81. 题目: Performance evaluation of crop residue and kitchen waste-derived biochar for eco-efficient removal of arsenic from soils of the Indo-Gangetic plain: A step towards sustainable pollution management
期刊: Environmental Research
作者: Abhishek Kumar, Tanushree Bhattacharya, Wasim Akram Shaikh, Arpita Roy, Santanu Mukherjee, Manish Kumar
摘要: Biochar was produced from wheat straw (Triticum aestivum), rice straw (Oryza sativa), and kitchen waste at varying pyrolysis temperatures (300°C–700 °C). The biochars were screened depending on their production and physicochemical properties for the adsorptive removal of arsenic (As). The morphological analysis by Field emission scanning electron microscope revealed a porous biochar surface. Spectroscopic characterization of biochars indicated the co-existence of minerals, carboxyl, carbonyl, amide, and hydroxyl groups, which implies the suitability of biochar to immobilize metal (loid)s from soils. Changes in peaks were observed in Fourier-transform infrared and X-ray diffraction images after As sorption indicating the involvement of chemisorption. The thermogravimetric analysis and a low H/C value derived from the CHNS analyzer confirmed the high stability of biochar. The BET analysis was used to estimate the surface areas of wheat straw (15.8 m2 g-1), rice straw (12.5 m2 g-1), and kitchen waste (2.57 m2 g-1) -derived biochars. Batch sorption studies were performed to optimize experimental parameters for maximum removal of As. Maximum removal of As was observed for wheat straw-derived biochar (pyrolyzed at 500 °C) at 8 mg L−1 initial concentration (IC), 7.5 % dose, 25 °C temperature, and 60 min contact time (83.7 ± 0.06 %); in rice straw-derived biochar (pyrolyzed at 500 °C) at 8 mg L−1 IC, 7.5 % dose, 25 °C temperature, 90 min contact time (83.6 ± 0.37 %); and in kitchen waste-derived biochar (pyrolyzed at 500 °C) at 8 mg L−1 IC, 5 % dose, 25 °C temperature, 60 min contact time (76.7 ± 0.16 %). The sorption model parameters suggested the possibility of chemisorption, physisorption, diffusion, and ion exchange for the removal of As. Therefore, it could be recommended to farmers that instead of disposing or burning straws and waste openly, they could adopt the process of charring to generate livelihood security and mitigation of geogenic contaminants from the soil/water dynamic systems.
82. 题目: Formation of nitrosamines during chloramination of two algae species in source water—Microcystis aeruginosa and Cyclotella meneghiniana
期刊: Science of The Total Environment
作者: Yunpeng Wang, Fei Li, Jiayu Du, Xiaoyang Shi, Aixi Tang, Ming-Lai Fu, Wenjie Sun, Baoling Yuan
摘要: The contribution of two algae species, Microcystis aeruginosa (M. aeruginosa) and Cyclotella meneghiniana (C. meneghiniana), to the formation of nitrosamines (NAs) during chloramination in drinking water treatment was investigated. A variety of factors including contact time, algae cell concentration, chloramine dosages, and algal cell components (cell debris (CD), intracellular organic matter (IOM), and extracellular organic matter (EOM)) were evaluated for influencing the formation of different NAs, such as N-Nitrosodiethylamine (NDMA), N-Nitrosomethylethylamine (NMEA), N-Nitrosodibutylamine (NDBA), N-Nitrosodi-n-propylamine (NDPA), and N-nitrosopyridine (NPyr). In addition, NAs formation from Chlorophyll-a and Microcystin-LR (MC-LR) after chloramination was studied. These results showed that the increase of reaction time and algae cell concentration enhanced the formation potential of five types of NAs from both algae species, except for the NDMA formation from C. meneghiniana, which increased first and then decreased with increased reaction time. The generation of NDMA was detected as the dominated type of NAs. The formation of total NAs from both algae species followed same pattern of increasing first and then decreasing with the increase of chloramine dosage. The largest NAs formation potential (NAsFP) of M. aeruginosa and C. meneghiniana showed at 1.5 mM and 1.0 mM monochloramine, respectively. Moreover, the impacts of algae cellular components on the formation potential of NAs followed the order of IOM > EOM ≫ CD and IOM ≫ CD > EOM for M. aeruginosa and C. meneghiniana, respectively, indicating that IOM was the main source of NAs precursors for both algae. Furthermore, EEM analysis before and after chloramination confirmed that the soluble microbial products (SMPs) and protein-like substances were the main cellular components that contributed to NAs formation for both algae. The NAs formation potential of Microcystin-LR was much higher than that of Chlorophyll-a chloramination.
