论文检索

总访问量：5359885次

总访客量：313660人

所有论文

24421. 题目: No tillage increases soil organic carbon storage and decreases carbon dioxide emission in the crop residue-returned farming system
文章编号: N20030414
期刊: Journal of Environmental Management
作者: Hao Wang, Shulan Wang, Qi Yu, Yujiao Zhang, Rui Wang, Jun Li, Xiaoli Wang
更新时间: 2020-03-04
摘要: Soil organic carbon (SOC) storage and carbon dioxide (CO2) emission under different tillage methods in a crop residue-returned farming system may not be consistent with result from studies of the usual tillage researches because crop residues are important carbon sources with significant effects on soil carbon input and output. Herein, we address a knowledge gap over the hot spot research on tillage practices on SOC storage and CO2 emission in crop residue-returned farming systems. In this study, a long-term (2007–2019) field experiment was conducted, and the crop residues were returned to the soil after harvest; then, three tillage methods were conducted: no tillage (NT), subsoiling tillage (ST), and a moldboard plow tillage (CT). Our results showed that in the crop residue-returned farming system, NT and ST still showed advantages of lower CO2 flux compared with CT, as well as a reduced average CO2 flux of 14.5% and 8.5%, respectively, over a two-year average. The results of our long-term study suggest that the NT had advantages of SOC accumulation. In addition, as of June 2018, NT increased SOC stocks with 5.85 Mg hm−2 at a 0–60-cm soil depth compared with CT, whereas no significant difference was found between ST and CT. Overall, adopting NT in a crop residue-returned farming system improved SOC storage to 5.85 Mg hm−2 after 11 years as well as decreased CO2 flux by 14.5% in comparison with CT, which is meaningful in improving soil carbon pool and decreasing soil CO2 emission during agriculture production.

24422. 题目: Sustainable soil amendments to improve nature-based solutions for wastewater treatment and resource recovery
文章编号: N20030413
期刊: Journal of Environmental Management
作者: Virtudes Martínez-Hernández, Raffaella Meffe, Jorge Hernández-Martín, Adriana Alonso González, Ana de Santiago-Martín, Irene de Bustamante
更新时间: 2020-03-04
摘要: Vegetation Filters (VFs) can be a sustainable solution to treat wastewater and to recover resources such as nutrients, water and biomass from small municipalities and isolated dwellings. However, under certain conditions, the leakage of nutrients, especially of nitrate, can represent a limitation. The addition of two sustainable soil amendments, woodchips and biochar, has been tested as a strategy to improve nutrient attenuation in VFs increasing sorption sites and microbial activity. To this end, unsaturated infiltration and batch experiments have been carried out at laboratory scale. The systems for infiltration experiments contain natural soil, natural soil amended with woodchips and natural soil amended with biochar. To determine the sorption capacity of NH4+, batch tests were performed using an amendment/SWW ratio of 1:20 and an NH4+ initial concentration ranging from 30 to 600 mg L−1. Results from the infiltration experiments show a high attenuation (~95%) of total phosphorous (TP) independently of the amendments. Different behaviour is observed for total nitrogen (TN). The removal of this species is obtained only in the soil amended with woodchips (>85%) whereas the natural soil alone and the soil with biochar have no impact on TN attenuation. In these two porous media, all the NH4+ input concentration is transformed to NO3− that infiltrates without further reactions. According to batch experiment results, the potential role of biochar in the nutrient attenuation is limited to sorption processes (Kd (NH4+) = 21.37–193.18 L kg−1). Woodchips act primarily as a labile source of carbon promoting biodegradation, being more effective for nutrient attenuation than the sorption capacity of biochar.

