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所有论文

81. 题目: Novel insights into formation mechanism of organic chloramines from pre-oxidized algae-laden water: Multiple roles of dissolved organic nitrogen
文章编号: N22051512
期刊: Science of The Total Environment
作者: Da Sheng, Lingjun Bu, Shumin Zhu, Nan Li, Lei Li, Shiqing Zhou
更新时间: 2022-05-15
摘要: Organic chloramines posed significant risks to drinking water safety. However, the formation mechanism of algae-derived organic chloramines remained unclear. In this study, it was observed that pre-oxidation of algal suspensions increased organic chloramine formation during chlorination. Compared to KMnO4 pre-oxidation, O3 significantly increased the organic chloramine formation potential of algal suspensions. Characterization was performed with size exclusion chromatography-multiple detectors (SEC-MDs) to better understand the organic chloramine formation mechanism. The results revealed that low molecular weight proteins (AMW ≤ 0.64 kDa) were the main precursors of organic chloramines after conventional water treatment processes. We then focused on 14 essential amino acids involved in protein formation. Their concentrations and organic chloramine formation potentials were determined, based on which the theoretical organic chloramine formation potentials of the studied samples were evaluated. However, dramatic gaps between theoretical and experimental organic chloramine formations were observed, which suggested that not all organic nitrogen could react with chlorine to form organic chloramine. The condensed dual descriptor (CDD) was calculated to predict the electrophilic substitution reaction sites on peptides. Furthermore, the activation barrier of each proposed reaction was computed to confirm that the reaction sites for chlorine were located on amino groups. This study clarified the formation mechanism of algal-derived organic chloramines, which could provide a powerful theoretical foundation for controlling organic chloramine formation in drinking water processes.

82. 题目: Organic matter removal and antifouling performance of sulfonated polyaniline nanofiltration (S-PANI NF) membranes
文章编号: N22051511
期刊: Journal of Environmental Chemical Engineering
作者: Hassan Alhweij, Emma Anna Carolina Emanuelsson, Salman Shahid, Jannis Wenk
更新时间: 2022-05-15
摘要: Natural organic matter (NOM) removal from water prior to other treatment processes can improve treatment efficiency and final water quality. Here, NOM removal across five size fractions by newly developed sulfonated polyaniline nanofiltration (S-PANI NF) membranes was compared with a commercial membrane and conventional adsorption-coagulation-flocculation, optimized for NOM removal. Artificially prepared surface water and seawater containing 10 – 100mgC L-1 NOM extract and a stabilized landfill leachate served as test solutions. S-PANI NF membranes showed best NOM separation performance for both surface and seawater followed by the commercial membrane and conventional treatment. For landfill leachate conventional treatment had the best performance followed by S-PANI NF membranes. S-PANI performed slightly better in removal of chemical oxygen demand (COD) (74%) compared to the commercial membrane (70%) and conventional treatment (70%). Both membranes performed consistent with increasing salinity and NOM concentration, while experiencing a modest carryover at higher salinity. During long-term fouling S-PANI exhibited slower growth in transmembrane pressure (TMP), less affinity towards organic matter and higher flux recovery compared to the commercial membrane, particularly at high NOM concentration. This is the first study to investigate S-PANI membranes for water treatment applications and under high-fouling conditions. Results indicate S-PANI NF membranes are promising for such applications. In addition, this study also provides an inter-process comparison for NOM removal over an extreme range of water matrix conditions.

83. 题目: Changes in dissolved organic pool and regulation of associated nutrients during green tides: A case study of Ulva prolifera bloom in the southern Yellow Sea
文章编号: N22051510
期刊: Science of The Total Environment
作者: Bing-Han Li, Jing-Wen Hu, Yu Xin, Chun-Ying Liu, Pei-Feng Li, Gui-Peng Yang
更新时间: 2022-05-15
摘要: To explore the spatial and temporal distributions of dissolved organic matter (DOM) affected by Ulva prolifera bloom and the regulation of DOM released by the addition of nitrate nutrients, the variation in DOM was analyzed by three cruises in the coastal waters of the southern Yellow Sea (SYS) off Qingdao during a 2018 U. prolifera bloom. A mesocosm experiment was conducted during the decay of U. prolifera. The U. prolifera bloom resulted in higher concentrations of the bulk DOM except for total dissolved amino acids (TDAA), compared with levels recorded during non-bloom periods. Three different fluorescent substances of chromophoric dissolved organic matter (CDOM) were identified, which were also affected by the bloom. Concentrations of total dissolved carbohydrates (TCHO), monosaccharides (MCHO), and polysaccharides (PCHO) peaked during the late bloom, with average levels of 49.78 ± 9.73, 14.23 ± 3.32, and 35.55 ± 9.19 μmol C L−1, respectively, accompanied by an increase of DOC, indicating release of DOM with U. prolifera decay. In contrast, the concentrations of CDOM and TDAA declined during the late bloom, with averages of 0.10 ± 0.10 m−1 and 1.16 ± 0.82 μmol L−1, suggesting that the yields of CDOM and TDAA were regulated by the U. prolifera bloom and other mechanism. These findings were confirmed by the mesocosm experiment. DOM production was obviously improved by NO3-N addition except for TDAA and CDOM. The release of protein-like CDOM was primarily regulated by NO3-N nutrients, however, it was not obvious with humic-like CDOM. Our findings provide evidence supporting the role of U. prolifera blooms in the coastal DOM pool and its significant effect on the marine carbon cycle.

