论文检索

主页 | 软件工具 | 课题库 | 公众号
:



总访问量:949877

总访客量:33386

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

241. 题目: Organic carbon and nitrogen accumulation in orchard soil with organic fertilization and cover crop management: A global meta-analysis
文章编号: N22090308
期刊: Science of the Total Environment
作者: Yingxiao Hu, Pengjie Zhan, Ben W Thomas, Jingkun Zhao, Xueliang Zhang, He Yan, Zhibin Zhang, Shuang Chen, Xiaojun Shi, Yuting Zhang
更新时间: 2022-09-03
摘要:

In orchard systems, organic amendments and cover crops may enhance soil organic carbon (SOC) and total nitrogen (STN) stocks, but on a global scale a comprehensive understanding of these practices is needed. This study reports a worldwide meta-analysis of 131 peer-reviewed publications, to quantify potential SOC and STN accumulation in orchard soils induced by organic fertilization and cover cropping. Annual gains of 3.73 Mg C/ha and 0.38 Mg N/ha were realized with the introduction of organic fertilizer, while cover crop management led to annual increases of 2.00 Mg C/ha and 0.20 Mg N/ha. The SOC and STN accumulation rates depended mostly on climatic conditions and initial SOC and STN content. The SOC and STN accumulated fastest during the first three years of cover crop implementation, at 2.98 Mg C/ha/yr and 0.25 Mg N/ha/yr and declined thereafter. Organic fertilization caused significantly more annual SOC and STN accumulation at higher (400–800 mm) than lower (<400 mm) rainfall levels. When cover cropping for more than five years, SOC accumulated the fastest with <800 mm of mean annual rainfall. Organic fertilization led to faster SOC accumulation with mean annual temperature between 15 and 20 °C than >20 °C. Organic amendments led to the slowest SOC accumulation rate when the initial SOC concentration was <10 g C/kg. This study provides policy makers and orchard managers science-based evidence to help guide adaptive management practices that build SOC stocks, improve soil conditions and enhance resilience of orchard systems to climate change.

242. 题目: Water soluble organic matter from soils at the terrestrial-aquatic interface in wetland-dominated landscapes
文章编号: N22090307
期刊: Journal of Geophysical Research: Biogeosciences
作者: Katherine M Wardinski, Erin R Hotchkiss, C Nathan Jones, Daniel L McLaughlin, Brian D Strahm, Durelle T Scott
更新时间: 2022-09-03
摘要: Hydrologic controls on carbon processing and export are a critical feature of wetland ecosystems. Hydrologic response to climate variability has important implications for carbon-climate feedbacks, aquatic metabolism, and water quality. Little is known about how hydrologic processes along the terrestrial-aquatic interface in low-relief, depressional wetland catchments influence carbon dynamics, particularly regarding soil-derived dissolved organic matter (DOM) transport and transformation. To understand the role of different soil horizons as potential sources of DOM to wetland systems, we measured water soluble organic matter (WSOM) concentration and composition in soils collected from upland to wetland transects at four Delmarva Bay wetlands in the eastern United States. Spectral metrics indicated that WSOM in shallow organic horizons had increased aromaticity, higher molecular weight, and plant-like signatures. In contrast, WSOM from deeper, mineral horizons had lower aromaticity, lower molecular weights, and microbial-like signatures. Organic soil horizons had the largest concentrations of WSOM, and WSOM decreased with increasing soil depth. WSOM concentrations also decreased from the upland to the wetland, suggesting that continuous soil saturation reduces WSOM concentrations. Despite wetland soils having lower WSOM, these horizons are thicker and continuously hydrologically connected to wetland surface and groundwater, leading to wetland soils representing the largest potential source of soil-derived DOM to the Delmarva Bay wetland system. Knowledge of which soil horizons are most biogeochemically significant for DOM transport in wetland ecosystems will become increasingly important as climate change is expected to alter hydrologic regimes of wetland soils and their resulting carbon contributions from the landscape.

243. 题目: Photochemical Production of Carbon Monoxide from Dissolved Organic Matter: Role of Lignin Methoxyarene Functional Groups
文章编号: N22090306
期刊: Environmental Science & Technology
作者: Rachele Ossola, Richard Gruseck, Joanna Houska, Alessandro Manfrin, Morgan Vallieres, Kristopher McNeill
更新时间: 2022-09-03
摘要: Carbon monoxide (CO) is the second most abundant identified product of dissolved organic matter (DOM) photodegradation after CO2, but its formation mechanism remains unknown. Previous work showed that aqueous photodegradation of methoxy-substituted aromatics (ArOCH3) produces CO considerably more efficiently than aromatic carbonyls. Following on this precedent, we propose that the methoxy aromatic groups of lignin act as the C source for the photochemical formation of CO from terrestrial DOM via a two-step pathway: formal hydrolytic demethylation to methanol and methanol oxidation to CO. To test the reasonableness of this mechanism, we investigated the photochemistry of eight lignin model compounds. We first observed that initial CO production rates are positively correlated with initial substrate degradation rates only for models containing at least one ArOCH3 group, regardless of other structural features. We then confirmed that all ArOCH3-containing substrates undergo formal hydrolytic demethylation by detecting methanol and the corresponding phenolic transformation products. Finally, we showed that hydroxyl radicals, likely oxidants to initiate methanol oxidation to CO, form during irradiation of all models. This work proposes an explicit mechanism linking ubiquitous, abundant, and easily quantifiable DOM functionalities to CO photoproduction. Our results further hint that methanol may be an abundant (yet overlooked) DOM photoproduct and a likely precursor of formaldehyde, formic acid, and CO2 and that lignin photodegradation may represent a source of hydroxyl radicals.

