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13801. 题目: Organic management increases soil nitrogen but not carbon content in a tropical citrus orchard with pronounced N2O emissions
文章编号: N19011002
期刊: Journal of Environmental Management
作者: Andréa Sibila Bisca Escanhoela, Leonardo Machado Pitombo, Carolina Braga Brandani, Acacio Aparecido Navarrete, Camila Bolfarini Bento, Janaina Braga do Carmo
更新时间: 2019-01-10
摘要: The use of organic amendments is important for the sustainability of organic farming, with implications for soil organic matter turnover, nutrient cycling and greenhouse gases (GHGs) emissions to the atmosphere. Here, we investigated how long-term citrus organic farming influenced carbon sequestration and GHG emissions under organic and conventional management. We assessed the effects of management systems on soil organic matter dynamics and GHG emissions, focusing on N2O direct emissions from fertilizers. Soil stable isotope C and N compositions (0–100 cm) were used as parameters to assess changes in soil organic matter dynamics, with native forest as the reference. After the conversion from forest to orange orchard, stocks of soil C increased approximately 40 Mg ha−1, whereas stocks were similar in the organic and conventional treatments. Enrichment of 13C through the entire soil profile showed that organic matter from fertilizer replaced the original soil C by at least 20%, considering that poultry was fed only with C4 plants. By contrast, organic farming increased soil N stocks and inorganic N. Nitrogen emission factors for inorganic and organic fertilizers were 1.47 and 3.14, respectively. Organic management increased soil GHG emissions, primarily N2O emissions. Carbon emissions either as CO2 or CH4 were greater at the mid-rows than those under the crop canopy. We conclude that organic management did not promote C sequestration after six years of management. Moreover, organic management increased N2O emissions, and the GHG balance was more negative for organic than that for conventional farming when the ratio between crop harvest and emissions was determined.
图文摘要:

13802. 题目: Different agricultural practices affect soil carbon, nitrogen and phosphorous in Kilombero -Tanzania
文章编号: N19011001
期刊: Journal of Environmental Management
作者: E. Alavaisha, S. Manzoni, R. Lindborg
更新时间: 2019-01-10
摘要: Converting natural and semi-natural vegetation to agriculture is currently the most significant land use change at global scale. This conversion leads to changes in soil nutrients and increased CO2 emissions. However, knowledge of how soil organic carbon and nutrients change under various farming management is still limited, especially for small scale farming systems. This study evaluated the effects of different farming systems on soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) in subsistence farming at Kilombero, Tanzania. We applied an in-situ experimental setup, comparing maize and rice farming with and without irrigation and difference in fertilizers, with replicated soil sampling at five soil depths to a depth of 60 cm. The results show that irrigation had a positive effect on profile-averaged concentrations of SOC and TN, while fertilization had a positive effect on TN. Higher concentrations and stocks of TN were found in maize field soils compered to rice fields. In the vertical profile, irrigation and fertilization had positive effects on concentrations of SOC and TN of top soil layers, and the interaction between irrigation and fertilization extended the effect to deeper soil layers. Our results indicate that moderate irrigation and fertilization can help to improve carbon storage and nutrient availability (TN) in small-scale farming soils in Africa.

13803. 题目: Impact of peatlands on carbon dioxide (CO2) emissions from the Rajang River and Estuary, Malaysia
文章编号: N19010920
期刊: Biogeosciences
作者: Denise Müller-Dum, Thorsten Warneke, Tim Rixen, Moritz Müller, Antje Baum, Aliki Christodoulou, Joanne Oakes, Bradley D. Eyre, Justus Notholt
更新时间: 2019-01-09
摘要: Tropical peat-draining rivers are known as potentially large sources of carbon dioxide (CO2) to the atmosphere due to the high loads of carbon they receive from surrounding soils. However, not many seasonally resolved data are available, limiting our understanding of these systems. We report the first measurements of carbon dioxide partial pressure (pCO2) in the Rajang River and Estuary, the longest river in Malaysia. The Rajang River catchment is characterized by extensive peat deposits found in the delta region, and by human impact such as logging, land use and river damming. pCO2 averaged 2540±189µatm during the wet season and 2350±301µatm during the dry season. Using three different parameterizations for the gas transfer velocity, calculated CO2 fluxes to the atmosphere were 1.5 (0.5–2.0)gCm−2d−1 (mean, minimum – maximum) during the wet season and 1.7 (0.6–2.6)gCm−2d−1 during the dry season. This is at the low end of reported values for Southeast Asian peat-draining rivers, but similar to values reported for Southeast Asian rivers that do not flow through peat deposits. In the Rajang River, peatlands probably do not contribute much to the CO2 flux due to the proximity of the peatlands to the coast, which limits the opportunity for degradation of organic C during transport. Thus, we suggest that peat coverage is, by itself, insufficient as the sole predictor of CO2 emissions from peat-draining rivers, and that other factors, like the spatial distribution of peat in the catchment and pH, also need to be considered.