83. 题目: Perennial legume intercrops provide multiple belowground ecosystem services in smallholder farming systems
期刊: Agriculture, Ecosystems & Environment
作者: Laurie E. Drinkwater, Charles A.O. Midega, Rachel Awuor, Dickens Nyagol, Zeyaur R. Khan
摘要: Soil degradation is a major underlying cause of poverty and malnutrition in smallholder agrarian communities across the globe. Legume diversification, through polyculture or intercropping, is a strategy that increases yields and income while improving family nutrition. However, the potential for these legume-cereal intercrops to restore soil functions in smallholder fields remains uncertain, with many studies failing to detect increases in soil organic matter (SOM). In sub-Saharan Africa, smallholders typically grow maize either intercropped with short-lived annual food legumes or as a monoculture. Recently, a novel maize system which includes perennial legumes in the genus Desmodium as intercrops, known as “push-pull” (hereafter, PP) has been increasingly adopted by smallholders across the region. The yield, nutritional and economic benefits of the PP system are well-documented. We investigated the effects of PP maize intercropping on soil fertility compared to the predominant maize culture systems (hereafter, NPP) using soils from long-term experiments and smallholder fields in western Kenya. Maize-desmodium intercrops promoted SOM accrual and increased plant available phosphorus. In the long-term research station experiments soil organic N was 20% greater and labile organic N reserves were five-fold greater in PP compared to NPP soils. Despite equal P fertilizer application rates, extractable soil P was two-fold greater in PP compared to NPP soils. Soils under maize-food legume intercrops did not show any detectable accrual of SOM compared to maize monocultures. Soil benefits in smallholder PP fields tended to mirror those found in the controlled experiments. Taken together, our results demonstrate that the perennial legumes in PP system restore soil function and fertility. Developing additional well-designed intercropping systems that include perennial legumes could play a significant role in reversing the trajectory of soil degradation in smallholder farming systems while enhancing human well-being.
84. 题目: Multifractal analysis on spatial variability of soil particles and nutrients of Benggang in granite hilly region, China
作者: Zuoli Wu, Yusong Deng, Chongfa Cai, Juan Huang, Wanxia Huang
摘要: Benggang erosion is a large-scale, rapidly developing phenomenon that commonly occurs in the granite hilly region of southern China and severely endangers local land resources and the ecological environment. A developing Benggang in southeast China was selected to explore the non-uniformity of soil particle size distribution (PSD) and the nutrient heterogeneity during Benggang erosion using multifractal theory. The results showed significant differences in the soil particle composition and nutrient components of different parts of Benggang. The generalized dimension spectra exhibited an inverse “S” decreasing pattern and the singularity spectra showed a left hook shape, indicating that the soil PSD of Benggang features high non-uniformity and can be described by the multifractal theory. The information dimension (D1) and the correlation dimension (D2) were high in the uppercatchment, the lowerportion ofthe collapsingwall, and the top ofthe alluvialfan. D1, D2, and the spectral width (Δα) were negatively correlated with clay and silt content but positively correlated with sand content. In contrast, D1–D2 and the degree of symmetry (Δf) showed opposite relationships. The multifractal singularity indexes α0 and Δα were significantly negatively correlated with soil organic matter but positively correlated with bulk density; opposite correlations were observed for Δf. The findings revealed that the multifractal theory can quantitatively characterize the characteristics of soil PSD and laterally reflect soil nutrient loss. This research introduces a scientific method for quantitatively describing the heterogeneity of soil PSD during Benggang development. In addition, it also provides a theoretical basis for controlling Benggang erosion to protect the environment of the southern granite region.
