil and transported with the water. Fluorescence EEM measurements indicate an allochthonous source of this organic carbon. This study can be used as baseline to assess future changes and serve as a supplement to ongoing studies of the spring ecosystems.

25276. 题目: Interactions of Emerging Contaminants with Model Colloidal Micro-plastics, C60 Fullerene, and Natural Organic Matter - Effect of Surface Functional Group and Adsorbate Properties
文章编号: N20032803
期刊: Environmental Sciences: Processes and Impacts
作者: Tyler A. Williams, Clare Walsh, Keith Murray, Mahamud Subir
更新时间: 2020-03-28
摘要: Surface adsorption of two commonly detected emerging contaminants, amlodipine (AMP) and carbamazepine (CBZ), onto model colloidal microplastics, natural organic matter (NOM), and fullerene nanomaterials have been investigated. It is found that AMP accumulation at these colloidal-aqueous interfaces is markedly higher than that of CBZ. Measurements of surface excess and particle zeta potential, along with pH-dependent adsorption studies, reveal a distinct influence of colloidal functional group on the adsorption properties of these pharmaceuticals. AMP shows a clear preference for a surface containing carboxylic group compared to an amine modified surface. CBZ, in contrast, exhibit a pH-dependent surface proclivity for both of these microparticles. The type of interactions and molecular differences with respect to structural rigidity and charge properties explain these observed behaviors. In this work, we also demonstrate a facile approach in fabricating uniform microspheres coated with NOM and C60 nanoclusters. Subsequent binding studies on these surfaces show considerable adsorption on the NOM surface but a minimal uptake of CBZ by C60. Adsorption induced colloidal aggregation was not observed. These findings map out the extent of contaminant removal by colloids of different surface properties available in the aquatic environment. The methodology developed for the adsorption study also opens up the possibility for further investigations into colloidal-contaminant interactions.

25277. 题目: Risk of phosphorus losses from Andosols under fertilized pasture
文章编号: N20032802
期刊: Environmental Science and Pollution Research
作者: Rui Bajouco, Jorge Pinheiro, Benilde Pereira, Rita Ferreira, João Coutinho
更新时间: 2020-03-28
摘要: Fertilization of grassland pastures may be a non-point pollution source in the Azores archipelago, despite the high phosphorus (P) retention of Andosols. To evaluate the risk of P desorption, representative Andosols samples (0–15 cm) were subdivided in five layers and different P pools were measured. The risk of P unloading into waters was assessed by the degree of phosphorus saturation (DPS), and by the P concentration in equilibrium solutions (0.01 M CaCl2). The higher contents in the superficial layers suggest P accumulation due to pasture overfertilization. The organic P represented about 54% of the total P, with an overall average of 2.66 g Pt/kg. Despite being above the agronomic threshold, the soil with the highest average mean values of extractable inorganic P, 77 mg POlsen/kg and and 73.7 mg PAL/kg, is still below environmental thresholds and none of the soils had DPS values above 25%, which is the critical value associated with eutrophication of surface waters. Similarly, all the P concentrations in the equilibrium CaCl2 solutions were below the critical limits. Therefore, P desorption from these soils did not seem to be the main process responsible for effective waterbodies eutrophication in the Azores. Since mineral fertilizers are applied superficially, the hypothesis of their direct runoff during rainfall events, even before their complete dissolution and interaction with the soil matrix, must be considered. Consequently, P fertilization with deep-banding systems may be the alternative to the interdiction of fertilizers in the most sensitive and hilly areas of the watersheds.

25278. 题目: Differences of the microbial community structures and predicted metabolic potentials in the lake, river, and wetland sediments in Dongping Lake Basin
文章编号: N20032801
期刊: Environmental Science and Pollution Research
作者: Jiaohui Fang, Ruirui Yang, Qingqing Cao, Junyu Dong, Changchao Li, Quan Quan, Miansong Huang, Jian Liu
更新时间: 2020-03-28
摘要: In freshwater ecosystems, wetlands are generally distinguished from deep-water ecosystems by 2-m water level as boundary. However, the difference of sediment microbial communities between wetlands and deep-water ecosystems is still unclear. We combined 16S rRNA gene sequencing and community metabolic prediction to compare sediment microbial communities and predicted metabolic genes of wetlands (natural and constructed wetlands) and deep-water ecosystems (river and lake) along with environmental factors in summer and autumn in Dongping Lake Basin. Results showed that the deep-water ecosystems had significantly higher community richness than the wetlands in autumn in the freshwater basin, which was mostly related to the pH of sediments. However, no significant difference in community richness was found in summer. Besides, the composition of both predicted metabolic genes and microbial communities was significantly affected by dissolved organic carbon (DOC) and dissolved oxygen (DO). The wetlands exhibited high predicted gene abundances related to xenobiotic biodegradation possibly due to the high DOC or DO level. Compared with the wetlands, most of the deep-water ecosystems exhibited high predicted gene abundances related to element (carbon, nitrogen, and sulfur) metabolism possibly due to the low DOC and DO levels in the freshwater basin. This study can expand the knowledge of ecological function distribution and detoxification mechanism of microbial communities in freshwater ecosystems.