24423. 题目: Treatment of industrial effluents and assessment of their impact on the structure and function of microbial diversity in a unique Anoxic-Aerobic sequential batch reactor (AnASBR)
文章编号: N20030412
期刊: Journal of Environmental Management
作者: Jyotsnarani Jena, Nitin Narwade, Trupti Das, Dhiraj Dhotre, Ujjaini Sarkar, Yogesh Souche
更新时间: 2020-03-04
摘要: A novel Anoxic-Aerobic Process (AnAP) that eliminated the anaerobic process was optimized and operated for the simultaneous remediation of phosphate, nitrate, and chemical oxygen demand (COD) from industrial effluents. Two sequential batch reactors (SBR) with AnAP were established for the treatment of effluent from two industries; phosphate fertilizer (AnASBR_PPL) and dairy industry (AnASBR_DW). The adaptability of the bacterial consortium in the SBRs, dominated by denitrifying phosphate accumulating organisms (DNPAOs), facilitates the stable performance of AnAP for simultaneous nutrient and COD removal. Up to 90% and ~80% of COD removal were achieved in AnASBR_PPL and AnASBR_DW, respectively. Nearly complete denitrification was observed along with phosphate removal accounted for ~90% in both the reactors. Granulation of sludge has been widely reported in aerobic reactors; however, interestingly, in this study, partial granulation of the sludge was observed in both the AnASBRs which facilitated the microorganisms to uptake a minimal amount of phosphate and nitrate even under the aerobic condition. The underlying mechanism of DNPAOs and other associated microbes in the consortium were investigated for microbial diversity by 16S rDNA based targeted amplicon sequencing using the Illumina platform and imputed metagenomic analysis. The dominance of Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria, and Bacteroidia was observed in AnASBRs. At steady-state operation, the identity of the core community members remained largly stable, but their relative abundances changed considerably in both the reactors as a function of varying industrial effluent. However, population of few strains such as Lactobacteriales, Enterobacteriales changed drastically with respect to the influent, as these strains were predominat in AnASBR_DW but not present in AnASBR_PPL. The dominant strains were the vital contributor to the gene pool encoding for denitrification, dephosphatation, TCA cycle, glycolysis, EPS production, and polyhydroxyalkanoate (PHA) storage, etc. Few less abundant but persistent species were also detected as contributors to these functional groups. It unveiled the TCA cycle remains preferable over conventional glycolysis in both the SBR irrespective of carbon source. The new AnASBR was proved to be an efficient alternative system that is energy efficient with higher ease of operation for the treatment of different industrial effluents without fail.

24424. 题目: Nitrogen-doped biochar fiber with graphitization from Boehmeria nivea for promoted peroxymonosulfate activation and non-radical degradation pathways with enhancing electron transfer
文章编号: N20030411
期刊: Applied Catalysis B: Environmental
作者: Shujing Ye, Guangming Zeng, Xiaofei Tan, Haipeng Wu, Jie Liang, Biao Song, Ning Tang, Peng Zhang, Yuanyuan Yang, Qiang Chen, Xiaopei Li
更新时间: 2020-03-04
摘要: Advanced oxidation has great promise in the degradation of organic pollutants, but the high preparation requirements, adjustment difficulty, high cost, potential hazard, and low repeatability of catalysts limit the practical applications of this technology. In this study, a metal-free biochar-based catalyst derived from biomass fiber was prepared assisted by graphitization and nitrogen incorporation (PGBF-N). The heterogeneous catalysis of peroxymonosulfate (PMS) was triggered by PGBF-N with degradation rate 7 times higher than that of pristine biochar. The high catalytic efficiency was attributed to the accelerated electron transfer originated from the high degree of graphitization and nitrogen functionalization of PGBF-N, in which the non-radical pathways containing carbon-bridge and singlet oxygen-mediated oxidation were elucidated as the predominant pathways for tetracycline degradation, instead of the dominant role of radical pathway in pristine biochar. Vacancies and defective edges formed on sp2-hybridized carbon framework as well as the nitrogen doping sites and ketonic group of PGNF-N were considered as possible active sites. The excellent degradation rate in actual water indicated that the PGBF-N/PMS system dominated by non-radical pathway exhibited a high anti-interference ability to surrounding organic or inorganic compounds. This study provides a facile protocol for converting biomass fiber into functional catalyst and enables underlying insight in mediating dominated degradation mechanism of heterogeneous catalysis by biochar fiber.

