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22761. 题目: Sensitivity of soil organic matter to climate and fire in a desert grassland
文章编号: N20111005
期刊: Biogeochemistry
作者: Enqing Hou, Jennifer A. Rudgers, Scott L. Collins, Marcy E. Litvak, Carleton S. White, Douglas I. Moore, Yiqi Luo
更新时间: 2020-11-10
摘要: Drylands contain a third of the organic carbon stored in global soils; however, the long-term dynamics of soil organic carbon in drylands remain poorly understood relative to dynamics of the vegetation carbon pool. We examined long-term patterns in soil organic matter (SOM) against both climate and prescribed fire in a Chihuahuan Desert grassland in central New Mexico, USA. SOM concentration was estimated by loss-on-ignition from soils at 0–20 cm depth each spring and fall for 25 years (1989–2014) in unburned desert grassland and from 2003 to 2014 following a prescribed fire. SOM concentration did not have a long-term trend but fluctuated seasonally at both burned and unburned sites, ranging from a minimum of 0.9% to a maximum of 3.3%. SOM concentration declined nonlinearly in wet seasons and peaked in dry seasons. These long-term results contrast not only with the positive relationships between aboveground net primary production and precipitation for this region, but also with previous reports that wetter sites have more SOM across drylands globally, suggesting that space is not a good substitute for time in predicting dryland SOM dynamics. We suggest that declines in SOM in wet periods are caused by increased soil respiration, runoff, leaching, and/or soil erosion. In addition to tracking natural variability in climate, SOM concentration also decreased 14% following prescribed fire, a response that magnified over time and has persisted for nearly a decade due to the slow recovery of primary production. Our results document the surprisingly dynamic nature of soil organic matter and its high sensitivity to climate and fire in a dry grassland ecosystem characteristic of the southwestern USA.

22762. 题目: Widespread heterogeneity in staple crop mineral concentration in Uganda partially driven by soil characteristics
文章编号: N20111004
期刊: Environmental Geochemistry and Health
作者: Leah Em Bevis, Rachel Hestrin
更新时间: 2020-11-10
摘要: Calcium (Ca), iron (Fe), selenium (Se), and zinc (Zn) deficiencies are widespread in sub-Saharan Africa, with severe implications for human health. In Uganda, where the predominant diet depends heavily on plant-based staples, crop mineral concentration is an important component of dietary mineral intake. Studies assessing the risk of nutrient deficiency or the effectiveness of nutrient-focused interventions often estimate dietary mineral intake using food composition tables that are based on crops grown in developed countries. However, little is known about the actual nutritional content of crops grown in Uganda. Here, we document the Ca, Fe, Se, and Zn concentration of staple crops collected from Ugandan household farms. While median mineral concentrations were similar to those reported previously, variation in crop mineral concentration was high, particularly for Fe and Se. An ordinary least squares regression showed that some soil characteristics were correlated with crop mineral concentrations. Of these, soil pH was often positively associated with crop mineral concentration, while sand and organic carbon concentrations were negatively associated with several crop mineral concentrations. However, much of the variation in crop mineral content was not associated with the soil characteristics measured. Overall, our results suggest that extensive heterogeneity in staple crop mineral concentration in Uganda is likely due to a combination of edaphic characteristics and other variables. Because staple foods constitute a large portion of dietary mineral intake in Uganda and other developing countries, these results have implications for estimates of dietary mineral intake and the development of effective intervention strategies in such regions.

22763. 题目: Alkali lignin and sodium lignosulfonate additives promote the formation of humic substances during paper mill sludge composting
文章编号: N20111003
期刊: Bioresource Technology
作者: Weiwu Wang, Yi Hou, Wenfeng Huang, Xiaoming Liu, Ping Wen, Yueqiang Wang, Zhen Yu, Shungui Zhou
更新时间: 2020-11-10
摘要: Alkali lignin (AL) and sodium lignosulfonate (SLS) are by-products of the papermaking industry and could influence composting processes due to their rich aromatic structures. In this study, the roles of AL and SLS additives in the formation of humic substances (HS) during paper mill sludge composting were investigated. Results showed that HS content and degree of polymerization of the final products in AL (44.42 mg·g-1 and 0.70, respectively) and SLS (45.87 mg·g-1 and 1.14, respectively) treatments were appreciably higher than those of the control sample (34.36 mg·g-1 and 0.67). Excitation-emission matrix-parallel factor coupled with two-dimensional FT-IR correlation spectroscopy analysis suggested that AL and SLS additives could speed the transformation of quinone-like substances by increasing the amounts of low molecular weight lignin depolymerized products, which led to higher HS concentrations. This work provided a way of promoting HS formation and the comprehensive utilization of papermaking wastes.

