21. 题目: Validation of the Tea Bag Index as a standard approach for assessing organic matter decomposition: A laboratory incubation experiment
期刊: Ecological Indicators
作者: Taiki Mori
摘要: The Tea Bag Index (TBI), a novel approach to assessing organic matter decomposition using commercial tea bags, has been increasingly used in academic studies worldwide. This approach was designed to obtain an early-stage decomposition constant (k) indicative of early-stage decomposition rates and a litter stabilization factor (S) indicative of long-term carbon stability by using two types of teas—green and rooibos. However, despite the worldwide usage of the method, the accuracy of this approach has never been validated in terrestrial ecosystems. Here, the validity of this approach was tested by examining the two essential premises of the TBI using a laboratory incubation experiment. The first premise of the TBI—namely, that the unstabilized hydrolyzable fraction of green tea is mostly decomposed within 90 days—did not hold in the present study, which caused overestimations of the S of green tea. The second premise—namely, that the ratio of stabilized to total hydrolyzable fractions (i.e., S) of rooibos tea is equal to that of green tea—was also rejected, which resulted in substantial underestimations of the S of rooibos tea and k. Overall, the TBI largely underestimated the S of rooibos tea and k (more than 1.5 and 5 times smaller than those determined by time-series data, respectively). The present study suggests that time-series mass loss data of rooibos tea should be obtained to accurately determine k, rather than assuming that the S of rooibos tea is equal to that of green tea.
22. 题目: Benthic Organic Matter Transformation Drives pH and Carbonate Chemistry in Arctic Marine Sediments
期刊: Global Biogeochemical Cycles
作者: F S Freitas, S Arndt, K R Hendry, J C Faust, A C Tessin, C März
摘要: Carbonate chemistry of the Arctic Ocean seafloor and its vulnerability to ocean acidification remains poorly explored. This limits our ability to quantify how biogeochemical processes and bottom water conditions shape sedimentary carbonate chemistry, and to predict how climate change may affect such biogeochemical processes at the Arctic Ocean seafloor. Here, we employ an integrated data-model assessment that explicitly resolves benthic pH and carbonate chemistry along a S—N transect in the Barents Sea. We identify the main drivers of observed carbonate dynamics and estimate benthic fluxes of dissolved inorganic carbon and alkalinity to the Arctic Ocean. We explore how bottom water conditions and in-situ organic matter degradation shape these processes and show that organic matter transformation strongly impacts pH and carbonate saturation (Ω) variations. Aerobic organic matter degradation drives a negative pH shift (pH < 7.6) in the upper 2—5 cm, producing Ω < 1. This causes shallow carbonate dissolution, buffering porewater pH to around 8.0. Organic matter degradation via metal oxide (Mn/Fe) reduction pathways further increases pH and carbonate saturation state. At the northern stations, where Ω > 5 at around 10–25 cm, model simulations result in authigenic carbonate precipitation. Furthermore, benthic fluxes of dissolved inorganic carbon (12.5—59.5 µmol cm−2 yr−1) and alkalinity (11.3—63.2 µmol cm−2 yr−1) are 2—3-fold greater in the northern sites due to greater carbonate dissolution. Our assessment is of significant relevance to predict how changes in the Arctic Ocean may shift carbon burial and pH buffering into the next century.
23. 题目: Fe-Mn Bimetallic Oxide-Enabled Facile Cleaning of Microfiltration Ceramic Membranes for Effluent Organic Matter Fouling Mitigation via Activation of Oxone
期刊: ACS ES&T Water
作者: Guicheng Zhang, Xueying Yang, Zhangxiong Wu, Winston Duo Wu, Xiaoning Wang, Xiao Dong Chen, Sheng-Peng Sun
摘要: Membrane fouling caused by effluent organic matters (EfOM) remains a major challenge in wastewater reclamation. Herein, we report a promising catalytic microfiltration ceramic membrane (CM) that features with ∼20 μm thickness of Fe-Mn bimetallic oxide (Mn1.5FeO6.35) active layer coating on the α-Al2O3 membrane base (α-Al2O3@Mn1.5FeO6.35 CM), which enables fantastic mitigation of irreversible EfOM fouling via in situ Oxone activation. Modeling results indicated that complete and standard pore blocking dominated an initial fouling mechanism on the α-Al2O3@Mn1.5FeO6.35 CM, followed by a cake mode as the fouling evolution. Critically, the cake fouling layer was effectively removed through a facile on-line cleaning with Oxone aqueous solutions, resulting in rapid flux restoration. The mechanism was dominated by radical cleaning pathways, and hydroxyl radicals (HO·) played a critical role in reducing EfOM fouling over other reactive species (e.g., sulfate radicals (SO4·–) and singlet oxygen (1O2)). A key feature of as-prepared α-Al2O3@Mn1.5FeO6.35 CM is the favorable slightly basic pH cleaning conditions (∼pH 10), restricting Fe and Mn leaching and maximizing the membrane-sustained activity and durability. Hence, this study highlights the robust cleaning capability of α-Al2O3@Mn1.5FeO6.35 CM toward EfOM fouling and proposes a new strategy in developing environmentally friendly catalytic CMs for wastewater reclamation.