24425. 题目: Natural organic matter decreases uptake of W(VI), and reduces W(VI) to W(V), during adsorption to ferrihydrite
文章编号: N20030410
期刊: Chemical Geology
作者: Huihui Du, Zelin Xu, Meng Hu, Huanjing Zhang, Caroline L. Peacock, Xin Liu, Ning Nie, Qin Xue, Ming Lei, Boqing Tie
更新时间: 2020-03-04
摘要: Tungsten is both naturally occurring and an anthropogenically released contaminant metal in soils, sediments and water systems that typically exits as the soluble tungstate oxyanions, W(VI)O42−. Tungsten mobility and fate are strongly dependent on the adsorption of tungstate to mineral surfaces. However, environmental mineral surfaces are commonly coated with natural organic matter (NOM), and the role of this coating in the tungsten adsorption process, and thus in controlling tungsten reactivity and transport, is unclear. This study investigates W(VI) adsorption to ferrihydrite (Fh), a ubiquitous iron (hydr)oxide in soils and sediments, both in the absence and presence of humic acid (HA), a widely occurring type of NOM, using batch experiments coupled with spectroscopic and thermodynamic techniques. Kinetic results indicate that access to the adsorption sites for W(VI) on the organomineral surfaces is limited when Fh is coprecipitated with HA. Commensurate with this observation, batch experiments show that HA decreases W(VI) adsorption to Fh over a wide pH range (4–11), and this inhibitory effect is more pronounced at higher HA concentration. X-ray photoelectron spectroscopy (XPS) measurements demonstrate the formation of inner-sphere type W complexes on both the Fh and HA fraction of the Fh-HA binary composite. In particular, ~40% of the adsorbed W(VI) species is reduced to W(V) in the presence of HA. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) results show the presence of poly tungstate species on Fh, particularly at lower pH and in the presence of HA. Isothermal titration calorimetry shows that W(VI) adsorption to Fh is an exothermic process both in the presence and absence of HA, and that process is accompanied by a positive entropy. The findings of this work suggest that NOM not only mobilizes tungstate but also reduces tungstate from W(VI) to W(V) at environmental iron (hydr)oxide-water interfaces, which is of significance for evaluating the migration and bioavailability of tungsten in both natural and contaminated environments.

24426. 题目: Spectroscopic response of soil organic matter in mining area to Pb/Cd heavy metal interaction: A mirror of coherent structural variation
文章编号: N20030409
期刊: Journal of Hazardous Materials
作者: Wei Chen, Li Peng, Keren Hu, Zhang Zhang, Changhong Peng, Chunying Teng, Kanggen Zhou
更新时间: 2020-03-04
摘要: Understanding the interaction between heavy metals and soil organic matter (SOM) in mining area is important for the clarification of the environmental behaviors of heavy metals. In this work, the coherence of structural changes of SOM during interaction with Pb2+ and Cd2+ ions were examined by using UV–vis/fluorescence spectroscopy coupled with correlation analyses. The result showed that phenolic- and carboxylic-like groups of SOM were engaged in the complexation of heavy metals (Pb2+ and Cd2+) with SOM, resulting in the formation of highly conjugated macromolecules/aggregates and an increase in molecular weight/size. Fluorescent humic-like, fulvic-like, and protein-like species were involved in the binding with Pb2+/Cd2+ ions, which were closely correlated with phenolic-like and carboxylic-like constitutes. SOM was more favorable to bind with Pb2+ ions than Cd2+ ions, with a less susceptive of SOM structure to Pb2+/Cd2+ ions in the mining area compared to those off the mining area under heavy metal stress. These results may provide a new insight for the treatment and remediation of heavy metal-polluted soil in mining area.

24427. 题目: Adsorptive removal of tetracycline from aqueous solution by maple leaf-derived biochar
文章编号: N20030408
期刊: Bioresource Technology
作者: Ji Eun Kim, Shashi Kant Bhatia, Hak Jin Song, Eunjin Yoo, Hyeon Jin Jeon, Jae-Yoon Yoon, Yunjeong Yang, Ranjit Gurav, Yung-Hun Yang, Hyung Joo Kim, Yong-Keun Choi
更新时间: 2020-03-04
摘要: The present study evaluates the physicochemical properties of maple leaf-derived biochars (M-BCs) produced at different pyrolytic temperatures (i.e., 350, 550, and 750 °C) and their adsorptive properties for tetracycline onto M-BCs. The increase in pyrolysis temperature to produce M-BCs led to a significant increase in the biochar's hydrophobicity, surface area, and calcite (CaCO3) crystallization. The M-BC750 produced without functionalization or activation possessed a high calcite composition and a hydrophobic nature with lower O/C and H/C, hydroxyl groups (-OH) on the surface, and functional groups (i.e., O-containing) as H-bond acceptors. Among M-BCs, the M-BC750 present a highest TC adsorption capacity owing to possible mechanisms such as metal complexation, H-bonding, and hydrophobic interactions. The isotherm and kinetic models for TC adsorption followed the Freundlich models and pseudo-second-order models, respectively. M-BCs produced from the waste fallen maple leaves could be applied as low-cost environmental adsorbents for TC removal.