22764. 题目: Interaction of metal oxide nanoparticles with microplastics: impact of weathering under riverine conditions
文章编号: N20111002
期刊: Water Research
作者: Nisha Singh, Nitin Khandelwal, Ekta Tiwari, Nabanita Naskar, Susanta Lahiri, Johannes Lützenkirchen, Gopala Krishna Darbha
更新时间: 2020-11-10
摘要: The ubiquitous distribution of microplastics (MPs) can lead to inevitable interactions with the toxic pollutants present in the environment including metal-oxide nanoparticles. This study investigates the interaction of CeO2 nanoparticles (CeNPs) on MPs generated from a disposable plastic container. Further, rough MPs (R-MPs), generated through mechanical abrasion of MPs with sand, were used to probe the impact of roughness. To understand the sorption kinetics and underlying interaction processes, batch experiments were carried out. The results distinctly indicate that CeNPs sorption occurred on MPs surfaces and was consistent with the pseudo-second order kinetics model. For pristine MPs, the sorption capacity was as high as 12.9 mg/g while for R-MPs kinetic equilibrium was achieved faster and an enhanced sorption capacity (13.4 mg/g) was identified. A rise in sorption with an increase in salinity was noted while pH and humic acid exhibited a negative correlation. The observed interactions were attributed to the aggregation profile and surface charge of CeNPs and MPs. Surprisingly, CeNPs also got loaded onto MPs in non-agitated and undisturbed conditions. The sorption process was influenced by the type of aqueous matrix and the sorption capacity at equilibrium followed the trend: distilled water> synthetic freshwater> river water. FTIR spectra, zeta potential, SEM imaging, and elemental mapping revealed electrostatic interaction as the dominant mechanism. This work contributes towards the knowledge gap on the environmental risk of MPs.

22765. 题目: Typhoon-induced increases in porewater nutrient concentrations and CO2 and CH4 emissions associated with salinity and carbon intrusion in a subtropical tidal wetland in China: A mesocosm study
文章编号: N20111001
期刊: Geoderma
作者: Chun Wang, Jordi Sardans, Chuan Tong, Josep Peñuelas, Weiqi Wang
更新时间: 2020-11-10
摘要: Typhoons can alter carbon cycling by increasing carbon inputs and by the oceanic water intrusion at low latitudes. Our understanding of how typhoons impacts C and N cycles by reflecting combine and separate effects of elevated salinity and carbon enrichment is poor. We conducted a mesocosm experiment simulating the effect of a salinity of 10‰ and dissolved organic carbon (DOC) enrichment of the surface water with acetate as DOC source on the dynamics of porewater nutrients and the emissions of carbonaceous greenhouse gases using plants and soil system from a Cyperus malaccensis freshwater wetland in the Min River estuary, southeastern China. The concentrations of NH4+-N and NO3−-N in porewater rose under elevated salinity but decreased with DOC enrichment, salinity and DOC in combination acted antagonistically such that there was no effect compared to the control. A 10‰ increase in salinity increased the cumulative CO2 emissions (+29%) and decreased the cumulative CH4 emissions (−61%) during the growing season. In response to DOC, The cumulative emissions of CO2 and CH4 increased by 79% and 84%, respectively. In response to the combined elevated salinity and DOC enrichment, the cumulative emissions of CO2 increased by 69% and cumulative methane emissions increased by 44%. Elevated salinity plus DOC enrichment decreased the activity of the N-cycling enzyme β-1,4-N-acetylglucosaminidase, but increased the activities of two C-cycling enzymes (β-1,4-glucosidase and 1,4-β-cellobiosidase) and the P-cycling enzyme acid phosphatase, indicating a higher demand for C and P relative to N. The combination of increased C as CO2 in all cases, increased CH4 only in the case of DOC addition, and rising inorganic N fluxes only in the case of salt suggeated that elevated salinity and DOC enrichment induced by typhoons may thus accelerate the release of C but have little influence on N release from tidal freshwater wetland ecosystems.