13804. 题目: Light absorption by ambient black and brown carbon and its dependence on black carbon coating state for two California, USA cities in winter and summer
文章编号: N19010919
期刊: Journal of Geophysical Research: Atmospheres
作者: Christopher D. Cappa, Xiaolu Zhang, Lynn M. Russell, Sonya Collier, Alex K. Y. Lee, Chia-Li Chen, Raghu Betha, Sijie Chen, Jun Liu, Derek J. Price, Kevin J. Sanchez, Gavin R. McMeeking, Leah R. Williams, Timothy B. Onasch, Douglas R. Worsnop, Jon Abbatt, Qi Zhang
更新时间: 2019-01-09
摘要: Observations from a wintertime and summertime field campaign are used to assess the relationship between black and brown carbon (BC and BrC, respectively) optical properties and particle composition and coating state. The wintertime campaign, in Fresno, CA, was impacted by primary emissions from residential wood burning, secondary organic and inorganic particle formation, and BC from motor vehicles. Two major types of BrC were observed in wintertime. One occurred primarily at night—the result of primary biomass burning emissions. The second was enhanced in daytime and strongly associated with particulate nitrate and the occurrence of fog. The biomass‐burning‐derived BrC absorbed more strongly than the nitrate‐associated BrC, but had a weaker wavelength dependence. The wintertime BC‐specific mass absorption coefficient (MACBC) exhibited limited dependence on the ensemble‐average coating‐to‐BC mass ratio (Rcoat‐rBC) at all wavelengths, even up to Rcoat‐rBC of ~5. For the summertime campaign, in Fontana, CA, BC dominated the light absorption, with negligible BrC contribution even after substantial photochemical processing. The summertime MACBC exhibited limited dependence on Rcoat‐rBC, even up to ratios of >10. Based on the four classes of BC‐containing particles identified by Lee et al. (2017) for the summertime measurements, the general lack of an absorption enhancement can be partly—although not entirely—attributed to an unequal distribution of coating materials between the BC‐containing particle types. These observations demonstrate that in relatively near‐source environments, even those impacted by strong secondary aerosol production, the ensemble‐average, mixing‐induced absorption enhancement for BC due to coatings can be quite small.

13805. 题目: Sulfur, iron, and phosphorus geochemistry in an intertidal mudflat impacted by shellfish aquaculture
文章编号: N19010918
期刊: Environmental Science and Pollution Research
作者: Tao Meng, Mao-Xu Zhu, Wei-Wei Ma, Zai-Xin Gan
更新时间: 2019-01-09
摘要: Dissolved sulfide, iron (Fe), and phosphorus (P) in a mudflat (Jiaozhou Bay, China) impacted by shellfish aquaculture were measured in situ by the diffusive gradients in thin films (DGT) technique. A combination of porewater and solid-phase chemistry was used to characterize the interplays of Fe and S, and their control on P mobilization. Below the subsurface layer, two times higher fluxes (FDGT) of dissolved Fe2+ from porewater to the DGT device than those of dissolved sulfide indicate that dissimilatory iron reduction (DIR) dominates over sulfate reduction (SR). Spatial coupling of dissolved Fe2+ and P points to P release driven mainly by reductive dissolution of Fe. Much higher FDGT values of dissolved Fe2+ relative to dissolved P imply that oxidative regeneration of Fe oxides at the sediment–water interfaces (SWIs) of the transitional mudflat serves as an effective “iron curtain” of upward diffusing P. In the mudflat sediments of DIR prevalence, the accumulation of total reduced inorganic sulfur (TRIS) is dampened, which can largely ascribed to enhanced oxidative loss of sulfide and/or limited availability of degradable organic carbon in the dynamic regimes. Low dissolved sulfide concentrations in the sediments leave the majority of reactive Fe unsulfidized and thus abundantly available to buffer newly produced sulfide.

