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22841. 题目: Organic nitrogen in residential stormwater runoff: Implications for stormwater management in urban watersheds
文章编号: N19122003
期刊: Science of The Total Environment
作者: Mary G. Lusk, Gurpal S. Toor, Patrick W. Inglett
更新时间: 2019-12-20
摘要: Stormwater runoff containing organic nitrogen (N) is a source of potentially bioavailable N in water bodies. Characterization and concentrations of dissolved organic N (DON) and particulate organic N (PON) in urban stormwater runoff are rarely reported and considered in stormwater management. Our objectives were to (1) characterize the organic (DON, PON) and inorganic (NO3− and NH4+) N pools in residential stormwater runoff and (2) determine the rainfall driven landscape sources of runoff PON using an isotopic mixing model with 13C and 15N during a wet season (June–September). We instrumented a 13 ha (0.13 km2) residential catchment located in Florida, United States with an ISCO autosampler and collected stormwater runoff samples (n = 52) over 11 individual stormwater runoff events. Mean concentration of total N in runoff during the wet season was 1.61 mg L−1, of which 37% was DON and 25% was PON. A strong seasonal first flush of PON, giving rise to a large PON:TN ratio, was observed as the wet season progressed from June (PON:TN = 0.39;) to September (PON:TN = 0.12), whereas DON did not display any seasonal variability (mean: 0.66 mg L−1). The isotope mixing model estimated that 76% of PON in the runoff originated from oak detritus (leaves: 50%, acorns: 26%) and the remaining 24% from lawn grass clippings. The dominance of organic N fractions in the urban stormwater runoff suggests that landscape controls on PON and DON are needed to reduce N loading in the urban stormwater runoff. The seasonal first flush of PON indicates that monitoring strategies should focus on how nutrient concentrations in runoff may respond to seasonal drivers such as leaf litterfall and that there may be optimal times for N management, such as after a prolonged dry season in which materials accumulate and pose the risk for later mobilization.
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22842. 题目: Aggregation and stability of nanoscale plastics in aquatic environment
文章编号: N19122002
期刊: Water Research
作者: Mehnaz Shams, Iftaykhairul Alam, Indranil Chowdhury
更新时间: 2019-12-20
摘要: The widespread use and release of plastics in nature have raised global concerns about their impact on public health and the environment. While much research has been conducted on macro- and micro-sized plastics, the fate of nanoscale plastics remains unexplored. In this study, the aggregation kinetics and stability of polyethylene and polystyrene nanoscale plastics were investigated over a wide range of aquatic chemistries (pH, salt types (NaCl, CaCl2, MgCl2), ionic strength) relevant to the natural environment. Results showed that salt types and ionic strength had significant effects on the stability of both polyethylene and polystyrene nanoscale plastics, while pH had none. Aggregation and stability of both polyethylene and polystyrene nanoscale plastics in the aquatic environment followed colloidal theory (DLVO theory and Schulze-Hardy rule), similar to other colloidal particles. The critical coagulation concentration (CCC) values of polyethylene nanoscale plastics were lower for CaCl2 (0.1 mM) compared to NaCl (80 mM) and MgCl2 (3 mM). Similarly, CCC values of polystyrene nanospheres were 10 mM for CaCl2, 800 mM for NaCl and 25 mM for MgCl2. It implies that CaCl2 destabilized both polyethylene and polystyrene nanoscale plastics more aggressively than NaCl and MgCl2. Moreover, polystyrene nanospheres are more stable in the aquatic environment than polyethylene nanoscale plastics. However, natural organic matter improved the stability of polyethylene nanoscale plastics in water primarily due to steric repulsion, increasing CCC values to 0.4 mM, 120 mM and 8 mM for CaCl2, NaCl and MgCl2 respectively. Stability studies with various water conditions demonstrated that polyethylene nanoscale plastics will be fairly stable in the natural surface waters. Conversely, synthetic surface water, wastewater, seawater and groundwater rapidly destabilized polyethylene nanoscale plastics. Overall, our findings indicate that significant aqueous transport of nanoscale plastics will be possible in natural surface waters.