22766. 题目: Spatial abundance distribution of prokaryotes is associated with dissolved organic matter composition and ecosystem function
文章编号: N20110909
期刊: Limnology and Oceanography
作者: Richard LaBrie, Simon Bélanger, Ronald Benner, Roxane Maranger
更新时间: 2020-11-09
摘要: Diverse prokaryotic communities consume and transform a broad suite of molecules in the dissolved organic matter (DOM) pool, which controls major biogeochemical cycles. Despite methodological advancements that provide increasingly more detailed information on the diversity of both prokaryotic communities and DOM components, understanding how these two component parts are structured to influence ecosystem functioning remains a major challenge in microbial ecology. Using empirical data collected along a gradient of productivity in the Labrador Sea, we characterized relationships among DOM compounds, metabolic processing, and prokaryotic diversity by structuring prokaryotic communities using spatial abundance distribution (SpAD) modeling. We identified strong associations of different SpAD taxonomic groups with specific organic substrates as well as with metabolic rates. Amplicon sequence variants (ASVs) with more cosmopolitan distributions (i.e. normal‐like) such as Bacteroidia were related to fresher DOM substrates such as free and combined amino acids whereas rare ASVs (i.e. logistic) like δ‐proteobacteria were associated with complex forms of organic matter. In terms of ecosystem function, rates of respiration and production were most strongly predicted by the abundance of certain SpAD taxonomic groups. Given the importance and complexity of linking environmental conditions, prokaryotic community structure, and ecosystem function, we propose a framework to bridge the gap between prokaryotic diversity, microbial ecology, and biogeochemistry among methods and across scales. Our work suggests that SpAD modeling can be used as an intermediate step to link prokaryotic community structure to both finer DOM details and larger ecosystem scale processes.

22767. 题目: Organic matter composition and heterotrophic bacterial activity at declining summer sea ice in the central Arctic Ocean
文章编号: N20110908
期刊: Limnology and Oceanography
作者: Judith Piontek, Luisa Galgani, Eva‐Maria Nöthig, Ilka Peeken, Anja Engel
更新时间: 2020-11-09
摘要: The Arctic Ocean is highly susceptible to climate change as evidenced by rapid warming and the drastic loss of sea ice during summer. The consequences of these environmental changes for the microbial cycling of organic matter are largely unexplored. Here, we investigated the distribution and composition of dissolved organic matter (DOM) along with heterotrophic bacterial activity in seawater and sea ice of the Eurasian Basin at the time of the record ice minimum in 2012. Bacteria in seawater were highly responsive to fresh organic matter and remineralized on average 55% of primary production in the upper mixed layer. Correlation analysis showed that the accumulation of dissolved combined carbohydrates (DCCHO) and dissolved amino acids (DAA), two major components of fresh organic matter, was related to the drawdown of nitrate. Nitrate‐depleted surface waters at stations adjacent to the Laptev Sea showed about 25% higher concentrations of DAA than stations adjacent to the Barents Sea and in the central Arctic basin. Carbohydrate concentration was the best predictor of heterotrophic bacterial activity in sea ice. In contrast, variability in sea‐ice bacterial biomass was largely driven by differences in ice thickness. This decoupling of bacterial biomass and activity may mitigate the negative effects of biomass loss due to ice melting on heterotrophic bacterial functions. Overall, our results reveal that changes in DOM production and inventories induced by sea‐ice loss have a high potential to enhance the bacterial remineralization of organic matter in seawater and sea ice of the Arctic Ocean.

22768. 题目: Weak mineralization despite strong processing of dissolved organic matter in Eastern Arctic tundra ponds
文章编号: N20110907
期刊: Limnology and Oceanography
作者: Isabelle Laurion, Philippe Massicotte, Flora Mazoyer, Karita Negandhi, Natalie Mladenov
更新时间: 2020-11-09
摘要: Permafrost thawing mobilizes large quantities of organic carbon that was sequestered in Arctic regions over the last glacial cycle. Processes involved in the oxidation of this carbon need to be further assessed to estimate the fraction to be released into the atmosphere. Shallow tundra ponds are sites of active carbon turnover on the landscape and significant sources of greenhouse gases. Dissolved organic matter (DOM) leached from thawing peat into these ponds is exposed to sunlight, with the potential to accelerate its mineralization directly into CO2 or through the production of more labile molecules. We tested the catalytic effect of sunlight on DOM mineralization in tundra ponds formed on organic‐rich polygonal landscapes originating from syngenetic permafrost, including a pond exposed to active permafrost erosion. Microbial decay rates, measured as the loss of chromophoric DOM, were similar to photodecay rates (1%–3% d−1). Groups of fluorescing molecules were formed through microbial transformation or lost through photolysis at differing rates among studied ponds, with the erosive trough pond presenting a unique response suggesting the involvement of soil microbes. Despite the stimulation of microbial growth under sunlight and the dynamic response of DOM optical properties, the loss of dissolved organic carbon was not significant under any treatment. This suggests that microbial and photochemical mineralization of DOM was slow and potentially substrate‐limited during the dry period when ponds were sampled. The static nature of tundra ponds, with their long water retention time, may thus constrain hot moments when water moves and transports carbon on the landscape.