13806. 题目: Influencing factors on soil nutrients at different scales in a karst area
文章编号: N19010917
期刊: CATENA
作者: Miaomiao Wang, Hongsong Chen, Wei Zhang, Kelin Wang
更新时间: 2019-01-09
摘要: Soil carbon (C), nitrogen (N), and phosphorus (P) are some of the most important indicators of soil quality, especially in fragile ecological environments with shallow soils. However, the differences in their variations and influencing factors related to scale in karst areas remain unclear. Therefore, variations in surface soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) distributions and their determinant factors were quantitatively analyzed at different scales (i.e., region, sub-region, and catchment) in a typical karst area, southwest China. Overall, both soil nutrient variations and the determinant factors involved varied with scale. The coefficients of variation for SOC, TN, and TP increased significantly from catchment to sub-region scales but changed only slightly between sub-region and region scales. At region and sub-region scales, lithology only affected TP significantly, while land use affected all soil nutrients significantly. However, the explanations for TP variation by lithology and for SOC, TN, and TP variations by land use increased by 12.2, 7.0, 11.0, and 12.8% at sub-region scale over the values observed at region scale, respectively. When lithology and land use were controlled, soil depth was observed playing an important role in soil nutrients at the three studied scales. At region and sub-region scales, other factors related to soil texture (clay, silt, or sand content), topography (elevation or TWI), and climate (MAT or MAP) were selected as significant variables and accounted for a larger proportion of nutrient variation. However, at catchment scale, bare rock rate and micro-topography (e.g., slope) explained soil nutrient variation to a larger proportion. Therefore, elucidation of the role of factors influencing soil nutrients at different scales can provide a guide for soil quality assessment in karst areas.

13807. 题目: DOM composition alters ecosystem function during microbial processing of isolated sources
文章编号: N19010916
期刊: Biogeochemistry
作者: Juliana D’Andrilli, James R. Junker, Heidi J. Smith, Eric A. Scholl, Christine M. Foreman
更新时间: 2019-01-09
摘要: Dynamics of dissolved organic matter (DOM) in ecosystems are controlled by a suite of interacting physical, chemical, and biological factors. Growing recognition of the associations between microbial communities and metabolism and intrinsic DOM characteristics, highlight the potential importance of microbe-DOM relationships to modulate the role and fate of DOM, yet these relationships are difficult to isolate because they often operate across confounding environmental gradients. In a controlled laboratory incubation (44 days), we integrated DOM bulk and molecular characterization, bacterial abundances, microbial assemblage composition, nutrient concentrations, and cellular respiration to discern the structural dynamics of biological processing among DOM sources from different allochthonous litters (grass, deciduous leaves, and evergreen needles). We identified two periods, consistent among DOM sources, where processing dynamics differed. Further, bulk fluorescent analyses showed shifts from low to high excitation and emission wavelengths, indicating the biological production of more complex/degraded materials over time. Molecular level analyses revealed similar temporal patterns among DOM sources in the production and consumption of individual chemical components varying in reactivity and heteroatomic content. Despite these similarities, total carbon (C) removed and carbon dioxide (CO2) accumulation differed by ~ 20% and 25% among DOM sources. This range in C processing was apparently tied to key chemical properties of the DOM (e.g., initial DOM composition, N content, and labile nature) as well as differential reorganization of the microbial populations that decomposed the DOM. We conclude that the production, transformation, and consumption of C in aquatic ecosystems is strongly dependent on the source and character of DOM as well as the structure of the microbial communities present, both of which change as DOM is processed over time. It is crucial that stream C processing models represent this complexity accurately.

13808. 题目: Biochar synthesized via pyrolysis of Broussonetia papyrifera leaves: mechanisms and potential applications for phosphate removal
文章编号: N19010915
期刊: Environmental Science and Pollution Research
作者: Guoqiang Qiu, Yunlin Zhao, Hui Wang, Xiaofei Tan, Fangxu Chen, Xinjiang Hu
更新时间: 2019-01-09
摘要: In this study, Broussonetia papyrifera leaves collected from land near a restored manganese mine in the Hunan Province of China were converted into biochar under high-temperature anaerobic conditions, regeneration and utilization of agricultural and forest waste, and applied to the prevention of eutrophication. The physicochemical properties of the B. papyrifera biochar were characterized using Micromeritics 3Flex analyzer, scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), thermogravimetric analyzer (TGA), X-ray photoelectron spectrometer (XPS), zeta potential meter (zeta), and X-ray diffraction (XRD). The effects of pH, ionic strength, coexisting ions, time, initial concentration, and temperature on the decontamination process of phosphate in water were studied. The results indicated that adsorption was enhanced under alkaline conditions. The pseudo-second-order model of adsorption kinetics was applied to illustrate the adsorption processes. The chemical adsorption reaction was the main rate-limiting step in the adsorption process. Isotherm experimental data were best fitted by the Freundlich model at 25 °C and by the Langmuir model at 35 °C. The phosphate combined with B. papyrifera biochar mainly in the forms of exchangeable phosphorus (Ex-P), Al-bound phosphorus (Al-P), and Fe-bound phosphorus (Fe-P). These results indicate that B. papyrifera biochar is a suitable candidate for the treatment of a eutrophic body of water.