24428. 题目: Engineered biochar with anisotropic layered double hydroxide nanosheets to simultaneously and efficiently capture Pb2+ and CrO42- from electroplating wastewater
文章编号: N20030407
期刊: Bioresource Technology
作者: Huabin Wang, Siqi Wang, Zhulei Chen, Xinquan Zhou, Jia Wang, Zhuqi Chen
更新时间: 2020-03-04
摘要: Cationic and anionic heavy metal contaminants generally co-exist in practical industrial effluent, and simultaneously removal of these species is a bottleneck for most of the bio-adsorbents because of their contrary charge. In this work, pinewood sawdust derived engineered biochar (BC) was fabricated with MgAl layered double hydroxide (MgAl-LDH) nanosheets, which could efficiently and simultaneously capture heavy metal cations and oxyanions from wastewater. The synergetic effect between loaded MgAl-LDH and BC substantially improves its adsorption performance towards both cationic and anionic contaminants, i.e., Pb2+ and CrO42-. The adsorption capacity of MgAl-LDH/BC for Pb2+ reached 591.2 mg/g, which is 263% higher than that of BC, and in the case of CrO42-, the adsorption capacity is 330.8 mg/g, 416% higher than that of BC. The elimination of Pb2+ was mainly attributed to forming complexations with surface functional groups. While for oxyanions removal, CrO42- can be reduced to Cr3+ by functional groups, and then generated Cr3+ could replace Al3+ via morphic substitution, consequently formed an MgCr-LDH structure. Further, in the continuous fixed-bed column study, 225 bed volume of simulating electroplating wastewater co-existed with Pb2+ and CrO42- can be efficiently treated. Hence, this study sheds light on the engineered biochar design to efficiently and simultaneously capture heavy metal cations and oxyanions and its feasibility on real wastewater purification.

24429. 题目: Biochar addition with Fe-impregnation to reduce H2S production from anaerobic digestion
文章编号: N20030406
期刊: Bioresource Technology
作者: Abhinav Choudhury, Stephanie Lansing
更新时间: 2020-03-04
摘要: Corn stover biochar (CSB) and maple biochar (MB) were added into anaerobic digesters and evaluated for hydrogen sulfide (H2S) reductions. This was the first study to show Fe-impregnated biochar can eliminate H2S production. The novel study evaluated biochar addition on H2S reduction and nutrient concentrations using three experiments to test the effect of: 1) biochar concentration, 2) biochar particle size, and 3) Fe-impregnated biochar using triplicate lab-scale reactors. At the highest biochar dose (1.82 g biochar/g manure TS), H2S production was 90.5% less than the control treatment (351 mL H2S/kg VS). Biochar particle size did not significantly affect H2S concentration. The Fe-impregnated biochar (0.5 g biochar/g manure TS) reactors had no H2S detected in the CSB-Fe system. Methane (CH4) in the biochar and control treatments were not significantly different in all three experiments. The results show that biochar added to digesters can significantly reduce H2S production without affecting CH4 production.