22769. 题目: Linking hydrology and dissolved organic matter characteristics in a subtropical wetland: a long‐term study of the Florida Everglades
文章编号: N20110906
期刊: Global Biogeochemical Cycles
作者: Peter Regier, Laurel Larsen, Kaelin Cawley, Rudolf Jaffé
更新时间: 2020-11-09
摘要: Dissolved organic matter (DOM) acts as an important biogeochemical component of aquatic ecosystems that controls nutrient cycling, influences water quality, and links terrestrial and oceanic carbon pools, yet long‐term studies of how changing environmental drivers alter its abundance and composition are rare. Using a ten‐year, spatially explicit dataset from Everglades National Park (ENP), a globally significant wetland, we investigated the relationships between DOM quality/quantity and hydrologic/climatic drivers along two contrasting marsh‐estuarine transects based on generalized linear modeling and a cumulative sums analysis. Analyses revealed distinct spatial, seasonal, and interannual patterns in variability of DOC and optical properties. Landscape‐scale seasonal patterns showed an enrichment in microbial‐like and protein‐like DOM during the dry season relative to the wet season. While some compositional constituents varied with the solar calendar, responsive to temperature and photoperiod, others varied with the hydrologic calendar. Independent water level and discharge effects indicated strong hydrologic control on DOM quality that differed between the two transects, evidencing differences in their connectivity to areas of high agricultural activity. Across all sites, a significant long‐term increasing trend in the fluorescence index was observed, associated with a positive correlation with precipitation and also potential changes in agricultural inputs, with other features associated with drought and hurricanes. Lastly, the cumulative sums analysis revealed differences between the two transects in the sensitivity of DOM composition to decreased water levels associated with 30‐year climate scenarios, with the less hydrologically dynamic transect exhibiting greater potential sensitivity.

22770. 题目: Estimation of Permafrost SOC Stock and Turnover Time Using a Land Surface Model with Vertical Heterogeneity of Permafrost Soils
文章编号: N20110905
期刊: Global Biogeochemical Cycles
作者: Shijie Shu, Atul K. Jain, Charles D. Koven, Umakant Mishra
更新时间: 2020-11-09
摘要: We developed vertically‐resolved soil biogeochemistry (carbon and nitrogen) module and implemented it into a land surface model, ISAM. The model captures the vertical heterogeneity of the Northern High Latitudes permafrost soil organic carbon (SOC). We also implemented Δ14C to estimate SOC turnover time, a critical determinant of SOC stocks, sequestration potential and the carbon cycle feedback under changing atmospheric CO2 concentration [CO2] and climate. ISAM accounted for the vertical movement of SOC caused by cryoturbation and its linkage to frost heaving process, oxygen availability, organo‐mineral interaction and, depth‐dependent environmental modifiers. After evaluating the model processes using the site and regional level heterotrophic respiration, SOC stocks and soil Δ14C profiles, the vertically‐resolved soil biogeochemistry version of the model (ISAM‐1D) estimated permafrost SOC turnover time of 1443 years, which is about three times more than the estimation based on the without vertically‐resolved version of ISAM (ISAM‐0D). ISAM‐1D simulated SOC stocks for permafrost regions was 319 PgC in the top 1 m soil depth by the 2000s, about 80% higher than the estimates based on ISAM‐0D. ISAM‐1D SOC stock and turnover time were compared well with the observations. However, the longer SOC turnover time preserves less SOC stocks due to the lower carbon use efficiency (CUE) for SOC than ISAM‐0D, thus respires more SOC than being transferred downward by cryoturbation. ISAM‐1D simulated reduced SOC sequestration (3.7 PgC) compared to ISAM‐0D (4.8 PgC) and published ESMs over 1860s‐2000s, due to weaker [CO2]‐carbon cycle and stronger climate‐carbon cycle feedbacks, highlighting the importance of the vertically heterogeneous soil for understanding the permafrost SOC sinks.

22771. 题目: Amplified Arctic Surface Warming and Sea Ice Loss Due to Phytoplankton and Colored Dissolved Material
文章编号: N20110904
期刊: Geophysical Research Letters
作者: Vasileios Pefanis, Svetlana N. Losa, Martin Losch, Markus A. Janout, Astrid Bracher
更新时间: 2020-11-09
摘要: Optically active water constituents attenuate solar radiation and hence affect the vertical distribution of energy in the upper ocean. To understand their implications, we operate an ocean biogeochemical model coupled to a general circulation model with sea ice. Incorporating the effect of phytoplankton and colored dissolved organic matter (CDOM) on light attenuation in the model increases the sea surface temperature in summer and decreases sea ice concentration in the Arctic Ocean. Locally, the sea ice season is reduced by up to one month. CDOM drives a significant part of these changes, suggesting that an increase of this material will amplify the observed Arctic surface warming through its direct thermal effect. Indirectly, changing advective processes in the Nordic Seas may further intensify this effect. Our results emphasize the phytoplankton and CDOM feedbacks on the Arctic ocean and sea ice system and underline the need to consider these effects in future modeling studies to enhance their plausibility.