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22843. 题目: Scaling behavior of iron in capacitive deionization (CDI) system
文章编号: N19122001
期刊: Water Research
作者: Tianyu Wang, Changyong Zhang, Langming Bai, Binghan Xie, Zhendong Gan, Jiajian Xing, Guibai Li, Heng Liang
更新时间: 2019-12-20
摘要: This study investigated the fouling and scaling behaviors in a capacitive deionization (CDI) system in the presence of iron and natural organic matter (NOM). It was found that the salt adsorption capacity (SAC) significantly decreased when treating Fe-containing brackish water, with higher Fe concentrations leading to severer SAC reduction. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis demonstrated that Fe2O3 appeared to be the predominant foulant attached on the electrode surface, which was difficult to be removed via backwashing, indicating the irreversible property of the foulant. Further characterizations (e.g., N2 sorption-desorption isotherms, electrochemical impedance spectroscopy and cyclic voltammetry) revealed that the CDI electrodes suffered from obvious deterioration such as specific surface area loss, resistance increase and capacitance decline with the occurrence of Fe scaling. While the presence of NOM alleviated the Fe scaling through NOM-Fe complexing effects, NOM itself was found to have negative impacts on CDI desalination performance due to their strong interactions with the carbon electrodes.
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22844. 题目: Leaching behavior of Cd, Zn and nutrients (K, P, S) from a contaminated soil as affected by amendment with biochar
文章编号: N19121912
期刊: Chemosphere
作者: Reinhart Van Poucke, Erik Meers, Filip M.G. Tack
更新时间: 2019-12-19
摘要: In Campine region in Flanders (Belgium) there are contaminated sites with Cd and Zn due to atmospheric deposition from industry. Flanders is also known for its large surpluses of nitrogen and phosphorous coming from intense livestock production. To solve both issues, the potential of biochar to sorb metals and nutrients was investigated. Experiments were conducted to examine whether biochar could reduce the leaching of nutrients (K, P and S) and metals (Cd and Zn) into the soil solution. Most biochars caused an increase in pH of approximately 1 unit which is often the main driver of the metal immobilization. Nutrient concentrations in the leachate of soil amended with oak-based biochar were lower compared to the blank soil. For the other amendments, however, the results were higher due to the nutrients leached from the applied products.The result of this experiment emphasize the potential of biochar to immobilize nutrients and metals in soil water systems, thus keeping the nutrients longer available for the plant and reducing the metal toxicity. However, the amount of metals immobilized was lower than expected. Further research is required to determine whether biochar from livestock products could act as a slow release fertilizer.
22845. 题目: Transformation of amino acid tyrosine in chromophoric organic matter solutions: Generation of peroxide and change of bioavailability
文章编号: N19121911
期刊: Chemosphere
作者: Qing Zhoua, Xu Zhang, Chi Zhou
更新时间: 2019-12-19
摘要: Studying the photochemical transformation mechanism of dissolved free amino acids (DFAA) in chromophoric dissolved organic matter (CDOM) solution facilitates the understanding of DFAA’s environmental fate and bioavailability change upon solar irradiation in natural surface waters. Tyrosine oxidation product (Tyr-OH) was synthesized to quantify the primary transformation product (tyrosine peroxide, Tyr-OOH) in CDOM solution. Both reactions between superoxide radical anion (O2−) and tyrosine radical (Tyr) and between singlet oxygen (1O2) and tyrosine (Tyr) yield Tyr-OOH, which is subsequently transformed into Tyr-OH. The reaction between O2− and Tyr not only generated Tyr-OOH but also caused the regeneration of Tyr. O2− and 1O2 contributed 30−44% to Tyr’s transformation in CDOM solutions at pH 8.0, in which 1O2 oxidation accounted for 6–11%. The contribution of O2− to Tyr’s phototransformation process was the difference between the total contribution of O2− and 1O2 and the individual contribution of 1O2. Compared with the fast assimilation of Tyr, Tyr-OH was stable in natural water under dark incubation, indicating that phototransformation decreased the bioavailability of Tyr.