13809. 题目: Application of a microbial fuel cell-based biosensor for the energy-saving operation of macrophyte residues bioreactor with low concentration of dissolved organic carbon in effluents
文章编号: N19010914
期刊: Chemosphere
作者: Chunliu Wang, Zongbao Yao, Leilei Bai, Changhui Wang, Helong Jiang
更新时间: 2019-01-09
摘要: The increasing application of plant residues bioreactor for aquatic environment remediation may release numerous dissolved organic carbon (DOC) into aquatic ecosystems. In this study, a microbial fuel cell (MFC) sensor was integrated with a macrophyte residues bioreactor (MRBR) to provide an energy-saving way for reduction of DOC concentrations in the effluent. Through re-utilization of macrophyte residues as solid carbon source, DOC concentrations in the effluent of MRBR increased to the maximum on day 5 and then dropped down rapidly to a low value, while the ratio of bioavailable DOC decreased gradually. Interestingly, it was found that there existed a linear relationship between DOC concentrations in initial residue leachate and the voltage from MFC biosensor (R2 = 0.9852). Accordingly, aerobic biofilm through aeration were applied in the upper part of MRBR to enhance the degradation of DOC prior to discharge to aquatic systems, and aeration rate was adjusted based on MFC sensor signal. Further experiments demonstrated that when voltage decreased from 0.18 V to 0.09 V, a half of aeration rate (7.5 L min−1) could still lead to a high DOC degradation efficiency (above 50%) and a low DOC concentration (∼10 mg L−1) in the reactor effluent. Thus, the integrated MFC signal could be used to regulate the aeration rate in order to obtain a low DOC concentration in effluents under an energy-saving way.

13810. 题目: A sustainable solution for removal of glutaraldehyde in saline water with visible light photocatalysis
文章编号: N19010913
期刊: Chemosphere
作者: Soklida Hong, Thunyalux Ratpukdi, Bunleu Sungthong, Jayaraman Sivaguru, Eakalak Khan
更新时间: 2019-01-09
摘要: Glutaraldehyde (GA) is the most common biocide used in unconventional oil and gas production. Photocatalytic degradation of GA in brine simulating oil and gas produced water using Ag/AgCl/BiOCl composite as a photocatalyst with visible light was investigated. Removal of GA at 0.1 mM in 200 g/L NaCl solution at pH 7 was 90% after 75 min irradiation using 5 g/L of the photocatalyst. The GA removal followed pseudo-first order reaction with a rate constant of 0.0303 min−1. At pH 5 or at 300 g/L NaCl, the photocatalytic removal of GA was almost completely inhibited. Similar inhibitions were observed when adding dissolved organic carbon (from humic acid) at 10 and 200 mg/L, or Br at 120 mg/L to the system. The removal rate of GA markedly increased with increasing pH (5–9), photocatalyst loading (2–8 g/L) and under 350 nm UV (compared to visible light). On the contrary, the removal rate of GA markedly decreased with increasing NaCl and initial GA concentrations (0–300 g/L for NaCl and 0.1–0.4 mM for GA). A quenching experiment was also conducted; electron holes (h+) and superoxide () were found as the main reactive species responsible for the removal of GA while ·OH had a very limited effect.