22772. 题目: An Abrupt Aging of Dissolved Organic Carbon in Large Arctic Rivers
文章编号: N20110903
期刊: Geophysical Research Letters
作者: M. S. Schwab, R. G. Hilton, P. A. Raymond, N. Haghipour, E. Amos, S. E. Tank, R. M. Holmes, E. T. Tipper, T. I. Eglinton
更新时间: 2020-11-09
摘要: Permafrost thaw in Arctic watersheds threatens to mobilize hitherto sequestered carbon. We examine the radiocarbon activity (F14C) of dissolved organic carbon (DOC) in the northern Mackenzie River basin. From 2003‐2017, DOC‐F14C signatures (1.00 ± 0.04; n = 39) tracked atmospheric 14CO2, indicating export of modern carbon. This trend was interrupted in June 2018 by the widespread release of aged DOC (0.85 ± 0.16, n = 28) measured across three separate catchment areas. Increased nitrate concentrations in June 2018 lead us to attribute this pulse of 14C‐depleted DOC to mobilization of previously frozen soil organic matter. We propose export through lateral perennial thaw zones occurred at the base of the active layer weakened by preceding warm summer and winter seasons. Although we are not yet able to ascertain the broader significance of this anomalous mobilization event, it highlights the potential for rapid and large‐scale release of aged carbon from permafrost.

22773. 题目: Ensemble modelling, uncertainty and robust predictions of organic carbon in long‐term bare‐fallow soils
文章编号: N20110902
期刊: Global Change Biology
作者: Roberta Farina, Renata Sándor, Mohamed Abdalla, Jorge Álvaro‐Fuentes, Luca Bechini, Martin A. Bolinder, Lorenzo Brilli, Chenu Claire, Hugues Clivot, Massimiliano De Antoni Migliorati, Claudia Di Bene, Christopher D. Dorich, Fiona Ehrhardt, Fabien Ferchaud, Nuala Fitton, Rosa Francaviglia, Uwe Franko, Donna L. Giltrap, Brian B.Grant, Bertrand Guenet, Matthew T. Harrison, Miko U.F. Kirschbaum, Katrin Kuka, Liisa Kulmala, Jari Liski, Matthew J. McGrath, Elizabeth Meier, Lorenzo Menichetti, Fernando Moyano, Claas Nendel, Sylvie Recous, Nils Reibold, Anita Shepherd, Ward N. Smith, Pete Smith, Jean‐François Soussana, Tommaso Stella, Arezoo Taghizadeh‐Toosi, Elena Tsutskikh, Gianni Bellocchi
更新时间: 2020-11-09
摘要: Simulation models represent soil organic carbon (SOC) dynamics in global carbon (C) cycle scenarios to support climate‐change studies. It is imperative to increase confidence in long‐term predictions of SOC dynamics by reducing the uncertainty in model estimates. We evaluated SOC simulated from an ensemble of 26 process‐based C models by comparing simulations to experimental data from seven long‐term bare‐fallow (vegetation‐free) plots at six sites: Denmark (two sites), France, Russia, Sweden, the United Kingdom. The decay of SOC in these plots has been monitored for decades since the last inputs of plant material, providing the opportunity to test decomposition without the continuous input of new organic material. The models were run independently over multi‐year simulation periods (from 28 to 80 years) in a blind test with no calibration (Bln) and with three calibration scenarios, each providing different levels of information and/or allowing different levels of model fitting: a) calibrating decomposition parameters separately at each experimental site (Spe); b) using a generic, knowledge‐based, parameterisation applicable in the Central European region (Gen); and c) using a combination of both a) and b) strategies (Mix). We addressed uncertainties from different modelling approaches with or without spin‐up initialisation of SOC. Changes in the multi‐model median (MMM) of SOC were used as descriptors of the ensemble performance. On average across sites, Gen proved adequate in describing changes in SOC, with MMM equal to average SOC (and standard deviation) of 39.2 (±15.5) Mg C ha‐1 compared to the observed mean of 36.0 (±19.7) Mg C ha‐1 (last observed year), indicating sufficiently reliable SOC estimates. Moving to Mix (37.5±16.7 Mg C ha‐1) and Spe (36.8±19.8 Mg C ha‐1) provided only marginal gains in accuracy, but modellers would need to apply more knowledge and a greater calibration effort than in Gen, thereby limiting the wider applicability of models.