84. 题目: Effect of organics on Cu and Cr in recovered struvite from synthetic swine wastewater
文章编号: N22051509
期刊: Journal of Cleaner Production
作者: Wenmin Wang, Xing Xin, Bing Li, Haiming Huang, Xiaoning Liu, Lan Song, Xiaofeng Wu, Yuefei Huang
更新时间: 2022-05-15
摘要: The fast development of struvite precipitation provides an excellent opportunity for cost-effective removal and recovery of nitrogen and phosphorus in swine wastewater. Meanwhile, swine wastewater is rich in heavy metals and organic matters, whose interaction might change heavy metals' distribution and toxicity in recovered struvite. This research investigates the effect of organic matter on heavy metals' speciation variation during phosphorus (P) recovery. The results demonstrate that when the concentration of citric acid, humic acid, and tetracycline increases from 0 to 500 mg/L, the P recovery efficiency decreases from 95.14% to 85.39%, 81.76%, and 74.28%, respectively. When the concentration of ammonium citrate, tetrasodium iminodisuccinate, and ethylenediaminetetraacetic acid vary from 0 to 100 mg/L, the P recovery efficiency decreases from 95.14 to 83.21, 85.97, and 81.32 mg/L, respectively, while the Cr in recovered struvite is increased from 1.88 to 2.92 mg/kg, 1.58–2.64 mg/kg and 0.86–12.6 mg/kg, respectively. It could be concluded that the pH increase promotes Cr and Cu's toxicity shifting to a stable state under the presence of citric acid, while Cr and Cu with humic acid or tetracycline shift to an active state. Besides, chelating agents can reduce heavy metal contents in the recovered struvite, but they also significantly inhibit the P recovery efficiency.

85. 题目: Biochar-based Microbial Agent Reduces U and Cd Accumulation in Vegetables and Improves Rhizosphere Microecology
文章编号: N22051508
期刊: Journal of Hazardous Materials
作者: Xin Qi, Shiqi Xiao, Xiaoming Chen, Imran Ali, Jialei Gou, Dan Wang, Bo Zhu, Wenkun Zhu, Ran Shang, Mengwei Han
更新时间: 2022-05-15
摘要: Microbial remediation of heavy metals in soil has been widely studied. However, bioremediation efficiency is limited in practical applications because of nutritional deficiency, low efficiency, and competition with indigenous microorganisms. Herein, we prepared a biochar-based microbial agent (BMA) by immobilizing the microbial agent (MA, containing Bacillus subtilis, Bacillus cereus, and Citrobacter sp.) on biochar for the remediation of U and Cd in soil. The results showed that BMA increased soil organic matter, cation exchange capacity, and fluorescein diacetate hydrolysis activity and dehydrogenase activity by 58.7%, 38.2%, 42.9%, and 51.1%. The availability of U and Cd were significantly decreased by 67.4% and 54.2% in BMA amended soil, thereby reducing their accumulation in vegetables. BAM greatly promoted vegetable growth. Additionally, BMA significantly altered the structure and function of rhizosphere soil microbial communities. Coincidently, more abundant ecologically beneficial bacteria like Nitrospira, Nitrosomonas, Lysobacter, and Bacillus were observed, whereas plant pathogenic fungi like Fusarium and Alternaria reduced in BMA amended soil. The network analysis revealed that BMA amendment increased the tightness and complexity of microbial communities. Importantly, the compatibility of niches and microbial species within co-occurrence network was enhanced after BMA addition. These findings provide a promising strategy for suppressing heavy metal accumulation in vegetables and promoting their growth.