24430. 题目: Adsorption characteristics of ciprofloxacin onto g-MoS2 coated biochar nanocomposites
文章编号: N20030405
期刊: Frontiers of Environmental Science & Engineering
作者: Zhenyu Yang, Rong Xing, Wenjun Zhou, Lizhong Zhu
更新时间: 2020-03-04
摘要: The g-MoS2 coated biochar (g-MoS2-BC) composites were synthesized by coating original biochar with g-MoS2 nanosheets at 300°C(BC300)/700°C (BC700). The adsorption properties of the g-MoS2-BC composites for ciprofloxacin (CIP) were investigated with an aim to exploit its high efficiency toward soil amendment. The specific surface area and the pore structures of biochar coated g-MoS2 nanosheets were significantly increased. The g-MoS2-BC composites provided more it electrons, which was favorable in enhancing the it-it electron donor-acceptor (EDA) interactions between CIP and biochar. As a result, the g-MoS2-BC composites showed faster adsorption rate and greater adsorption capacity for CIP than the original biochar. The coated g-MoS2 nanosheets contributed more to CIP adsorption on the g-MoS2-BC composites due to their greater CIP adsorption capacity than the original biochar. Moreover, the synergistic effect was observed for CIP adsorption on g-MoS2-BC700, and suppression effect on g-MoS2-BC300. In addition, the adsorption of CIP onto g-MoS2-BC composites also exhibited strong dependence on the solution pH, since it can affect both the adsorbent surface charge and the speciation of contaminants. It was reasonably suggested that the mechanisms of CIP adsorption on g-MoS2-BC composites involved pore-filling effects, it-it EDA interaction, electrostatic interaction, and ion exchange interaction. These results are useful for the modification of biochar in exploiting the novel amendment for contaminated soils.

24431. 题目: Nitrogen deep placement mitigates methane emissions by regulating methanogens and methanotrophs in no-tillage paddy fields
文章编号: N20030404
期刊: Biology and Fertility of Soils
作者: D. J. Fan, T. Q. Liu, F. Sheng, S. H. Li, C. G. Cao, C. F. Li
更新时间: 2020-03-04
摘要: This study investigated the effects of placement of N at different soil depths on CH4 emissions and related microbial communities in no-tillage paddy soil. Five fertilizing treatments, including no N fertilizer, N surface broadcasting, and N deep placement at the soil depths of 5 cm, 10 cm, and 20 cm were applied in the paddy field. The composition of main microbial groups were determined using phospholipid fatty acid (PLFA) analysis. The absolute real-time quantitative PCR was applied to determine the abundance of the methanogenic and methanotrophic populations with mcrA, pmoA, mmoX, and mxaF as the functional gene markers. Compared with N surface broadcasting, the deep placement of N (i) significantly increased the microbial biomass carbon (C) and dissolved organic C by 7–90% and 6–75%, respectively; (ii) significantly enhanced the amount of the total PLFAs by 12–70% and the bacterial PLFAs by 15–82%; (iii) significantly mitigated the CH4 emissions by 6–39%; and (iv) significantly enhanced the abundance of the methanogenic and methanotrophic populations by 16–55% and 13–210%, respectively. The percent changes varied over a wide range due to different N placement depths as well as the seasonal variations. Moreover, structural equation modeling revealed that N deep placement directly or indirectly affected the CH4-related microbial communities through the increased labile soil organic C fractions by activating plant growth and soil microbial abundance, thereby mitigating the CH4 emissions in no-tillage paddy soil.

24432. 题目: Assessment of soil aggregation properties after conversion from rice to greenhouse organic cultivation on SOC controlling mechanism
文章编号: N20030403
期刊: Journal of Soils and Sediments
作者: Lingying Xu, Meiyan Wang, Xinqiao Xie, Xuezheng Shi, Shengxiang Xu, Weixia Sun, Yijie Shi, Quanbo Yu, Jinhua Pan, Xiangwei Li, Yutian Tian, Yuncong Zhu
更新时间: 2020-03-04
摘要: Organic manure is beneficial for macro-aggregate formation and soil organic carbon (SOC), but how SOC change in aggregate fractions in time-series is still uncertain. Moreover, greenhouse systems converted from cereal fields quickly faced soil degradation. Thus, the role of organic manure here should be discussed. The main objectives of this study were to determine the change of SOC fractions in bulk soil and aggregation level affected by long-term organic manure application.

