论文检索

总访问量：5926902次

总访客量：428932人

所有论文

25621. 题目: Organic carbon burial and sources in soils of coastal mudflat and mangrove ecosystems
文章编号: N19122814
期刊: CATENA
作者: Sigit D. Sasmito, Yakov Kuzyakov, Ali Arman Lubis, Daniel Murdiyarso, Lindsay B. Hutley, Samsul Bachri, Daniel A. Friess, Christopher Martius, Nils Borchard
更新时间: 2019-12-28
摘要: Mangrove organic carbon is primarily stored in soils, which contain more than two-thirds of total mangrove ecosystem carbon stocks. Despite increasing recognition of the critical role of mangrove ecosystems for climate change mitigation, there is limited understanding of soil organic carbon sequestration mechanisms in undisturbed low-latitude mangroves, specifically on organic carbon burial rates and sources. This study assessed soil organic carbon burial rates, sources and stocks across an undisturbed coastal mudflat and mangrove hydrogeomorphological catena (fringe mangrove and interior mangrove) in Bintuni Bay, West Papua Province, Indonesia. ²¹⁰Pb radionuclide sediment dating, and mixing model of natural stable isotope signatures (δ ¹³C and δ¹⁵N) and C/N ratio were used to estimate organic carbon burial rates and to quantify proportions of allochthonous (i.e., upland terrestrial forest) and autochthonous (i.e., on-site mangrove forest) organic carbon in the top 50 cm of the soil. Burial rates were in the range of 0.21–1.19 Mg C ha⁻¹ yr⁻¹. Compared to the fringe mangroves, organic carbon burial rates in interior mangroves were almost twice as high. Primary productivity of C₃ upland forest vegetation and mangroves induced soil organic carbon burial in interior mangroves and this was consistent with the formation of the largest organic carbon stocks (179 ± 82 Mg C ha⁻¹). By contrast, organic carbon stored in the fringe mangrove (68 ± 11 Mg C ha⁻¹) and mudflat (62 ± 10 Mg C ha⁻¹) soils mainly originated from upland forests (allochthonous origin). These findings clearly indicate that carbon sequestered and cycling in mangrove and terrestrial forest ecosystems are closely linked, and at least a part of carbon losses (e.g., erosion) from terrestrial forests is buried in mangrove ecosystems.
图文摘要:

25622. 题目: Modeling soil organic carbon spatial distribution for a complex terrain based on geographically weighted regression in the eastern Qinghai-Tibetan Plateau
文章编号: N19122813
期刊: CATENA
作者: Dong Wang, Xinxing Li, Defu Zou, Tonghua Wu, Haiyan Xu, Guojie Hu, Ren Li, Yongjian Ding, Lin Zhao, Wangping Li, Xiaodong Wu
更新时间: 2019-12-28
摘要: Permafrost regions store a large amount soil organic carbon (SOC), and the decomposition of these carbon pools can release greenhouse gases and further strength climate warming. An explicit spatial distribution of SOC is one of the basic databases for Earth System Models. However, efficient approaches for obtaining the spatial distribution of SOC remain challenging, especially in mountainous areas which are characterized by complex terrains. Here, we modeled the spatial SOC distribution using the geographically weighted regression (GWR) approach in an area on the eastern part of the Qinghai-Tibetan Plateau (QTP). We analyzed multiple environmental variables and soil profile data (n = 73) to find the best prediction models for the SOC density (SOCD) for the 0–50 cm layers. The results showed that normalized difference vegetation index (NDVI), elevation, and slope gradient are the significant predictors for the SOCD. For the upper 50 cm soil layers, the SOCD ranged from 1.08 to 18.32 kg·m⁻², with higher values in mountain slopes but lower values in mountain valleys and basins. The GWR model had a higher prediction accuracy in the modeling SOCD in comparison with other models such as ordinary kriging (OK) interpolation, multiple linear regression (MLR) model. Our results showed that GWR model is a useful tool for modeling of SOC distribution and potentially can be integrated into Earth system models in areas of complex terrains.