22774. 题目: Assessing the effects of harvesting with and without burning and vinasse application in sugarcane crops: Evaluation of soil fertility and phosphorus pools in different ethanol production systems
文章编号: N20110901
期刊: Agriculture, Ecosystems & Environment
作者: José de Souza Oliveira Filho, Otavio Augusto Queiroz dos Santos, Celeste Queiroz Rossi, Yan Vidal de Figueiredo Gomes Diniz, Hugo de Souza Fagundes, Luiz Alberto da Silva Rodrigues Pinto, Willian Pereira, Marcos Gervasio Pereira
更新时间: 2020-11-09
摘要: Ethanol is recognized worldwide as a clean and renewable energy source. In tropical and subtropical countries, it is produced from sugarcane (Saccharum officinarum). In this study, we investigated the effects of sugarcane management systems: a) burning of sugarcane for harvest for 37 years (SCB37); b) burning of sugarcane for 3 years after 5 years of fallow (SCB3); c) sugarcane field without burning for harvest for 3 years (SCWB), and d) burning for harvest with the application of vinasse for 3 years (SCV), on soil fertility and accumulation of organic and inorganic fractions of phosphorus (P) in sugarcane crops for bioenergy production in south-east Brazil. Soil samples were collected at depths of 0–5, 5–10, 10–20, and 20–40 cm between planting rows in each management system and submitted for evaluation of soil fertility and accumulation of P fractions via sequential fractionation. We observed that application of vinasse reduced the pH (3.7–4.2) and the availability of Ca2+, Mg2+, and K+ on the surface, associated with the increase in Al3+ content and potential acidity. However, its use increased the availability of K+ and inorganic P content of higher lability (extracted with NaHCO3) in the subsurface. The maintenance of straw on the surface promoted reductions in pH values and an increase in the potential acidity and was inefficient in the accumulation of organic and inorganic fractions of P, compared to the system with the application of vinasse. Overall, we observed that the moderately labile fraction (organic and inorganic) represented on average 60 % (higher participation) of the total P content of soil in the experimental areas and was more significant in the soil under vinasse application and less evident in the treatments without burning and in the 3-year burning. This fraction can represent an important reserve of P (legacy) for the crops, reducing the use of phosphate mineral fertilizers over the years. Our findings are important for the selection and implementation of efficient and sustainable sugarcane cultivation systems, with implications for the ethanol industry to meet the growing demand for renewable fuel in the world.

22775. 题目: Effects of tillage management on soil carbon decomposition and its relationship with soil chemistry properties in rice paddy fields
文章编号: N20110811
期刊: Journal of Environmental Management
作者: Jian-Ying Qi, Zhen-Huan Jing, Cong He, Qiu-Yue Liu, Xing Wang, Zheng-Rong Kan, Xin Zhao, Xiao-Ping Xiao, Hai-Lin Zhang
更新时间: 2020-11-08
摘要: Decreasing the soil organic carbon (SOC) decomposition is critical to improve the quality of the soil and mitigate atmospheric CO2 emissions. To improve the ability to protect the SOC by optimizing tillage management, this study investigated the laboratory-based SOC mineralization (decomposition) and soil chemical properties under different tillage practices, including no tillage with straw mulch (NTS), rotary tillage with straw incorporated (RTS), moldboard plow tillage with straw incorporated (CTS) and moldboard plow tillage with straw removal (CT). Soil samples of six sampling dates from April 2017 to October 2018 were incubated at 25 °C and 70% water holding capacity for 60 d. Repeated Variance Analyses were conducted to compare the means of different treatments. The results showed that the average cumulative SOC mineralization (Cm) at the 0–5 cm soil depth was 7.09 g CO2 kg−1 soil under NTS, which was higher (P < 0.05) than that of the other treatments. However, the C mineralizability at both the 0–5 and 5–10 cm soil depths were lower (P < 0.05) under the NTS (0.16 and 0.15 g CO2 g−1 SOC) compared with the CTS and CT. Non-microbial CO2 emissions (CO2 emissions in sterilized soil) contributed to the lower C mineralizability under NTS, due to the lower mineralizability (0.041–0.089 g CO2 g−1 SOC) of sterilized soil under this treatment. Furthermore, some of the abiotic factors (e.g., C/N ratio and SOC content) significantly correlated with the Cm and C mineralizability. These factors might be critical for the ability to protect SOC under NTS. In summary, conservation tillage is an optimal management due to its protection on SOC, and part of this protection appeared to have been contributed by the soil abiotic factors, which were formed by long-term tillage management.