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22846. 题目: Humic acid functionalized magnetic nanomaterials for remediation of dye wastewater under ultrasonication: Application in real water samples, recycling and reuse of nanosorbents
文章编号: N19121910
期刊: Chemosphere
作者: Ravindra Kumar Gautam, Ida Tiwari
更新时间: 2019-12-19
摘要: Water pollution by industrial sector is a great problem which hampers the sustainable development goals. Dye containing water effluent poses vast challenge to clean water before its discharge in to the surrounding ecosystem. Herein, we prepared humic acid functionalized Fe3O4 nanosorbents through an eco-friendly route and applied for decolorization of carcinogenic dye from water. The nanosorbents was characterized by AFM, BET surface area analyzer, FTIR, SEM-EDX, TEM, TGA/DTG, VSM and XRD. Adsorption experiments were conducted by taking the appropriate amount of dye in different sources of water under ultrasonication. Adsorption process was controlled by chemisorption in nature making pseudo-second-order model most suitable. Multilayer adsorption was taking place on the active sites of nanosorbents showing applicability of Freundlich isotherm model with highest adsorbed amount of 199.986 mg g−1 at 323 K. Rise in temperature favors the remediation of colored effluent thus positive value of ΔH° (74.234 kJ mol−1) and negative value of ΔG° shows endothermic and spontaneous nature of adsorption system. Cationic surfactant CTAB favors the adsorption (<80%) while anionic SDS gives very low removal (>48%) because of the micelle formation at the surface of nanosorbents. Decolorization from real water samples shows that the adsorption of malachite green was 97, 90, 91, 87, and 86% for Ganga river water, tap water, well water, hand pump water and submersible water, respectively. The used Fe3O4/HA nanosorbents was easily recycled from water samples through 0.1 M HCl and nanosorbents was used up to five cycles with greater percentage of removal at 85%.
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22847. 题目: Biochar promotes the reduction of N2O to N2 and concurrently suppresses the production of N2O in calcareous soil
文章编号: N19121909
期刊: Geoderma
作者: Wenxu Dong, Anna Walkiewicz, Andrzej Bieganowski, Oene Oenema, Magdalena Nosalewicz, Chaohui He, Yuming Zhang, Chunsheng Hu
更新时间: 2019-12-19
摘要: Biochar additions may mitigate N2O emissions from soil. The mechanisms underpinning the mitigation of emissions remain to be elucidated. A series of incubation experiments were performed to investigate the effects of biochar on N2O production and reduction in columns with a low-fertility or high-fertility soil, with or without the injection of N2O in the subsoil and with and without glucose (to stimulate denitrification). Biochar was added to the calcareous soils in 0 and 1% (w/w) amounts and moisture was maintained at 70% water-filled pore space (WFPS) over the incubation period. The results revealed that biochar reduced the emissions of soil-produced N2O by 37–47% and those of injected N2O by 23–44%. The addition of glucose solution strongly increased N2O emissions, while biochar reduced total N2O emissions by as much as 64–81% and those of injected N2O alone by 29–51%. Differences between the low-fertility and high-fertility soils in the apparent N2O emission mitigation by biochar were relatively small, but tended to be larger for the low-fertility soil. The results suggest that biochar addition can suppress the production of N2O in soil and simultaneously stimulate the reduction of N2O to N2. Further studies are needed to elucidate the regulatory effects of biochar in soil.
22848. 题目: Linking thermogravimetric data with soil organic carbon fractions
文章编号: N19121908
期刊: Geoderma
作者: David Tokarski, Martin Wiesmeier, Helena Doležalová Weissmannová, Karsten Kalbitz, Michael Scott Demyan, Jiří Kučerík, Christian Siewert
更新时间: 2019-12-19
摘要: Different soil fractionation approaches are frequently used to separate soil organic carbon (SOC) pools of different turnover time and shed light on soil carbon dynamics. However, these methods are laborious and time consuming. Thermogravimetry might be an alternative. Previous studies revealed relationships between soil organic matter (SOM), total nitrogen, clay content, and soil respiration and thermogravimetry (TG) data represented by TG indicators (mass loss in 10 °C intervals) and TG fractions (mass loss in larger temperature intervals). In this work, both TG indicators and fractions were correlated with the contents of SOC fractions representing different turnover times. The fractions we used were particulate organic carbon, dissolved organic carbon, organic C in the sand fraction and in stable aggregates, organic C attached to silt and clay particles and a chemically resistant fraction (<63 µm and not oxidizable by NaOCl). Fractionation and thermogravimetry was applied to 144 samples from arable and grassland top- and subsoils. The results revealed that both TG indicators and fractions or their combinations correlated with SOC fractions in grassland topsoils (R2 between = 0.70–0.92, p < 0.001 except for the chemically resistant fraction), while the correlation with SOC fractions in arable soils were significantly lower (R2 between 0.36 and 0.72, p < 0.001). No correlations were observed between TG data and SOC fractions in subsoils of arable and grassland soils. Importantly, most of the correlations were observed in soils in which carbon content correlated with TG indicator between 340 and 350 °C. This TG indicator can be used as a differentiator for the application of developed equations for modeling the functional SOC fractions of different turnover times in various types of soils. Thermogravimetry is not able to replace classical fractionation schemes. However, the results showed that thermogravimetry can be an additional tool to assess SOM quality in different land use systems besides traditional chemical-physical fractionation methods.