24. 题目: Benthic Carbon Remineralization and Iron Cycling in Relation to Sea Ice Cover along the Eastern Continental Shelf of the Antarctic Peninsula
期刊: Journal of Geophysical Research: Oceans
作者: M Baloza, S Henkel, W Geibert, S Kasten, M Holtappels
摘要: Rapid and profound climatic and environmental changes have been predicted for the Antarctic Peninsula with so far unknown impact on the biogeochemistry of the continental shelves. In this study, we investigate benthic carbon sedimentation, remineralization and iron cycling using sediment cores retrieved on a 400 mile transect with contrasting sea ice conditions along the eastern shelf of the Antarctic Peninsula. Sediments at comparable water depths of 330-450 m showed sedimentation and remineralization rates of organic carbon, ranging from 2.5-13 and 1.8-7.2 mmol C m-2 d-1, respectively. Both rates were positively correlated with the occurrence of marginal sea ice conditions (5-35% ice cover) along the transect, suggesting a favorable influence of the corresponding light regime and water column stratification on algae growth and sedimentation rates. From south to north, the burial efficiency of organic carbon decreased from 58% to 27%, while bottom water temperatures increased from -1.9 to -0.1 °C. Net iron reduction rates, as estimated from pore-water profiles of dissolved iron, were significantly correlated with carbon degradation rates and contributed 0.7-1.2% to the total organic carbon remineralization. Tightly coupled phosphate-iron recycling was indicated by significant covariation of dissolved iron and phosphate concentrations, which almost consistently exhibited P/Fe flux ratios of 0.26. Iron efflux into bottom waters of 0.6-4.5 µmol Fe m-2 d-1 was estimated from an empirical model. Despite the deep shelf waters, a clear bentho-pelagic coupling is indicated, shaped by the extent and duration of marginal sea ice conditions during summer, and likely to be affected by future climate change.
25. 题目: ALOS-2 L-band SAR backscatter data improves the estimation and temporal transferability of wildfire effects on soil properties under different post-fire vegetation responses
期刊: Science of The Total Environment
作者: José Manuel Fernández-Guisuraga, Elena Marcos, Susana Suárez-Seoane, Leonor Calvo
摘要: Remote sensing techniques are of particular interest for monitoring wildfire effects on soil properties, which may be highly context-dependent in large and heterogeneous burned landscapes. Despite the physical sense of synthetic aperture radar (SAR) backscatter data for characterizing soil spatial variability in burned areas, this approach remains completely unexplored. This study aimed to evaluate the performance of SAR backscatter data in C-band (Sentinel-1) and L-band (ALOS-2) for monitoring fire effects on soil organic carbon and nutrients (total nitrogen and available phosphorous) at short term in a heterogeneous Mediterranean landscape mosaic made of shrublands and forests that was affected by a large wildfire. The ability of SAR backscatter coefficients and several band transformations of both sensors for retrieving soil properties measured in the field in immediate post-fire situation (one month after fire) was tested through a model averaging approach. The temporal transferability of SAR-based models from one month to one year after wildfire was also evaluated, which allowed to assess short-term changes in soil properties at large scale as a function of pre-fire plant community type. The retrieval of soil properties in immediate post-fire conditions featured a higher overall fit and predictive capacity from ALOS-2 L-band SAR backscatter data than from Sentinel-1 C-band SAR data, with the absence of noticeable under and overestimation effects. The transferability of the ALOS-2 based model to one year after wildfire exhibited similar performance to that of the model calibration scenario (immediate post-fire conditions). Soil organic carbon and available phosphorous content was significantly higher one year after wildfire than immediately after the fire disturbance. Conversely, the short-term change in soil total nitrogen was ecosystem-dependent. Our results support the applicability of L-band SAR backscatter data for monitoring short-term variability of fire effects on soil properties, reducing data gathering costs within large and heterogeneous burned landscapes.