25279. 题目: Improving soil carbon estimates of mudflats in Araçá Bay using spatial models that consider riverine input, wave exposure and biogeochemistry
文章编号: N20032717
期刊: Estuarine, Coastal and Shelf Science
作者: Daniel Gorman, Paulo Y.G. Sumida, Rubens C.L. Figueira, Alexander Turra
更新时间: 2020-03-27
摘要: A persistent challenge to managing coastal wetlands in a way that will mitigate climate impacts is understanding how soil organic carbon (Corg) stocks change over spatial and temporal scales. This study tested how seasonal change in riverine flows and soil biogeochemical attributes (grain-size, degree of wave disturbance and microphytobenthic productivity) can influence the Corg stock estimates of an unvegetated tidal flat within a Brazilian subtropical bay. We used a Generalized Additive Modelling (GAM) approach to accurately predict and map subtle changes in the Corg pools of these expansive, but often overlooked coastal ecosystems. The most important predictors across seasons were sediment grain-size and wave exposure. Seasonally important covariates were riverine flow and microphytobenthic productivity (during the warm and wet summer season). We then compared the high-resolution map outputs derived from models with more traditional approaches (interpolation and extrapolation) to see how these different methods might influence estimates of the carbon stocks for the entire bay (i.e., an area covering 115 ha). Modelled estimates for the bay (1945 ± 45 Mg Corg) where more conservative and had lower associated error than interpolated (2196 ± 185 Mg) and extrapolation estimates (2535 ± 117 Mg). Given the current urgency to understand the carbon sequestration potential of coastal ecosystems, the present findings are important and draw attention to the often overlooked, but important carbon pools of intertidal mudflats.

25280. 题目: Contribution of glomalin-related soil proteins to soil organic carbon in trifoliate orange
文章编号: N20032716
期刊: Applied Soil Ecology
作者: Jia-Dong He, Ge-Ge Chi, Ying-Ning Zou, Bo Shu, Qiang-Sheng Wu, A.K. Srivastava, Kamil Kuča
更新时间: 2020-03-27
摘要: Arbuscular mycorrhizal fungi (AMF) produce glomalin-related soil protein (GRSP) that influences organic carbon (C) storage in soil; however, how much purified GRSP fractions contribute to soil organic carbon (SOC) is yet not known. The present study evaluated the contribution of GRSP towards changes in SOC in trifoliate orange grown in a rootbox divided into a roots + hyphae chamber (roots colonized by AMF hyphae and AMF extraradical hyphae) and a hyphae chamber (only the presence of AMF extraradical hyphae, without roots). Three AMF species (Diversispora epigaea, Paraglomus occultum and Rhizoglomus intraradices) were inoculated into the roots + hyphae chamber. Following four months of plant growth, P. occultum showed higher AMF hyphal growth in roots, soils and nylon mesh than D. epigaea or R. intraradices. Mycorrhizal inoculation improved the plant growth performance and increased easily extractable GRSP (EE-GRSP) and difficultly extractable GRSP (DE-GRSP) concentrations in both chambers, regardless of AMF species. The C content observed in total GRSP of the soil after purification was 2.71 ± 0.49 mg g−1, while purified EE-GRSP and DE-GRSP showed the C content of 1.01 ± 0.19 mg g−1 and 1.70 ± 010.34 mg g−1, respectively. The C contribution by purified EE-GRSP and DE-GRSP accounted for 8.67 ± 0.95% and 14.59 ± 2.21%, respectively, of total SOC, with a total C contribution of purified GRSPs accounting for 23.26 ± 2.67% of total SOC. A significantly higher C content of GRSP and the C contribution of GRSP to SOC were observed in DE-GRSP than in EE-GRSP, as well as the soil of the roots + hyphae chamber than the soil of the hyphae chamber. The proportionate distribution of water-stable aggregate in 2–4 and 1–2 mm sizes and their stability were higher under AMF hyphae than under non-AMF hyphae. This study thus provided a database evidence of increased contribution of GRSP towards build-up of SOC in response to mycorrhizal symbiosis.