85. 题目: Desiccation time and rainfall control gaseous carbon fluxes in an intermittent stream
作者: Maria Isabel Arce, Mia M. Bengtsson, Daniel von Schiller, Dominik Zak, Jana Täumer, Tim Urich, Gabriel Singer
摘要: Droughts are recognized to impact global biogeochemical cycles. However, the implication of desiccation on in-stream carbon (C) cycling is not well understood yet. We subjected sediments from a lowland, organic rich intermittent stream to experimental desiccation over a 9-week-period to investigate temporal changes in microbial functional traits in relation to their redox requirements, carbon dioxide (CO 2 ) and methane (CH 4 ) fluxes and water-soluble organic carbon (WSOC). Concurrently, the implications of rewetting by simulated short rainfalls (4 and 21 mm) on gaseous C fluxes were tested. Early desiccation triggered dynamic fluxes of CO 2 and CH 4 with peak values of 383 and 30 mg C m −2 h −1 (mean ± SD), respectively, likely in response to enhanced aerobic mineralization and accelerated evasion. At longer desiccation, CH 4 dropped abruptly, likely because of reduced abundance of anaerobic microbial traits. The CO 2 fluxes ceased later, suggesting aerobic activity was constrained only by extended desiccation over time. We found that rainfall boosted fluxes of CO 2 , which were modulated by rainfall size and the preceding desiccation time. Desiccation also reduced the amount of WSOC and the proportion of labile compounds leaching from sediment. It remains questionable to which extent changes of the sediment C pool are influenced by respiration processes, microbial C uptake and cell lysis due to drying-rewetting cycles. We highlight that the severity of the dry period, which is controlled by its duration and the presence of precipitation events, needs detailed consideration to estimate the impact of intermittent flow on global riverine C fluxes.
86. 题目: Enhancement of sludge dewaterability via the thermal hydrolysis anaerobic digestion mechanism based on moisture and organic matter interactions
期刊: Science of The Total Environment
作者: Wei Zhang, Bin Dong, Xiaohu Dai, Lingling Dai
摘要: It is known that sludge dewaterability improves during the thermal hydrolysis process (THP); however, the effect of thermal hydrolysis and anaerobic digestion (THP-AD) on sludge dewaterability is unclear. Further, the difference between thermal hydrolysis as pre-treatment for anaerobic digestion (pre-THP-AD) and as post-treatment (post-THP-AD) is also unclear. Based on the evolution of the interaction between organic matter and moisture, the mechanism of pre-THP-AD and post-THP-AD improving the sludge dewaterability was explored. The capillary suction time values of pre-THP-AD and post-THP-AD increased by 58% and 59%, respectively, and the proportion of free moisture increased by 10.44% and 10.59%, respectively, compared with the conventional anaerobic digestion (CAD) process. The cell structure was destroyed and most organic matter was converted into dissolved form through THP, organic matter degraded during AD, the interaction between moisture and organic matter declined, and the mechanically bound moisture transformed into free moisture. Additionally, the intensity of hydrophilic functional groups, such as amide I decreased and amide II disappeared after (pre- and post-) THP-AD. The surface hydrophobicity of sludge samples was enhanced and sludge dewaterability improved. The mechanism of pre-/post-THP-AD enhanced sludge dewaterability based on the interaction between moisture and organic matter; additionally, this will provide a reference for optimised moisture-sludge separation processes and guidance for the optimisation of engineering operation parameters.
87. 题目: Assessing the arsenic-saturated biochar recycling potential of vermitechnology: Insights on nutrient recovery, metal benignity, and microbial activity
作者: Shuvrodeb Roy, Dibyendu Sarkar, Rupali Datta, Satya Sundar Bhattacharya, Pradip Bhattacharyya
摘要: Biochar mediated pollutant removal is gaining attention because of high efficiency of the process. However, effective recycling avenues of the pollutant-saturated biochars are scarce in the knowledge base; while such materials can be a new source of long-range contamination. Therefore, potential of vermitechnology for eco-friendly recycling of pollutant-loaded biochar was assessed by using arsenic-saturated native (NBC) and exfoliated (EBC) biochars as feedstocks for the first time. Interestingly, the bioavailable arsenic fractions (water soluble and exchangeable) considerably reduced by 22–44 % with concurrent increment (∼8–15 %) of the recalcitrant (residual and organic bound) fractions in the biochar-based feedstocks. Consequently, ∼2–3 folds removal of the total arsenic was achieved through vermicomposting. The earthworm population growth (2.5–3 folds) was also highly satisfactory in the biochar-based feedstocks. The results clearly imply that Eisenia fetida could compensate the arsenic-induced stress to microbial population and greatly augmented microbial biomass, respiration and enzyme activity by 3–12 folds. Moreover, biochar-induced alkalinity was significantly neutralized in the vermibeds, which remarkably balanced the TOC level and nutrient (N, P, and K) availability particularly in EBC + CD vermibeds. Overall, the nutrient recovery potential and arsenic removal efficiency of vermitechnology was clearly exhibited in NBC/EBC + CD (12.5:87.5) feedstocks. Hence, it is abundantly clear that vermitechnology can be a suitable option for eco-friendly recycling of pollutant-saturated sorbing agents, like biochars.