22849. 题目: Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis
文章编号: N19121907
期刊: Journal of Environmental Sciences
作者: Jin Zhang, Fanhao Song, Tingting Li, Kefu Xie, Huiying Yao, Baoshan Xing, Zhongyu Li, Yingchen Bai
更新时间: 2019-12-19
摘要: Simulated photo-degradation of fluorescent dissolved organic matter (FDOM) in Lake Baihua (BH) and Lake Hongfeng (HF) was investigated with three-dimensional excitation-emission matrix (3DEEM) fluorescence combined with the fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and multi-order kinetic models. In the FRI analysis, fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM. Four individual components were identified by use of PARAFAC analysis as humic-like components (C1), fulvic-like components (C2), protein-like components (C3) and unidentified components (C4). The maximum 3DEEM fluorescence intensity of PARAFAC components C1–C3 decreased by about 60%, 70% and 90%, respectively after photo-degradation. The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient (Radj2) (0.963–0.998). The photo-degradation rate constants (kn) showed differences of three orders of magnitude, from 1.09× 10−6 to 4.02 × 10−4 min−1, and half-life of multi-order model T12n) ranged from 5.26 to 64.01 min. The decreased values of fluorescence index (FI) and biogenic index (BI), the fact that of percent fluorescence response parameter of Region I (PI,n) showed the greatest change ratio, followed by percent fluorescence response parameter of Region II (PII,n), while the largest decrease ratio was found for C3 components, and the lowest T12n was observed for C3, indicated preferential degradation of protein-like materials/components derived from biological sources during photo-degradation. This research on the degradation of FDOM by 3DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FDOM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.
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22850. 题目: Cadalenes and norcadalenes in organic-rich shales of the Permian Irati Formation (Paraná Basin, Brazil): tracers for terrestrial input or also indicators of temperature-controlled organic-inorganic interactions?
文章编号: N19121906
期刊: Organic Geochemistry
作者: Laercio Lopes Martins, Hans-Martin Schulz, Hélio Jorge Portugal Severiano Ribeiro, Caroline Adolphsson do Nascimento, Eliane Soares de Souza, Georgiana Feitosa da Cruz
更新时间: 2019-12-19
摘要: Cadalene, isocadalene and a series of norcadalenes were identified in black shales of the Permian Irati Formation in the northeastern and central eastern Paraná Basin (Brazil). The origin of their α-isomers with an isopropyl substituent is potentially related to higher plants, and likely reflects the spreading of pteridophytes and gymnosperms after the glaciation of southern Gondwana. A general increase in the relative abundance of isocadalene (1,6-dimethyl-3-isopropylnaphthalene, the β-isomer) co-occurs in with increasing thermal maturity at the base of the Amaral Machado Quarry (northeastern basin), and refers to the acid-catalyzed rearrangement of cadalene (1,6-dimethyl-4-isopropylnaphthalene, the α-isomer) due to the presence of montmorillonite, via an organic-inorganic interaction. This localized and incipient maturation can be related to diabase sills of the Serra Geral Formation. Similar maturation due to heating also affected the distribution of the norcadalenes by thermally stabilizing their α-isomers with an isopropyl substituent, in addition to the formation of related compounds with an ethyl substituent. Based on this, a norcadalene ratio is proposed, which is the sum of the 1,6-dimethyl-4-ethylnaphthalene and 1,6-dimethyl-3-ethylnaphthalene over the sum of the 1-isopropyl-4-methylnaphthalene and 1-isopropyl-7-methylnaphthalene. The results of this ratio and the established cadalene ratio resemble each other whereas samples from the São Mateus do Sul Quarry (central eastern basin) were not affected by thermal maturation and are characterized by a uniform distribution of the cadalenes and norcadalenes.
22851. 题目: Nano-manganese oxides-modified biochar for efficient chelated copper citrate removal from water by oxidation-assisted adsorption process
文章编号: N19121905
期刊: Science of The Total Environment
作者: Ying Zhu, WenHong Fan, Kai Zhang, HuiDong Xiang, XiangRui Wang
更新时间: 2019-12-19
摘要: Removal of chelated copper from wastewater is more difficult than that of copper ions owing to its stable structure, wide range of pH tolerance, and stronger mobility. Copper citrate (CuCA) widely exists in the water system and inevitably poses serious hazards to human health and environment. Biochar as economic functional material has been widely used for environmental applications, especially in wastewater treatment. This study focused on the performance of manganese oxide-modified biochar (BC-MnOx) toward uptake and removal of CuCA and to understand the related mechanism. The result indicated that the CuCA removal efficiency reached up to 99%. High removal efficiency and low concentration of dissolved Mn over a wide pH range proved that the BC-MnOx is efficient and chemically stable. Furthermore, the removal mechanism may involve the following processes: First, CuCA was removed via the chemical bonds formed between CuCA and MnOx on the surface of BC. Second, chemisorption due to the oxygen-containing functional groups or physisorption of porous structure in BC worked synergistically on CuCA. Third, CuCA was partially oxidized into low molecular weight acids by means of MnOx, while the released Cu ions were retained on the adsorbent surface. This study demonstrates that BC-MnOx is a promising material for the removal of CuCA from wastewater.