244. 题目: Effect of water chemistry on nitrogen transformation, dissolved organic matter composition and microbial community structure in hyporheic zone sediment columns
文章编号: N22090305
期刊: Environmental Research
作者: Longfei Wang, Yutao Wang, Yi Li, Linqiong Wang, Jinxin Zhu, Wenlong Zhang, Huanjun Zhang, Lihua Niu, Jun Wu
更新时间: 2022-09-03
摘要:

Controlled surface water systems, including those with dams lead to dynamic stage changes that alter the fluctuation directions of flow exchange in the hyporheic zones (HZ). However, the nitrogen transformation, dissolved organic matter (DOM) composition, and microbial community responding to variable scenarios of water source and hyporheic exchange are poorly studied. The present work investigated nitrogen transformation in HZ sediments, focusing on how microbial community structure and biological functions related to nitrogen transformation and sediment-attached DOM compositions. Upwelling of synthesized groundwater, downwelling of synthesized river water and exchangeable elution of both feed water created distinct microbial zonation and N-transformation processes. Mixing of river water and groundwater enhanced microbial diversity, microbial co-occurrence network complexity and N-transformation functions. In terms of the sediment-attached DOM properties after hyporheic exchanges, humic fractions occupied the predominant chromophoric DOM. Correlation analysis implied that there were more DOM properties, e.g., tryptophan-like proteins, humic-like fractions, and the source of humic fractions, involved in affecting the microbial community under downwelling flow. Co-occurrence network analysis verified that fluorescent components, protein-like and lignin-like fractions in sediment-detached DOM were clustered with microbial communities in one module in downwelling column, implying closer interactions among microbial communities and DOM fractions. The strains of Nitrospinae, Dinghuibacter, and Lentimicrobium etc. were key species collaborating to metabolize both nitrogen and DOM in HZ sediments. The work provides insights into how the nitrogen transformation, DOM compositional changes, as well as the linkages between community structure and DOM factions, response to the changes in water chemistry, leading to valuable insights into hyporheic zone functions.

245. 题目: Characterizing the source apportionment of black carbon and ultrafine particles near urban roads in Xi'an, China
文章编号: N22090304
期刊: Environmental Research
作者: Di Nie, Zhaowen Qiu, Xin Wang, Zhen Liu
更新时间: 2022-09-03
摘要:

Better knowledge of the sources of black carbon (BC) and ultrafine particles (UFPs) in urban roadway region will provide helpful information for improving road air pollution caused by vehicle emissions. For this purpose, we conducted daily observation of BC and UFPs at two trafficked sites (intersection and roadside), and a background site in Xi'an, China. The concentration data of BC and UFPs measured were combined with Aethalometer model and UFPs source apportion model, to determine and analyze the sources of BC in an urban road region. Further, the source and variation characteristics of primary and secondary UFPs at the roadside sites were clarified. The results showed that average BC concentrations at the intersection, roadside, and background were respectively 3577 ± 2771, 3078 ± 2343, and 1914 ± 1229 ng/m3. The BC source apportionment results revealed contribution rates of on-board fossil fuel combustion (BCff) at the intersection and near the road of ca. 78.7% and 73.6%, respectively. Moreover, the proportion of particles number concentrations directly emitted from vehicles and nucleated upon emission (47%) was lower than that of particles formed during the dilution and cooling of vehicle emissions and by in-situ new particle formation (53%) at the roadside site. At 49%, the proportion of primary particles number was slightly higher at the intersection. The impacts of new particle-formation events on the diurnal variation of secondary particles were explored. Generally, the majority of BC originated from traffic exhausts, while the secondary particles from non-traffic sources are dominant at the road intersections. By providing a better understanding of near-road pollution issues, this study's findings can be useful for taking effective regulatory efforts to improve air quality and reduce people's exposure to traffic-pollutants in an urban environment.