25623. 题目: Comparative study of individual and Co-Application of biochar and wood vinegar on blueberry fruit yield and nutritional quality
文章编号: N19122812
期刊: Chemosphere
作者: Yuchan Zhang, Xiao Wang, Bingjie Liu, Qiang Liu, Hao Zheng, Xiangwei You, Ke Sun, Xianxiang Luo, Fengmin Li
更新时间: 2019-12-28
摘要: Biochar and its by-product, wood vinegar, have attracted extensive attention owing to their great potentials in improving degraded soil, which is a global concern because of the threats to soil productivity and food security. However, the effect of biochar or wood vinegar on blueberry production is unknown. Therefore, a field trial was conducted to investigate the effects of individual and co-application of biochar (BC450) and wood vinegar (WV450) derived from blended wood waste on the blueberry tree (Vaccinium corymbosum L.) growth, fruit yield, appearance, and nutritional quality as well as the soil properties and nutrient availability. Regardless of individual or co-application, all the amendments had little effect on tree growth. Although BC450 and WV450 increased the fruit yield, the differences between the amended treatments were non-significant. Both the amendments had little effect on the apparent fruit quality, but improved the nutritional quality has been improved (e.g., increased vitamin C and decreased titratable acidity). Additionally, the individual or co-application of BC450 and WV450 had little effect on soil properties (except for soil organic matter), but increased the soil nutrient availability (e.g., NH₄⁺-N, NO₃⁻-N, and Mg). The enhancement in the nutritional quality of the blueberry fruit can be mainly attributed to the increased nutrient availability. This is the first preliminary study that demonstrates that the individual or co-application of biochar and wood vinegar can be a potential strategy for reclaiming degraded soil and enhancing blueberry production.
图文摘要:

25624. 题目: Synergistic construction of green tea biochar supported nZVI for immobilization of lead in soil: A mechanistic investigation
文章编号: N19122811
期刊: Environment International
作者: Sandip Mandal, Shengyan Pu, Lixiang Shangguan, Shibin Liu, Hui Ma, Sangeeta Adhikari, Deyi Hou
更新时间: 2019-12-28
摘要: Biochar-based nanocomposites with functional materials provide an excellent prospect in reactivity and stability. Most biochar reported have no reusability upon aging and offer the risk of release of immobilized components after short-term immobilization. To overcome this, we developed nano zero-valent iron (nZVI) impregnated magnetic green tea biochar (nZVI@GTBC) and studied its performance in immobilizing Pb and long-term effectiveness in the soil. The reactive nZVI units were obtained from iron oxide solution by reducing with polyphenol solution (green tea extract) and were successively stabilized by impregnation onto the remaining green tea waste matrix through co-precipitation technique. Finally, the magnetic biochar was developed from the above nZVI impregnated green tea waste through oven drying and slow pyrolysis technique in different temperature range (150–650 °C). The synthesized nZVI@GTBC biochar was characterized and studied by XRD, FTIR, Raman, UV–Vis, TG/DSC, XPS, SEM, and TEM. The nZVI@GTBC obtained with a particle size of 130 nm and surface charge of +2.8 C/m² at 450 °C. Moreover, colloidal stability and mobility experiments were considered to explain the transport behavior and stability of bare nZVI and magnetic nZVI@GTBC in the soil. The immobilization of Pb by pristine nZVI, GTBC, and nZVI@GTBC was compared and explained under different soil pH conditions. The bioavailability of Pb content before and after immobilization was investigated through leaching experiments. Further, thirty days of soil incubation were carried out to examine different species of Pb according to the Tessier sequential extraction scheme. The study suggested that nZVI@GTBC enhanced the immobilization efficiency by 19.38% in comparison with pristine nZVI and 57.14% in comparison with bare GTBC biochar.
图文摘要:

25625. 题目: (Im)mobilization and speciation of lead under dynamic redox conditions in a contaminated soil amended with pine sawdust biochar
文章编号: N19122810
期刊: Environment International
作者: Jingzi Beiyuan, Yasser M. Awad, Felix Beckers, Jianxu Wang, Daniel C.W. Tsang, Yong Sik Ok, Shan-Li Wang, Hailong Wang, Jörg Rinklebe
更新时间: 2019-12-28
摘要: Biochar can reduce the mobility and availability of potentially toxic elements (PTEs) in soils and improve soil properties. However, immobilization efficiencies of biochar can be varied according to environmental conditions, such as pH and redox potential (E_h), especially for soils under flood-dry cycles. In the current study, biochar produced at 300 and 550 °C (referred as BC300 and BC550, respectively) and its feedstock (pine sawdust biomass, BM) were used to amend a lead (Pb)-contaminated soil under pre-defined redox windows (from −300 to +250 mV). Key features of the soil-solution were evaluated in detail, including pH, dissolved organic carbon, sulphate, and dissolved Al, Fe, and Mn. The BC550 reduced the amount of dissolved Pb and showed a different pattern of E_h-pH in the soil slurry compared with BM and BC300. This might be attributed to its higher alkalinity and surface area. The highest amount of dissolved Pb was found at slightly anoxic conditions (−100 to 0 mV) in CS (control soil), S&BM (soil amended with BM), and S&BC300 (soil amended with BC300), which could be associated with the dissolution of Fe/Mn oxides. Moreover, the fitting results of Pb X-ray absorption fine structure (XAFS) indicated that the proportion of Pb(CH₃COO)₂ was decreasing when changing from anoxic to oxic condition in S&BC300, while the Pb speciation pattern in soil was stable in S&BC550. These results suggested that BC550 is more suitable amendment for Pb immobilization than BM and BC300 in this study. In addition, biochar produced at higher temperatures can be more stable so it can be suitable for remediation of Pb-contaminated soils which are frequently flooded.
图文摘要:

25626. 题目: Disturbance, carbon physicochemical structure, and soil microenvironment codetermine soil organic carbon stability in oilfields
文章编号: N19122809
期刊: Environment International
作者: Juejie Yang, Jian Wang, Aiyang Li, Guanghe Li, Fang Zhang
更新时间: 2019-12-28
摘要: The stability of soil organic carbon (SOC) is crucial for soil quality, fertility, and natural attenuation processes of pollutants. The physicochemical structures of SOC were believed to control its stability, yet has become controversial. Here we hypothesized that disturbance intensity and variations in the soil environment can also influence the SOC stability, and conducted a case study with oil contaminated soils to quantify the contributions to SOC stability of various factors including contamination level, carbon physicochemical structure, and soil properties. Oil contamination led to increased SOC stability, as suggested by appreciably decreased soil CO₂ fluxes, the enrichment of the δ¹³C in the oil contaminated soils, as well as analysis of soil aggregates and humic substances. Redundancy analysis indicated that overall SOC stability were highly correlated to microaggregate (M2), HA/FA, Fe, soil porosity, EC, pH, and total petroleum hydrocarbon (TPH) in oilfields. Variance partitioning analysis showed that carbon physicochemical structure (S), soil properties (P), and oil contamination (O) could explain the variance of overall SOC stability by up to 90%, while 18% of the variation was explained by S × P and 43% by S × P × O. These results show that multiple factors of the disturbance, carbon physicochemical structure, and soil properties should be essential for future studies of SOC stability.
图文摘要:

25627. 题目: Treatment of biodigested coffee processing wastewater using Fenton’s oxidation and coagulation/flocculation
文章编号: N19122808
期刊: Environmental Pollution
作者: Valciney Gomes de Barros, Carmen S.D. Rodrigues, Wilmar Alirio Botello-Suárez, Rose Maria Duda, Roberto Alves de Oliveira, Eliana S. da Silva, Joaquim L. Faria, Rui A.R. Boaventura, Luis M. Madeira
更新时间: 2019-12-28
摘要: Biodigested coffee processing wastewater (CPW) presents a high organic load and does not meet the limits imposed by legislation (namely in Brazil) for discharge into water bodies. Anaerobic digestion generally cannot provide a satisfactory organic matter reduction in CPW as a significant fraction of recalcitrant compounds still persists in the treated effluent. So, this study aims to find alternative ways to remove refractory organic compounds from this wastewater in order to improve the biodegradability and reduce the toxicity, which will allow its recirculation back into the anaerobic digester. Three treatment approaches (Fenton’s oxidation - Approach 1, Coagulation/flocculation (C/F) - Approach 2, and the combination of C/F with Fenton’s process - Approach 3) were selected to be applied to the biodigested CPW in order to achieve that objective.The application of the Fenton process under the optimal operating conditions (initial pH = 5.0; T = 55 °C, [Fe³⁺] = 1.8 g L⁻¹ and [H₂O₂] = 9.0 g L⁻¹) increased the biodegradability (the BOD₅:COD ratio raised from 0.34 ± 0.02 in biodigested CPW to 0.44 ± 0.01 after treatment) and eliminated the toxicity (0.0% of Vibrio fischeri inhibition) along with moderate removals of organic matter (51.3%, 55.7% and 39.7% for total organic carbon – TOC, chemical oxygen demand – COD and biochemical oxygen demand - BOD₅, respectively). The implementation of a coagulation/flocculation process upstream from Fenton’s oxidation, under the best operating conditions (pH 10–11 and [Fe³⁺] = 250 mg L⁻¹), also allowed to slightly increase the biodegradability (from 0.34 to 0.47) and reduce the toxicity, whereas providing a higher removal of organic matter (TOC = 76.2%, COD = 76.5 and BOD₅ = 66.3% for both processes together). Approach 1 and Approach 3 showed to be the best ones, implying similar operating costs (∼74 R$ m⁻³/∼17 € m⁻³) and constitute an attractive option for managing biodigested CPW.
图文摘要:

25628. 题目: Degradation of glyphosate in a Colombian soil is influenced by temperature, total organic carbon content and pH
文章编号: N19122807
期刊: Environmental Pollution
作者: Angelica M. Muskus, Martin Krauss, Anja Miltner, Ute Hamer, Karolina M. Nowak
更新时间: 2019-12-28
摘要: Glyphosate is one of the most used herbicides in the world. The fate of glyphosate in tropical soils may be different from that in soils from temperate regions. In particular, the amounts and types of non-extractable residues (NER) may differ considerably, resulting in different relative contributions of xenoNER (sorbed and sequestered parent compound) and bioNER (biomass residues of degraders). In addition, environmental conditions and agricultural practices leading to total organic carbon (TOC) or pH variation can alter the degradation of glyphosate. The aim of this study is thus to investigate how the glyphosate degradation and turnover are influenced by varying temperature, pH and TOC of sandy loam soil from Colombia. The pH or TOC of a Colombian soil was modified to yield five treatments: control (pH 7.0, TOC 3%), 4% TOC, 5% TOC, pH 6.5, and pH 5.5. Each treatment received 50 mg kg⁻¹ of ¹³C₃¹⁵N-glyphosate and was incubated at 10 °C, 20 °C and 30 °C for 40 days. Rising temperature increased the mineralization of ¹³C₃¹⁵N-glyphosate from 13 to 20% (10 °C) to 32–39% (20 °C) and 41–51% (30 °C) and decreased the amounts of extractable ¹³C₃¹⁵N-glyphosate after 40 days of incubation from 13 to 26% (10 °C) to 4.6–12% (20 °C) and 1.2–3.2% (30 °C). Extractable ¹³C₃¹⁵N-glyphosate increased with higher TOC and higher pH. Total ¹³C-NER were similar in all treatments and at all temperatures (47%–60%), indicating that none of the factors studied affected the amount of total ¹³C-NER. However, ¹³C-bioNER dominated within the ¹³C-NER pool in the control and the 4% TOC treatment (76–88% of total ¹³C-NER at 20 °C and 30 °C), whereas in soil with 5% TOC and pH 6.5 or 5.5 ¹³C-bioNER were lower (47–61% at 20 °C and 30 °C). In contrast, the ¹⁵N-bioNER pool was small (between 14 and 39% of the ¹⁵N-NER). Thus, more than 60% of ¹⁵N-NER is potentially hazardous xenobiotic NER which need careful attention in the future.
图文摘要:

25629. 题目: Impacts of the Three-North shelter forest program on the main soil nutrients in Northern Shaanxi China: A meta-analysis
文章编号: N19122806
期刊: Forest Ecology and Management
作者: Han Gao, Yimei Huang
更新时间: 2019-12-28
摘要: Vegetation restoration in arid and semi-arid areas plays an extremely important role in improving the ecological environment and preventing soil erosion. The construction of the Three-North Shelter Forest (SF) in Northwestern China commenced several decades ago to increase forest productivity, improve soil fertility, and achieve better ecological benefits in arid and semi-arid zone. To date, many studies have researched the effect of SF on the soil nutrients in Northern Shaanxi, China, but their results have often been contradictory. Therefore, we could comprehensively review these studies to evaluate the impacts of SF on soil nutrients from the following three aspects: soil layer, planting year and tree species. This study compiles the results of 2308 observations from studies ranging from 1978 to 2018 to assess the effects of SF on the distribution of the soil organic carbon, total nitrogen, available phosphorus, and available potassium contents in Northern Shaanxi, China. Compared with farmland or abandoned land, the results showed that the greatest increases in the soil organic carbon (118.57%) and total nitrogen (86.19%) contents were observed in the 0–20 and 20–40 cm soil layers, respectively. However, compared with farmland or abandoned land, the greatest increases in both the soil available phosphorus (14.17%) and available potassium (71.13%) contents were observed in the 0–20 cm soil layer. Planting Pinus Sylvestris var. mongolica (PS) is more conducive for increasing the soil organic carbon (120.86%) and available phosphorus (74.33%) contents. Additionally, Pinus tabuliformis (PT) is more beneficial for increasing the soil total nitrogen content (73.82%). Meanwhile, Robinia pseudoacacia (RP) and Caragana korshinskii (CK) are more effective for increasing the available potassium (72.93%) content. This study demonstrated that soil organic carbon (104.07%), total nitrogen (130.28%), and available potassium (125.60%) contents were most affected in planting years >30 years, and the available phosphorus content was most affected in planting years 0–10 years (27.33%). In conclusion, SF can significantly increase soil nutrient contents in areas of Northern Shaanxi, China. Planting shelter forest is recommended to improve the soil environment and achieve the greatest soil fertility benefits.

25630. 题目: Fabrication of sustainable manganese ferrite modified biochar from vinasse for enhanced adsorption of fluoroquinolone antibiotics: Effects and mechanisms
文章编号: N19122805
期刊: Science of The Total Environment
作者: Yujia Xiang, Xiao Yang, Zhangyi Xu, Wenyong Hu, Yaoyu Zhou, Zhonghao Wan, Yuhui Yang, Yuyi Wei, Jian Yang, Daniel C.W. Tsang
更新时间: 2019-12-28
摘要: An effective adsorbent towards fluoroquinolone antibiotics was synthesized via a facile two-step approach, the co-precipitation of Fe, Mn with vinasse wastes and then pyrolysis under controlled conditions which denoted as FMB. Its adsorption behavior was examined based on a batch adsorption experiment of fluoroquinolone antibiotics pefloxacin (PEF) and ciprofloxacin (CIP). Experimental factors, such as pH, adsorbent dose, ionic strength, contact time and temperature have done a great deal to influence the adsorption of PEF and CIP. The FMB demonstrated excellent performance in reusability tests towards to both PEF and CIP, which showed that the recycling efficiency of PEF and CIP could remain ~55% and ~80% after five recycle cycles, respectively. The dominated adsorption mechanisms included pore filling effect, π-π stacking interaction, π-π EDA, hydrogen bonding and hydrophobicity. Overall, this work presented FMB was recognized as an effective, environmental-friendly and magnetically separable adsorbent for alleviating fluoroquinolone antibiotics contamination from water.
图文摘要:

25631. 题目: Critical contribution of south Asian residential emissions to atmospheric black carbon over the Tibetan plateau
文章编号: N19122804
期刊: Science of The Total Environment
作者: Junhua Yang, Shichang Kang, Zhenming Ji
更新时间: 2019-12-28
摘要: Black carbon (BC) over the Tibetan Plateau (TP), both in the air and deposited on the surface of snow and ice, has been shown to accelerate the retreat of mountain glaciers. Previous study indicated that South Asian anthropogenic emissions primarily contributed to atmospheric loading of BC over the TP, it is essential to further identify the major sector in South Asia and provide guidance for potential mitigation strategies. In this study, the regional atmospheric chemistry model WRF-Chem was run for an entire year. The results suggested that residential BC emissions from South Asia contributed the largest (25.8% in summer and 44.8% in winter) to BC concentrations over the TP compared to other anthropogenic emission sectors in the region. Furthermore, significant seasonal variability existed in the transport process of residential BC from South Asia to the TP. The South Asia monsoon during summer and the mountain-valley wind system during spring could transport South Asian residential BC across the Himalayas to the TP. However, the higher transportation flux along 30°N indicated that the transport was mainly influenced by westerly winds, implying that residential emissions from northern India were the critical source of BC aerosols over the TP. A further assessment of emission control strategies suggested that reducing emissions from South Asian residential sources can effectively reduce BC concentrations over the TP, which may potentially alleviate the TP's accelerating glacier melting.
图文摘要:

25632. 题目: Carbon isotopes of n-alkanoic acids in Antarctic ornithogenic sediments as indicators of sedimentary lipid sources and paleocological change
文章编号: N19122803
期刊: Science of The Total Environment
作者: Xin Chen, Yangyang Wei, Yaguang Nie, Jianjun Wang, Steven D. Emslie, Xiaodong Liu
更新时间: 2019-12-28
摘要: Sedimentary n-alkanoic acids are ubiquitous in the environment and their carbon isotopic composition is increasingly used to identify the source of organic matter and to reconstruct past climatic and ecological changes. Here we investigate the distribution and carbon isotope ratios of n-alkanoic acids in two sediment profiles influenced by animal excrement in Antarctica. We found that organic matter input from animal excrement is the predominate source of short- and mid-chain n-alkanoic acids in the ornithogenic sediments. Decreased δ¹³C values are closely related to increased excrement input of penguins and seals that occupied the study site, especially in C₁₆ n-alkanoic acid. Long-chain (>C₂₄) n-alkanoic acids likely originate from moss and heterotrophic microbes, and the δ¹³C values of C₂₆ n-alkanoic acid were consistent with organic biomarkers and bio-elements from animal excrement. Two possible processes are suggested to explain the close relationship between C₂₆ n-alkanoic acid δ¹³C values and animal excrement input. All the results indicate that the carbon isotopes of n-alkanoic acids in ornithogenic sediments can be used to indicate historical population change of penguins or seals in Antarctica.
图文摘要:

25633. 题目: An agricultural practise with climate and food security benefits: “Claying” with kaolinitic clay subsoil decreased soil carbon priming and mineralisation in sandy cropping soils
文章编号: N19122802
期刊: Science of The Total Environment
作者: Samantha P. Grover, Clayton R. Butterly, Xiaojuan Wang, Deirdre B. Gleeson, Lynne M. Macdonald, David Hall, Caixian Tang
更新时间: 2019-12-28
摘要: As the agricultural sector seeks to feed a growing global population, climate-smart agriculture offers opportunities to concurrently mitigate climate change by reducing greenhouse gas emissions and/or increasing carbon storage in soils. This study examined the potential for clay addition to reduce CO₂ emissions from plant residues and soil organic matter in a sandy soil. Soils were sourced from a 15-year-old field trial where claying (200 t ha⁻¹) had already demonstrated improvements in water infiltration, grain yield and profits. Isotopically labelled plant residues (wheat, canola, or pea) were used to separate residue-derived and soil-derived CO₂ sources from a nil-clay control, a historically clayed, and two freshly created soils with either high (10%) or low (3%) subsoil clay additions. Laboratory incubations demonstrated that historically clayed soils released less CO₂ from plant residues and soil organic matter. Clay addition also decreased the priming effect of adding fresh residue to soils. The results from clay experimentally added in the laboratory varied. Differences in chemical and biological indicators (pH, microbial biomass C and N, extractable organic C and N, NO₃⁻, NH₄⁺, abundance of bacterial, archaeal, fungal, LMCO, GH48 and CbhI genes) did not correlate with patterns of CO₂ emissions across treatments. While claying practices have previously demonstrated benefits to crop productivity, this research demonstrates long-term changes in carbon-cycling that could promote greater carbon sequestration.
图文摘要:

25634. 题目: Characterization and fate of EfOM during ozonation applied for effective abatement of recalcitrant micropollutants
文章编号: N19122801
期刊: Separation and Purification Technology
作者: Alberto Cruz-Alcalde, Santiago Esplugas, Carme Sans
更新时间: 2019-12-28
摘要: Alterations occurring in the effluent organic matter (EfOM) during ozonation could be detrimental depending on the final application of the treated effluent. In this work, the fate of EfOM in different ozonized wastewaters was assessed through the monitoring of general water quality parameters and organic fractions determined through size-exclusion chromatography combined with organic carbon detection (SEC-OCD) analysis. These different components of EfOM were distinguished based on relative molecular weights and assigned to fractions named as biopolymers, humic substances, building blocks and low molecular weight neutrals and acids. The significant abatement (60–90%) of an ozone-refractory micropollutant (MP) was employed as reference to simulate potential scenarios in which also the presence of these species is wanted to be attenuated. Ultraviolet absorbance at 254 nm (UVA₂₅₄) and chemical oxygen demand (COD) reductions ranged from 40 to 80% and from 10 to 45%, respectively, for ozone doses between 0.6 and 1.0 mM, depending on the organic matter content (both dissolved and suspended) and alkalinity of the effluents. Dissolved organic carbon (DOC) analysis showed 21–27% reductions in Membrane bioreactor (MBR) effluents, whereas for conventional activated sludge (CAS) samples this value increased (6–35%) during the oxidative treatment. This was attributed to the continuous solubilization of humic substances, according to SEC-OCD results. Moreover, accumulation of lower molecular weight fractions such as building blocks or acids was observed in all the tested effluents, and attributed to the breakdown of largest EfOM fractions, mainly humic substances. Relationships proposed in this work between humic substances evolution, water quality (UVA₂₅₄) and process parameters (immediate ozone demand (IOD), IOD-normalized hydroxyl radical exposure (∫[OH]dt/IOD) and transferred ozone dose (TOD)) might be useful for EfOM variations estimations along ozonation.
图文摘要:

25635. 题目: DNA metabarcoding reveals organisms contributing to particulate matter flux to abyssal depths in the North East Pacific ocean
文章编号: N19122706
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: Christina M. Preston, Colleen A. Durkin, Kevan M. Yamahara
更新时间: 2019-12-27
摘要: The sequestration of carbon in the deep ocean relies on the export of sinking particulate organic matter (POM) originating in the surface waters and its attenuation by organisms that reprocess and repackage it. Despite decades of research, predicting the variability of POM to the deep ocean remains difficult as there is still a gap in the knowledge as to which and how organisms control or influence POM export. Here, we used DNA metabarcoding of the 16S and 18S rRNA genes to investigate the community in sinking particulates collected over 9-months (November 2016–July 2017) at Station M, located within the California Current ecosystem. Particle-associated communities were collected in sediment traps (3900 m and 3950 m), in aggregates that settled on the sea floor (4000 m), and in seawater from the overlying water column. For a majority of the deployment, particulate organic carbon (POC) fluxes were within the Station M long-term time series mean ± σ (8.3 ± 7.9 mg C m−2 d−1). In late June, a high flux event (>long-term POC mean+2σ) was captured, accounting for 44% of the POC collected during the study. The rRNA genes within the sinking particles indicated highly variable eukaryal communities over time, including the export of oligotrophic autotrophs likely by various metazoan taxa during winter, the sporadic and dominant presence of diverse radiolarian orders, and the important role of coastal diatoms during seasonal increases in POC flux. Specifically, the onset of the high POC flux event in June was attributed to the export of a single coastal diatom species. A coincident increase in the relative abundance of metazoan sequences suggests that zooplankton grazing on the diatom community played a role in rapid transport of large quantities of POC to the deep sea. Analysis of the 16S rRNA gene community supported the presence of highly processed POM during winter due to the high relative abundance of deep sea Gammaproteobacteria, that transitioned to fresher, more labile POM with the arrival of a diatom bloom community. These observations support long standing paradigms of particulate export to the deep sea, including its origin and mechanisms of export mediated by a diverse community of organisms, and implicate rapidly exported diatom blooms as at least one source of the increasingly frequent episodic flux events that account for most POC sequestered in the deep ocean at Station M.