24433. 题目: Kinetic Consideration of Photochemical Formation and Decay of Superoxide Radical in Dissolved Organic Matter Solutions
文章编号: N20030402
期刊: Environmental Science & Technology
作者: Jianzhong Ma, JianXin Nie, Huaxi Zhou, Hui Wang, Lushi Lian, Shuwen Yan, Weihua Song
更新时间: 2020-03-04
摘要: The photochemical formation and decay rates of superoxide radical ions (O2•–) in irradiated dissolved organic matter (DOM) solutions were directly determined by the chemiluminescent method. Under irradiation, uncatalyzed and catalyzed O2•– dismutation account for ∼25% of the total O2•– degradation in air-saturated DOM solutions. Light-induced O2•– loss, which does not produce H2O2, was observed. Both the O2•– photochemical formation and light-induced loss rates are positively correlated with the electron-donating capacities of the DOM, suggesting that phenolic moieties play a dual role in the photochemical behavior of O2•–. In air-saturated conditions, the O2•– quantum yields of 12 DOM solutions varied in a narrow range, from 1.8 to 3.3‰, and the average was (2.4 ± 0.5)‰. The quantum yield of O2•– nonlinearly increased with increasing dissolved oxygen concentration. Therefore, the quantum yield of one-electron reducing intermediates, the precursor of O2•–, was calculated as (5.0 ± 0.4)‰. High-energy triplets (3DOM*, ET > 200 kJ mol–1) and 1O2 quenching experiments indicate that 3DOM* and 1O2 play minor roles in O2•– production. These results are useful for predicting the photochemical formation and decay of O2•– in sunlit surface waters.

24434. 题目: Dissolved Organic Matter Singlet Oxygen Quantum Yields: Evaluation Using Time-Resolved Singlet Oxygen Phosphorescence
文章编号: N20030401
期刊: Environmental Science & Technology
作者: Sarah B. Partanen, Paul R. Erickson, Douglas E. Latch, Kyle J. Moor, Kristopher McNeill
更新时间: 2020-03-04
摘要: Singlet oxygen (1O2) generation quantum yields from chromophoric dissolved organic matter (CDOM) have been reported for many samples over the past 4 decades. Yet even for standardized isolates such as those from the International Humic Substance Society (IHSS), wide-ranging values exist in the literature. In this manuscript, time-resolved 1O2 phosphorescence was used to determine the 1O2 quantum yields (ΦΔ) of a variety of dissolved organic matter (DOM) isolates and natural waters. In general, the 1O2 quantum yield values in this study are in the middle, although below the median of the range of past reported values (e.g., for Suwannee River Natural Organic Matter IHSS isolate: 1.8% vs 0.23–2.89%). Notably, hydrophobic neutral fractions of DOM isolates were found to possess the highest 1O2 quantum yields, an interesting result given that these fractions are not retained in typical humic and fulvic acid isolation procedures that use XAD resins. The excitation wavelength dependence of 1O2 generation from CDOM was also examined, and an approximate linear decrease with longer excitation wavelength was observed. This work advances the understanding of CDOM photoprocesses, especially in relation to wavelength-dependent 1O2 production, which is valuable for assessing real-world environmental behavior.

24435. 题目: Inhibited effect of biochar application on N2O emissions is amount and time-dependent by regulating denitrification in a wheat-maize rotation system in North China
文章编号: N20030308
期刊: Science of The Total Environment
作者: Hongyuan Liu, Hongbo Li, Aiping Zhang, Md Arifur Rahaman, Zhengli Yang
更新时间: 2020-03-03
摘要: Biochar application is considered an effective method of reducing nitrous oxide (N2O) emissions in soil. However, the mechanism and temporal effect of different doses of biochar on N2O emissions is still obscure. Here, we conducted a two-year field experiment to test the effects of different input amounts and frequencies of biochar on soil N2O emissions in North China. Biochar was applied in six different treatments in a winter wheat and summer maize rotation system: applications of 0 t/ha biochar (C0), 2.25 t/ha biochar (C1), 4.5 t/ha biochar (C2), 9 t/ha biochar (C3), and 13.5 t/ha biochar (C4) each year, and a single application of 13.5 t/ha biochar (CS) in the first year. The results showed that biochar could inhibit N2O emissions, reaching 20.6% to 60.1% in the wheat season and 18.1% to 39.4% in the maize season. The inhibitory effect of biochar on soil N2O emissions was dependent on amount and time. C3 had the best results in the wheat season, although its inhibitory effect in the maize season was not as good relative to C4 due to the lower biochar application. In addition, CS significantly reduced (27.7%) the cumulative N2O emissions in the first year, although the inhibitory effect disappeared in the second year. Biochar increased the nosZ gene copy numbers and promoted a reduction of N2O in the soil via the denitrification process. In conclusion, the inhibition of N2O emissions during denitrification is an important factor for reducing soil N2O emissions by biochar, and the inhibition of biochar is influenced by the input amount and time.