246. 题目: The production of diverse brGDGTs by an Acidobacterium providing a physiological basis for paleoclimate proxies
文章编号: N22090303
期刊: Geochimica et Cosmochimica Acta
作者: Yufei Chen, Fengfeng Zheng, Huan Yang, Wei Yang, Ruijie Wu, Xinyu Liu, Huayang Liang, Huahui Chen, Hongye Pei, Chuanlun Zhang, Richard D Pancost, Zhirui Zeng
更新时间: 2022-09-03
摘要:

Microbial lipid biomarkers preserved in geological archives can be used to explore past climate changes. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are unique bacterial biomarkers that have been used as molecular tools for the quantitative determination of terrestrial temperatures and the pH of depositional environments over a range of geological timescales. However, the exact biological source organisms – especially of the entire suite of brGDGTs found in the environment – remains unclear; by extension, so do the mechanisms that govern these proxies. Here, we identified a brGDGT-producing strain Candidatus Solibacter usitatus Ellin6076, by identifying archaeal tetraether synthase homologs in bacterial genomes. This strain synthesizes diverse brGDGTs, including regular C5-methylated and cyclic brGDGTs, and brGDGTs comprise up to 66% of the major quantified lipids, far exceeding the proportions found in previous studies. The degree of C5-methylation in cultured strain Ellin6076 is primarily determined by temperature, whereas cyclization appears to be influenced by multiple factors, such as temperature, pH and oxygen availability. Consequently, culture-derived paleoclimate indices are in agreement with the global soil-derived MBT’5ME (methylation index of C5-methyl brGDGTs) proxy for temperature, albeit with a differed slope, but not the CBT5ME (cyclization index of C5-methyl brGDGTs) proxy for pH. Our findings provide insights from a physiological perspective into the underlying mechanism of brGDGT-based proxies.

247. 题目: Organic carbon dynamics in the continental shelf waters of the eastern Arabian Sea
文章编号: N22090302
期刊: Environmental Monitoring and Assessment
作者: Suhas S Shetye, K Nandakumar, Siby Kurian, Mangesh Gauns, Damodar M Shenoy, Hema Naik, P J Vidya, Supriya G Karapurkar
更新时间: 2022-09-03
摘要:

The seasonal and spatial distribution of total organic carbon (TOC) is presented for the coastal waters of the eastern Arabian Sea, which experiences seasonal suboxia during the late southwest monsoon (SWM). This study reveals that high TOC was observed off Kochi as compared to Goa and Mangalore transects, and may be attributed to stronger upwelling along the Kerala coast. This is also supported by the excess carbon due to upwelling during the late SWM that varied from 37 μM (Goa), 39 μM (Mangalore), to 51 μM (Kochi). Our seasonal data from 2014 to 2020 at the Goa transect indicates that high TOC is seen during late SWM to fall inter monsoon (FIM) and between the late northeast monsoon (NEM) to the early spring inter monsoon (SIM). The high TOC concentrations and C/N ratios observed during the FIM are a combination of high primary production, the buildup of remnant organic matter from the previous season (due to prevailing low oxygen conditions), accumulation of refractory organic carbon, and release from diatoms (especially Chaetoceros sp.). Inter-annual variations indicate that phytoplankton blooms resulted in higher TOC concentrations, especially during the year 2020. Based on a comparison with an Elnino-Southern Oscillation (ENSO) year (2015), we can infer that the partitioning of carbon may increase from particulate to dissolved phase in future warming scenarios.

248. 题目: Organic matter source traced by n-alkane records derived from lacustrine sediments from Daping swamp in the western Nanling Mountains (South China) and its response to climatic variability since the last Deglacial
文章编号: N22090301
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Durui Lin, Wei Zhong, Yingbing Lin, Yongdong Zhang, Tianhang Li, Mingying Quan
更新时间: 2022-09-03
摘要:

Previous multi-proxy records have revealed the advantages of well-preserved and long-scale geological archives from the lake sediments of Daping swamp in the western Nanling Mountains in South China. However, the exact organic matter (OM) sources in the sediments and their response to climatic variability still remain unclear. In this study, we present a 15.3-kyr n-alkane record extracted from lacustrine sediments in this swamp to explore the OM sources and the relationship between OM input and climatic changes. The results indicated that the n-alkane composition in sediments was dominated by long-chain n-alkanes (C27-C31), implying that the OM mainly originated from the terrestrial higher plants and emergent aquatic plants. The n-alkane data further verified that changes in OM sources were related to the surface erosion-transportation-deposition processes controlled by climatic changes. Lake level change, which was also regulated by climate conditions, played an important role in impacting OM accumulation; warmer and wetter conditions would result in rising lake levels that favored more aquatic OM and less terrestrial OM input, and vice versa. Variability of the Asian summer monsoon intensity regulated by the dynamic variations in low-latitude processes (e.g., solar insolation, intertropical convergence zone, and El Niño/Southern Oscillation), as well as high-latitude processes (e.g., meltwater input in the North Atlantic), was closely related to the OM accumulation in sediments.