88. 题目: Histosol pedogenesis in floodplain coastal environments in the state of Rio de Janeiro, Brazil
作者: Paula Fernanda Chaves Soares, Rafael Cipriano da Silva, Eduardo Carvalho da Silva Neto, Marcos Gervasio Pereira, Carlos Roberto Pinheiro Junior, Luiz Carlos Ruiz Pessenda, Lúcia Helena Cunha dos Anjos
摘要: This study aimed to evaluate the morphological, physical, and chemical properties of Histosols in wetlands and to infer aspects related to their pedogenesis based on C and N isotopes and 14C dating to better understand ecosystem services, paleo-environments, and post-depositional processes based on preliminary results. Two Histosol pedons, located in different floodplains that refer to different sedimentation environments, were sampled in the state of Rio de Janeiro. Morphological, physical, and chemical characterization were performed, and the total C and N content of the substrate and the C content of humic substances were assessed. Elemental C and N and isotope analyses (δ13C and δ15N) were performed every 10 cm, while 14C dating of the humin fraction was performed at 40–50 and 190–200 cm. The interproxy approach combining pedological analyses, radiocarbon dating, and elemental and isotopic analyses of total C and N of organic matter, showed a mixture of algae and continental errestrial organic matter deposited in peatlands, over the last ~ 4000 cal years before present (BP). The studied soils were formed by geogenic and pedogenic processes (terrestrialization, paludization, and aggradation). Considering the relationships between δ13C and δ15N, between C/N and δ13C, and the soil characteristics, these deposits were probably formed by vertical accretion in lake environments. However, near 2300 cal yr BP, the radiocarbon dating and isotopic analyses suggest the occurrence of deposition of alluvial sediments transported by the Suruí River in RJ-01. It is likely that the modern age obtained by 14C dating in RJ-02, near 3600 cal yr BP, is probably due to the intense bioturbation by plant roots and the input of young material during the seasonal flood period.
89. 题目: Trends in renewable energy production employing biomass-based biochar
期刊: Bioresource Technology
作者: Shashi Kant Bhatia, Akshaya K. Palai, Amit Kumar, Ravi Kant Bhatia, Anil Kumar Patel, Vijay Kumar Thakur, Yung-Hun Yang
摘要: Tremendous population growth and industrialization have increased energy consumption unprecedentedly. The depletion of fossil-based energy supplies necessitates the exploration of solar, geothermal, wind, hydrogen, biodiesel, etc. as a clean and renewable energy source. Most of these energy sources are intermittent, while bioelectricity, biodiesel, and biohydrogen can be produced using abundantly available organic wastes regularly. The production of various energy resources requires materials that are costly and affect the applicability at a large scale. Biomass-derived materials (biochar) are getting attention in the field of bioenergy due to their simple method of synthesis, high surface area, porosity, and availability of functional groups for easy modification. Biochar synthesis using various techniques is discussed and their use as an electrode (anodic/cathodic) in a microbial fuel cell (MFC), catalysts in transesterification, and anaerobic digestion for energy production are reviewed. Renewable energy production using biochar would be a sustainable approach to create an energy secure world.
90. 题目: Biochar-based activation of peroxide: multivariate-controlled performance, modulatory surface reactive sites and tunable oxidative species
期刊: Chemical Engineering Journal
作者: Jia Wang, Jiayi Cai, Siqi Wang, Xinquan Zhou, Xintao Ding, Jawad Ali, Li Zheng, Songlin Wang, Lie Yang, Shuang Xi, Mingju Wang, Zhuqi Chen
摘要: Recently, biochar emerged as a promising peroxide activator due to its chemical-saving/facile synthesis processes, high efficiency, tunable physicochemical properties and capacity to endow both radical and non-radical oxidative species. However, serious knowledge gaps and controversies have been raised on the mechanism to modulate reactive sites on its surface and dominated reaction pathways in biochar-involving systems. Insight understanding of the activation processes will remarkably advance its functional synthesis and application in practical wastewater treatment. Therefore, this paper aims to provide an up-to-date review on application and modification of biochar activator to alter their reactive sites and physicochemical properties and design their synthesis processes to achieve a satisfactory performance. Also, formation of reactive oxidative species on various reactive sites was discussed. Lastly, future research directions on evaluation and improving the physicochemical properties of biochar catalysts were proposed as well as their potential applications in real wastewater systems.