26. 题目: Carbon-based adsorbents as proficient tools for the removal of heavy metals from aqueous solution: A state of art-review emphasizing recent progress and prospects
期刊: Environmental Research
作者: Narayanan Mahesh, Srinivasan Balakumar, Shanmugasundaram Shyamalagowri, Jagadeesan Manjunathan, M.K.S. Pavithra, Palanisamy Suresh Babu, Murugesan Kamaraj, Muthusamy Govarthanan
摘要: Carbon-centric adsorbents (CCA) are diverse forms, from simple biochar (BC) to graphene derivatives, carbon nanotubes (CNTs), and activated carbon (AC), which have been vastly explored for their removal of a plethora of pollutants, including heavy metals (HM). The prominent features of CCA are their operational attributes like extensive surface area, the occurrence of flexible surface functional groups, etc. This work offers a comprehensive examination of contemporary research on CCA for their superior metal removal aptitude and performances in simulated solutions and wastewater flows; via portraying the recent research advances as an outlook on the appliances of CACs for heavy metal adsorption for removal via distinct forms like AC, BC, Graphene oxide (GO), and CNTs. The bibliometric analysis tool was employed to highlight the number of documents, country-wise contribution, and co-occurrence mapping based on the Scopus database. The coverage of research works in this review is limited to the last 5 years (2017–2021) to highlight recent progress and prospects in using CCAs such as AC, BC, GO, and CNTs to remove HM from aqueous media, which makes the review unique. Besides an overview of the common mechanisms of CACs, the future scope of CAC, especially towards HM mitigation, is also discussed in this review. This review endorses that further efforts should be commenced to enhance the repertory of CCAs that effectively eliminate multiple targeted metals in both simulated and real wastewater.
27. 题目: Alfalfa biochar supported Mg-Fe layered double hydroxide as filter media to remove trace metal(loid)s from stormwater
期刊: Science of The Total Environment
作者: Yuanyuan Yang, Xiaofei Tan, Eydhah Almatrafi, Shujing Ye, Biao Song, Qiang Chen, Hailan Yang, Qianmin Fu, Yuanyuan Deng, Zhuotong Zeng, Guangming Zeng
摘要: Polluted stormwater (PSW) treatment is becoming increasingly important because of the existence of multiple pollutants from non-point pollution sources. Alfalfa biochar loaded with Mg/Fe layered double hydroxide (AF-LDH) was successfully synthesized to remove trace metal(loid)s from stormwater. The adsorption kinetics and isotherms of metal(loid)s in a mono-component system and the reusability of the composite materials was investigated in this study. The result showed that the maximum removal efficiency for Pb(II), Cu(II), Zn(II), Cd(II), As(V), and Cr(VI) were 98.98 %, 98.11 %, 97.88 %, 97.71 %, 98.81 %, and 50.89 %, respectively, when added calcined AF-LDH (AF-LDO) composite material to the multi-component solution. The AF-LDH and AF-LDO could efficiently remove trace pollutants (10–100 μg/L) from multi-component solution, especially for AF-LDO, which could completely remove the tested six trace metal(loid)s. Furthermore, Fourier transform infrared spectra and X-ray diffraction characterizations supported the Mg/Fe layered double hydroxide reconstruction. The main mechanisms of Pb(II), Cu(II), Zn(II), and Cd(II) (cationic metals) removal were ion exchange and surface precipitation, whereas As(V) and Cr(VI) (anionic metals) were mainly dislodged through the formation of surface complexation, electrostatic attraction, and interlayer anion exchange, concerning the –OH and –COOH of AF-LDH. Importantly, the results of the column experiment demonstrated that AF-LDO was superior to AF-LDH for anionic metal removal from stormwater. In this study, we synthesized AF-LDH and AF-LDO for trace metal(loid) removal and proposed a new and practical approach for stormwater purification.