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22852. 题目: Use of hardwood and sulfurized-hardwood biochars as amendments to floodplain soil from South River, VA, USA: Impacts of drying-rewetting on Hg removal
文章编号: N19121904
期刊: Science of The Total Environment
作者: Alana O. Wang, Carol J. Ptacek, David W. Blowes, Y. Zou Finfrock, Dogan Paktunc, E. Erin Mack
更新时间: 2019-12-19
摘要: Periodic flooding and drying conditions in floodplains affect the mobility and bioavailability of Hg in aquatic sediments and surrounding soils. Sulfurized materials have been recently proposed as Hg sorbents due to their high affinity to bind Hg, while sulfurizing organic matter may enhance methylmercury (MeHg) production, offsetting the beneficial aspects of these materials. This study evaluated hardwood biochar (OAK) and sulfurized-hardwood biochar (MOAK) as soil amendments for controlling Hg release in a contaminated floodplain soil under conditions representative of periodic flooding and drying in microcosm experiments in three stages: (1) wet biochar amended-systems with river water in an anoxic environment up to 200 d; (2) dry selected reaction vessels in an oxic environment for 90 d; (3) rewet such vessels with river water in an anoxic environment for 90 d. In Stage 1, greater Hg removal (17–98% for unfiltered total Hg (THg) and 47–99% for 0.45-μm THg) and lower MeHg concentration (<20 ng L−1) were observed in MOAK-amended systems (10%MOAKs). In Stage 3, release of Hg in 10%MOAKs was eight-fold lower than in soil controls (SedCTRs), while increases in aqueous (up to 21 ng L−1) and solid (up to 88 ng g−1) MeHg concentrations and were observed. The increases in MeHg corresponded to elevated aqueous concentrations of Mn, Fe, SO42−, and HS− in Stage 3. Results of S K-edge X-ray absorption near edge structure (XANES) analysis suggest oxidation of S in Stage 2 and increases in polysulfur in Stage 3. Results of pyrosequencing analysis indicate sulfate-reducing bacteria (SRB) became abundant in Stage 3 in 10%MOAKs. The shifts in biogeochemical conditions in 10%MOAKs in Stage 3 may increase the bioavailability of Hg to methylating bacteria. The results suggest limited impacts on Hg removal during drying and rewetting, while changes in biogeochemical conditions may affect MeHg production in sulfurized biochar-amended systems.
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22853. 题目: Improved lead removal from aqueous solution using novel porous bentonite and calcite-biochar composite
文章编号: N19121903
期刊: Science of The Total Environment
作者: Sudipta Ramola, Tarun Belwal, Cun Jun Li, Yu Ying Wang, Haohao Lyu, Sheng Mao Yang, Chun Hui Zhou
更新时间: 2019-12-19
摘要: Biochar-mineral (bentonite/calcite) composite (BC-CM) prepared at different temperatures were tested under varied conditions for effective removal of lead (Pb) from aqueous solution. With increasing pyrolysis temperature, increased surface area, pore volume, bentonite decomposition and less or no decomposition of calcite occurred. Bentonite-biochar (BCS) and calcite-biochar (CCS) prepared at 700 °C were found most suitable for efficient removal of Pb (99.9%). Bentonite and calcite acted as catalyst and contributed to changes in yield, pH, texture, functional groups, minerals and carbonization that facilitated efficient Pb removal by BCS 700 and CCS 700. Pb concentration, pH, dose of BCS and CCS, and contact time were further optimized using response surface methodology (RSM) for maximizing removal percentage (R%) of Pb and adsorption capacity (qt). Both BCS 700 and CCS 700 showed similar effects (positive/negative) of factors on R% and qt. Under optimized conditions, 0.21 g of BCS 700 effectively removed 99.2% of 431 mg/L in 3.6 h at solution pH of 4.2, while 0.07 g CCS 700 removed 97.06% of 232 mg/L in 3.5 h at 5.5 pH. Removal of Pb onto both BCS and CCS was by monolayer adsorption with maximum adsorption capacity of 500 mg/g. Rapid Pb removal was observed within 2 h of contact time (CCS 700 > BCS 700) and equilibrium was achieved within 10 h. BCS 700 followed first order and CCS 700 followed second order kinetic model. Electrostatic attraction between Pb ions and mineral groups present in BCS 700 and CCS 700 also played important role in Pb removal. This study clearly demonstrated that composite of biochar with bentonite or calcite under optimized conditions significantly improved Pb removal and adsorption capacity that can be further utilized for larger scale applications.