86. 题目: Quantification of blue carbon stocks associated with Posidonia oceanica seagrass meadows in Corsica (NW Mediterranean)
文章编号: N22051507
期刊: Science of The Total Environment
作者: Briac Monnier, Gérard Pergent, Miguel Ángel Mateo, Philippe Clabaut, Christine Pergent-Martini
更新时间: 2022-05-15
摘要: In the last decades, the increasing necessity to reduce atmospheric carbon dioxide (CO2) concentrations has intensified interest in quantifying the capacity of coastal ecosystems to sequester carbon, referred to commonly as ‘Blue Carbon’ (BC). Among coastal habitats, seagrass meadows are considered as natural carbon sinks due to their capacity to store large amounts of carbon in their sediments over long periods of time. However, the spatial heterogeneity of carbon stocks in seagrass sediments needs to be better understood to improve the accuracy of BC assessments, particularly where there is high environmental variability. In the Mediterranean, Posidonia oceanica (L.) Delile constitutes extensive meadows considered as long-term carbon sinks due to the development of an exceptional structure known as ‘matte’, reaching several meters in height, which can be preserved over millennia. In order to specify the role of P. oceanica meadows in climate change mitigation, an estimate of carbon stocks has been conducted along the eastern coast of Corsica (NW Mediterranean). The approach is mainly based on the biogeochemical analysis of 39 sediment cores. Organic carbon (Corg; 327 ± 150 t ha−1, mean ± SE) and inorganic carbon stocks (Cinorg; 245 ± 45 t ha−1) show a high variability related to water depth, matrix (sandy vs rocky substrate) or the depositional environment (coastal vs estuary). The isotopic signature (δ13C) revealed a substantial contribution of allochthonous inputs of organic matter (macroalgae and sestonic sources) mainly in estuarine environment and shallow areas. The carbon stocks in the first 250 cm of matte (average thickness) were estimated at 5.6–14.0 million t Corg (study site) and 14.6–36.9 million t Corg (Corsica), corresponding to 11.6–29.2 and 30.4–76.8 years of CO2 emissions from the population of Corsica.

87. 题目: Unveiling the role of dissolved organic matter on phosphorus sorption and availability in a 5-year manure amended paddy soil
文章编号: N22051506
期刊: Science of The Total Environment
作者: Kejie Li, Qingfang Bi, Xipeng Liu, Haibo Wang, Chengliang Sun, Yongguan Zhu, Xianyong Lin
更新时间: 2022-05-15
摘要: Dissolved organic matter (DOM) is an active component of organic manure that is widely used in agroecosystems to increase nutrient availability and consequently enhance crop yields. However, the ways in which soil DOM characteristics are influenced by organic manure and how it contributes to crop yield and soil P availability remains unclear. Here, we conducted a 5-year field experiment and demonstrated that partial replacement of chemical P fertilizer with swine manure could maintain high rice yield and soil available P levels and increase P fertilizer use efficiency (PUE) in comparison to chemical fertilization, even when the total P input was reduced. This suggests that organic manure application can significantly mobilize soil P and increase P availability. Structural equation modeling analysis indicated that the soil pH and humification degree of DOM, rather than DOM content, directly decreased maximum P adsorption capacity. The combined results of the optical spectroscopy and ultrahigh-resolution mass spectroscopy obtained from the laboratory validation experiment based on the DOM-removed soil demonstrated that manure-derived DOM competing with P for adsorption was one of the main reasons for the increase in soil P availability and that the effective DOM components were N-containing lignins, tannins, and condensed polycyclic aromatics with higher O/C and lower H/C ratios. Overall, our results provide solid evidence that soil DOM characteristics are influenced by manure application and facilitate soil P availability, which could help guide the sustainable P management and manure application in agroecosystems.

88. 题目: The application and potential non-conservatism of stable isotopes in organic matter source tracing
文章编号: N22051505
期刊: Science of The Total Environment
作者: Zhongwu Li, Shilan Wang, Xiaodong Nie, Yize Sun, Fengwei Ran
更新时间: 2022-05-15
摘要: Organic matter (OM) tracing is critical for understanding the processes of soil redistribution and global carbon cycling. It effectively supports ecological management and global climate change prediction. Stable isotopes are generally more source-specific compared with other tracers and identify OM sources with a higher level of accuracy. Nevertheless, stable isotopes may be enriched or depleted by physical and biochemical processes such as selective migration of particles and OM mineralization in transport and sedimentary environments, making it difficult to establish links between the source and sink regions. Literature on OM source identification tends to assume a direct link between stable isotope sources and sinks, ignoring the non-conservatism of stable isotopes. There is further literature on understanding and modeling the processes that link the sources to sinks in terms of the non-conservatism of stable isotopes. The disagreement in response to the non-conservatism lies in the lack of comprehensive understanding of stable isotope fingerprinting systems and non-conservatism. The development of stable isotope fingerprinting technology is full of challenges. This review outlines the applicability of stable isotope tracers, identification mechanisms, and associated quantitative models, intending to improve the stable isotope fingerprinting system. We highlight the non-conservatism of stable isotopes in space and time caused by physical and biochemical processes. Additionally, a decision tree is established to determine the quantitative tools, evaluation indicators, and procedures related to non-conservatism. This decision tree clarifies the process from non-conservatism detection to threshold determination of statistical quantification, which can guide the end-users to better apply stable isotope to trace OM sources.