24436. 题目: Acidification in corn monocultures favor fungi, ammonia oxidizing bacteria, and nirK-denitrifier groups
文章编号: N20030307
期刊: Science of The Total Environment
作者: G.D. Behnke, M.C. Zabaloy, C.W. Riggins, S. Rodríguez-Zas, L. Huang, M.B. Villamil
更新时间: 2020-03-03
摘要: Agricultural practices of no-till and crop rotations are critical to counteract the detrimental effects of monocultures and tillage operations on ecosystem services related to soil health such as microbial N cycling. The present study explored the main steps of the microbial N cycle, using targeted gene abundance as a proxy, and concerning soil properties, following 19 and 20 years of crop monocultures and rotations of corn (Zea mays L.), and soybean [Glycine max (L.) Merr.], either under no-till or chisel tillage. Real-time quantitative polymerase chain reaction (qPCR) was implemented to estimate phylogenetic groups and functional genes related to the microbial N cycle: nifH (N2 fixation), amoA (nitrification) and nirK, nirS, and nosZ (denitrification). Our results indicate that long-term crop rotation and tillage decisions affect soil health as it relates to soil properties and microbial parameters. No-till management increased soil organic matter (SOM), decreased soil pH, and increased copy numbers of AOB (ammonia oxidizing bacteria). Crop rotations with more corn increased SOM, reduced soil pH, reduced AOA (ammonia oxidizing archaea) copy numbers, and increased AOB and fungal ITS copy numbers. NirK denitrifier groups were also enhanced under continuous corn. Altogether, the more corn years included in a crop rotation multiplies the amount of N needed to sustain yield levels, thereby intensifying the N cycle in these systems, potentially leading to acidification, enhanced bacterial nitrification, and creating an environment primed for N losses and increased N2O emissions.

24437. 题目: Linking transformations of organic carbon to post-treatment performance in a biological water recycling system
文章编号: N20030306
期刊: Science of The Total Environment
作者: Christopher Ziemba, Odile Larivé, Eva Reynaert, Theo Huisman, Eberhard Morgenroth
更新时间: 2020-03-03
摘要: Ozone, electrolysis and granular activated carbon (GAC) were examined as potential post-treatments to follow a household-scale biologically activated membrane bioreactor (BAMBi), treating a wash water containing trace urine and feces contamination. Each post-treatment was evaluated for abilities and reaction preferences to remove or transform dissolved organic carbon (DOC), chemical structures that contribute color, and assimilable organic carbon (AOC), which can support bacterial regrowth. Batch treatment with each technology demonstrated an ability to remove ≥95% DOC. Ozone demonstrated a reaction selectivity through increased reaction rates with larger compounds and color-contributing compounds. Electrolysis and GAC demonstrated generally less-selective reactivity. Adding post-treatments to full-scale systems reduced DOC (55–91%), AOC (34–62%), and color (75–98%), without significant reaction selectivity. These reductions in DOC and AOC were not linked to reduction of bacterial concentrations in treated water. Reductions in bacterial concentrations were observed with ozone and electrolysis, but this is credited to oxidation chemicals produced in these systems and not the removal or transformations of organic materials.