28. 题目: In Situ Application of Mechanochemically Oxidized Lignite for Improving Soil Productivity on the Highway Divider Lawn
期刊: Water, Air, & Soil Pollution
作者: Tatiana Skripkina, Olga Rozhanskaya, Aleksey Bychkov, Igor Gossen, Oleg Lomovsky
摘要: Mechanochemical modification of lignite in the presence of an eco-friendly oxidizer, sodium percarbonate, ensures one-step solvent-free oxidation of lignite organic matter. The product is characterized by high yield of humic acids and increases the content of phenolic and carboxyl groups. The study aimed to conduct in situ tests of mechanochemically oxidized lignite for restoring the highway divider lawn, with allowance for specific features of lawns maintained by public utility service providers. Adding oxidized lignite statistically reliably increased grass height and weight in the experimental sites compared to the control one. Applying oxidized lignite (30 g/m2) increased grass height and weight by ~ 40% and 25%, respectively, compared to those on the control site. Applying oxidized lignite (10 g/m2) together with N120P60K60 fertilizer and additional sowing of gramineous plant mixture increased grass height and weight by ~ 65% and 25%, respectively. Additional sowing of gramineous plants did not cause significant predominance of the gramineous component. The recommendations for the technology for maintaining lawns in this type of plots are provided.
29. 题目: A comparative study on the activation of persulfate by mackinawite@biochar and pyrite@biochar for sulfamethazine degradation: The role of different natural iron-sulfur minerals doping
期刊: Chemical Engineering Journal
作者: Zilan Jin, Yangju Li, Haoran Dong, Shuangjie Xiao, Junyang Xiao, Dongdong Chu, Xiuzhen Hou, Shuxue Xiang, Qixia Dong, Long Li
摘要: In this work, two novel heterogeneous catalysts were prepared by loading natural mackinawite (FeS) and pyrite (FeS2) particles into peanut shell-derived biochar (i.e., FeS@BC and FeS2@BC), and the persulfate (PS) activation processes by these two composites for sulfamethazine (SMT) degradation were systematically examined. After doping natural iron-sulfur ores, the catalytic removal performance of the above two composites were 37.2%–80.0% and 31.0%–35.2% higher than those of their respective original minerals and primitive biochar. Simultaneously, FeS@BC had better catalytic performance than FeS2@BC. The larger specific surface areas, abundant micropores, higher defect degree, better conductivity and FeS crystals favored the release of more iron, resulting in higher reaction stoichiometric efficiency (RSE) value, excellent catalytic activity, and enhanced SMT mineralization. In the FeS@BC/PS system, surface ketonic groups (C = O), Fe(II), and highly active S-thiophene groups all accounted for PS activation. In the FeS2@BC/PS system, C = O groups, Fe(II), highly reductive S2−/Sn2– species, and graphene structure participated in the catalytic reaction. The electron-rich S-thiophenic groups, S2−/Sn2– species, and ketonic moieties could act as electron donors, prompting the regeneration of Fe(II) in the lattice (≡Fe(II)) and solution (Fe2+) by direct or indirect electron transfer. In view of the higher catalytic activity of FeS@BC, we further investigated different influencing factors on SMT degradation, activation mechanism, and degradation pathway of SMT in the FeS@BC/system. Overall, this study would fill the gap in the research on the difference in the catalytic activity of catalysts prepared by loading different natural iron-sulfur minerals onto biochar for persulfate activation.
30. 题目: Extensive production and evolution of free radicals during composting
期刊: Bioresource Technology
作者: Ruizhi Xing, Xinggui Yang, Hanyue Sun, Xiaoyu Ye, Hanpeng Liao, Shuping Qin, Zhi Chen, Shungui Zhou
摘要: The production of free radicals has been widely documented in natural systems, where they play an important role in most organic matter and contaminants transformation. Here, the production and evolution of free radicals were systematically investigated during composting. Results indicated that multiple reactive oxygen species and environmentally persistent free radicals (G-factor 2.003–2.004) were generated with dynamic changes during composting. The ·OH yield fluctuated significantly with a maximum content of 365.7–1,262.3 μmol/kg at the thermophilic phase of composting, which was closely correlated with the changes of Fe (II) (Pearson’s r = 0.928–0.932) and the electron-donating capacity of humus (Pearson’s r = 0.958–0.896) during composting. Further investigation suggested that microorganisms driven iron/humus redox conversion could contribute to the production and dynamic changes of free radical during composting. These findings highlight the abiotic processes involving free radicals, and provide a new perspective for humification and contaminants removal during composting.