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22854. 题目: N2O emission factors from a wastewater irrigated land in a semiarid environment in Mexico
文章编号: N19121902
期刊: Science of The Total Environment
作者: Blanca González-Méndez, Luis Gerardo Ruiz-Suárez, Christina Siebe
更新时间: 2019-12-19
摘要: Irrigation with wastewater is an increasing practice around the world triggered by the large needs of water for agriculture. Many times this source of water is added by flooding to the fields, creating short temporal oxygen-depleted environments, where nitrous oxide (N2O) emissions are promoted. Agriculture is responsible for up to 60% of the global annual emissions of this gas, and its emission factors (EF) must be reported. During 21 months, we installed closed chambers to measure the N2O emissions from a wastewater irrigated plot in the Mezquital Valley. Here, alfalfa, rye grass, and maize were grown in succession, receiving mainly organic N contained in the untreated wastewater and the residues of the previous crop; only maize received extra mineral fertilization of 100 kg of N ha−1. We obtained a time series where the gaps were filled by linear interpolation. EF and N2O direct emissions were estimated by the Tier 1 approach of the IPCC. We found that the alfalfa and rye grass, which only receive organic nitrogen, produced minor N2O emissions, that reflected in lower EF (0.004 and 0.001, respectively), compared with the default value of the IPCC (0.01). In contrast, maize, which receives organic and inorganic N, lost 1% of this N input as N2O, the same as the default value (0.01). It seems that the form of N, the crop age and type influence greatly the N dynamics in this wastewater irrigated land-use system. Therefore, the Tier I approach of the IPCC seems to underestimate the N efficiency of this agroecosystem and overestimates the N2O direct emissions from alfalfa and rye grass.
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22855. 题目: Exploring anaerobic CO2 production response to elevated nitrate levels in Gulf of Mexico coastal wetlands: Phenomena and relationships
文章编号: N19121901
期刊: Science of The Total Environment
作者: Zhuo Wei, Jim J. Wang, Syam K. Dodla, Lisa M. Fultz, Lewis A. Gaston, Jong-hwan Park, Ronald D. DeLaune, Yili Meng
更新时间: 2019-12-19
摘要: Recent studies have shown the effect of nitrate (NO3−) on carbon gas emissions from wetland soils that contradict thermodynamic predictions. In this study, CO2 production in three Mississippi River deltaic plain wetland soils (forest swamp, freshwater and saline marshes) with the presence of different NO3− levels (0.2, 2.0, and 3.2 mM) was evaluated in an anaerobic microcosm. Molecular composition of dissolved organic matter (DOM) of these soils was investigated using pyrolysis-GC/MS, and soil microbial community was characterized based on phosphorus lipid fatty acid (PLFA) method to elucidate the underlying mechanisms. Addition of NO3− promoted CO2 production in swamp forest soil, but inhibited CO2 emission from marsh soils. Pyrolysis-GC/MS analysis showed that swamp soil contained more polysaccharides, whereas both marsh soils had high abundance of phenolic compounds. Total PLFAs of forest swamp soil were 34% and 66% higher than freshwater and saline marsh soils, respectively. The PLFA profiles indicated different microbial distribution along a salinity gradient with the forest swamp having a higher proportion of fungi and NO3− reducers but lower sulfate (SO42−) reducers than marsh soils. Overall, the study indicated that the inherent differences in soil DOM and microbial community led to the contrasting response in soil CO2 respiration between forest swamp and marsh ecosystems to NO3− loading. These differences should be considered in determining the fate of nitrate entering Louisiana coastal wetlands from river diversions and other sources and their management.
