论文检索

主页 | efc软件 | 课题库 | 公众号
:



总访问量:362613

总访客量:20380

关键词:
Organic Matter |
DOM |
POM |
Soil OM |
Sediment OM |
Organic Carbon |
Organic Nitrogen |
Biomarker |
Humic Substances |
Fulvic Substances |
Humins |
Biochar |
Black Carbon |
GDGT |
Lignin |
Free Radical |
...
最新文章  | 
昨日文章 | 
前日文章
期刊:
Agriculture, Ecosystems & Environment |
Agricultural Water Management |
Applied Geochemistry |
Applied Soil Ecology |
Aquatic Geochemistry |
Atmospheric Research |
Biogeochemistry |
Biogeosciences |
Biology and Fertility of Soils |
Bioresource Technology |
CATENA |
Chemical Engineering Journal |
Chemical Geology |
Chemosphere |
CLEAN - Soil, Air, Water |
Colloids and Surfaces A: Physicochemical and Engineering Aspects |
Deep Sea Research Part II: Topical Studies in Oceanography |
Earth-Science Reviews |
Ecological Engineering |
Ecology Letters |
Ecology |
Ecotoxicology and Environmental Safety |
Environment International |
Environmental Earth Sciences |
Environmental Geochemistry and Health |
Environmental Monitoring and Assessment |
Environmental Pollution |
Environmental Research |
Environmental Science & Technology |
Environmental Science and Pollution Research |
Environmental Science: Processes Impacts |
Environmental Science: Water Research & Technology |
Environmental Toxicology and Chemistry |
Estuarine, Coastal and Shelf Science |
European Journal of Soil Science |
Forest Ecology and Management |
Geochimica et Cosmochimica Acta |
Geoderma |
Geophysical Research Letters |
Global Change Biology |
Global Biogeochemical Cycles |
Groundwater |
Harmful Algae |
International Journal of Coal Geology |
Journal of Environmental Chemical Engineering |
Journal of Environmental Management |
Journal of Environmental Sciences |
Journal of Geophysical Research: Biogeosciences |
Journal of Geophysical Research: Oceans |
Journal of Hazardous Materials |
Journal of Membrane Science |
Journal of Soils and Sediments |
Land Degradation & Development |
Limnology and Oceanography |
Marine Chemistry |
Marine Pollution Bulletin |
Nature Communications |
Nature Geoscience |
Ocean Science Journal |
Oikos |
Organic Geochemistry |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Plant and Soil |
Progress in Oceanography |
Quaternary International |
Science of The Total Environment |
Sedimentary Geology |
Separation and Purification Technology |
Soil and Tillage Research |
Soil Biology and Biochemistry |
Waste Management |
Water Research |
Water, Air, & Soil Pollution |
Wetlands |
...

所有论文

161. 题目: Temporal dynamics of litter quality, soil properties and microbial strategies as main drivers of the priming effect
文章编号: N20071812
期刊: Geoderma
作者: Nicolas Fanin, Gonzague Alavoine, Isabelle Bertrand
更新时间: 2020-07-18
摘要:

The priming effect describes the change in the rate of soil organic matter (SOM) mineralisation due to the addition of fresh organic matter (FOM), and is thus central to the evaluation of carbon fluxes in terrestrial ecosystems. However, little is known about how litter quality interact with soil properties and microbial communities to explain the priming effect. Here, we provide new empirical evidence showing how litter, soil and microbial parameters control FOM and SOM decomposition. We monitored the kinetics of carbon fluxes over 202 days and at 23 dates after additions of two 13C-labelled plant litters of contrasted quality (nutrient-rich and labile litter [i.e., high quality] vs nutrient-poor and recalcitrant litter [i.e., low quality]) using four soil types originating from different ecosystems (forest, grassland, cropland and plantation). We found that the priming effect varied over time with: (i) an 'immediate' priming effect after the addition of high quality litter, which rapidly decreases when nitrogen is available; and (ii) a 'delayed' priming effect after the addition of low quality litter, which increases continuously when nitrogen is depleted. The 'immediate' priming was mainly related to the decomposition of accessible carbon compounds, whereas the 'delayed priming' was mainly related to the decomposition of recalcitrant carbon compounds. These results were linked to changes in microbial resource acquisition strategies as indicated by shifts in enzyme activities from hydrolytic to oxidative and nitrogen-related enzymes, therefore suggesting that two series of mechanisms act in succession at different time scales in relation to litter quality and nitrogen availability. Furthermore, our data demonstrate that incorporating carbon in the soil via the increase in soil microbial biomass can counterbalance carbon losses via priming effect. This highlights the importance to assess the balance between the carbon outputs and inputs to determine whether terrestrial ecosystems act as a sink or a source of carbon. We conclude that shifts in litter quality, nutrient availability and microbial resource acquisition strategies need to be taken into consideration for accurate assessment of the variability of the priming effect from the short to the long term.