31. 题目: Immobilization of hexavalent chromium in soil-plant environment using calcium silicate hydrate synthesized from coal gangue
作者: Zhang Qing, Liu Guijian, Peng Shuchuan, Zhou Chuncai, Muhammad Arif
摘要: The presence of excessive hexavalent chromium (Cr(VI)) in the contaminated soils and plants has become a global environmental issue due to its toxicity and carcinogenicity. This work investigated the feasibility of immobilizing Cr(VI) in the soil-plant environment using calcium silicate hydrate (C–S–H) synthesized from coal gangue. The results revealed that the C–S–H amendment increased soil pH and organic matter (OM), which further promoted Cr(VI) immobilization. Results also revealed that exchangeable and carbonate bound fractions of Cr were either converted into Fe/Mn oxide and OM bound fractions of Cr or hardly released residual fraction of Cr due to C–S–H treatment. The C–S–H accelerated conversion of Cr(VI) into Cr(III) promoting plant growth and alleviating the toxic effect of Cr(VI). Cr(VI) was mainly immobilized and accumulated in the plant roots which resulted in comparatively lower Cr(VI) content in the edible part of plants. The exchangeable fraction of Cr in soil could be used as a bioavailability evaluation index of Cr(VI) in plants. In short, C–S–H was proved to be a practical and environmentally friendly amendment for in-situ immobilization of Cr(VI) contaminated soil.
32. 题目: Waste-derived biochar for water pollution control and sustainable development
期刊: Nature Reviews Earth & Environment
作者: Mingjing He, Zibo Xu, Deyi Hou, Bin Gao, Xinde Cao, Yong Sik Ok, Jörg Rinklebe, Nanthi S Bolan, Daniel C W Tsang
摘要: Biochar, a carbon-rich material made from the partial combustion of biomass wastes, is an emerging material of interest as it can remediate pollutants and serve as a negative carbon emission technology. In this Review, we discuss the application of biochar in municipal wastewater treatment, industrial wastewater decontamination and stormwater management in the context of sustainable development. By customizing the biomass feedstock type and pyrolysis conditions, biochar can be engineered to have distinct surface physicochemical properties to make it more efficient at targeting priority contaminants in industrial wastewater treatment via adsorption, precipitation, surface redox reactions and catalytic degradation processes. Biochar enhances flocculation, dewatering, adsorption and oxidation processes during municipal wastewater treatment, which in turn aids sludge management, odour mitigation and nutrient recovery. The addition of biochar to sustainable drainage systems decreases potential stormwater impact by improving the structure, erosion resistance, water retention capacity and hydraulic conductivity of soils as well as removing pollutants. The feasibility of scaling up engineered biochar production with versatile, application-oriented functionalities must be investigated in collaboration with multidisciplinary stakeholders to maximize the environmental, societal and economic benefits.
33. 题目: Formation of halogenated disinfection byproducts in chlorinated real water during making hot beverage: Effect of sugar addition
作者: Chuyin Qiu, Weiting He, Yu Li, Feng Jiang, Yang Pan, Meihui Zhang, Daying Lin, Kaili Zhang, Yanduo Yang, Wen Wang, Pei Hua
摘要: Chlorine disinfection is widely applied in drinking water treatment plant to inactivate pathogens in drinking water, but it unintentionally reacts with organic matter present in source waters and generates halogenated disinfection byproducts (DBPs). Sugar is one of the most commonly used seasoning in our diet. The addition of sugar could significantly improve the taste of the beverages; however, the effects of sugar on DBP formation and transformation remain unknown. In this study, the effects of sugar type and dose on the halogenated DBP formation in chlorinated boiled real tap water were evaluated during making hot beverages. We found that sugar can react with chlorine residual in tap water and generate halogenated DBPs. As the most commonly used table sugar, the addition of sucrose in the water sample at 100 or 500 mg/L as C could increase the level of total organic halogen (TOX) by ∼35%, when compared with the boiled tap water sample without sugar addition. In addition, fifteen reported and new polar brominated and chlorinated DBPs were detected and proposed from the reaction between chlorine and sucrose; accordingly, the corresponding transformation pathways were also proposed. Moreover, the DBP formation in the chlorinated boiled real tap water samples with the addition of xylose, glucose, sucrose, maltose and lactose were also investigated. By comparing with the TOX levels in the water samples with different sugar addition and their calculated TOX risk indexes, it was suggested that applying xylose as a sweetener in beverages could not only obtain a relatively high sweetness but also minimize the adverse effect inducing by halogenated DBPs during making hot beverages.