22776. 题目: Utilizing eco-friendly kaolinite-biochar composite adsorbent for removal of ivermectin in aqueous media
文章编号: N20110810
期刊: Journal of Environmental Management
作者: Bamidele I. Olu-Owolabi, Paul N. Diagboya, Fanyana M. Mtunzi, Rolf-Alexander Düring
更新时间: 2020-11-08
摘要: Several emerging contaminants are currently used in an unregulated manner worldwide, resulting in their increasing stringent limits in water by regulatory bodies. Thus, more viable and cheap treatment technologies are required. Recently, synergistic combinations of low-cost adsorbents have shown huge potential for aqueous toxic metals adsorption in water treatment processes. However, there is dearth of data on their potential for emerging contaminant removal. Here, low-cost kaolinite (KAC) clay was synergistically combined with blended Carica papaya or pine cone seeds, and calcined to obtain composites of KAC-Carica papaya seeds (KPA) and KAC-pine cone seeds (KPC). These adsorbents were characterized and evaluated for ivermectin adsorption at varying operating times (15–1440 min), pH (3–11), concentration (100–600 μg/L), and temperature (19.5–39.5 °C), as well as testing adsorbents' reusability. The composites exhibited marked property differences including over 250% cation exchange capacity increases and ≥50% surface area decreases, but unchanged KAC clay primary lattice structure. Ivermectin adsorption data were explained using kinetics and adsorption isotherm models. The rate of adsorption on KAC decreased over time, while rates for KPA and KPC increased until equilibrium at 180 min; the presence of biomaterials in the composites conferred better ivermectin adsorption and retention under continuous agitation. The adsorbents exhibited dual adsorption peaks one each at the acidic and alkaline pH regions as solution pH changed from 3 to 11. The rate data fitted (≥0.9232) the homogeneous fractal Pseudo-Second Order (FPSO) better than any other kinetics model, as well as the Freundlich adsorption isotherm model (≥0.9887); these indicate complex interactions between ivermectin and the adsorption sites of both composites. Ambient temperature increase up to ≈30 °C caused higher ivermectin adsorption but beyond this temperature there was drastic drop in adsorption. The KPA and KPC adsorption capacities are 105.3 and 115.8 μg/g, respectively. The KPC was better at reducing ivermecitn in low-concentration solution (≈75 μg/L) to less than 5.0 μg/L compared with KPA with ≈20.0 μg/L. Though KPC showed better efficiency in adsorption capacity and lowering concentration in low-concentration solutions, KPA exhibited better reusability with 83.5 and 67.5% initial adsorption strengths remaining in the second and third adsorption cycles, respectively, compared to the 73.8 and 58.8% for the KPC. These results indicate that KPA and KPC composites have the economic potential for application in water treatment processes.

22777. 题目: Biochar facilitates rapid restoration of methanogenesis by enhancing direct interspecies electron transfer after high organic loading shock
文章编号: N20110809
期刊: Bioresource Technology
作者: Chen Wang, Yang Liu, Caiqin Wang, Bo Xing, Shaodong Zhu, Jinjing Huang, Xiangyang Xu, Liang Zhu
更新时间: 2020-11-08
摘要: This study evaluated the effectiveness of biochar addition against high organic loading shock (OLS) of 80 kg COD/m3/d in up-flow anaerobic sludge blanket (UASB) reactors (R1 with biochar; R2 without biochar). After OLS of 24 h, R2 suffered the irreversible acidification (pH of 5.42 ± 0.07) with low biogas production of 0.08 ± 0.01 m3/kg COD/d. In contrast, the biogas production in R1 restored rapidly to 0.33 ± 0.04 m3/kg COD/d, and effluent pH in R1 returned to 7.01 ± 0.22. With addition of biochar, potential direct interspecies electron transfer (DIET) partners, including volatile fatty acids (VFAs)-oxidizing bacteria (Bacteroidetes, Smithella, Desulfovibrio, Geobacter) and methanogens (Methanosaeta, Methanosarcina) were enriched in R1, which were conductive to maintain the balance of acidogenesis and methanogenesis. Moreover, the retention of Methanosaeta and Methanosarcina coupled with biochar maintained the structural stability of granular sludge in R1 under the pressure of OLS and VFAs, which guaranteed the stability of anaerobic system.