162. 题目: Insight into the improvement of dewatering performance of waste activated sludge and the corresponding mechanism by biochar-activated persulfate oxidation
文章编号: N20071811
期刊: Science of the Total Environment
作者: Junyuan Guo, Xiaojuan Jia, Qifan Gao
更新时间: 2020-07-18
摘要:

A novel activator, corn biochar, was produced to activate persulfate to dewater waste activated sludge (WAS). Results demonstrated that the biochar-activated persulfate oxidation can effectively improve the dewatering performance of WAS. After treating WAS by biochar-activated persulfate oxidation (biochar dosage: 2.1 g/L, persulfate concentration: 7.5 mM) at the original WAS pH, standardized-capillary suction time (SCST) increased to 4.21 times and moisture content (MC) decreased to 43.4%, indicating an excellent performance of WAS dewatering. The decrease of residual persulfate with the increasing biochar dosage during WAS dewatering process illustrated that the role of persulfate in improving WAS dewatering was because of the biochar activation. The behaviors of extracellular polymers (EPS) proved that the protein in tightly bound EPS (TB-EPS) linked to WAS dewatering, and its content significantly reduced to 10.5 mg/g-volatile solids (VS) after WAS treatment. Three-dimensional fluorescence spectroscopy for EPS once again proved that the disintegration of tryptophan protein and humic acid (hydrophobic organic substances in EPS) was responsible for the improvement of WAS dewatering. To sum up, the biochar-activated persulfate oxidation was a feasible application in improving WAS dewatering.

163. 题目: Responses of phytoremediation in urban wastewater with water hyacinths to extreme precipitation
文章编号: N20071810
期刊: Journal of Environmental Management
作者: Hongjie Qin, Muhe Diao, Zhiyong Zhang, Petra M. Visser, Yingying Zhang, Yan Wang, Shaohua Yan
更新时间: 2020-07-18
摘要:

Climate change not only intensifies eutrophication and enhances the rainfall, but also elevates the contents of greenhouse gases, which can further increase the intensity and frequency of extreme precipitation events. The effectivity of phytoremediation of urban wastewaters by water hyacinths under an extreme rainfall event (up to 380 mm d−1) was investigated using self-designed fabrications with six flow rates (2–15 m3 d−1) in situ on pilot scale for 30 days. The results suggest that water hyacinths had high N and P removal capacities even under adverse conditions such as low dissolved oxygen concentrations (DO, <1 mg L−1) and high ammonium concentrations (NH4+-N, >7 mg L−1). Specifically, the highest removal yields of N and P were 13.14 ± 0.47 g N·m−2·d−1 and 2.12 ± 0.04 g P·m−2·d−1, respectively. The results indicate that water hyacinths can be used for water treatment to reduce the amounts of NH4+-N, dissolved organic nitrogen (DON) and phosphate (PO43−) even during extreme precipitation events. Moreover, DO increased due to wet deposition, runoff and surface flows during the extreme rainfall event, resulting in shifts between nitrification and denitrification processes which significantly altered nitrogen forms in urban wastewater. Results of this study suggest that water hyacinths could be recommended as a cost-effective and eco-friendly technology for urban wastewater phytoremediation in areas suffering from frequent extreme precipitation events.

164. 题目: Phosphorus binding to soil organic matter via ternary complexes with calcium
文章编号: N20071809
期刊: Chemosphere
作者: Yuki Audette, D. Scott Smith, Christopher T. Parsons, Weibin Chen, Fereidoun Rezanezhad, Philippe Van Cappellen
更新时间: 2020-07-18
摘要:

Soil organic matter (SOM) is known to exert a major control on the mobility and bioavailability of cationic nutrients. However, the role of SOM in the fate of anionic nutrients, especially phosphorus (P), is less well characterized. The objectives of this study were to (1) compare the formation of binary complexes of calcium (Ca) with humic acids (HA) extracted from two contrasting soils, and (2) determine if binary HA-Ca complexes could incorporate P by forming ternary HA-Ca-P complexes. The Ca binding capacities of the HA extracted from an agricultural organic soil (AOS) and a pristine riparian soil (RS) were measured via potentiometric titrations; the formation of ternary complexes was analyzed by size fractionation using MWCO tubes. Proton and Ca binding capacities of RS-HA were higher than AOS-HA, and pH had a weaker effect on Ca binding to RS-HA. These differences are consistent with lower proportions of aromatic groups, and a higher proportion of alkyl groups derived from 13C NMR spectroscopy. Together, the NMR, titration and MWCO data indicate that Ca binds to RS-HA through monodentate complexes and electrostatic attraction that are capable of binding P producing ternary complexes. In contrast, at pH 8.5 Ca forms bidentate complexes with AOS-HA, which do not provide bridging positions to incorporate P. Overall, our results imply that the formation of HA-Ca and HA-Ca-P complexes depend on the structure of the HA, and that complexation to HA may play an important role in the fate of P in terrestrial and aquatic environments.