89. 题目: Organic carbon metabolism is a main determinant of hydrogen demand and dynamics in anaerobic soils
文章编号: N22051504
期刊: Chemosphere
作者: Megan Meinel, Anca G Delgado, Zehra Esra Ilhan, Marisol Luna Aguero, Samuel Aguiar, Rosa Krajmalnik-Brown, César I Torres
更新时间: 2022-05-15
摘要: Hydrogen (H2) is a crucial electron donor for many processes in the environment including nitrate-, sulfate- and, iron-reduction, homoacetogenesis, and methanogenesis, and is a major determinant of microbial competition and metabolic pathways in groundwater, sediments, and soils. Despite the importance of H2 for many microbial processes in the environment, the total H2 consuming capacity (or H2 demand) of soils is generally unknown. Using soil microcosms with added H2, the aims of this study were 1) to measure the H2 demand of geochemically diverse soils and 2) to define the processes leading to this demand. Study results documented a large range of H2 demand in soil (0.034–1.2 millielectron equivalents H2 g−1 soil). The measured H2 demand greatly exceeded the theoretical demand predicted based on measured concentrations of common electron acceptors initially present in a library of 15 soils. While methanogenesis accounted for the largest fraction of H2 demand, humic acid reduction and acetogenesis were also significant contributing H2-consuming processes. Much of the H2 demand could be attributed to CO2 produced during incubation from fermentation and/or acetoclastic methanogenesis. The soil initial total organic carbon showed the strongest correlation to H2 demand. Besides external additions, H2 was likely generated or cycled in the microcosms. Apart from fermentative H2 production, carboxylate elongation to produce C4–C7 fatty acids may have accounted for additional H2 production in these soils. Many of these processes, especially the organic carbon contribution is underestimated in microbial models for H2 consumption in natural soil ecosystems or during bioremediation of contaminants in soils.

90. 题目: Phytofabrication of bimetallic silver-copper/biochar nanocomposite for environmental and medical applications
文章编号: N22051503
期刊: Journal of Environmental Management
作者: Mohamed Hosny, Manal Fawzy, Abdelazeem S Eltaweil
更新时间: 2022-05-15
摘要: In the current study, a novel, green, low-cost, and sustainable path for the phyto-fabrication of Ag–Cu biochar nanocomposite (Ag–Cu/biochar) by Atriplex halimus biomass and aqueous extract is described. Surface plasmon resonance peaks were detected at 450 nm and 580 nm signifying the formation of both silver and copper nanoparticles, respectively on the biochar surface. XRD analysis confirmed the crystal structure of the phytosynthesized Ag–Cu/biochar whereas FT-IR, SEM, EDX, and XPS analyses confirmed the successful phytofabrication of the composite. Ag and Cu nanoparticles loaded on the biochar surface were almost spherically-shaped with a particle size ranging from 25 nm to 45 nm. Zeta potential of −25.5 mV showed the stability of Ag–Cu/biochar. The potential of this novel nanocomposite in the removal of doxycycline (DOX) was evident under different conditions as it reached nearly 100% under the optimum reaction conditions (DOX concentration; 50 ppm, pH; 9, a dose of Ag–Cu/biochar; 0.01 g, temperature; 25 °C, and H2O2 concentration; 100 mM). The promising regeneration of Ag–Cu/biochar was evident as the removal efficiency was 81% after 6 consecutive cycles. Ag–Cu/biochar was also shown an excellent antimicrobial activity against gram-negative bacteria as well a promising antioxidant activity.