25636. 题目: Soil nitrogen cycling is determined by the competition between mycorrhiza and ammonia‐oxidizing prokaryotes
文章编号: N19122705
期刊: Ecology
作者: Chikae Tatsumi, Takeshi Taniguchi, Sheng Du, Norikazu Yamanaka, Ryunosuke Tateno
更新时间: 2019-12-27
摘要: Mycorrhizal fungi have considerable effects on soil carbon (C) storage, as they control the decomposition of soil organic matter (SOM), by modifying the amount of soil nitrogen (N) available for free‐living microbes. Through their access to organic N, ectomycorrhizal (ECM) fungi compete with free‐living soil microbes; this competition is thought to slow down SOM decomposition. However, arbuscular mycorrhizal (AM) fungi cannot decompose SOM, and therefore must wait for N to first be processed by free‐living microbes. It is unclear what form of N the ECM fungi and free‐living microbes compete for, or which microbial groups compete for N with ECM fungi. To investigate this, we focused on the N transformation steps (i.e., the degradation of high‐molecular‐weight organic matter, mineralization, and nitrification) and the microbes driving each step. Simple comparisons between AM forests and ECM forests are not sufficient to assert that mycorrhizal types would determine the N transformation steps in soil, because soil physiochemistry, which strongly affects N transformation steps, differs between the forests. We used an aridity gradient with large differences in soil moisture, pH, and SOM quantity and quality, to distinguish the mycorrhizal and physicochemical effects on N transformation. Soil samples (0–10 cm depth) were collected from AM‐symbiotic black locust forests under three aridity levels, and from ECM‐symbiotic oak forests under two aridity levels. Soil physicochemical properties, extractable N dynamics and abundance, composition, and function of soil microbial communities were measured. In ECM forests, the ammonia‐oxidizing prokaryotic abundance was low, whereas that of ECM fungi was high, resulting in lower nitrate N content than in AM forests. Since ECM forests did not have lower saprotrophic fungal abundance and prokaryotic decompositional activity than the AM forests, the hypothesis that ECM fungi could reduce SOM decay and ammonification by free‐living microbes, might not hold in ECM forests. However, the limitation of ECM fungi on nitrate N production would result in a feedback that will accelerate plant dependence on these fungi, thereby raising soil C storage through an increase in the ECM biomass and plant C investment in soils.

25637. 题目: Potential of pistachio shell biochar and dicalcium phosphate combination to reduce Pb speciation in spinach, improved soil enzymatic activities, plant nutritional quality, and antioxidant defense system
文章编号: N19122704
期刊: Chemosphere
作者: Veysel Turan
更新时间: 2019-12-27
摘要: Lead-contaminated soils are becoming an ecological risk to the environment because of producing low-quality food which is directly causing critical health issues in humans and animals. We hypothesized that incorporation of dicalcium phosphate (DCP), eggshell powder (ESP) and biochar (BH) at diverse rates into a Pb-affected soil can proficiently immobilize Pb and decline its bioavailability to spinach (Spinacia oleracea L.). A soil was artificially spiked with Pb concentration (at 600 mg kg⁻¹) and further amended with DCP, ESP, and BH (as sole treatments at 2% and in concoctions at 1% each) for immobilization of Pb in the soil. The interlinked effects of applied treatments on Pb concentrations in shoots and roots, biomass, antioxidants, biochemistry, and nutrition of spinach were also investigated. Results depicted that the highest reduction in DTPA-extractable Pb and the concentrations of Pb in shoots and roots was achieved in DCP1%+BH1% treatment that was up to 58%, 66%, and 53%, respectively over control. Likewise, the DCP1%+BH1% treatment also showed the maximum shoot and root dry weight (DW), chlorophyll-a (Chl-a) and chlorophyll-b (Chl-b) contents and relative water content (RWC) in spinach up to 92%, 121%, 60%, 65%, and 30%, respectively, compared to control. Likewise, DCP1%+BH1% treatment noticeably improved antioxidant enzymes, biochemistry, and nutrition in the leaves. Moreover, the DCP1%+BH1% treatment depicted mostly enhanced activities of dehydrogenase, catalase, acid phosphatase, alkaline phosphatase, phosphomonoesterase, urease, protease and B-glucosidase in the post-harvested soil up to 118%, 345%, 55%, 92%, 288%, 107%, 53% and 252%, respectively over control.