165. 题目: Effects of organic matter components and incubation on the cement-based stabilization/solidification characteristics of lead-contaminated soil
文章编号: N20071808
期刊: Chemosphere
作者: Shangqi Ge, Yize Pan, Lingwei Zheng, Xinyu Xie
更新时间: 2020-07-18
摘要:

Stabilization/solidification (S/S) has been studied since 1950s and widely used for the treatment of potentially toxic elements (PTEs). The coexistence of organic matter (OM) and PTEs can cause a very complicated mechanism for cement-based S/S applications and bring challenges from both scientific and engineering perspectives. To fill in the knowledge gap, this paper investigates for the first time the effects on S/S characteristics of OM components and incubation, which are the two main factors that result in the inconsistency in the leaching characteristics from the available studies. OM samples with different components (humic acid (HA) and fulvic acid (FA)) and contents were mixed into lead-contaminated soil and incubated for different durations of up to 90 days. The experimental results show that the strength of stabilized soils increases with increasing incubation duration and the lead leaching concentration of stabilized soils is decreased by 60.7%–83.6% from zero to 90 days. The lead leaching concentration of the HA group, which is 144.0% higher with no incubation than the non-OM group, becomes 58.3% lower with 90 days of incubation. The leaching concentration of the FA group remains much higher than those of the other groups. Finally, a competing mechanism of HA—weakening cement hydration reactions and stabilizing lead with a critical incubation duration of 14 days—is proposed, together with a cooperating mechanism of FA—weakening cement hydration reactions and releasing lead.

166. 题目: Enhanced electrochemical degradation of 2,4-dichlorophenol with the assist of hydrochar
文章编号: N20071807
期刊: Chemosphere
作者: Weiming Cao, Chaju Zeng, Xiaofei Guo, Qiang Liu, Xiaolei Zhang, Naresh Mameda
更新时间: 2020-07-18
摘要:

Effective treatment of 2,4-dichlorophenol (2,4-DCP) in wastewater is essential, as it could pose great threat to the environment. A hydrothermal biochar (hydrochar) was used to assist the electrochemical oxidation treatment of 2,4-DCP. The removal of 2,4-DCP using hydrochar in anode and cathode area with and without proton exchange membrane (PEM) under 3–9 V of electrolysis was investigated. Enhanced 2,4-DCP degradation in the anode area was achieved compared with the adsorption or electrolysis alone. The highest 2,4-DCP removal (∼76%) was obtained using the hydrochar in the anode area with PEM under 9 V. The mechanism for the 2,4-DCP removal during the electrolysis included adsorption by hydrochar and electrochemical degradation by the reactive oxygen species (ROS) generated by the electrode as well as the persistent free radicals (PFR) on hydrochar. The OH produced from anode was the predominant ROS contributing to the 2,4-DCP degradation under 9 V of electrolysis.

167. 题目: Use of Brassica juncea and Dactylis glomerata for the phytostabilization of mine soils amended with compost or biochar
文章编号: N20071806
期刊: Chemosphere
作者: Donato Visconti, Ma José Álvarez-Robles, Nunzio Fiorentino, Massimo Fagnano, Rafael Clemente
更新时间: 2020-07-18
摘要:

Phytostabilization of mine soils contaminated by potentially toxic elements (PTEs) requires plants tolerant to PTE toxicity and to the poor soil physico-chemical characteristics of these areas. A pot experiment was carried out to assess the phytostabilization potential of Brassica juncea and Dactylis glomerata in mine soils amended with compost and biochar. Furthermore, the Environmental Risk of the soils and the effects of the phytostabilization process on the microbiological population size and activity in the soils were also determined. According to the Ecological Risk Index (ERI) the soils studied presented very high risk and As, Cd and Pb were the target elements for phytostabilization. Both amendments improved soil conditions (e.g., increasing total-N and total organic-C concentrations) and contributed to PTE (Cd, Pb and Zn) immobilization in the soil. Compost showed a more marked effect on soil microbial biomass and nutrients release in soil, which led to higher B. juncea and D. glomerata biomass in compost treated soils. Biochar treatment showed a positive effect only on D. glomerata growth, despite it provoked strong PTE immobilization in both soils. The addition of both amendments resulted in an overall reduction of PTE concentration in the plants compared to the control treatment. In addition, both plant species showed higher accumulation of PTE in the roots than in the shoots (transfer factor<1) independently of the treatment received. Therefore, they can be considered as good candidates for the phytostabilization of PTE contaminated mine soils in combination with organic amendments like biochar and compost.