91. 题目: Bioremediation strategies with biochar for polychlorinated biphenyls (PCBs)-contaminated soils: A review
期刊: Environmental Research
作者: Soheil Valizadeh, Sang Soo Lee, Kitae Baek, Yong Jun Choi, Byong-Hun Jeon, Gwang Hoon Rhee, Kun-Yi Andrew Lin, Young-Kwon Park
摘要: Polychlorinated biphenyls (PCBs) are hazardous organic contaminants threatening human health and environmental safety due to their toxicity and carcinogenicity. Biochar (BC) is an eco-friendly carbonaceous material that can extensively be utilized for the remediation of PCBs-contaminated soils. In the last decade, many studies reported that BC is beneficial for soil quality enhancement and agricultural productivity based on its physicochemical characteristics. In this review, the potential of BC application in PCBs-contaminated soils is elaborated as biological strategies (e.g., bioremediation and phytoremediation) and specific mechanisms are also comprehensively demonstrated. Further, the synergy effects of BC application on PCBs-contaminated soils are discussed, in view of eco-friendly, beneficial, and productive aspects.
92. 题目: Nitrogen loss processes in response to upwelling in a Peruvian coastal setting dominated by denitrification – a mesocosm approach
作者: Kai G. Schulz, Eric P. Achterberg, Javier Arístegui, Lennart T. Bach, Isabel Baños, Tim Boxhammer, Dirk Erler, Maricarmen Igarza, Verena Kalter, Andrea Ludwig, Carolin Löscher, Jana Meyer, Judith Meyer, Fabrizio Minutolo, Elisabeth von der Esch, Bess B. Ward, Ulf Riebesell
摘要: . Upwelling of nutrient-rich deep waters make eastern boundary upwelling systems (EBUSs), such as the Humboldt Current system, hot spots of marine productivity. Associated settling of organic matter to depth and consecutive aerobic decomposition results in large subsurface water volumes being oxygen depleted. Under these circumstances, organic matter remineralisation can continue via denitrification, which represents a major loss pathway for bioavailable nitrogen. Additionally, anaerobic ammonium oxidation can remove significant amounts of nitrogen in these areas. Here we assess the interplay of suboxic water upwelling and nitrogen cycling in a manipulative offshore mesocosm experiment. Measured denitrification rates in incubations with water from the oxygen-depleted bottom layer of the mesocosms (via 15N label incubations) mostly ranged between 5.5 and 20 nmol N2 L−1 h−1 (interquartile range), reaching up to 80 nmol N2 L−1 h−1. However, actual in situ rates in the mesocosms, estimated via Michaelis–Menten kinetic scaling, did most likely not exceed 0.2–4.2 nmol N2 L−1 h−1 (interquartile range) due to substrate limitation. In the surrounding Pacific, measured denitrification rates were similar, although indications of substrate limitation were detected only once. In contrast, anammox (anaerobic ammonium oxidation) made only a minor contribution to the overall nitrogen loss when encountered in both the mesocosms and the Pacific Ocean. This was potentially related to organic matter C / N stoichiometry and/or process-specific oxygen and hydrogen sulfide sensitivities. Over the first 38 d of the experiment, total nitrogen loss calculated from in situ rates of denitrification and anammox was comparable to estimates from a full nitrogen budget in the mesocosms and ranged between ∼ 1 and 5.5 µmol N L−1. This represents up to ∼ 20 % of the initially bioavailable inorganic and organic nitrogen standing stocks. Interestingly, this loss is comparable to the total amount of particulate organic nitrogen that was exported into the sediment traps at the bottom of the mesocosms at about 20 m depth. Altogether, this suggests that a significant portion, if not the majority of nitrogen that could be exported to depth, is already lost, i.e. converted to N2 in a relatively shallow layer of the surface ocean, provided that there are oxygen-deficient conditions like those during coastal upwelling in our study. Published data for primary productivity and nitrogen loss in all EBUSs reinforce such conclusion.