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13811. 题目: Comparison of UV-AOPs (UV/H2O2, UV/PDS and UV/Chlorine) for TOrC removal from municipal wastewater effluent and optical surrogate model evaluation
文章编号: N19010912
期刊: Chemical Engineering Journal
作者: D.B. Miklos, W.-L. Wang, K.G. Linden, J.E. Drewes, U. Hübner
更新时间: 2019-01-09
摘要: UV-based advanced oxidation processes (AOPs) have been widely explored to remove organic contaminants from water streams. In this lab-scale study, the removal of 17 trace organic chemicals (TOrCs) by UV/H2O2, UV/PDS and UV/Chlorine was investigated at equimolar radical promoter concentrations in municipal wastewater. Direct comparison of the UV-AOPs was conducted with eight TOrCs being resistant to direct oxidation by H2O2, PDS and chlorine and revealed a general oxidation performance following the order of UV/Chlorine > UV/H2O2 ≈ UV/PDS while UV/PDS and UV/Chlorine exhibited higher compound selectivity than UV/H2O2. However, although oxidation performance of UV/Chlorine is outstanding in comparison of the three UV-AOPs, it has to be noted that oxidation byproduct (OBP) formation potential might be substantially higher during both UV/PDS and UV/Chlorine compared to UV/H2O2 which was not investigated in this study. Evaluating potential optical surrogates to predict trace organic chemical (TOrCs) removal in UV-AOPs, nine parameters were selected representing chromophore and fluorophore features of DOM including components derived by parallel factor analysis (PARAFAC) of excitation-emission matrices. UV absorbance (UVA), total fluorescence (TF) and the selected fluorescence peak P_IV revealed highest linear correlation coefficients and were therefore identified as surrogates representing underlying mechanistic reactions of each UV-AOP. As none of the surrogates directly reacted with UV irradiation, slopes of surrogate-indicator correlations for photo-susceptible TOrCs decreased towards higher oxidant dosages. Correlations for these compounds should therefore only be determined for a limited range of oxidant dosage.
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13812. 题目: Horizontal and vertical food web structure drives trace element trophic transfer in Terra Nova Bay, Antarctica
文章编号: N19010911
期刊: Environmental Pollution
作者: Geraldina Signa, Edoardo Calizza, Maria Letizia Costantini, Cecilia Tramati, Simona Sporta Caputi, Antonio Mazzola, Loreto Rossi, Salvatrice Vizzini
更新时间: 2019-01-09
摘要: Despite a vast amount of literature has focused on trace element (TE) contamination in Antarctica during the last decades, the assessment of the main pathways driving TE transfer to the biota is still an overlooked issue. This limits the ability to predict how variations in sea-ice dynamics and productivity due to climate change will affect TE allocation in the food web. Here, food web structure of Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica) was first characterised by analysing carbon and nitrogen stable isotopes (δ13C, δ15N) in organic matter sources (sediment and planktonic, benthic and sympagic primary producers) and consumers (zooplankton, benthic invertebrates, fish and birds). Diet and trophic position were also characterised using Bayesian mixing models. Then, relationships between stable isotopes, diet and TEs (Cd, Cr, Co, Cu, Hg, Ni, Pb and V) were assessed in order to evaluate if and how horizontal (organic matter pathways) and vertical (trophic position) food web features influence TE transfer to the biota. Regressions between log[TE] and δ13C revealed that the sympagic pathway drives accumulation of V in primary consumers and Cd and Hg in secondary consumers, and that a coupled benthic/pelagic pathway drives Pb transfer to all consumers. Regressions between log[TE] and δ15N showed that only Hg biomagnifies across trophic levels, while all the others TEs showed a biodilution pattern, consistent with patterns observed in temperate food webs. Although the Cd behavior needs further investigations, the present findings provide new insights about the role of basal sources in the transfer of TEs in polar systems. This is especially important nowadays in light of the forecasted trophic changes potentially resulting from climate change-induced modification of sea-ice dynamics.
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13813. 题目: Transport of biochar colloids in saturated porous media in the presence of humic substances or proteins
文章编号: N19010910
期刊: Environmental Pollution
作者: Wen Yang, Scott A. Bradford, Yang Wang, Prabhakar Sharma, Jianying Shang, Baoguo Li
更新时间: 2019-01-09
摘要: Application of biochar in the field has received considerable attention in recent years, but there is still little known about the fate and transport of biochar colloids (BCs) in the subsurface. Natural organic matter (NOM), which mainly consists of humic substance (HS) and proteins, is ubiquitous in the natural environment and its dissolved fraction is active and mobile. In this study, the transport of BCs in saturated porous media has been examined in the presence of two HS (humic and fulvic acids) and two proteins. Bull serum albumin (BSA) and Cytochrome c (Cyt) were selected to present the negatively and positively charged protein, respectively. At low and high salt concentration and different pH conditions, the transport of BCs was strongly promoted by HS. HS significantly increased the mobility of BCs in porous media under both low and high salt conditions due to the enhanced electrostatic repulsion and modification of surface roughness and charge heterogeneity. While BC mobility in porous media was suppressed by both BSA and Cyt in the low salt solution, the presence of BSA largely promoted and Cyt slightly enhanced the transport of BCs in high salt solutions. BSA and Cyt adsorption onto BC surface decreased the negative charge of BC and resulted in a less repulsive interaction in low salt solutions. In high salt solutions, the adsorbed BSA layers disaggregated BCs and reduced the strength of the interaction between BC and the sand. Adsorbed Cyt on BCs caused more attractive patches between BC and sand surface, and greater retention than BSA.