168. 题目: Effect of Natural Organic Matter on the Fate of Cadmium During Microbial Ferrihydrite Reduction
文章编号: N20071805
期刊: Environmental Science & Technology
作者: Zhe Zhou, E. Marie Muehe, Elizabeth J. Tomaszewski, Juan Lezama-Pacheco, Andreas Kappler, James M. Byrne
更新时间: 2020-07-18
摘要: Natural organic matter (NOM) is known to affect the microbial reduction and transformation of ferrihydrite, but its implication toward cadmium (Cd) associated with ferrihydrite is not well-known. Here, we investigated how Cd is redistributed when ferrihydrite undergoes microbial reduction in the presence of NOM. Incubation with Geobacter sulfurreducens showed that both the rate and the extent of reduction of Cd-loaded ferrihydrite were enhanced by increasing concentrations of NOM (i.e., C/Fe ratio). Without NOM, only 3–4% of Fe(III) was reduced, but around 61% of preadsorbed Cd was released into solution due to ferrihydrite transformation to lepidocrocite. At high C/Fe ratio (1.6), more than 35% of Fe(III) was reduced, as NOM can facilitate bioreduction by working as an electron shuttle and decreased aggregate size, but only a negligible amount of Cd was released into solution, thus decreasing Cd toxicity and prolonging microbial Fe(III) reduction. No ferrihydrite transformation was observed at high C/Fe ratios using Mössbauer spectroscopy and X-ray diffraction, and X-ray absorption spectroscopy indicated the proportion of Cd-OM bond increased after microbial reduction. This study shows that the presence of NOM leads to less mobilization of Cd under reducing condition possibly by inhibiting ferrihydrite transformation and recapturing Cd through Cd-OM bond.

169. 题目: Optical characteristics of colored dissolved organic matter during blooms of Trichodesmium in the coastal waters off Goa
文章编号: N20071804
期刊: Environmental Monitoring and Assessment
作者: Siby Kurian
更新时间: 2020-07-18
摘要: Trichodesmium, a marine cyanobacterium, plays a significant role in the global nitrogen cycle due to its nitrogen fixing ability. Large patches of Trichodesmium blooms were observed in the coastal waters, off Goa during spring intermonsoon (SIM) of 2014–2018. Zeaxanthin was the dominant pigment in the bloom region. Here, we present the spectral absorption and fluorescence characteristics of colored dissolved organic matter (CDOM) during these blooms. CDOM concentration was much higher in the bloom patches as compared with nonbloom regions. During the bloom spectral CDOM absorption had distinct peaks in the UV region due to the presence of UV-absorbing/screening compounds, mycosporine-like amino acids (MAAs) and in the visible region due to phycobiliproteins (PBPs). The spectral fluorescence signatures by the traditional peak picking method exhibited three peaks, one was protein-like, and the other two were humic-like. Apart from these, Trichodesmium exhibited strong protein-like fluorescence with 370/460 nm (Ex/Em), which is a signature of cyanobacteria. A parallel factor analysis (PARAFAC) on the fluorescence excitation-emission matrix (EEM) of Trichodesmium dataset fitted a 3-component model of which one was protein-like, and two were humic-like. The fluorescence index (FI) values during Trichodesmium bloom was very high (~ 3) compared with the typical range of 1.2–1.8 observed for the natural waters. Bloom degradation experiments proved that increase in tryptophan fluorescence enhances the CDOM absorption. Our study indicates that Trichodesmium blooms provide a rich source of organic matter in the coastal waters and long-term monitoring of these blooms is essential for understanding the health of ecosystem.

170. 题目: Saturated permeability behavior of biochar-amended clay
文章编号: N20071803
期刊: Journal of Soils and Sediments
作者: Wen-Jing Sun, Ming-Yu Li, Wen-Jie Zhang, Yun-Zhi Tan
更新时间: 2020-07-18
摘要: Purpose Biochar has the characteristics of loose porosity, high specific surface area, and strong adsorption properties. Recently, the compacted biochar amended clay has been proposed as a sustainable alternative material for the final cover of landfills. However, the effect of biochar on saturated hydraulic conductivity (ksat) is not yet conclusive. The objective of this study was to determine the influence of biochar content on the permeability of biochar-clay mixed soils. Materials and methods The clay used in the study belongs to the low liquid limit clay. The biochar is produced by heating the rice straw under an oxygen-deficient condition at a temperature of 500 °C. To study the effect of biochar content on the permeability of biochar-clay mixed soils, the biochar-clay mixed soils with the mass percentage of biochar being 0%, 5%, 10%, 15%, and 20% were used. The saturated hydraulic conductivity of the biochar-clay mixed soils was measured by the head pressure control permeameter. Meanwhile, the micro-pore structure of the saturated biochar-clay mixed soils was obtained by the nuclear magnetic resonance (NMR) technique. Results and discussion It can be observed that the saturated hydraulic conductivity ksat of biochar-clay mixed soils increases linearly as the biochar content increases. The NMR results show that the T2 distribution curve of pure clay is a unimodal pattern, while the T2 distribution curve of biochar-clay mixed soils presents the bimodal pattern, where T2 is the transverse relaxation time, reflecting the pore size of the soil specimens. With the increase of biochar content, the T2 spectrum of the mixed soils moves slightly to the right, and T2 at main peak increases gradually, correspondingly the most probable pore size of biochar-clay mixed soils increases. Conclusions The pore size distribution of the soil was changed by the addition of biochar and subsequently affects the permeability of biochar-clay mixed soils. This study provides some useful suggestions for optimizing the pore structure of the biochar amended clay anti-seepage layer in the final cover of landfills. Introduction