93. 题目: Biochar and earthworms synergistically improve soil structure, microbial abundance, activities and pyraclostrobin degradation
期刊: Applied Soil Ecology
作者: Qingming Zhang, Sizhu Li, Muhammad Saleem, Muhammad Yasir Ali, Jiabaihui Xiang
摘要: As a widely used fungicide, the toxic impacts of pyraclostrobin on soil ecosystems have attracted extensive concern. Thus, it is very important and meaningful to develop effective strategies to alleviate its toxic effects. Therefore, in this study, we used corn straw-derived biochar produced at 500 °C as a soil amendment to study its effects on soil microbial populations, aggregation, enzymatic activities, and earthworm Eisenia fetida in pyraclostrobin-contaminated soil. Our results showed that biochar application (1%, w/w) significantly (Tukey test, p < 0.05) increased microbial abundance (culturable fungi, bacteria, actinomycetes), enzyme activities (urease, invertase, and dehydrogenase), and the formation of soil macroaggregates (>0.25 mm). Moreover, biochar application eliminated the toxic effects of pyraclostrobin on soil microorganisms and reduced oxidative stress and DNA damage in E. fetida by increasing the dissipation of pyraclostrobin in soil. We also found that biochar and earthworms synergistically improved the soil structure and degradation of pyraclostrobin, thus indicating that the combined application of biochar and earthworms is a better strategy to improve soil physical structure, biological properties, and health. Finally, we conclude that increasing the soil food web and physical complexity by adding biochar and earthworms may improve soil health stressed by xenobiotic pollutants.
94. 题目: The chemical-microbial release and transformation of arsenic induced by citric acid in paddy soil
期刊: Journal of Hazardous Materials
作者: Lin Liu, Yu-Ping Yang, Gui-Lan Duan, Jun Wang, Xian-Jin Tang, Yong-Guan Zhu
摘要: Citric acid (CA) is the major exudate of rice roots, yet the effects of CA on arsenic (As) transformation and microbial community in flooded paddy soil have not been clearly elucidated. In this study, microcosms were established by amending CA to As contaminated paddy soils, mimicking the rhizosphere environment. Results showed that 0.5% CA addition significantly enhanced As mobilization after one-hour incubation, increased total As in porewater by about 20-fold. CA addition induced arsenate release into porewater, and subsequently formed ternary complex of As, iron and organic matters, inhibiting further As transformation (including arsenate reduction and arsenite methylation). Furthermore, the results of linear discriminant analysis (LDA) effect size (LEfSe) and network analysis revealed that CA addition significantly enriched bacteria associated with arsenic and iron reductions, such as Clostridium (up to 35-fold) and Desulfitobacterium (up to 4-fold). Our results suggest that CA exhibits robust ability to mobilize As through both chemical and microbial processes, increasing the risk of As accumulation by rice. This study sheds light on our understanding of As mobilization and transformation in rhizosphere soil, potentially providing effective strategies to restrict As accumulation in food crops by screening or cultivating varieties with low CA exuding.
95. 题目: Terrestrial lipid biomarkers in marine aerosols over the western North Pacific during 1990–1993 and 2006–2009
期刊: Science of The Total Environment
作者: Jing Chen, Kimitaka Kawamura, Wei Hu, Cong-Qiang Liu, Qiang Zhang, Pingqing Fu
摘要: Terrestrial lipid biomarkers are one of the key tracers in the studies of atmospheric aerosols. Here, we investigated such organic compounds in marine aerosols collected at Chichijima Island, the western North Pacific for two 4-year periods: 1990–1993 and 2006–2009. A homologous series of lipid biomarkers including C18–C37 n-alkanes, C9–C34 fatty acids, and C14–C35 fatty alcohols were determined by gas chromatography/mass spectrometry (GC/MS). The atmospheric levels of these tracers increased from 1990 to 1993 to 2006–2009. Their seasonal trends were clearly characterized by winter–spring maxima and summer–fall minima. The relative abundance of the high-molecular-weight (HMW) n-alkanes (C25–C37) and n-alcohols (C20–C35) in total HMW lipids peaked in winter and winter/fall, respectively, whereas those of HMW fatty acids (C20–C34) peaked in summer. Air-mass backward trajectory analyses suggest that the Asian continent, Southeast Asia including tropical regions, and the Central Pacific are the main source regions. The seasonal shift and distribution of the carbon preference index and average chain length for the HMW lipids were controlled by the changes in climatic factors and source regions. The higher abundance of terrestrial lipids during 2006–2009 than 1990–1993 indicates a higher emission from terrestrial plantation in the 2000s than in the early 1990s in upwind regions of East Asia. Furthermore, HMW lipid compounds exhibited much stronger positive correlations with levoglucosan, a biomass-burning tracer, during 2006–2009 than 1990–1993, suggesting that biomass-burning emissions contributed more significantly in this century.