249. 题目: Biochar-mediated abiotic and biotic degradation of halogenated organic contaminants – A review
文章编号: N22090211
期刊: Science of the Total Environment
作者: Mariah Dorner, Srinidhi Lokesh, Yu Yang, Sebastian Behrens
更新时间: 2022-09-02
摘要:

Prevailing global increases in population, urbanization, and agricultural production are causing increased pressures on water resources, especially as the use of chemicals in agriculture, industry, and medicine provide new challenges for water treatment and reuse. Organohalogen compounds are persistent contaminants that often evade current wastewater treatment technologies, resulting in their accumulation in the environment and posing a serious threat to ecosystem health. Recent advances in understanding pyrogenic carbons as electron shuttling and storing materials have exposed their potential for enhancing the dehalogenation and overall degradation of organohalide contaminants in soil, sediment, surface water, and wastewater systems. Biochar is a porous carbonaceous material produced during the thermochemical decomposition of biomass feedstock in the presence of little or no oxygen (pyrolysis). Interest in biochar for application towards environmental remediation is largely based on its three distinct benefits: (1) carbon sequestration to offset greenhouse gas emissions, (2) adsorption of (in-) organic contaminants and nutrients, and (3) a strong electron exchange capacity. Due to the innate complexity of biochar materials, several electron transfer mechanisms exist by which biochar may mediate contaminant degradation. These electron transfer pathways include electron-accepting and donating cycles through redox-active functional groups and direct electron transfer via conductive carbon matrices. These mechanisms are responsible for biochar's participation in multiple redox-driven biogeochemical transformations with proven consequences for effective organohalogen remediation. This literature review summarizes the current knowledge on the mechanisms and processes through which biochar can directly or indirectly mediate the transformation of organohalogen compounds under various environmental conditions. Perspectives and research directions for future application of biochars for targeted remediation strategies are also discussed.

250. 题目: The characterization of a novel magnetic biochar derived from sulfate-reducing sludge and its application for aqueous Cr(Ⅵ) removal through synergistic effects of adsorption and chemical reduction
文章编号: N22090210
期刊: Chemosphere
作者: Yongjun Chen, Rui Ma, Xunchi Pu, Xiaoying Fu, Xiaoyu Ju, Muhammad Arif, Xueqian Yan, Jin Qian, Yu Liu
更新时间: 2022-09-02
摘要:

Removal of heavy metals from the aqueous environment via physiochemical adsorption always remains a great challenge owing to the slow kinetics and low removal capacity for the conventional adsorbent. In this study, the sulfate-reducing bacteria (SRB)-rich anaerobic sludge was pyrolyzed for the preparation of magnetic biochar, i.e. SBC-20-500 (SBC: sulfate-reducing sludge-based biochar; 20 denotes the biochar dosage, namely 8 g dried sludge in 400 mL iron solution which is equal to 20 g/L; 500 represents the pyrolysis temperature, i.e. at 500 °C) with tunable pore structure and surface properties towards efficient removal of chromium (Cr (Ⅵ)). The characterization revealed that magnetic biochar SBC-20-500 exhibited higher surface area and larger pore volume compared to non-magnetic SBC-500. Batch experiments on Cr (Ⅵ) removal were performed under different biochar dosages, pH values, initial Cr (Ⅵ) concentrations and temperatures. The results illustrated that magnetic biochar demonstrated much larger Cr (Ⅵ) adsorption capacity with qe of 5.3585 mg/g as compared to non-modified one (qe = 0.7206 mg/g). The maximum Cr (Ⅵ) removal efficiency of SBC-20-500 reached approximately 93.7% within 24 h under the conditions of pH = 3.0, biochar dosage = 0.8 g and initial Cr (Ⅵ) concentration = 50 mg/L. The kinetic and isotherm fitting results suggested that the pseudo-second-order kinetic and Langmuir isotherm model were more suitable for describing the adsorption behavior of Cr (Ⅵ) by SBC-20-500. The XPS and FTIR results confirmed that chemical reduction of Cr (Ⅵ) to Cr (Ⅲ) also played a role in Cr (Ⅵ) removal in the presence of SBC-20-500. Moreover, the Cr (Ⅵ) removal capacity could still achieve 3.50 mg/g even after five adsorption-desorption cycles, indicating the satisfactory reusability of the as-prepared biochar. The results of this study may provide a win-win approach for simultaneous resource recovery from the wasted sulfate-reducing sludge (SRS) and highly-efficient remediation of Cr (Ⅵ)-contaminated environment.