34. 题目: The effects of weathering-induced degradation of polymers in the microplastic study involving reduction of organic matter
期刊: Environmental Pollution
作者: Maria Clara Lessa Belone, Marika Kokko, Essi Sarlin
摘要: The analysis of microplastics in complex environmental samples requires the use of chemicals to reduce the organic matrix. This procedure should be evaluated in terms of the preservation of the microplastic's integrity, typically done with pristine reference microplastics. However, real microplastics are most likely degraded due to weathering, so pristine reference microplastics might not depict the appropriateness of the process. This study performed a purification process using sodium dodecyl sulfate and hydrogen peroxide on sewage sludge containing LLDPE, HDPE, PP, PS, PET, PA66 and SBR samples exposed to simulated environmental weathering. The degradation of the polymers was assessed by analyzing surface morphology, mass variation, and mechanical, thermal and chemical properties. Comparison with pristine polymers revealed that the purification process can lead to more detrimental effects if the polymers are weathered. After the purification process, some important observations were: 1) LLDPE, PP and SBR surfaces had cracks in the weathered samples that were not observed in the pristine samples, 2) weathered LLDPE, PP and PA66 experienced greater mass loss than pristine, 3) the fragmentation propensity of weathered LLDPE, HDPE, PP, PS and SBR increased compared to pristine samples and 4) the main characteristic peaks in FTIR spectrum could be identified and used for chemical identification of most polymers for pristine and weathered samples. Based on the findings of this study, when analyzing the efficiency and adequacy of a purification process with methods based on surface morphology, mass variation and particle counting indicators, it is recommended to consider the differences that potentially arise between pristine and weathered microplastics, especially for polyolefins (PEs and PP).
35. 题目: Soil controls on carboxylate-driven processes and opportunities
期刊: Plant and Soil
作者: Jean-Thomas Cornelis, F de Tombeur
摘要: Through their influence on microbial processes, carboxylates exuded by roots are key drivers of nutrient acquisition and organic carbon (C) storage in terrestrial ecosystems. However, the simultaneous interactions between environmental factors controlling the production and fates of carboxylates lead to uncertainty in understanding their role in terrestrial ecosystems. Here we suggest a more integrative view which points out that carboxylate-driven processes (metal chelation and formation of organo-mineral associations) can vary according to the soil physicochemical context. We show that variation in soil properties can substantially influence plant production of C surplus and discharge as root exudates. In addition, the control of soil processes (adsorption, complexation, leaching and biodegradation) on carboxylate fates is strongly governed by the physicochemical context. To illustrate this, the first soil scenario we present is characterized by fine-textured and nutrient-rich soils, which leads to a relatively lower root exudation rate but high potential of carboxylate associations with minerals. This soil context is more inclined to contribute to soil C storage. In the second scenario, coarse-textured and nutrient-poor soils lead to higher rates of carboxylate production and higher carboxylate ability to mobilize nutrients through chelation. In this case, the carboxylate-induced mobilization of nutrients is maximized. We wish to emphasize the need to integrate the diversity of soil properties when it comes to propose regenerative agricultural practices that capitalize on the carboxylate-driven soil processes and their related ecological functions, whose potential benefits must be evaluated on a case-by-case basis according to the soil physicochemical context.