91. 题目: Deep insights into the anaerobic co-digestion of waste activated sludge with concentrated leachate under different salinity stresses
文章编号: N22051502
期刊: Science of The Total Environment
作者: Meng Gao, Jiahui Yang, Yang Liu, Junjie Zhang, Jianhao Li, Yongli Liu, Baocun Wu, Li Gu
更新时间: 2022-05-15
摘要: Treatment of high-salinity organic wastewater (e.g., concentrated leachate) is a major challenge. Anaerobic co-digestion can effectively treat high-salinity organic wastewater and recover energy. In this study, the concentrated landfill leachate and waste activated sludge (WAS) were anaerobic co-digested in the lab-scale continuous stirred tank reactors (CSTR) to understand their co-digestion performance under different salinity stresses. As revealed by the results, when the salinity was low (<10 g/L), the removal ratio of organic matter in the digester was kept at a high level (>91.3%), and the concentration of total volatile fatty acids (TVFAs) was low (<100 mg COD/L), indicating that the digester could operate efficiently and stably. However, when the salinity level was elevated from 10 g/L to 30 g/L, the removal ratio of organic matter in the digester decreased from ~91.3% to ~64.5%, the TVFAs continued to accumulate, the yields of biogas and methane also dropped sharply, and the performance of the digester decreased gradually. The results of microbial community and diversity analysis showed that there is limited adaptability of microbial community to high salinity in such process. Salinity could cause significant changes in the microbial community and diversity, thereby affecting the digestive performance. Metagenomic analysis showed that under high salinity conditions, the content of genes encoding hydrolase and methanogenic enzyme decreased, whereas the pathway of acetotrophic methanogenesis was weakened. Mechanism study showed that with the increase of salinity, the activity of microbial cells decreased, the structure of sludge flocs was damaged more significantly, and the extracellular polymeric substances (EPS) secreted by microbe increased continuously, which was used to resist the toxic effects of salinity stresses on microorganisms. The results of this study could provide certain theoretical guidance for anaerobic digestion under salinity stresses.

92. 题目: Effects of biological activated carbon filter running time on disinfection by-product precursor removal
文章编号: N22051501
期刊: Science of The Total Environment
作者: Feifei Wang, Jiazheng Pan, Yulin Hu, Jie Zhou, Haoqian Wang, Xin Huang, Wenhai Chu, Jan Peter van der Hoek
更新时间: 2022-05-15
摘要: Biological activated carbon (BAC) filtration is usually considered to be able to decrease formation potentials (FPs) of disinfection by-products (DBPs) in drinking water treatment plant (DWTP). However, BAC filters with long running time may release microbial metabolites to effluents and therefore increase FPs of nitrogenous DBPs with high toxicity. To verify this hypothesis, this study continuously tracked BAC filters in a DWTP for one year, and assessed effects of old (running time 8–9 years) and new (running time 0–13 months) BAC filters on FPs of 15 regulated and unregulated DBPs. Results revealed that dissolved organic carbon (DOC) removal was slightly higher in the new BAC than the old one. All fluorescent components of dissolved organic matter evidently declined after new BAC filtration, but fulvic acid-like and soluble microbial product-like substances increased after old BAC filtration, which could be caused by microbial leakage. Correspondingly, new BAC filter generally removed more DBP FPs than the old one. 50.6% HAA4 FPs from chlorination and 43.5% THM4 FPs from chloramination were removed by new BAC filter. However, some DBP FPs, especially HAN FPs, were poorly removed or even increased by the old BAC filter. Proteobacteria could be a main contributor for DBP precursor removal in BAC filters. Herminiimonas, most abundant genera in new BAC filter, may explain its better DOC and UV254 removal performance and lower DBP FPs, while Bradyrhizobium, most abundant genera in old BAC filter, might produce more extracellular polymeric substances and therefore increased N-DBP FPs in old BAC effluent. This study provided insight into variations of DBP FPs and microbial communities in the new and old BAC filters, and will be helpful for the optimization of DWTP design and operation for public health.

93. 题目: Raspberry stalks-derived biochar, magnetic biochar and urea modified magnetic biochar - Synthesis, characterization and application for As(V) and Cr(VI) removal from river water
文章编号: N22051411
期刊: Journal of Environmental Management
作者: Joanna Dobrzyńska, Anna Wysokińska, Rafał Olchowski
更新时间: 2022-05-14
摘要: Raspberry stalks-derived biochar (BC), magnetic biochar-iron oxide composite (BC–Fe) and its derivative modified with urea (BC–Fe–U) were synthesized, characterized and tested as(V) and Cr(VI) ion sorbents. The surface area of BC, BC-Fe and BC-Fe-U was 259, 163 and 117 m2 g−1, respectively. The structure of BC was dominated by micropores, while in BC-Fe and BC-Fe-U mesopores predominated. Based on the XRD results, it was found that the magnetic properties of the biochar-iron oxide composites are due to the presence of ferrimagnetic magnetite (Fe3O4) and maghemite (Fe2O3). The optimal pH of As(V) and Cr(VI) adsorption onto the studied sorbents is in the range of 2.3–5.7. Pristine biochar (BC) does not adsorb As(V) ions; however, it enables rapid adsorption of Cr(VI) with the static adsorption capacity of 19.2 mg g−1. The maximum static adsorption capacities of As(V) and Cr(VI) ions onto BC-Fe and BC-Fe-U are within the range of 13.5–16.3 mg g−1. For most adsorption systems tested, adsorption equilibrium is reached within 4 h, though even a few minutes is enough to reach half of the adsorption static value. Phosphates over 0.005 mol L−1 hinder adsorption of As(V) and Cr(VI) ions. Application of at least 5 mol L−1 nitric acid allows about 95% of Cr(VI) and As(V) to be desorbed from adsorbate-loaded BC-Fe material. For other materials, the desorption efficiencies are significantly lower. BC-Fe and BC-Fe-U materials were successfully used for simultaneous Cr(VI) and As(V) removal from river water.