251. 题目: Microalgae-derived Nanoporous Biochar for Ammonia Removal in Sustainable Wastewater Treatment
文章编号: N22090209
期刊: Journal of Environmental Chemical Engineering
作者: Xixia Zhang, Jaroslav Kaštyl, Mariano Casas-Luna, Lubomír Havlíček, Marek Vondra, Vladimír Brummer, Kateřina Sukačová, Vítězslav Máša, Sin Yong Teng, Petr Neugebauer
更新时间: 2022-09-02
摘要:

Ammonia is a critical pollutant in biological wastewater and is not easily separated mechanically due to similar physical properties (e.g. molecular weight, polarity, etc.) to water. Currently, an agent for ammonia removal from wastewater using zeolites must be mined, which is not environmental-friendly. The development of a sustainable and biological absorbent for ammonia-containing wastewater is therefore desirable. Since microalgae can grow rapidly by feeding on waste nutrients in wastewater and up-taking carbon dioxide flue gas, it is of high interest to be used as a bio-absorbent for secondary wastewater treatment. The problem statement of this work is to explore and understand the use of microalgae as a biological source for effective ammonia absorbent. In this work, nanoporous microalgae biochar (NP-MBC) is proposed to be synthesized by using formaldehyde-stabilized hydrothermal and KOH-activated high-temperature pyrolysis. The novelty of this work is that the mechanism for NP-MBC ammonia removal is being uncovered via spectroscopic and sorption analysis. Formaldehyde-stabilization maintains the morphology of the microalgae particles for higher quality pore formation during pyrolysis. Pyrolysis temperatures up to 700 °C improve pore structure and surface chemistry of the NP-MBC, leading to a specific surface area of 1 137 m2·g-1 and increased activation of COO- groups for ammonia adsorption. Further pyrolysis at 800 °C damages the textual characteristics of the synthesized NP-MBC, causing pores agglomeration and lower ammonia adsorption. The best ammonia adsorption performance was obtained on NP-MBC prepared by pyrolysis at 700 °C with maximum ammonia removal of 72% (within 120 minutes) and adsorption capacity over 69 mg·g-1. Nanoporous structure by stabilized hydrothermal treatment and high-temperature pyrolysis are interesting as a paradigm to convert particulate biomass feedstock to functional material with tunable properties.

Data availability

Data are available upon reasonable request from authors.

252. 题目: The dominant role of sunlight in degrading winter dissolved organic matter from a thermokarst lake in a subarctic peatland
文章编号: N22090208
期刊: Biogeosciences
作者: Flora Mazoyer, Isabelle Laurion, Milla Rautio
更新时间: 2022-09-02
摘要: Dissolved organic matter (DOM) leaching from thawing permafrost may promote a positive feedback on the climate if it is efficiently mineralized into greenhouse gases. However, many uncertainties remain on the extent of this mineralization, which depends on DOM lability that is seemingly quite variable across landscapes. Thermokarst peatlands are organic-rich systems where some of the largest greenhouse gas (GHG) emission rates have been measured. At spring turnover, anoxic waters release the GHG accumulated in winter, and the DOM pool is exposed to sunlight. Here, we present an experiment where DOM photoreactivity and bioreactivity were investigated in water collected from a thermokarst lake in a subarctic peatland during late winter (after 6 months of darkness). We applied treatment with or without light exposure, and manipulated the bacterial abundance with the aim to quantify the unique and combined effects of light and bacteria on DOM reactivity at ice-off in spring. We demonstrate that sunlight was clearly driving the transformation of the DOM pool, part of which went through a complete mineralization into CO2. Up to 18 % of the initial dissolved organic carbon (DOC, a loss of 3.9 mgC L−1) was lost over 18 d of sunlight exposure in a treatment where bacterial abundance was initially reduced by 95 %. However, sunlight considerably stimulated bacterial growth when grazers were eliminated, leading to the recovery of the original bacterial abundance in about 8 d, which may have contributed to the DOC loss. Indeed, the highest DOC loss was observed for the treatment with the full bacterial community exposed to sunlight (5.0 mgC L−1), indicating an indirect effect of light through the bacterial consumption of photoproducts. Dark incubations led to very limited changes in DOC, regardless of the bacterial abundance and activity. The results also show that only half of the light-associated DOC losses were converted into CO2, and we suggest that the rest potentially turned into particles through photoflocculation. Sunlight should therefore play a major role in DOM processing, CO2 production and carbon burial in peatland lakes during spring, likely lasting for the rest of the open season in mixing surface layers.

253. 题目: Endogenic methylmercury in a eutrophic lake during the formation and decay of seston
文章编号: N22090207
期刊: Biogeosciences
作者: Laura Balzer, Carluvy Baptista-Salazar, Sofi Jonsson, Harald Biester
更新时间: 2022-09-02
摘要: . Anoxic microniches in sinking particles in lakes have been identified as important water phase production zones of monomethylmercury (MeHg) (endogenic MeHg). However, the production and decay of MeHg during organic matter (OM) decomposition in the water column and its relation to the total Hg concentration in seston are poorly understood. We investigated Hg speciation and chemical changes in sinking seston in a small and shallow (12-m-deep) eutrophic lake during phytoplankton blooms from April to November 2019. The results show that MeHg proportions are high in seston at the water surface (up to 22 %) and at the oxic-suboxic redox boundary (up to 26 %). During suboxic OM decomposition, and with decreasing redox-potential, the concentration and proportion of MeHg in seston strongly decrease (< 0.5 %) as the water depth increases. Under these conditions, total Hg concentrations show a 3.8 to 26-fold increase. In the hypolimnion environment, changes in MeHg proportions were minimal in sinking seston, and samples collected by sediment traps had MeHg values similar to those measured at the sediment-water interface, though higher MeHg concentrations were found deeper in the sediment. Our results indicate that cycling of MeHg and total Hg (THg) in seston within small productive lakes is largely controlled by the decomposition processes of settling seston and that the endogenic MeHg pool appears to be largely disconnected from the sedimentary MeHg pool.