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22856. 题目: Modeling riverine dissolved and particulate organic carbon fluxes from two small watersheds in the northeastern United States
文章编号: N19121814
期刊: Environmental Modelling & Software
作者: Junyu Qi, Xinzhong Du, Xuesong Zhang, Sangchul Lee, Yiping Wu, Jia Deng, Glenn E. Moglen, Ali M. Sadeghi, Gregory W. McCarty
更新时间: 2019-12-18
摘要: The coupled carbon (C) cycle across terrestrial and aquatic environments at the watershed scale has been identified as an important, but poorly constrained component of the global carbon budget. Here, we extended Soil and Water Assessment Tool (SWAT) with coupled riverine particulate organic carbon (POC) and dissolved organic carbon (DOC) modules (referred to as SWAT-C hereafter). Results show that SWAT-C reproduced daily POC and DOC fluxes well in two watersheds in the Northeastern United States. We found that SWAT-C tended to underestimate high flows and peak DOC and POC fluxes. Uncertainty analysis indicated flux uncertainties associated with POC and DOC simulations were larger than those for flow simulation. Sensitive parameters controlling POC and DOC biogeochemical processes were identified along with how these parameters influence mechanisms underlying C cycling. We anticipate that the tool developed and applied here will inform C related ecosystem services in watershed assessment and planning.
22857. 题目: Strengths of correlations with formation of chlorination disinfection byproducts: effects of predictor type and other factors
文章编号: N19121813
期刊: Environmental Science and Pollution Research
作者: Bhuvaneshwari Manivannan, Mikhail Borisover
更新时间: 2019-12-18
摘要: Measurements of the UV–Vis absorbance (Abs) and intensity of fluorescence emission (Fluor), as well as of concentrations of total or dissolved organic carbon (OC) in aqueous samples are commonly used to estimate the potential for disinfection byproducts (DBPs) formation during water chlorination. In this work, based on 574 linear associations collected from 70 experimental research papers published over the period of 1997–2019, the strengths of the correlations of Abs, Fluor, and OC with DBPs concentrations are compared. The correlations were expressed as approximately normally distributed Z-scores using Fisher variance-stabilizing transformation. The effects of specific prediction method, chlorination agent, water source, and DBPs type, with consideration of possible effects due to the presence of bromide, are examined against Z-scores by ANOVA, testing main effects and some variables interactions. The performed analysis is a first attempt to expose differences and patterns in correlation strengths associated with DBPs formation, based on systematically covered broad existing literature. Abs and OC concentration of water samples tend to demonstrate the strongest correlations with DBPs formation as compared with specific UV absorbance (SUVA) or intensity of fluorescence emission. Correlations of DBPs formation during chloramination demonstrated weaker strengths as compared with other chlorination agents, suggesting more caution in predicting DBPs concentrations, based on simple descriptors such as Abs, OC, and Fluor. In a series of different water types, the correlations with DBPs formation are expected to be enhanced, when wastewater is chlorinated. Non-fluorescent matter may be an important contributor to DBPs formation during water chlorination. When fluorescence intensity is considered as a predicting tool, choosing humic-like rather than proteinaceous fluorescence may enhance the strengths of the correlations with DBPs formation. Different performances of Abs, OC, and Fluor in correlating with DBPs formation may be beneficial for their concurrent use helping to optimize removal of different DBPs precursors.
22858. 题目: Runoff-driven export of terrigenous particulate organic matter from a small mountainous river: sources, fluxes and comparisons among different rivers
文章编号: N19121812
期刊: Biogeochemistry
作者: Jing Qiao, Hongyan Bao, Dekun Huang, Da-Wei Li, Tsung-Yu Lee, Jr-Chuan Huang, Shuh-Ji Kao
更新时间: 2019-12-18
摘要: The land-to-ocean export and subsequent preservation of terrestrial particulate organic carbon (POC) in oceans represents a major carbon sink in the global carbon cycle. Small mountainous rivers (SMRs) are hotspots of this process; however, how the sources and fluxes of POC change during rain events in low-gradient SMRs and how they compare with those in steep SMRs are unknown. Here, we combined the bulk properties and lignin phenols to trace changes in POC sources and fluxes in a low-gradient SMR (stream gradient: 0.6%) in southeastern China. Our results were further compared with other SMRs to understand the geomorphological influences on the POC export from SMRs. The results indicated that POC sources changed from aquatic organisms and deep soils during low-flow periods to surface soils and plant debris during high-flow periods. The lignin concentration showed a significant positive relationship with the runoff, suggesting that hydrology played an important role in exporting terrigenous POC in low-gradient SMRs. We further estimated that approximately 22%, 56% and 79% of annual water, POC and particulate lignin were exported during high-flow periods, respectively. Furthermore, we found that with increasing water discharge, the magnitude of the lignin increase was greater in SMRs with smaller stream gradients. Our results suggest that the export of terrigenous POC from low-gradient SMRs is driven by hydrology and is more sensitive to rain events than that in steep SMRs.