171. 题目: Characteristics and significance of dissolved organic matter in river sediments of extremely water-deficient basins: a Beiyun River case study
文章编号: N20071802
期刊: Journal of Cleaner Production
作者: Li Zhang, Han Liu, Yongzhen Peng, Yanan Zhang, Qingxuan Sun
更新时间: 2020-07-18
摘要:

The characteristics of dissolved organic matter in river sediments, affected by microorganisms, are of great significance to water management strategies. Based on three-dimensional excitation and emission matrix fluorescence, ultraviolet-visible spectroscopy, and high-throughput sequencing technology, this study jointly analyzed the composition and transformation mechanisms of dissolved organic matter as well as the microbial community structure in sediments of the Beiyun River, the main river within a basin with extreme water shortages. Moreover, we evaluated N and P contents in sediments to identify parameters to reflect potential eutrophication risks. Our results demonstrated that the content of dissolved organic matter in sediments was between 30.2 and 49.9 g/kg in the Tongzhou area of the Beiyun River. Humic substances were the largest components of dissolved organic matter in the sediments, followed by protein-like substances and soluble microbial byproducts. Furthermore, the proportion of humic matter decreased from upstream to downstream. The proportion of carbonyl, carboxyl, hydroxyl, and ester substituents on the aromatic structures of dissolved organic matter was significantly higher in the upstream, whereas the proportion of substances with aliphatic chain substituents on their aromatic structures was relatively low. The variation in downstream sediment microbial communities was much greater than that in the upstream (analyzed at the phylum level). Proteobacteria was the most abundant phylum (47.97%), which was closely related to the aromaticity of the dissolved organic matter in sediments. The N and P contents in the sediments of the Beiyun River were high and exhibited active transformation. The maximum fluorescence intensity of fulvic-acid-like components in the sediments [Fmax(C4)] can indirectly reflect the potential risk of eutrophication in the Beiyun River. Therefore, our results provide a theoretical basis for the assessment of water quality and pollution control in the Beiyun River and other water-deficient regions worldwide.

172. 题目: Catalytic co-pyrolysis of sewage sludge and rice husk over biochar catalyst: Bio-oil upgrading and catalytic mechanism
文章编号: N20071801
期刊: Waste Management
作者: Zhenzi Qiu, Yunbo Zhai, Shanhong Li, Xiangmin Liu, Xiaoping Liu, Bei Wang, Yali Liu, Caiting Li, Yanjun Hu
更新时间: 2020-07-18
摘要:

In this study, the effects of different biochar catalysts on the quality of bio-oil derived from the co-pyrolysis of sewage sludge (SS) and rice husk (RH) are explored. Catalysts include SS biochar (SWC), RH biochar (RHC), mixed SS and RH biochar (SRC), and RH ash (RHA). The quality of bio-oil was evaluated based on the results of gas chromatography-mass spectrometry (GC–MS; including the contents of hydrocarbons and N-species), oxygen content, higher heating value, and pH. The GC–MS analysis results illustrated that N-species content in the bio-oil reduced with the addition of the biochar catalyst, while the hydrocarbons content increased from 15.51% for co-pyrolysis to 38.74–61.84% for different biochar catalysts at a catalytic temperature of 650 °C. RHC exhibited the best catalytic effect in terms of decreasing the content of N-species by 58.79% and increasing the content of hydrocarbons by nearly four times compared to co-pyrolysis. The higher heating value of bio-oil raised from 25.75 to 34.67 MJ/kg, while oxygen content decreased from 31.1 to 8.81 wt%, and the pH increased from 4.06 to 5.48. Moreover, the catalytic mechanism of catalytic co-pyrolysis over RHC, including the hydrocarbon generation pathway and nitrogen removal, is also discussed here. High specific surface area of RHC provides sufficient active sites (e.g. O-containing and N-containing functional groups) for the catalytic reaction of pyrolytic intermediates.