94. 题目: hvRevisiting paleoenvironmental analyses and interpretations of organic-rich deposits: The Importance of TOC corrections
文章编号: N22051410
期刊: Organic Geochemistry
作者: Bruce S Hart, Michael H Hofmann
更新时间: 2022-05-14
摘要: Methods for reconstructing present-day TOC values to their original values are widely used in petroleum systems analysis. However, the importance of making these corrections appears to be underappreciated when TOC is used for paleoenvironmental interpretation. In this paper we demonstrate how differences between present-day TOC (TOCPD) values (e.g., as measured via LECO and similar methods) and those at the time of deposition (TOCO) can materially affect paleoenvironmental interpretations that use TOC as a variable. The difference between those two values depends on the thermal maturity of the deposits and the original kerogen type. We illustrate the effects of restoring and using TOCO values on samples from the Upper Cretaceous Eagle Ford Formation of South Texas and the Upper Devonian Lower Bakken Shale of North Dakota. Making this correction requires programmed pyrolysis (“Rock Eval”) data rather than simple TOC measurements. We use plots of molybdenum and sulfur versus TOCPD and TOCO to illustrate the effects of restoring TOC, but any analysis that involves TOC as a variable will be affected. There are uncertainties associated with defining the original organic matter type, and other unknowns that can affect TOC reconstruction. As such we advocate presentation of a range of possible TOCO values, i.e., deliberately capturing uncertainty, rather than a single value. The method used to restore TOC has minimal impact on the interpretations, at least for the two methods employed herein.

95. 题目: Impact of long-term residue burning versus retention on soil organic carbon sequestration under a rice-wheat cropping system
文章编号: N22051409
期刊: Soil and Tillage Research
作者: Asik Dutta, Ranjan Bhattacharyya, Ved Prakash Chaudhary, Chhemendra Sharma, Chaitanya Prasad Nath, Soora Naresh Kumar, Brajendra Parmar
更新时间: 2022-05-14
摘要: Despite rice residue burning is popularized against its retention under rice-wheat system in the Indo-Gangetic Plains (IGP), limited information is available on the impacts of long-term rice residue burning versus its retention on carbon stock, soil aggregation and aggregated-associated carbon in the region. Hence, a 18 (1998–2016) years old conservation agriculture (different combinations of tillage and residue management) experiment was selected to understand the impact of CA on soil aggregation, carbon pools and soil organic carbon (SOC) stock in a rice-wheat system. Experiment was laid down in a split-plot design with three replications having three tillage management viz. zero-tillage (ZT), conventional tillage (CT) and strip tillage (ST) as main plots and three residue management options namely residue retention (R), residue burning (RB) and no-residue (NR). The total SOC content was 20% higher (p < 0.05) under ZT and residues retention over CT and residue removal, in the 0–5 cm layer. The SOC stock increased with depth (from 0 to 5 cm to 5–15 cm). ZT with added residues had 25% higher (p < 0.05) SOC stock than CT without residues because of higher aggregation with lesser disturbance in ZT promoted SOC accumulation over time. Macro-aggregate fraction was higher in ZT by 18% (p < 0.05) than CT in the 0–5 cm soil depth. Whereas, CT without residues resulted in higher silt and clay size fraction than ZT. Labile carbon (very labile + labile fractions) was 7–25% increased (p < 0.05) under ZT+R than CT-R across depth. Recalcitrant carbon (less-labile + non-labile) followed the same trend. Notably, ZT with residues retention (conservation agriculture, CA) increased 32.6–41.7% potassium permanganate oxidizable carbon than CT without residues in the 0–5 cm and 5–15 cm, respectively. No mechanical tillage in ZT with added residues over the years promoted bridging between aggregates that brought about carbon accumulation. The study highlighted the importance of CA in enhancing SOC stock, soil aggregation and managing long-term SOC content.