36. 题目: Global pattern of soil priming effect intensity and its environmental drivers
作者: Fei Mo, Chengjie Ren, Kailiang Yu, Zhenghu Zhou, Richard P Phillips, Zhongkui Luo, Yeye Zhang, Yuteng Dang, Juan Han, Jiansheng Ye, Nangia Vinay, Yuncheng Liao, Youcai Xiong, Xiaoxia Wen
摘要: The microbial priming effect – the decomposition of soil organic carbon (SOC) induced by plant inputs – has long been considered an important driver of SOC dynamics, yet we have limited understanding about the direction, intensitiy, and drivers of priming across ecosystem types and biomes. This gap hinders our ability to predict how shifts in litter inputs under global change can affect climate feedbacks. Here, we synthesized 18,919 observations of CO2 effluxes in 802 soils across the globe to test the relative effects (i.e., log response ratio; RR) of litter additions on native SOC decomposition, and identified the dominant environmental drivers in natural ecosystems and agricultural lands. Globally, litter additions enhanced native SOC decomposition (RR = 0.35, 95% CI: 0.32 ~ 0.38), with greater priming effects occurring with decreasing latitude, and more in agricultural soils (RR = 0.43) than in uncultivated soils (RR = 0.28). In natural ecosystems, soil pH and microbial community composition (e.g., bacteria:fungi ratio) were the best predictors of priming, with greater effects occurring in acidic, bacterial-dominated, sandy soils. In contrast, substrate properties of plant litter and soils were the most important drivers of priming in agricultural systems, as soils with high C:N ratio and those receiving large inputs of low quality litter had the highest priming effects. Collectively, our results suggest that while different factors may control priming effects, the ubquitious nature of priming means that alterations of litter quality and quantity owing to global changes will likely have consequences for global C cycling and climate forcing.
37. 题目: Derivation of copper water quality criteria in the Bohai Sea of China considering the effects of multiple environmental factors on copper toxicity
期刊: Environmental Pollution
作者: Yang Li, Di Mu, Hong-Qing Wu, Dan-Dan Tan, Xian-Hua Liu, Jun Sun, Zhi-Yong Ji
摘要: Copper has become one of the most important heavy metal pollutants in the environment because of its wide application and high toxicity, but research on water quality criteria (WQCs) on copper is limited, especially the derivation of seawater WQC. In addition, the toxicity of copper in the seawater system is affected by various environmental factors. Therefore, establishing a WQC that meets the characteristics of the regional environment is a top priority. The correlations between four factors of temperature, salinity, pH, dissolved organic carbon (DOC) and the toxic effect values of copper were analyzed in this study, and the temperature was determined as the most influential factor among the four factors in the Bohai Sea. A specific correlation between temperature and the toxic effects of copper was identified, and WQCs were derived based on the identified correlation and the variations of the Bohai Sea's temperature in different seasons by species sensitivity distribution (SSD) method. Under the condition of the winter, spring, autumn, and summer with an average water temperature of 0.09, 15.96, 17.83, and 24.87 °C, the obtained short-term water quality criteria (SWQCs) were 44.29, 4.70, 4.31, and 3.33 μg/L; the long-term water quality criteria (LWQCs) were 18.14, 1.93, 1.77 and 1.36 μg/L. The findings indicated the importance of introducing specific environmental conditions during the derivation process. This work could provide valuable information for pollution prevention and aquatic life protection in the Bohai Sea and provide a valuable reference for the derivation of criteria in other regions alike.
38. 题目: Erosion-deposition positively reconstruct the bacterial community and negatively weaken the fungal community
作者: Wanglin Hao, Bin Xia, Mingxiang Xu
摘要: Soil erosion and deposition are general ecological processes that have been widely described in terms of their effects on the physical and chemical properties of soil. However, their effects on soil microbes remain unclear, especially how microbial communities respond to erosion–deposition in soils with different organic carbon levels. A long-term field experiment was conducted to examine the effects of erosion and deposition on soil microbial communities across full slopes with different organic carbon levels on the Loess Plateau of China. The results showed that erosion reduced soil bacterial alpha diversity, weakened bacterial network complexity while deposition increased bacterial alpha diversity, and enhanced the complexity of the bacterial network. However, both erosion and deposition caused a decrease in fungal alpha diversity and network complexity. There was a weak reverse cooperative covariation relationship between bacterial and fungal alpha diversity. There was a higher bacterial and fungal diversity at the eroded and depositional sites with high soil organic carbon (SOC) level than low and medium SOC levels. An increase in the SOC level effectively strengthened the network complexity of bacteria and fungi at the eroded and depositional sites.. Erosion-deposition and SOC levels significantly increased variation in bacterial community structure. In contrast, the fungal community structure only differed at the eroded and depositional sites at high SOC levels. The key factors driving variation in bacterial community structure in soil properties were not significantly affected by SOC levels. Conversely, key factors resulting in differences in fungal community structure were regulated by the SOC level. Our results demonstrate that erosion–deposition reconstruct the bacterial community and weakens the fungal community, organic carbon regulate soil microbial communities and functions by controlling earth surface processes induced by erosion–deposition.