173. 题目: Comparing optical versus chromatographic descriptors of dissolved organic matter (DOM) for tracking the non-point sources in rural watersheds
文章编号: N20071709
期刊: Ecological Indicators
作者: Mi-Hee Lee, Seung Yoon Lee, Ha-Young Yoo, Kyung-Hoon Shin, Jin Hur
更新时间: 2020-07-17
摘要:

Identification of the major dissolved organic matter (DOM) sources in watersheds is critical for an efficient management to control the non-point sources associated with DOM and for an understanding of the local carbon cycle. In this study, several DOM indicators, which are derived from fluorescence spectroscopy and size exclusion chromatography, were compared for their applicability to track DOM sources in three forested-agricultural watersheds. Several potential source end-members were collected from upper catchments, which included fallen leaves, riparian reeds, riparian weeds, paddy soils, field soil, riverside soil, cow manure, swine manure, and poultry manure, and the values of their representative DOM descriptors were estimated along with those of the stream samples during high flow periods. The relative source contributions to streams were estimated via an end member mixing analysis using the paired descriptors that were selected based on the criteria in terms of the value ranges and the significant differences in stream samples between the high and low flow periods. Biological index (BIX) and the ratio of the terrestrial humic-like to the humic-like component were found to be optimum optical tracers, while the aromaticity and the C/N ratio of humic substance fraction were an applicable pair of chromatographic tracers. The optical tracers were superior to the latter because of more consistent and less variability in the assigned sources between the different streams in the same watersheds. The optical tracer-based estimations revealed that the major DOM sources to the high flow stream samples were soil (22.3%–58.5%) and manures (12.9%–51.3%). This comparative study provides new insights into the practical feasibility and the overlooked limitations of the common DOM descriptors for source discrimination.

174. 题目: Sediment deposition changes the relationship between soil organic and inorganic carbon: Evidence from the Chinese Loess Plateau
文章编号: N20071708
期刊: Agriculture, Ecosystems and Environment
作者: L.S. Tong, N.F. Fang, H.B. Xiao, Z.H. Shi
更新时间: 2020-07-17
摘要:

Soil erosion has a significant impact on the distribution and sequestration of soil carbon, affecting the global C cycle. Although the transport and transformation of soil organic carbon (SOC) during the erosion process have been widely studied, there is still a lack of understanding of the impacts of soil erosion on soil inorganic carbon (SIC) and its relationships with SOC. In this study, 62 erosional sites (including 16 gullies, 17 grasslands, 16 forestlands and 13 croplands) and 35 depositional sites (check dams) on the Chinese Loess Plateau were selected. Partial least squares regression (PLSR) was carried out to explore the main influential factors of SIC variation. The results showed that, compared with erosional sites, the mean SOC and SIC content in depositional sites (0–25 cm) increased by 24.4 % and 15.4 %, respectively. Both SOC and SIC contents in depositional sites exhibited a decreasing tendency with depth. SIC was significantly negatively correlated with SOC (R2 = 0.25, P < 0.01) across all erosional sites (0–25 cm). In contrast, SIC was significantly positively correlated with SOC in all depositional layers beneath 100 cm (P < 0.05), and R2 increased from 0.23 (100–200 cm) to 0.68 (300–400 cm) and then decreased to 0.46 (500–600 cm). Sediment transport and deposition converted the negative relationship between SOC and SIC in the erosional sites to a positive relationship in deep depositional soil. The PLSR analysis suggested that SOC had an important (VIP > 1) positive impact on predicting SIC in depositional sites, which indicated that SOC increase contributed to enhancing SIC accumulation under the depositional conditions in the semi-arid region. We believe that the influencing mechanism of soil erosion on the relationship between SOC and SIC revealed in this study will contribute to understanding the soil C cycle.

175. 题目: Particulate organic carbon dynamics with sediment transport in the upper Yangtze River
文章编号: N20071707
期刊: Water Research
作者: Yuyang Wu, Hongwei Fang, Lei Huang, Zhenghui Cui
更新时间: 2020-07-17
摘要:

Understanding the behaviour of particulate organic carbon (POC) with sediment transport allows for a more accurate estimation of global carbon cycling and the conditions of aquatic ecosystems. River damming alters POC dynamics profoundly by the retention of sediments on which organic carbon (OC) is adsorbed. In this study, we developed a mechanism-based approach to investigate organic carbon (OC) adsorption on river sediment, integrating sediment particle properties (particle size, particle density, surface site density, and particle morphology) and environmental factors (dissolved OC concentration, pH, and suspended sediment concentration). We used this approach to assess the POC concentration in the dammed upper Yangtze River and to compare it with observed POC values in literature; model results and observations correlated very well (R2 = 0.89; NSE = 0.83; p < 0.001). OC adsorption on sediment was found to correlate positively with dissolved organic carbon concentration and negatively with pH and suspended sediment concentration. We found that hydroelectric cascade development contributed to a decrease in suspended sediment concentration, with a significant increase in POC concentration both at reservoir sites, and upstream and downstream. The average suspended sediment concentration near the watershed outlet decreased from 2.08 kg m−3 (individual reservoir period) to 1.57 kg m−3 (early stage of reservoir construction/operation) and then to 0.01 kg m−3 (cascade reservoir period). In contrast, the average POC concentration in the dammed river increased from less than, or around 1 %, to 1 % and finally to 3 % during each of these three periods, respectively. Our results highlight the pronounced impacts of cascade reservoirs on river sediment and POC dynamics. By providing a method for assessing OC adsorption on sediment and the dynamics of POC in aquatic systems, this work advances our understanding of carbon cycling in aquatic systems in times of global change.