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13814. 题目: Responses of leaf-associated biofilms on the submerged macrophyte Vallisneria natans during harmful algal blooms
文章编号: N19010909
期刊: Environmental Pollution
作者: Mengqi Jiang, Yanping Zhou, Xiyan Ji, Huimin Li, Zheng Zheng, Jibiao Zhang
更新时间: 2019-01-09
摘要: The present study investigated the physiological responses, photosynthetic activity, and microbial community structure of leaf-associated biofilms on the microphyte Vallisneria natans during a harmful algal bloom. Results of the physiological and photosynthetic indices (Fv/Fm ratios [maximum quantum yield of photosystem II (PSII)]; malondialdehyde content; total chlorophyll; and activities of superoxide dismutase, catalase and peroxidase) indicated that algal blooms could cause inhibition of photosynthesis, oxidative stress and an antioxidant system stress response in Vallisneria natans leaf-associated biofilms. Multifractal analysis suggested that allelochemicals or algal organic matter released by cyanobacteria could reduce the surface roughness of the leaf. Microbial diversity analysis of the biofilms showed that algal blooms slightly altered the microbial community structure while the richness and evenness of the microbial composition remained stable. This study provided useful information to better understand the adverse effects of algal blooms on submerged macrophytes.
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13815. 题目: The effect of water treatment unit processes on cyanobacterial trichome integrity
文章编号: N19010908
期刊: Science of The Total Environment
作者: Carlos J. Pestana, José Capelo-Neto, Linda Lawton, Samylla Oliveira, Ismael Carloto, Helísia P. Linhares
更新时间: 2019-01-09
摘要: Many toxic and/or noxious cyanobacteria appear in nature with a filamentous, stacked cell arrangement called trichomes. Although water treatment can be optimized to keep cyanobacterial cells intact and avoid the release of toxic and/or noxious compounds, many physical and chemical stresses encountered during the treatment process may result in trichome truncation, decreasing treatment efficiency by allowing single cells or short trichomes to reach the product water. This makes it possible for harmful/noxious compounds as well as organic matter to enter the distribution system. Investigations in a pilot and three full-scale water treatment plants were carried out in order to elucidate the degree of trichome truncation across different unit processes. It was found that genera (Pseudanabaena, Planktolyngbya) with short trichomes (<10–12 cells per trichome), are hardly affected by the unit processes (loss of one to four cells respectively), while genera (Planktothrix, Geitlerinema, Dolichospermum) with longer trichomes (30+ cells per trichome) suffer from high degrees of truncation (up to 63, 30, and 56 cells per trichome respectively). The presence of a rigid sheath and/or mucilaginous layer appears to offer some protection from truncation. It was observed that certain unit processes alter the sensitivity or resilience of trichomes to disruption by physical stress. Some genera (Planktothrix, Geitlerinema) were sensitive to pre-oxidation making them more susceptible to shear stress, while Dolichospermum sp. appears more robust after pre-oxidation. While the potential of toxicogenic genera breaking through into the product water is a real danger, in the current study no toxicogenic cyanobacteria were observed. This work stresses the need for plant operators to study the incoming cyanobacterial composition in the raw water in order to adjust treatment parameters and thus limit the potential of toxic/noxious compound breakthrough.
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13816. 题目: Labile and recalcitrant components of organic matter of a Mollisol changed with land use and plant litter management: An advanced 13C NMR study
文章编号: N19010907
期刊: Science of The Total Environment
作者: Shui-Hong Yao, Yue-Ling Zhang, Ya Han, Xiao-Zeng Han, Jing-Dong Mao, Bin Zhang
更新时间: 2019-01-09
摘要: Soil organic matter (SOM) changes with land use and soil management, yet the controlling factors over the chemical composition of SOM are not fully understood. We applied quantitative 13C nuclear magnetic resonance and spectral editing techniques to measure chemical structures of SOM from different land use types. The land use types included a native grassland (nGL), a crop land with straw burning in the field (bCL), a restored grassland (rGL) and a cropland with straw removed out of the field (rCL) for 28 years. The abundances of OCH groups from carbohydrates were higher in the SOMs of the nGL and rGL than in those of the rCL and bCL, while the abundances of OCH3 and aromatic CO groups from lignin were higher in the SOMs of the three-ever cultivated lands (rGL, rCL and bCL) than in that of the nGL. Although aromatic CC groups were most dominant in the Mollisols, they did not consistently decrease after the burnings of straw were ceased in the fields of the rCL and rGL compared to the bCL with continuous burning. In addition, the COO groups were bound with the aromatic CC groups in all the land use types, and the sizes of the aromatic clusters were affected by the land use types. The labile and recalcitrant components were correlated with SOC contents the mineral-associated and particular SOM in a contrasting way. Our results suggested that the chemical composition of SOM in the Mollisol depended on land use types, and that labile and recalcitrant components might be protected through mineral associations and aggregation, respectively. The most abundant aromatics in the Mollisols might not just be pyrogenic and could be oxidized to different extents, depending on field drainage conditions.