25638. 题目: Effects of spent mushroom substrate-derived biochar on soil CO₂ and N₂O emissions depend on pyrolysis temperature
文章编号: N19122703
期刊: Chemosphere
作者: Bangliang Deng, Yanzhen Shi, Ling Zhang, Haifu Fang, Yu Gao, Laicong Luo, Weixun Feng, Xiaofei Hu, Songze Wan, Wei Huang, Xiaomin Guo, Evan Siemann
更新时间: 2019-12-27
摘要: Edible mushroom cultivation is an important industry in intensively managed forest understories. However, proper disposal of spent mushroom substrate (SMS) presents a challenge to its sustainable development. Biochar derived from SMS could be used to improve soil quality while providing a solution for SMS disposal. But SMS biochar pyrolyzed at different temperatures may alter carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions associated with global warming, especially under the context of nitrogen (N) addition and warming. We conducted a factorial incubation study to examine greenhouse gas emissions and N transformations in moso bamboo forest soil amended with SMS-biochar (control vs. pyrolyzed at 300, 450 or 600 °C) in different N-addition (0 or 100 mg N kg^-1 soil) and temperature (20, 25 or 30 °C) treatments. Pyrolysis temperature affected pH, C and N of SMS-biochars. N-transformations depended on the interaction of pyrolysis temperature, N-addition, and incubation temperature but were generally lower with 450 °C biochar addition. Soil N₂O emissions increased with N-addition and they were more sensitive to incubation temperatures without biochar. Soil CO₂ emissions increased with incubation temperature or biochar pyrolyzed at lower temperatures. Pyrolysis temperature might have regulated the effects of SMS-derived biochar on N₂O emissions via changes in dissolved C, N, pH and associated changes in soil microbial community compositions. Because of the importance of sustainable development of this understory industry, amending soils with biochar produced at higher temperatures may be the best strategy for both the disposal of SMS and the mitigation of greenhouse gas emissions.
图文摘要:

25639. 题目: Carbon budget for a large drowned river valley estuary adjacent to an emerging megacity (Sydney Harbour)
文章编号: N19122702
期刊: Journal of Geophysical Research: Biogeosciences
作者: E.L. Tanner, B.D. Eyre
更新时间: 2019-12-27
摘要: Annual organic and inorganic carbon budgets were constructed for the Sydney Harbour Estuary. Net ecosystem metabolism was the main control on carbon fluxes in the system. Sydney Harbour Estuary was slightly net heterotrophic, which is consistent with a small CO₂ emission of 0.8x10⁸ mol C y^‐1. Terrestrial carbon loads were 70% dissolved inorganic carbon (DIC), 21% dissolved organic carbon (DOC) and 9% particulate organic carbon (POC). DIC was exported to the ocean (4.19x 10⁸ mol C y ^‐1) and an import of organic carbon (OC) (1.92 x 10⁸ mol C y^‐1) from the ocean was required to balance the budget. Sydney Harbour had high sediment organic carbon burial rates similar to other river valley estuaries including the Hudson River and Chesapeake Bay. Productivity was the main sink of inorganic carbon followed by sediment burial, emissions of CO₂ to the atmosphere and oyster sequestration. This study highlights the importance of determining the sources, sinks and transformations of all carbon forms in constructing estuarine budgets.

25640. 题目: Aerobic release and biodegradation of dissolved organic matter from frozen peat: Effects of temperature and heterotrophic bacteria
文章编号: N19122701
期刊: Chemical Geology
作者: Dahédrey Payandi-Rolland, Liudmila S. Shirokova, Paty Nakhle, Marawit Tesfa, Ahmed Abdou, Carole Causserand, Bruno Lartiges, Jean-Luc Rols, Frédéric Guérin, Pascale Bénézeth, Oleg S. Pokrovsky
更新时间: 2019-12-27
摘要: Understanding the conditions of dissolved organic matter (DOM) release from thawing peat in the Arctic regions and identifying the pathways of processing DOM by soil and aquatic heterotrophic bacteria are critical in the context of rapid climate change. Until now, experimental approaches did not allow quantitative predictions of temperature and biota effects on carbon release from peat in permafrost-affected aquatic environments. In this study, we incubated frozen peat and its aqueous leachate at various temperatures (4, 25 or 45 °C), with and without culturable heterotrophic bacteria Iodobacter sp., extracted from thermokarst lakes, to quantify the release and the removal rate of organic carbon (OC) with time. The metabolic diversity of the native microbial community associated with the substrates involved in OC processing was also characterized. Transmission electron microscopy revealed that, after degradation, the associated bacteria are mostly located in the inner parts of plant cells, and that the degradation of organic matter around bacteria is more pronounced at 4 and 25 °C compared to 45 °C. The metabolic diversity of heterotrophic bacteria was equally high at 4 and 25 °C, but lower at 45 °C. Regardless of the microbial consortium (native community alone or with added culturable heterotrophs), both the OC release from peat and the OC removal from peat leachate by bacteria were similar at 4 and 25 °C. Very low apparent activation energies of DOM biodegradation between 4 and 25 °C (−4.23 ± 12.3 kJ mol⁻¹) suggest that the short-period of surface water warming in summer would have an insignificant effect on DOM microbial processing. Such duration (1–3 weeks) is comparable with the water residence time in peat depressions and permafrost subsidences, where peat degradation and DOM microbial processing occur. This questions the current paradigm of a drastic effect of temperature rise on organic carbon release from frozen peatlands, and should be considered for modelling short-term climate impacts in these regions.