254. 题目: Effects of substitution of chemical fertilizer by Chinese milk vetch on distribution and composition of aggregates-associated organic carbon fractions in paddy soils
文章编号: N22090206
期刊: Plant and Soil
作者: Yanan Huang, Li Huang, Jun Nie, Mingjian Geng, Yanhong Lu, Yulin Liao, Bin Xue
更新时间: 2022-09-02
摘要:

Purpose

Green manure plays a key role in reducing chemical fertilizer applications and increasing soil organic carbon (SOC) stock. The effects of chemical fertilizer substitution by Chinese milk vetch (MV) on the distribution and composition of organic carbon fractions in macroaggregates and microaggregates and SOC stability mechanism were investigated in paddy soils in southern China.

Methods

A 10-year (2008–2018) field experiment was conducted, including no fertilizer (CK), 100% NPK fertilizer (F100), MV with different percentages of chemical fertilizer (MV + F100, MV + F80, MV + F60 and MV + F40). The soil was separated into distinct organic carbon fractions using aggregate density fractionation and SOC chemical structure was analyzed by fourier-transform infrared and nuclear magnetic resonance.

Results

Chemical fertilizer substitution by MV increased SOC contents in the bulk soil by 9.1% (MV + F80), 5.8% (MV + F60), 17.9% (MV + F40) compared to F100. Organic carbon fraction mainly existed in mineral associated organic carbon (mSOC), accounting for 70.3–83.7% and 69.4–84.0% of the relative mass of macroaggregates and microaggregates, respectively. Compared to F100, aromatic C increased by 11.6% and 29.1% under MV + F60 within mSOC in macroaggregates and microaggregates. Within the mSOC in macroaggregates, compared to CK, MV + F80 and MV + F60 promoted the proportion of alkyl C by 9.6% and 6.7%, and decreased the content of O-alkyl C by 14.1% and 11.0%, respectively, which correspondingly increased alkyl C/O-alkyl C ratio.

Conclusions

Substitution of chemical fertilizer by MV (especially MV + F80 and MV + F60) improved the stability of SOC via increasing recalcitrant structure in mSOC, and was conducive to the sequestration of SOC in paddy soils.

255. 题目: Effects of litter input on the balance of new and old soil organic carbon under natural forests along a climatic gradient in China
文章编号: N22090205
期刊: Biogeochemistry
作者: Tian Chen, Xiao-Min Hong, Ya-Lin Hu, Qing-Kui Wang, Li-Zhong Yu, Xian-Wei Wang
更新时间: 2022-09-02
摘要:

Litter input plays an important role in the soil organic carbon (SOC) balance between new C formation and old C loss in forests. However, the relative contributions of aboveground litter vs. belowground litter inputs to the SOC balance in various forests along a climatic gradient remain highly uncertain. In this study, we experimentally transplanted sugarcane soil with a heavy δ13C value to forest soil with a light δ13C value to evaluate the relative effects of aboveground and belowground litter inputs on new SOC formation and old SOC retention in natural secondary forests (boreal, temperate, subtropical and tropical forests) located across four different climatic regions in China. Our results showed that belowground root litter inputs can potentially lead to higher new SOC formation and lower old SOC retention compared to aboveground litter inputs. Moreover, the magnitudes of new SOC and old SOC change after litter inputs varied among natural forests, with SOC in tropical forests being more sensitive to belowground root inputs than SOC in temperate and subtropical forests. While the total and new SOC contents were positively correlated with mean annual temperature (MAT) and precipitation (MAP), the old SOC contents were negatively correlated with MAT and MAP. Our findings indicated that belowground root litter inputs have more profound influences on new SOC formation and old SOC loss than aboveground litter inputs, and climatic factors play a fundamental role in determining litter input-induced changes in SOC balance across different forest ecosystems.