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13817. 题目: Microbial Lipid Biomarkers Detected in Deep Subsurface Black Shales
文章编号: N19010906
期刊: Environmental Science: Processes Impacts
作者: Rawlings Akondi, Shikha Sharma, Ryan Vincent Trexler, Paula Mouser, Susan Pfiffner
更新时间: 2019-01-09
摘要: Evidence for microbes has been detected in extreme subsurface environments as deep as 2.5 km with temperatures as high as 90˚C, demonstrating that microbes can adapt and survive extreme environmental conditions. Deep subsurface shales are increasingly exploited for their energy applications, thus characterizing the prevalence and role of microbes in these ecosystems essential for understanding biogeochemical cycles and maximizing production from hydrocarbon-bearing formations. Here, we describe the distribution of bacterial ester-linked phospholipid fatty acids (PLFA) and diglyceride fatty acids (DGFA) in sidewall cores retrieved from three distinct geologic horizons collected to 2,275 m below ground surface in a Marcellus Shale well, West Virginia, USA. We examined the abundance and variety of PLFA and DGFA prior to energy development within and above the Marcellus Shale Formation into the overlying Mahantango Formation of the Appalachian Basin. Lipid biomarkers in the cores suggest the presence of microbial communities comprising Gram (+), Gram (-) as well as stress indicative biomarkers. Microbial PLFA and DGFA degradation in the subsurface can be influenced by stressful environmental conditions associated with the subsurface. The PLFA concentration and variety were higher in the transition zone between the extremely low permeability Marcellus Shale Formation and the more permeable Mahantango Formation. In contrast to this distribution, more abundant and diverse DGFA membrane profiles were associated with the Mahantango Formation. The stress indicative biomarkers like the trans-membrane fatty acids, oxiranes, keto-, and dimethyl lipid fatty acids were present in all cores, potentially indicating that the bacterial communities had experienced physiological stress or nutrient deprivation during or after deposition. The DGFA profiles expressed more stress indicative biomarkers as opposed to the PLFA membrane profiles. These findings suggest the probable presence of indigenous microbial communities in the deep subsurface shale and also improves our understanding of microbial survival mechanisms in ancient deep subsurface environments.

13818. 题目: Combined effects of dissolved organic matter, pH, ionic strength and halides on photodegradation of oxytetracycline in simulated estuarine waters
文章编号: N19010905
期刊: Environmental Science: Processes Impacts
作者: Ya-nan Zhang, Jianchen Zhao, Yangjian Zhou, Jiao Qu, Jingwen Chen, Chao Li, Weichao Qin, Yahui Zhao, Willie J. G. M. Peijnenburg
更新时间: 2019-01-09
摘要: Estuarine waters of variable compositions are sinks for many micropollutants. The varying water properties can impact the photodegradation of organic pollutants. In this study, the combined effects of dissolved organic matter (DOM), pH, ionic strength, and halides on the photodegradation of the model organic pollutant oxytetracycline (OTC) were investigated. Suwannee River natural organic matter (SRNOM) was used as a representative DOM. The results showed that the observed photolysis rate constant (kobs) of OTC increased rapidly upon increase of pH. SRNOM induced a 11.0–17.9% decrease of the kobs for OTC. In the presence of SRNOM, the ionic strength and specific halide effects promote OTC photodegradation with a 39.2–84.2% and 7.1–28.8% increase of the kobs, respectively. The effects of SRNOM, ionic strength and halides on OTC photodegradation are pH-dependent. Direct photolysis half-lives (t1/2) of OTC were estimated in view of the more important role of direct photolysis compared to indirect photolysis. The estimated t1/2 values decreased from 187.4–206.6 d to 34.4–36.6 d as the pH increases in the Yellow River estuarine region. The results of this research demonstrate that the photodegradation rate of OTC increases rapidly in the gradient from river water to marine water in estuarine regions.