176. 题目: Spatial distribution and factors influencing the different forms of ammonium in sediments and pore water of the aquitard along the Tongshun River, China
文章编号: N20071706
期刊: Environmental Pollution
作者: Rui Liu, Teng Ma, Dongtao Zhang, Chaohong Lin, Juan Chen
更新时间: 2020-07-17
摘要:

Nitrogen pollution of groundwater has created problems worldwide. Riparian zones form a connection hub for terrestrial and aquatic ecosystems. As a potential source of ammonium in groundwater, aquitards have an important effect on the environment of riparian zones. The spatial distribution and factors influencing the ammonium content in the riparian zone aquitard of a small watershed were analyzed through three geological boreholes with increasing distances from the river: boreholes A > B > C. The results show that the distribution of ammonium was closely related to the lithology of sediments. Under the influence of the river and floods, the average content of ion exchange form of ammonium of sediments in borehole A (stable sedimentary environment) was 94.31 mg kg−1, accounting for 21.2% of the transferable ammonium. The average proportions of ion exchange form of ammonium in the transferable ammonium of boreholes B and C (unstable sedimentary environment) were 19.1% and 17.4%, respectively. The carbonate and iron-manganese oxide forms of ammonium content of sediments in three boreholes were 0.96–15.28 mg kg−1 and 2.3–54.4 mg kg−1, respectively; this was mainly affected by the pH and Eh of the sedimentary environment. Organic sulfide, the form of transferable ammonium of sediments mainly exists in organic matter. The ammonium content in pore water generally increased with depth and was mainly derived from the mineralization of humic-like organic matter in borehole A. The ammonium in pore water in boreholes B and C mixed with ammonium from the mineralization of organic matter and the desorption of ion exchange form ammonium within sediments. The ammonium content in the pore water (up to 5.34 mg L−1) was much higher than the limit for drinking water of 0.5 mg L−1 in China. Therefore, the aquitard has a high risk of releasing ammonium and poses a certain threat to the quality of groundwater.

177. 题目: The biochar-supported iron-copper bimetallic composite activating oxygen system for simultaneous adsorption and degradation of tetracycline
文章编号: N20071705
期刊: Chemical Engineering Journal
作者: Jiale Liu, Kun Luo, Xiaoming Li, Qi Yang, Dongbo Wang, You Wu, Zhuo Chen, Xiaoding Huang, Zhoujie Pi, Wenjie Du, Zhiling Guan
更新时间: 2020-07-17
摘要:

An economical biochar-supported iron-copper bimetallic composite (BC-FeCu) was successfully prepared and used to remove tetracycline (TC) from water. The experiment results expressed that BC-FeCu exhibited higher removal (92.50%) than FeCu (67.30%) under the same condition (pH 4.50, TC concentration 10 mg/L, and catalyst dose 0.05 g/L). Moreover, the TC removal by BC-FeCu constantly increased with the pH value from 4.50 to 9.03. Desorption experiments showed that adsorption and degradation accounted for 26.09% and 73.91% of the total TC removal by BC-FeCu, respectively. N2 sparging experiments concluded that the degradation led by dissolved oxygen (DO) and the direct degradation by BC-FeCu accounted for 17.02% and 56.89% of the total TC removal, respectively. The existence of O2, •OH, 1O2 was testified by electron spin resonance (ESR) analysis. And O2 was proved to be the dominating active substance for TC degradation by BC-FeCu through quenching experiments. It could be that the electron transferred from –COOH, –OH and Cu/Cu+ in BC-FeCu to O2 to form O2, thus realizing the activation of O2. Finally, three possible TC degradation ways were presented through the analysis of eight intermediates.