96. 题目: Assessing effects of Ca2+ addition on membrane bioreactor performance and macro-floc sludge characteristics
期刊: Science of The Total Environment
作者: Lijie Zhou, Nan Dong, Biao Ye, Wei-Qin Zhuang, Siqing Xia
摘要: Calcium ions (Ca2+) can trigger coagulation-flocculation process to form macro-flocculated sludge (MFS). Thus, dosing Ca2+-containing reagents into membrane bioreactors (MBRs) is considered as a promising approach to mitigate membrane biofouling. However, a mechanistic understanding of Ca2+ addition to MBR performance remains elucidated, such as physicochemical characteristics of MFS and their functionality variations. Consequently, this study was sought to understand the interplays of Ca2+ addition and MBR performance with a focus on characterizing MFS in detail. Three parallel MBRs were amended with 82, 208 and 410 mg-Ca2+/L final concentrations. Particle size analyses revealed that MFS formation was overall enhanced by the Ca2+ addition and granular sludge with diameters of up to 900 μm was formed in the 410 mg-Ca2+/L scenario. We believed that cationic bridges facilitated by elevated Ca2+ concentrations in conjunction with coagulation-flocculation were primary mechanisms of the formation of large flocs. Moreover, significant portions of soluble proteins and polysaccharides were flocculated and precipitated by Ca2+, which demonstrated a negative correlation between extracellular polymeric substances (EPS) concentrations and the formation of MFS. Furthermore, the population abundancies of Thiotrichaceae, Sphingomonadales and Hyphomicrobiaceae decreased in the sludge with Ca2+ addition resulted in profound changes of the microbial communities in the MBRs. But MBR performance, such as chemical oxygen demand removal (over 90%), showed no variation during the MBR operation. On the contrary, total nitrogen removal was inhibited in the MBRs. It was because the enlarging MFS formed diffusion barriers to prevent organic component from entering into the sludge flocs to be consumed.
97. 题目: Soil carbon response to long‐term biosolids application
期刊: Journal of Environmental Quality
作者: Yocelyn B. Villa, Rebecca Ryals
摘要: A study was conducted in three agroecosystems in California (Sacramento, Solano, and Merced counties) that received biosolids applications for twenty-years. Management varied in application rates and frequencies, resulting in average cumulative amount of biosolids applied of 74 (Solano), 105 (Merced), and 359 (Sacramento) Mg biosolidsdry /ha., resulting in the addition of 26 (Solano), 36 (Merced), and 125 (Sacramento) Mg biosolids-C/ha. Measurements included SOC and total nitrogen (N) concentrations from 0–100 cm, and microbial biomass C (MBC) and N (MBN) from 0–30 cm in biosolids-amended and controls. Biosolids treatments had greater amounts of soil organic carbon (SOC) and total N at all sites, and microbial biomass C and N at Sacramento and Solano. Largest increases in SOC were at the site that received the lowest cumulative loading rate of biosolids (Solano), where SOC content to 100 cm was 50% greater in amended soils (p<0.001). Net changes in soil C stocks to 30 cm were 0.4±0.1 (Solano), -0.04 ± 0.1 (Merced), and 0.3±0.2 (Sacramento) Mg C ha–1 yr–1. These values change when considering deeper soil depths (0-100 cm) to 0.5±0.1 (Solano), 0.2 ±0.2(Merced), and 0.216 ±0.2 (Sacramento) Mg C ha–1 yr–1, reflecting differences in C stocks changes in surface and subsurface soils across sites. Rates of C storage per dry Mg of biosolids per year applied were 1±0.2 (Solano), 0.5±0.4 (Merced), and 0.04±0.1 (Sacramento). Our results suggests that local controls on soil C stabilization are more important than amendment application amount at predicting climate benefits, and that accounting for soil C changes below 30 cm can provide insight for sequestering C in agroecosystems.