39. 题目: Cover crop functional types differentially alter the content and composition of soil organic carbon in particulate and mineral‐associated fractions
期刊: Global Change Biology
作者: Ziliang Zhang, Jason P Kaye, Brosi A Bradley, Joseph P Amsili, Vidya Suseela
摘要: Cover crops (CCs) can increase soil organic carbon (SOC) sequestration by providing additional OC residues, recruiting beneficial soil microbiota, and improving soil aggregation and structure. The various CC species that belong to distinct plant functional types (PFTs) may differentially impact SOC formation and stabilization. Biogeochemical theory suggests that selection of PFTs with distinct litter quality (C:N ratio) should influence the pathways and magnitude of SOC sequestration. Yet, we lack knowledge on the effect of CCs from different PFTs on the quantity and composition of physiochemical pools of SOC. We sampled soils under monocultures of three CC PFTs [legume (crimson clover); grass (triticale); and brassica (canola)] and a mixture of these three species, from a long-term CC experiment in Pennsylvania, USA. We measured C content in bulk soil and C content and composition in contrasting physical fractions: particulate organic matter, POM; and mineral-associated organic matter, MAOM. The bulk SOC content was higher in all CC treatments compared to the fallow. Compared to the legume, monocultures of grass and brassica with lower litter quality (wider C: N) had higher proportion of plant-derived C in POM, indicating selective preservation of complex structural plant compounds. In contrast, the legume soils had greater accumulation of microbial-derived C in MAOM. Our results for the first time, revealed that the mixture contributed to a higher concentration of plant-derived compounds in POM relative to the legume, and a greater accumulation of microbial-derived C in MAOM compared to monocultures of grass and brassica. Mixtures can thus increase the short- and long-term SOC persistence balancing the contrasting effects on the chemistries in POM and MAOM imposed by monoculture CC PFTs. Thus, despite different cumulative C inputs in CC treatments from different PFTs, the total SOC stocks did not vary between CC PFTs, rather PFTs impacted whether C accumulated in POM or MAOM fractions. This highlights that CCs of different PFTs may shift the dominant SOC formation pathways (POM vs. MAOM), subsequently impacting short- and long-term SOC stabilization and stocks. Our work provides a strong applied field test of biogeochemical theory linking litter quality to pathways of C accrual in soil.
40. 题目: Humic acids alleviate the toxicity of reduced graphene oxide modified by nanosized palladium in microalgae
期刊: Ecotoxicology and Environmental Safety
作者: Xiaokang Li, Yan Yan, Xiaoqiang Li, Li Mu, Jingqi Zhao, Mingqi Yao, Xiangang Hu
摘要: The use of graphene-family materials modified by nanosized palladium (Pd/GFMs) has intensified rapidly in various fields; however, the effects of environmental factors (e.g., natural organic matter (NOM)) on the transformation and ecotoxicity of Pd/GFMs remain largely unknown. In this study, reduced graphene oxide modified by nanosized Pd (Pd/rGO) was incubated with humic acid (HA) under light irradiation for 56 d to explore the effects of NOM on the physicochemical transformations (e.g., defects, surface charges and dispersity) and biological toxicity (e.g., growth inhibition, oxidative stress and ultrastructural damage on algae cells) of Pd/GFMs. The results revealed that HA increased the defects and dispersity of Pd/rGO. Growth inhibition, damage to cellular ultrastructures, and oxidative stress in microalgae cells were induced by Pd/rGO, and corresponding defense responses (e.g., superoxide dismutase, peroxidase and glutathione) were activated. HA diminished the above defense responses in microalgae triggered by Pd/rGO by regulating GSH metabolism and the alanine biosynthesis pathway. In the presence of HA, cell wall damage (i.e., hole formation) caused by exposure to Pd/rGO was restored, and the plasmolysis area was reduced by 28.6 %. In addition, growth inhibition, lipid peroxidation, loss of mitochondrial membrane potential and ROS formation induced by 1.0 mg/L MoS2NPs were decreased by 1.4–65.6 %, 13.9–26.1 %, 21.8–58.3 % and 9.6–16.1 %, respectively. These findings highlight the need to consider the effects of HA on the environmental transformation and biological toxicity of Pd/GFMs, which presents significant implications for the management of Pd/GFMs.