24438. 题目: Bromine biogeodynamics in the NE Atlantic: A perspective from natural wetlands of western Portugal
文章编号: N20030305
期刊: Science of The Total Environment
作者: F. Moreno, J. Moreno, F. Fatela, L. Guise, C. Vieira, M. Leira
更新时间: 2020-03-03
摘要: Bromine (Br) cycling in natural wetlands is highly complex, including abiotic/biotic processes and multiphase inorganic/organic Br-species. Wetland ecosystems receive Br primarily from the ocean, functioning as either sinks or sources of Br, with the overall imbalance largely decided by the prevailing climate. Aiming to trace the present-day transport of oceanogenic Br (i.e., derived from salt-water spray-droplets) and its uptake and storage in brackish and freshwater wetlands, we surveyed waters, autochthonous plants, and soils/sediments from coastal marshes and mountain peatlands in the westernmost fringe of northern Portugal. The calculated enrichment factors of bromide (Br−) relative to chloride in rainfall (EFsea = 16.8–75.3), rivers (EFsea = 1.3–13.9) and wetland waters, superficial (EFsea = 5.8–13.1) and interstitial (EFsea = 2.1–8.9), increased towards the inland highlands. We hypothesized that these values derived mostly from a known Br autocatalytic (heterogeneous) chemical cycle, starting at the seawater-aqueous interface and progressing in altitude. Br-bearing air masses are carried far from the Atlantic Ocean by moist westerlies, with Br− rainout from the atmosphere supplying the neighbouring mountain peatlands. Average [Br] in sampled wetland soils/sediments (111–253 mg/kg) agreed with values from other coastal regions, and they were directly correlated with organic matter, varying irrespective the [Br−] of interstitial waters (129 μg/L–79 mg/L). According to the computed bioconcentration factors, the aqueous component was the major source of Br for all plant species investigated (BFplant/water = 2.1–508.0), as described elsewhere. However, Br contents in plants (14–173 mg/kg) evidenced interspecific differences, also suggesting a divergence from the acknowledged halophytic-glycophytic model. As plants are recognized producers of Br volatile molecules (e.g., methyl bromide, CH3Br), we interpreted translocation factors less than one in vascular species as explanatory of phytovolatilization rather than restriction of Br− upward movement in plants. Further investigation is needed since considerable intrinsic plant variations in CH3Br emissions are mentioned in the literature.

24439. 题目: Assessing the cyto-genotoxic potential of model zinc oxide nanoparticles in the presence of humic-acid-like-polycondensate (HALP) and the leonardite HA (LHA)
文章编号: N20030304
期刊: Science of The Total Environment
作者: Ioanna Efthimiou, Yiannis Georgiou, Dimitris Vlastos, Stefanos Dailianis, Yiannis Deligiannakis
更新时间: 2020-03-03
摘要: The present study investigates the potential cyto-genotoxic effects of model zinc oxide nanoparticles (ZnO NPs) on human lymphocytes, with and/or without humic acids (HAs). Two types of HAs were studied, a natural well-characterized leonardite HA (LHA) and its synthetic-model, a humic-acid-like-polycondensate (HALP). The Cytokinesis Block Micronucleus (CBMN) assay was applied in cell cultures treated with different concentrations of ZnO NPs (0.5, 5, 10, 20 μg mL−1) and under different concentrations of either HALP or LHA (ZnO NPs-HALP and ZnO NPs-LHA, at concentrations of 0.5–0.8, 5–8, 10–16, 20–32 and 0.5–2, 5–20, 10–40, 20–80 μg mL−1, respectively). According to the results, ZnO NPs lacked genotoxicity but demonstrated cytotoxic potential. Binary mixtures of ZnO NPs-HAs (ZnO NPs-HALP or ZnO NPs-LHA) showed negligible alterations of micronuclei (MN) formation in challenged cells, with cytotoxic effects revealed only in case of cells treated with ZnO NPs-LHA at the concentration 5–20 μg mL−1. Furthermore, no genotoxic phenomena were exerted neither by the ZnO NPs nor from their mixtures with HAs. These findings indicate [i] the cytotoxic activity of used ZnO NPs on human lymphocytes, and [ii] reveal the protective role of HAs against ZnO NPs mediated cytotoxicity.

24440. 题目: Investigating the nutrient landscape in a coastal upwelling region and its relationship to the biological carbon pump
文章编号: N20030303
期刊: Geophysical Research Letters
作者: M.R. Stukel, K.A. Barbeau
更新时间: 2020-03-03
摘要: We investigated nutrient patterns and their relationship to vertical carbon export using results from 38 Lagrangian experiments in the California Current Ecosystem. The dominant mode of variability reflected onshore‐offshore nutrient gradients. A secondary mode of variability was correlated with silica excess and dissolved iron and likely reflects regional patterns of iron‐limitation. The biological carbon pump was enhanced in high nutrient and Fe‐stressed regions. Patterns in the nutrient landscape proved to be better predictors of the vertical flux of sinking particles than contemporaneous measurements of net primary production. Our results suggest an important role for Fe‐stressed diatoms in vertical carbon flux. They also suggest that either preferential recycling of N or non‐Redfieldian nutrient uptake by diatoms may lead to high PO43‐:NO3‐ and Si (OH)4:NO3‐ ratios, following export of P‐ and Si‐enriched organic matter. Increased export following Fe‐stress may partially explain inverse relationships between net primary productivity and export efficiency.