256. 题目: Saccharides in atmospheric PM2.5 in tropical forest region of southwest China: Insights into impacts of biomass burning on organic carbon aerosols
文章编号: N22090204
期刊: Chemosphere
作者: Xin Wang, Yukun Chen, Xiao Guo, Wenting Dai, Yali Liu, Feng Wu, Jianjun Li
更新时间: 2022-09-02
摘要:

Biomass burning (BB) in South and Southeast Asia have a strong impact on regional air quality, yet their impact on atmospheric PM2.5 of tropical rainforest regions, a background region occupying a large area in South Asia, has rarely been investigated. In this work, we performed one-year PM2.5 sampling during December 2018 to October 2019 at a tropical rainforest site in southwest China. PM2.5 mass concentration, major chemical components, and ten saccharides were determined to study seasonal variations of PM2.5 chemical composition, and further to understand possible impacts of BB to organic carbon (OC) aerosols at this background region. The concentration levels of PM2.5, major PM2.5 components, and total saccharides were significantly higher in dry season than in wet season. Besides, PM2.5, OC, and total saccharides were highly correlated (R2 > 0.64, p < 0.001) during the sampling period, suggesting they might share common sources. Source apportionment of saccharides revealed that BB was the main source in both seasons. Furthermore, the contributions of BB to OC (BB/OC) were estimated using levoglucosan as a molecular tracer while levoglucosan's chemical degradation was considered. It was found that over 80% of LG was degraded in both seasons, suggesting BB sources were largely from the transport of external air mass. The estimated BB/OC were over 50%, indicating BB was an important source of OC and likely of PM2.5 in both seasons. The air-mass backward trajectory analysis and active fire spots data indicate intense BB emission sources were from South and Southeast Asia in dry season and the BB emissions in southern region of China could impact on the studied area in wet season.

257. 题目: Winter wheat cover crop increased subsoil organic carbon in a long-term cotton cropping system in Tennessee
文章编号: N22090203
期刊: Soil and Tillage Research
作者: Rounak Patra, Debasish Saha, Sindhu Jagadamma
更新时间: 2022-09-02
摘要:

Long-term cover-cropping and no-tillage practices can facilitate soil organic carbon (SOC) accumulation in agroecosystems for soil health and climate mitigation benefits. However, the contribution of these conservation management practices to SOC gain from the subsoil layers is not extensively studied. To understand this knowledge gap, it is essential to determine the distribution of total SOC and SOC fractions in response to management practices across the soil profile. Therefore, this study was conducted by leveraging a 40-year replicated field experiment in a continuous cotton (Gossypium hirsutum) system. The management treatments examined included three cover crop treatments: 1) hairy vetch, HV (Vicia villosa); 2) winter wheat, WW (Triticum aestivum L.), and 3) no cover crop, NC; and two tillage treatments: 1) chisel-tillage, CT (10 cm deep) and 2) no-tillage, NT. Soil samples were collected from four depths (0–5, 5–10, 10–30, and 30–60 cm) and analyzed for total SOC and C fractions such as microbial biomass (MBC), particulate organic matter (POM-C), and mineral-associated organic matter (MAOM-C). Results showed that the profile-scale (0–60 cm) SOC stock was greater for WW (33.7 Mg ha −1) compared to HV (29.1 Mg ha −1) and NC (24.4 Mg ha −1), while the tillage effect was non-significant (28 Mg ha −1 for NT and 29.3 Mg ha −1 for CT). The NT increased SOC in the top 5-cm layer, which was reflected in the concentrations of POM-C and MBC. Below the tillage depth (10–30 cm), SOC accrual was greater under CT (10.4 Mg ha −1) than NT (8.9 Mg ha −1), despite similar profile-scale SOC stocks. Further analysis revealed that total SOC in topsoil and subsoil were driven by POM and MAOM-related parameters, respectively. We also observed a limited accumulation of C in POM fraction (0.2–6.1 g C kg−1 soil in tilled topsoil and 0.01–0.71 g C kg−1 soil in subsoil) with a weak relationship with total SOC concentration (topsoil slope = 0.29, subsoil slope = 0.13). Contrastingly, accumulation of C in MAOM fraction was greater (2.7–12.7 g C kg−1 soil in topsoil and 0.6–5.4 g C kg−1 soil in subsoil), and it was strongly related to total SOC concentration than POM-C, especially in the subsoil (topsoil slope = 0.43, subsoil slope = 0.71). Growing deep-rooted winter wheat cover crop increased SOC in the subsoil, indicating the need for climate, soil, and ecosystem-specific management practices for profile-scale net SOC accumulation and redistribution in agroecosystems.

258. 题目: Simultaneous oxidation and adsorption of phosphite by magnetic La2(CO3)3/CoFe2O4/biochar composite with peroxymonosulfate
文章编号: N22090202
期刊: Chemical Engineering Journal
作者: Rui Zhao, Yacong Hu, Wei Ding, Ke Ren, Xinyi Gou, Chun Zhao, Huaili Zheng
更新时间: 2022-09-02
摘要:

Phosphite [P(III)], an emerging eutrophication pollutant, has attracted limited attention in recent years. Owing to the higher solubility and resistance to biotransformation of P(III), oxidation of P(III) to phosphate [P(Ⅴ)] is considered to be necessary to enhance P(III) removal. Herein, an efficient and regenerable magnetic La2(CO3)3/CoFe2O4/biochar composite (LCB) was constructed through a facile one-pot hydrothermal method to treat phosphite-laden wastewater. LCB coupled with peroxymonosulfate (PMS) exhibited satisfactory P(III) removal performance through a one-step process for simultaneous oxidation and adsorption of P(III). The adsorption capacity of LCB/PMS for P(III) (71.94 mg/g) was much higher than that of LCB. LCB/PMS system showed high P(III) removal efficiency of 96.62%, wide pH ranging from 4.0 to 9.0, and good reusability. It also worked well in the existence of anions and humic acid. The quenching experiments and electron spin resonance tests (ESR) revealed the critical role of SO4- in the P(III) oxidation process. Characterization results demonstrated that electrostatic attraction and ligand exchange were responsible for P(III)/P(Ⅴ) adsorption. Moreover, LCB/PMS system presented desirable performance in eliminating a series of typical organic and inorganic phosphorus. The LCB/PMS system provides a promising and sustainable technology for the purification of P(III)-contaminated water.

259. 题目: Biochar alleviating heavy metals phytotoxicity in sludge-amended soil varies with plant adaptability
文章编号: N22090201
期刊: Environmental Research
作者: Daoming Wu, Weixin Peng, Li'an Bao, Xiaoli Yu, Xiaoquan Dong, Mingli Lai, Zhiqi Liang, Shanyan Xie, Douglass F Jacobs, Shucai Zeng
更新时间: 2022-09-02
摘要:

Recycling sewage sludge (SS) to soil potentially causes soil heavy metal (HM) pollution and plant phytotoxicity. Biochar plays an important role in alleviating HM phytotoxicity, and responses vary with the feedstocks and usage of biochar. However, the effect of plant adaptability on biochar-mediated alleviation is poorly understood. Here, SS-derived biochar (SB) and rice straw-derived biochar (RB) applied at rates of 1.5% and 3% (W/W, SB1.5, SB3, RB1.5, and RB3) were used to improve the properties of soil amended with SS at 50% (W/W). Alleviation of phytotoxicity by biochar was further analyzed with SS-sensitive plant Monstera deliciosa and SS-resistant plant Ruellia simplex. Results revealed that both SB and RB significantly decreased the soil's bulk density and increased water retention. They also changed soil organic matter content and HMs fractionation. The addition of SB or RB alleviated the SS phytotoxicity, and they significantly promoted the growth and the root morphology and physiological index of M. deliciosa. But for R. simplex, these significant changes only synchronously occurred in SB3 treatment. The alleviation in M. deliciosa was more prominent and more closely connected with soil property changes than in R. simplex. Also, more soil property predictors were observed to play an important role in M. deliciosa growth than in R. simplex growth. These results indicated that biochar alleviating HMs phytotoxicity in SS-amended soil is associated with the changes of soil property. Moreover, the alleviation varies more prominently with plant adaptability than with biochar feedstocks and usage.

260. 题目: Microplastics addition reduced the toxicity and uptake of cadmium to Brassica chinensis L.
文章编号: N22090110
期刊: Science of the Total Environment
作者: Zhiqin Zhang, Yan Li, Tianyi Qiu, Chengjiao Duan, Li Chen, Shuling Zhao, Xingchang Zhang, Linchuan Fang
更新时间: 2022-09-01
摘要:

The coexistence of microplastics (MPs) and toxic metal contaminants in soils is becoming increasingly common, thereby posing serious threat to soil–plant systems. Cadmium (Cd) is the most common metal contaminant in soil and can easily combine with MPs, thereby altering its bioavailability. However, few studies have focused on the co-pollution of MPs and Cd, particularly the complex phytotoxicity caused by their interaction and the effect of co-exposure on Cd uptake in plants. We conducted pot experiments to compare the effects of exposure to polystyrene (PS) and Cd, as well as the effects of co-exposure (PS + Cd), on the physiological characteristics of Brassica chinensis L. and explored the regulatory factors of MPs on Cd uptake in plant tissues. The results showed that plant biomass, photosynthetic parameters, and chlorophyll content significantly decreased (p < 0.05) with increasing PS doses under treatment with MPs alone. Although the negative effects of PS and Cd co-exposure on plants were higher than those of PS alone, however, the addition of MPs reduced the toxicity effects of Cd on plants and decreased the uptake and accumulation of Cd by plants compared with the Cd treatment alone. Furthermore, plants can resist the increased malondialdehyde content and oxidative stress induced by PS and Cd exposure by increasing the activities of superoxide dismutase and peroxidase. Under the PS + Cd treatment, linear models showed that soil organic carbon and sucrase activity were the key variables affecting Cd uptake by plant shoots and roots, respectively. The results of the partial least squares path modeling further showed that PS indirectly affected Cd uptake by B. chinensis by significantly affecting the physicochemical properties of soil, Cd concentration, and enzyme activity. Our results provide a new perspective and an important reference for further understanding the effects of MPs on the bioavailability and fate of heavy metals.

 共 17423 条记录  本页 20 条  本页从 241-260 条  13/872页  首页 上一页  8 9 10 11 12 13 14 15 16 17 18  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。