178. 题目: Soil carbon dynamics in diverse organic land use systems in North Eastern Himalayan ecosystem of India
文章编号: N20071704
期刊: Catena
作者: Subhash Babu, K.P. Mohapatra, Gulab Singh Yadav, Rattan Lal, Raghavendra Singh, R.K. Avasthe, Anup Das, Puran Chandra, B.A. Gudade, Amit Kumar
更新时间: 2020-07-17
摘要:

Land use management exerts a tenacious impact on soil organic carbon (SOC) dynamics; however, the impact varies with climate, soils, and management practices. Therefore, an in-depth understanding of changes in SOC pools and its fractions is necessary to reduce carbon (C) emissions and adopt efficient land use planning for sustainable soil management in the North Eastern Himalayan (NEH) region of India. The soils under five prominent land uses [e.g., alder (Alnus nepalensis) + large cardamom (Amomum subulatum), alder + turmeric (Curcuma longa), ginger (Zingiber officinale) + maize (Zea mays), ginger and undisturbed forest] were sampled down to 45 cm depth to assess the impacts of land use systems on SOC content and storage, its fractions, microbial biomass carbon (MBC) and the dehydrogenase (DHA) activities. Results demonstrated that undisturbed forest soil had the highest organic carbon (OC, 145.8 Mg ha−1), active C (AC, 73.7 Mg ha−1), passive C (PC, 72.1 Mg ha−1) pools, MBC and DHA activities followed by alder + large cardamom system (140.7 Mg OC ha−1, 70.9 Mg AC ha−1, and 69.8 Mg PC ha−1, respectively). The soils under undisturbed forest and alder + large cardamom system had a higher share of the very labile C fractions for all depths than other land uses. Conversely, soils under sole ginger and ginger + maize land uses had a greater proportion of non-labile C (NLC) fractions; however, absolute values of the NLC pool were the highest under undisturbed forest soil. Alder + large cardamom land use system had the highest AC: PC pool ratio (1.13) and C stratification (1.02–1.05) compared to the other land uses. Of the various land uses, SOC pools (0–45 cm) in six years were reduced nominally under alder + large cardamom system (4.2%), while the reduction was maximum under the ginger system (11.2%) as compared to the SOC pools of undisturbed forest. The study demonstrated that the cultivation of crops like maize and/or ginger is more degrading and will always have a negative impact on the fertility and overall health of the Himalayan soil. Hence, alder + large cardamom system may be promoted to restore the soil C in the Sikkim Himalayan region of NEH, India, and other similar regions of the world.

179. 题目: Removing organic matters from reverse osmosis concentrate using advanced oxidation-biological activated carbon process combined with Fe3+/humus-reducing bacteria
文章编号: N20071703
期刊: Ecotoxicology and Environmental Safety
作者: Xiaoyan Wang, Jiaohui Xia, Shaoxuan Ding, Shuo Zhang, Menghong Li, Zhenxiao Shang, Jie Lu, Jincheng Ding
更新时间: 2020-07-17
摘要:

The high-concentration wastewater produced in the industrial reverse osmosis (RO) process contains a large amount of refractory organic matters, which will have serious impacts on the natural environment and human health. Among them, contaminants can be transformed by humus-reducing bacteria based on humus. In this study, O3- assisted UV-Fenton method was applied as pretreatment. Biological activated carbon (BAC) technology in which humus-reducing bacteria were the dominant bacteria, enhanced by electron donor and Fe3+, was used to dispose of RO concentrate (ROC). The results showed that water treatment process combining oxidation with biological filtration had a positive effect on the removal of stubborn contaminants in ROC. The system was strengthened by adding electron donor and Fe3+, and the chemical oxygen demand (COD) removal efficiency was up to 80.1%. However, when the removal efficiency of UV254 absorbing pollutants reached optimal value (87.3%), that means only Fe3+ was added.

180. 题目: Water and humic acid transport in graphene-derived membrane: Mechanisms and implications to functional membrane design
文章编号: N20071702
期刊: Journal of Membrane Science
作者: Lanlan Qin, John E. Tobiason, Haiou Huang
更新时间: 2020-07-17
摘要:

Graphene-derived membranes (GDM) have drawn broad attentions due to their superb water permeation and contaminant retention capabilities. In this paper, the transport of model humic acid (HA) and water through GDM is studied using the molecular dynamics simulation approach. By systematically varying the positions of functional groups and membrane pore dimensions, we find that the introduction of functional groups at the slit edge, the basal plane or the interlayer of bilayer graphene nanosheets reduces water permeation through the membranes to significantly different extents. Comparatively, -COO- at the slit edge of GE nanosheet produces the strongest electrostatic interaction for enhanced HA retention and greater water permeability than graphene oxide membranes. Furthermore, HA adsorbed inside GDM may cause membrane fouling due to pore blocking at the slit entrance or pore constriction inside the slit or the interlayer. Meanwhile, the reversibility of membrane fouling depends upon HA desorption, which is easier for HA anchored via functional groups than stacked via π-π interaction onto graphene surfaces. Our findings emphasize that the performance of functional GDM for water treatment is highly dependent upon the specific position of chemical modification, which has been commonly overlooked in previous studies.

 共 8434 条记录  本页 20 条  本页从 161-180 条  9/422页  首页 上一页  4 5 6 7 8 9 10 11 12 13 14  下一页  末页   

本数据库数据来源自各期刊,所有权归属各期刊。数据仅供分享学习,不作商业用途,特此申明。