96. 题目: Soil Amended with Organic Matter Increases Fluvial Erosion Resistance of Cohesive Streambank Soil
文章编号: N22051408
期刊: Journal of Geophysical Research: Biogeosciences
作者: D J Smith, M Snead, T M Thompson
更新时间: 2022-05-14
摘要: Fluvial erosion of cohesive soil is mediated by interactions between soil physical, biological, and chemical characteristics such as soil aggregate stability and extracellular polymeric substances (EPS). While labile organic matter (OM) stimulates microbial EPS production and significantly improves soil aggregate stability in agricultural soils, these interactions remain unexplored in streambank soils. The study goal was to quantify the impact of OM on aggregate stability, EPS, and fluvial erosion rates of cohesive streambank soil. Increasing amounts of 1-mm sieved dry grass were incorporated at rates of 0, 1 and 4 g per 100 g of 2-mm sieved silt-loam soil (treatments T0, T1, and T4, respectively). Samples (eight replicates per treatment) were matured in a greenhouse for 50 days prior to flume erosion testing. EPS carbohydrates were significantly (p < 0.05) lower in T1 (324±63 µg/g) compared to T0 (388±37 µg/g) and T4 (376±44 µg/g). EPS proteins were significantly higher in T1 (194±15 µg/g) and T4 (223±61 µg/g) compared to T0 (101±20 µg/g) and positively correlated with mean weight diameter (MWD), a measure of soil stability against slaking. MWD was 16% and over 100% higher for T1 and T4, respectively, than for T0. Similarly, the average soil erodibility coefficient of T1 and T4 was 25% and 61% lower than the erodibility of T0; however, only the reduction for T4 was significant. The data presented here underscore the important role labile OM plays in improving soil physical stability and increasing the resistance of cohesive soil to fluvial erosion of streambanks.

97. 题目: Sources of ammonium enriched in groundwater in the central Yangtze River Basin: Anthropogenic or geogenic?
文章编号: N22051407
期刊: Environmental Pollution
作者: Ying Liang, Rui Ma, Athena Nghiem, Jie Xu, Liansong Tang, Wenhao Wei, Henning Prommer, Yiqun Gan
更新时间: 2022-05-14
摘要: The occurrence of excessive ammonium in groundwater threatens human and aquatic ecosystem health across many places worldwide. As the fate of ammonium in groundwater systems is often affected by a complex mixture of transport and biogeochemical transformation processes, identifying the sources of groundwater ammonium is an important prerequisite for planning effective mitigation strategies. Elevated ammonium was found in both a shallow and an underlying deep groundwater system in an alluvial aquifer system beneath an agricultural area in the central Yangtze River Basin, China. In this study we develop and apply a novel, indirect approach, which couples the random forest classification (RFC) of machine learning method and fluorescence excitation-emission matrices with parallel factor analysis (EEM-PARAFAC), to distinguish multiple sources of ammonium in a multi-layer aquifer. EEM-PARAFAC was applied to provide insights into potential ammonium sources as well as the carbon and nitrogen cycling processes affecting ammonium fate. Specifically, RFC was used to unravel the different key factors controlling the high levels of ammonium prevailing in the shallow and deep aquifer sections, respectively. Our results reveal that high concentrations of ammonium in the shallow groundwater system primarily originate from anthropogenic sources, before being modulated by intensive microbially mediated nitrogen transformation processes such as nitrification, denitrification and dissimilatory nitrate reduction to ammonium (DNRA). By contrast, the linkage between high concentrations of ammonium and decomposition of soil organic matter, which ubiquitously contained nitrogen, suggested that mineralization of soil organic nitrogen compounds is the primary mechanism for the enrichment of ammonium in deeper groundwaters.