98. 题目: Identifying the role of exogenous amino acids in catalyzing lignocellulosic biomass into humus during straw composting
期刊: Bioresource Technology
作者: Guangren Zheng, Chengguo Liu, Ze Deng, Zimin Wei, Yue Zhao, Haishi Qi, Xinyu Xie, Di Wu, Zhechao Zhang, Hongyan Yang
摘要: This study was aimed at exploring the mechanism of promoting humus formation by the addition of exogenous amino acids. Amino acids not only participated in the synthesis of humus directly as precursors, but also changed the functions of bacterial communities. The composition and diversity of bacterial community changed with the addition of amino acids. The ability of bacterial community to degrade lignocellulose was enhanced, which provided precursors for humus synthesis. The key bacteria for humus formation and organic matter transformation were identified using random forests. These bacteria showed growth advantage with the addition of amino acids. The results showed that exogenous amino acids tended to transform organic matter and synthesize humus. Variance partitioning analysis confirmed that the bacterial community was the driving force of humus synthesis. These results were further verified by the structural equation model. These findings provided new ideas and understanding for straw waste composting.
99. 题目: How humic acid and Tween80 improve the phenanthrene biodegradation efficiency: insight from cellular characteristics and quantitative proteomics
期刊: Journal of Hazardous Materials
作者: Lei Zhang, Minghui Wang, Haiyang Cui, Jie Qiao, Dongsheng Guo, Biao Wang, Xiujuan Li, He Huang
摘要: Polycyclic aromatic hydrocarbons (PAHs) are toxic and recalcitrant pollutants, with an urgent need for bioremediation. Systematic biodegradation studies show that surfactant-mediated bioremediation is still poorly understood. Here, we investigated a comprehensive cellular response pattern of the PAH degrading strain B. subtilis ZL09-26 to (non-)green surfactants at the cellular and proteomic levels. Eight characteristic cellular factor investigations and detailed quantitative proteomics analyses were performed to understand the highly enhanced phenanthrene (PHE) degradation efficiency (2.8- to 3-fold improvement) of ZL09-26 by humic acid (HA) or Tween80. The commonly upregulated pathway and proteins (Arginine generation, LacI-family transcriptional regulator, and Lactate dehydrogenase) and various metabolic pathways (such as phenanthrene degradation upstream pathway and central carbon metabolism) jointly govern the change of cellular behaviors and improvement of PHE transport, emulsification, and degradation in a network manner. The obtained molecular knowledge empowers engineers to expand the application of surfactants in the biodegradation of PAHs and other pollutants.
100. 题目: Pathways and mechanisms by which biochar application reduces nitrogen and phosphorus runoff losses from a rice agroecosystem
期刊: Science of The Total Environment
作者: Meihui Wang, Yuxi Fu, Yi Wang, Yong Li, Jianlin Shen, Xinliang Liu, Jinshui Wu
摘要: Biochar application has the potential to reduce nitrogen (N) and phosphorus (P) losses in agricultural runoff, but little is known about how and to what extent biochar is effective in rice agroecosystems. In this study, in a typical double-rice cropping system, N and P runoff losses and soil carbon (C), N, and P contents (soil CNP contents) were observed under three different biochar application rates (0, 24, and 48 t ha−1, which were defined as CK, LB, and HB, respectively) from 2017 to 2019. The results showed that the two-year averages of soil total organic C (TOC), total N (TSN), total P (TSP), available P (Olsen P), microbial biomass N (MBN), and microbial biomass P (MBP) contents were generally higher in the biochar treatments than in CK (P < 0.05). Specifically, the TSP, TOC, and MBN contents increased with the increasing biochar application rate, thus demonstrating the significant effects of biochar application on the paddy soil CNP contents and composition. The HB and LB treatments reduced the seasonal mean runoff flow-weighted total N (TN_wc) and total P (TP_wc) concentrations by 32.4% and 42.1%, respectively, compared to CK. Structural equation modeling (SEM) further revealed that the paths and mechanisms by which biochar reduced the TN_wc and TP_wc were different, depending on the different application rates. HB reduced the TN_wc mainly through the direct absorption of N, followed by the indirect inhibition of N mineralization, whereas LB decreased the TP_wc mainly through the strong P sorption capacity of the biochar. The direct effect of HB on the TN_wc was 1.58 times as strong as the indirect effect (path coefficients: −0.68 vs. 0.43, respectively), and the direct effect of LB on the TP_wc was 1.78 times as strong as the indirect effect (path coefficients: −0.89 vs. 0.50, respectively). Given the distinct pathways and mechanisms by which biochar reduced NP runoff losses, in practice, the biochar application rate should be optimized according to a targeted priority of reducing either N or P runoff losses in rice agroecosystems.