22778. 题目: Enhanced methane production and organic matter removal from tequila vinasses by anaerobic digestion assisted via bioelectrochemical power-to-gas
文章编号: N20110808
期刊: Bioresource Technology
作者: Edson Baltazar Estrada-Arriaga, Ma. Guadalupe Reynoso-Deloya, Rosa Angélica Guillén-Garcés, Axel Falcón-Rojas, Liliana García-Sánchez
更新时间: 2020-11-08
摘要: In this study, showed a strategy to generate methane and remove organic matter removal from tequila vinasses through of anaerobic digestion assisted via bioelectrochemical power to-gas. Specific methanogenic activity (SMA) assays in batch mode were tested and a single-stage bioelectrochemical upflow anaerobic sludge blanket reactor (UASB) was evaluated to generate methane during tequila vinasses treatment. The results showed that the methane production in the bioelectrochemical UASB reactor applied at low voltage of 0.5 V and under HRT of 7 d was higher than the in the conventional UASB reactor. The specific methane production rate in bioelectrochemical UASB reactor was up to 2.9 NL CH4/L d, with a maximum methane yield of 0.32 NL CH4/g CODremoved. Similar COD removals were observed in the bioelectrochemical UASB reactor and conventional reactors (92–93%). High carbon dioxide reduction and hydrogen production were observed in the bioelectrochemical UASB reactor.

22779. 题目: Characterisation of heteroatomic compounds in free and bound bitumen from different source rocks by ESI FT-ICR MS
文章编号: N20110807
期刊: Organic Geochemistry
作者: Bin Jiang, Yankuan Tian, Zheng Zhai, Zhao-Wen Zhan, Yuhong Liao, Yan-Rong Zou, Ping'an Peng
更新时间: 2020-11-08
摘要: Catalytic hydropyrolysis (HyPy) has been widely used in the study of covalently bonded biomarkers from macromolecular organic matter. Current HyPy studies mainly focus on nonpolar aliphatic biomarkers, whereas studies of polar non-volatile heteroatomic compounds are lacking. In this study, heteroatomic compounds in free and bound bitumen released via HyPy of kerogen from three different source rocks were characterised and compared by electrospray ionisation (ESI) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). These analyses suggest that heteroatomic compounds in bound bitumen are better proxies of the original biogenic sources and contain more aromatic structures than in heteroatomic compounds occurring in the free bitumen. From studies of three source rocks, we found that differences in the maturity, depositional environment, and diagenetic conditions seem to have significantly influenced the composition and distribution of heteroatomic compounds in free and bound bitumen. Nitrogen-containing compounds (N1 and N1OX species) in the free bitumen were mainly affected by maturity – only being detected in the rock of highest maturity – although they occurred in similar composition in the bound bitumen of all three rocks. With increasing maturity, nitrogen compounds were partitioned from bound to free bitumen, resulting in compositional differences between these two bitumen types (especially for basic nitrogen compounds). Sulfur-containing compounds (mainly S1, OXS1, and OXS2 species) were mainly influenced by the depositional environment and were abundant in the two rocks from a reducing depositional environment. Their composition was more complex and less saturated in bound bitumen. Oxygen compounds were common to all three rocks, but of highest abundance in the one source rock deposited in a freshwater environment.

22780. 题目: Lipid biomarker estimates of seasonal variations of aerosol organic carbon sources in coastal Qingdao, China
文章编号: N20110806
期刊: Organic Geochemistry
作者: Qu Chen, Zhigang Guo, Meng Yu, Julian P. Sachs, Pengfei Hou, Li Li, Gui'e Jin, Yueying Liu, Meixun Zhao
更新时间: 2020-11-08
摘要: Aerosols represent a significant source of organic carbon (OC) to China's marginal seas, but their provenance and chemical composition remain understudied. At the boundary of the East Asian continent and China's marginal seas, the coastal city of Qingdao is well-situated to study the sources and seasonal variations of organic aerosols and their contribution to marginal seas. Twenty-nine aerosol samples collected in 2015–2016 were analyzed for total OC (TOC), n-alkanes (C17–C33), n-alkanols (C20–C32) and n-fatty acids (n-FAs, C14–C32). Concentrations of TOC (5.7–18 μg/m3), n-alkanes (17.5–143 ng/m3), n-alkanols (18–41 ng/m3) and n-FAs (99.3–160 ng/m3) were highest in winter when total aerosol concentrations were highest. Organic carbon-normalized (OC-normalized) biomarker concentrations were used to apportion different sources of aerosol OC: short- and mid-chain n-alkanes (< C26) for fossil fuel residues; long-chain n-alkanes (≥ C26), mid- and long-chain n-alkanols (≥ C20) and mid- and long-chain n-FAs (≥ C20) for terrestrial plant OC; short-chain n-FAs (< C20) for marine OC. From these we inferred higher fossil fuel OC contributions during cold seasons when aerosols were mainly transported to Qingdao by continental air masses, higher terrestrial plant OC contributions during warm seasons when terrestrial plant productivity was at its peak, and higher marine OC contributions in warm seasons when marine air masses were transported to Qingdao. Comparing these results with those from other continental and marine locations demonstrates the utility of this biomarker approach in providing semi-quantitative estimates of temporal and spatial variations in the sources of organic aerosols at the land-sea interface of marginal seas, where carbon burial rates tend to be high.