98. 题目: Thermal plasticity of coral reef symbionts is linked to major alterations in their lipidome composition
文章编号: N22051406
期刊: Limnology and Oceanography
作者: Marina T. Botana, Adriano B Chaves‐Filho, Alex Inague, Arthur Z. Güth, Flavia Saldanha‐Corrêa, Marius N Müller, Paulo Y G Sumida, Sayuri Miyamoto, Matthias Y Kellermann, Raymond C Valentine, Marcos Y Yoshinaga
更新时间: 2022-05-14
摘要: Coral bleaching caused by ocean warming is leading to worldwide coral decline. The physiological processes underlying this ecological event are still incompletely understood, although previous research has suggested oxidative stress as major player in the impairment of symbiont thylakoid membranes and in symbiosis breakdown. Lipids are interesting targets of investigation, given their susceptibility to thermal and oxidative stresses. Here, an untargeted lipidomic approach was employed to examine changes in lipidome and pigments of three coral reef symbionts (Symbiodiniaceae) after a heat shock in in vitro experiments. The acute thermal stress induced species-specific changes in lipidome and pigments compositions of both heat sensitive and tolerant symbionts. Heat sensitivity was characterized by a steep and steady decline in cell densities over time (4 and 240 h after heat shock). At the membrane level, heat sensitive symbiont displayed a quantitative decrease in glycolipids linked to polyunsaturated fatty acids, followed by enrichment in oxidized lipids and sphingolipids. Despite showing distinct adaptations, the two heat tolerant symbionts were characterized by the preservation of membrane lipids after heat shock, particularly glycolipids. This finding suggests the action of powerful antioxidant systems, preventing the escalation of oxidized lipids concentration in thylakoid membranes under thermal stress. Although limited by the examination of free-living symbionts, our study provides a solid baseline for the investigation of lipidome and pigments alterations of Symbiodiniaceae in response to heat stress. Novel potential lipid biomarkers linked to thermal stress are suggested. In particular, oxidized lipids—which are implicated in coral symbiosis establishment and breakdown—appear as attractive targets for further research.

99. 题目: High-resolution soil organic carbon mapping at the field scale in Southern Belgium (Wallonia)
文章编号: N22051405
期刊: Geoderma
作者: Yue Zhou, Caroline Chartin, Kristof Van Oost, Bas van Wesemael
更新时间: 2022-05-14
摘要: Accurate soil organic carbon content estimation is critical as a proxy for carbon sequestration, and as one of the indicators for soil health. Here, we collected 497 soil samples during 2015 and 2019, as well as five environmental covariates (organic carbon (OC) input from the crops, normalized difference vegetation index (NDVI), elevation, clay content and precipitation) at a resolution of 30 m. We then aggregated these to represent agricultural fields and compiled a soil organic carbon (SOC) content map for the agricultural soils of Wallonia using Gradient Boosting Machine. We calculated OC input from both main crops and cover crops for each individual field. As the cover crops do not occur in the agricultural census, we identified cover crops based on long time-series of NDVI values obtained from the Google Earth Engine platform. The quality of the SOC predictions was assessed by validation data and we obtained an R2 of 0.77. The Empirical Mode Decomposition indicated that OC input and NDVI were the dominant factors at field scale, whereas the remaining covariates determined the distribution of SOC at the scale of the entire Walloon region. The SOC map showed an overall northwest to southeast trend i.e. an increase in SOC contents up to the Ourthe river followed by a decrease further to the South. The map shows both regional trends in SOC and effects of differences in land use and/or management (including crop rotation and frequency of cover crops) between individual fields. The field-scale map can be used as a benchmark and reference to farmers and agencies in maintaining SOC contents at an appropriate level and optimizing decisions for sustainable land use.

100. 题目: Vertical intertidal variation of organic matter stocks and patterns of sediment deposition in a mesotidal coastal wetland
文章编号: N22051404
期刊: Estuarine, Coastal and Shelf Science
作者: Carmen B de los Santos, François Lahuna, André Silva, Cátia Freitas, Márcio Martins, A. Rita Carrasco, Rui Santos
更新时间: 2022-05-14
摘要: Tidal coastal wetlands, common home to seagrass and salt marshes, are relevant carbon sinks due to their high capacity to accumulate and store organic carbon in their sediments. Recent studies demonstrated that the spatial variability of this organic carbon within the same wetland system can be significant. Some of the environmental drivers of this spatial variability remain understudied and the selection of the most relevant ones can be context dependent. Here we investigated the role of bed elevation, hydrodynamics, and habitat type (salt marsh and seagrass) on the organic matter (OM) net deposition-resuspension rate and superficial sedimentary stocks (top 5 cm) at the tidal wetlands of the Ria Formosa, a mesotidal coastal lagoon in South Portugal. Results showed that two vectors of spatial variation need to be considered to describe the intertidal sedimentary OM stocks: the bed elevation that imposes a decrease of the hydroperiod and thus the change of habitat from the lower seagrass Z. noltei to the upper saltmarsh S. maritimus, and the horizontal spatial variation along the secondary channels of the lagoon that imposes a decrease in the flow velocity magnitude. The multiple linear regression analyses using data from 40 sampling points explained 59% of the variation of the superficial sedimentary stocks of OM in salt marshes and seagrasses of the Ria Formosa lagoon and revealed that stocks generally decrease with elevation, yet with variation among sites and habitats. It was also found that the decrease of the OM net deposition-resuspension rate with bed elevation was exponential. Our study emphasizes the importance of considering multiple environmental drivers and spatial variation for regional estimations of organic matter (and organic carbon) sedimentary stocks in wetlands.

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