22859. 题目: Preparation and Characterization of Raw and Inorganic Acid-Activated Pine Cone Biochar and Its Application in the Removal of Aqueous-Phase Pb 2+ Metal Ions by Adsorption
文章编号: N19121811
期刊: Water, Air, & Soil Pollution
作者: Subrata Biswas, Hammad Siddiqi, Bhim Charan Meikap, Tushar Kanti Sen, Mehdi Khiadani
更新时间: 2019-12-18
摘要: In this work, the synthesized slow pyrolysis biomass pine cone (Pinus radiata)–based biochar was acid activated, characterized, and tested for its effectiveness in the adsorptive removal of aqueous-phase Pb2+ metal ions. The adsorbent surface modification was conducted by treatment with H2SO4 and H3PO4 and was characterized by BET surface area, pore volume, pore size, C-H-N-S analysis, the presence of various functional groups through FT-IR (Fourier Transform- Infrared), the crystallinity of the material and presence of minerals by XRD (X-ray diffraction spectrum), and surface morphology by FESEM. The specific surface area after acid modification has been increased from 145 to 472 m2/g. Also, acid treatment causes an increase of the COO− functional group on the adsorbent surface which are responsible for adsorption. All three types of biochar, namely BC (raw biochar without modification), AC1 (modified by H3PO4), and AC2 (modified with H2SO4) were used for the removal of aqueous-phase Pb2+ by batch adsorption and compared. Various physicochemical process parameters such as initial solution pH, initial metal ion dose or adsorbate concentration, adsorbent dose, and system temperature and their effect on metal ion adsorption mechanism have been identified and optimized here. Maximum Pb 2+ adsorption capacities were obtained as 251, 283 mg/g and 321 mg/g for BC, AC1, and AC2 respectively which are very much comparative with other reported adsorbents including commercial activated carbon under similar experimental conditions. This study indicated that pine cone biochar was an environment-friendly and cost-effective adsorbent in sustainable solution for water and wastewater treatment.
22860. 题目: Long-term fertilization and intensive cropping enhance carbon and nitrogen accumulated in soil clay-sized particles of red soil in South China
文章编号: N19121810
期刊: Journal of Soils and Sediments
作者: Hu Xu, Kailou Liu, Wenju Zhang, Yichao Rui, Jingye Zhang, Lei Wu, Gilles Colinet, Qinghai Huang, Xianni Chen, Minggang Xu
更新时间: 2019-12-18
摘要: Purpose: Understanding the underlying mechanism of soil carbon (C) and nitrogen (N) accumulation is of great significance for soil C sequestration and climate change mitigation, as well as soil fertility improvement. The objective of this study was to evaluate the response of C and N accumulation in aggregates and fine soil particles to long-term mineral fertilizer and manure application. Materials and methods: Five treatments from a long-term experiment with double maize cropping were examined in this study, i.e., (1) no fertilizer (control); (2) mineral nitrogen, phosphorus, and potassium application (NPK); (3) doubled application rate of the NPK (2NPK); (4) pig manure alone (M); and (5) mineral NPK fertilizers and manure combination (NPKM). By using physical particle-sized fractionation, we analyzed soil organic carbon (OC) and total nitrogen (N), and δ13C of OC in bulk soil and aggregates (53–2000 μm) and, coarse silt-sized fraction (5–53 μm), fine silt-sized fraction (2–5 μm), and clay-sized fraction (< 2 μm) under those five treatments. Results and discussion: Fertilizer application for 24 years, particularly M and NPKM treatments, significantly increased the concentration and proportion of OC and total N associated with aggregates and clay-sized fraction as compared with control. Manure application significantly increased the proportion of OC by 6.6–7.8 points in aggregates, whereas it was by 22.6–25.0 points in clay-sized fraction. Clay-sized fraction-associated C and N showed a non-linear response to C and N accumulation in bulk soil, contributing approximately 47% and 69% to soil OC and total N, respectively. Moreover, the mass proportion of aggregates and the mass ratio of aggregates to fine soil particles increased significantly with C accumulation in fine silt-sized and clay-sized fraction. Conclusions: Organic carbon and total nitrogen accumulation in soil clay-sized particles play important role in soil C and N sequestration in red soil. Our results also suggested that C accumulation in fine soil particles might benefit soil aggregation in intensive cropping system of South China.