图文摘要:

13819. 题目: Predicting visual clarity and light penetration from water quality measures in New Zealand estuaries
文章编号: N19010904
期刊: Estuarine, Coastal and Shelf Science
作者: Mark Gall, Andrew Swales, Rob Davies-Colley, David Bremner
更新时间: 2019-01-09
摘要: Estuaries are biogeochemically and physically dynamic environments, resulting in diverse optical water properties that vary in space and time. This natural variability challenges effective monitoring. We develop semi-empirical linear models of the two main water clarity aspects, visual clarity and light penetration, as functions of more routinely monitored and/or modelled water quality measures, to simplify approximations and allow more expansive modelling in space and time. At multiple points along salinity gradients in six northern New Zealand estuaries, we made discrete measurements of horizontal black disk visibility (yBD) and downwelling irradiance attenuation (Kd(PAR)), with surface concentrations of the main light-attenuating constituents (LACs): total suspended solids (TSS), coloured dissolved organic matter (CDOM – ag(340)), and phytoplankton chlorophyll a (Chl.a). Estuaries on the east coast (Tauranga and Tairua Harbours) were relatively clear compared to those on the west coast (Kaipara and Raglan Harbours). Although Kd(PAR) (controlling light penetration and euphotic zone depth) and yBD (inversely proportional to beam attenuation at 550 nm, controlling visual clarity) were strongly corelated over all estuaries (r2 > 0.8), there were small, yet significant, differences between regression lines in different estuaries. This suggests regional differences in light scattering and absorption properties of the LACs. Variability in water clarity was mainly accounted for by TSS alone in west coast Kaipara Harbour sub-estuaries (r2 > 0.7), while in east coast estuaries, TSS was a weak predictor (r2 < 0.5), and prediction was significantly improved by accounting for CDOM (r2 > 0.7). West coast Raglan Harbour had intermediary responses. In most cases, the inclusion of CDOM significantly improved estuary models, but Chl.a was a significant term only in a few cases, such as during one survey on the Kaipara River sub-estuary. Co-linearity of LACs was an issue in some cases for semi-empirical models. The application of a literature-derived Lambert-Beer Law (LBL) type model to our data more effectively partition the contributions of the LACs, which confirmed and quantified differences between west coast (TSS dominant), and east coast (TSS + CDOM) estuaries. Although we expect that ‘simple’ semi-empirical models will have wide practical application for estimating visual clarity and light penetration in estuaries in New Zealand and elsewhere, consideration of all LACs in an LBL type model is advised across entire estuaries, and local verification and ‘tuning’ is desirable.
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13820. 题目: Estimating greenhouse gases emissions from horticultural peat soils using a DNDC modelling approach
文章编号: N19010903
期刊: Journal of Environmental Management
作者: Helen E. Taft, Paul A. Cross, Astley Hastings, Jagadeesh Yeluripati, Davey L. Jones
更新时间: 2019-01-09
摘要: Peat soils represent an important global carbon (C) sink, but can also provide a highly fertile medium for growing horticultural crops. Sustainable crop production on peat soils involves a trade-off between ensuring food security and mitigating typically high greenhouse gas (GHG) emissions and rates of soil C loss. An alternative approach to resource intensive field-based monitoring of GHG fluxes for all potential management scenarios is to use a process-based model driven by existing field data to estimate emissions. The aim of this study was to evaluate the suitability of the Denitrification-Decomposition (DNDC) model for estimating emissions of CO2, N2O and CH4 from horticultural peat soils. The model was parameterised using climatic, soil, and crop management data from two intensively cultivated sites on soils of contrasting soil organic matter (SOM) contents (∼35% and ∼70% SOM content). Simulated emissions of CO2, N2O and CH4, and simulated soil physical and crop output values, were compared to actual GHG, soil and crop measurements. Model performance was assessed using baseline parameterisation (i.e. model defaults), then calibrated using pre-simulation and sensitivity analysis processes. Under baseline parameterisation conditions, DNDC proved poor at predicting GHG emissions and soil/crop variables. Calibration and validation improved DNDC performance in estimating the annual magnitude of emissions, but model refinement is still required for reproducing seasonal GHG patterns in particular. Key constraints on model functioning appear to be its ability to reliably model soil moisture and some aspects of C and nitrogen dynamics, as well as the quality of input data relating to water table dynamics. In conclusion, our results suggest that the DNDC (v. 9.5) model cannot accurately reproduce or be used to replace actual field measurements for estimation of GHG emission factors under different management scenarios for horticultural peat soils, but may be able to do so with further modification.

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