论文检索

总访问量：4109449次

总访客量：170630人

所有论文

26241. 题目: Treatment of organic wastewater containing nitrogen and chlorine by combinatorial electrochemical system: Taking biologically treated landfill leachate treatment as an example
文章编号: N19020106
期刊: Chemical Engineering Journal
作者: Yang Deng, Nan Chen, Chuanping Feng, Fangxin Chen, Haishuang Wang, Peijing Kuang, Zhengyuan Feng, Tong Liu, Yu Gao, Weiwu Hu
更新时间: 2019-02-01
摘要: This study presents a combinatorial electrochemical system (CES) for the treatment of refractory organic wastewater containing nitrogen and chloride ion. The CES was composed of iron anode reactor (IAR), Ti/RuO₂ anode reactor (TAR) and available chlorine removal reactor (CRR). Biologically treated landfill leachate (BTLL) was selected as the treatment object to evaluate the performance of CES. The results showed that CES could simultaneously remove chemical oxygen demand (COD) and total nitrogen (TN) by 94.6% and 98.3%, respectively. Reduction of nitrite-N by cathode in IAR and oxidation of ammonium-N by available chlorine in TAR were the major pathways for TN removal. Fluorescence spectroscopy and parallel factor analysis (PARAFAC) showed that the main organic components in BTLL were humic-like substances and soluble microbial degradation products. These substances were removed by CES and the remaining organics were some hydrocarbons and carboxylic acids. The available chlorine was rapidly reduced into chloride ion by IAR precipitates, thus decreasing the cytotoxicity. In addition, the formation of stable Fe³⁺ crystals was promoted by the oxidation of available chlorine in CRR, which increased the density of the precipitates and reduced their volume. Therefore, the CES is a promising solution for the treatment of refractory organic wastewater containing nitrogen and chlorine ion.
图文摘要:

26242. 题目: A novel magnetic biochar/MgFe-layered double hydroxides composite removing Pb²⁺ from aqueous solution: isotherms, kinetics and thermodynamics
文章编号: N19020105
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Yang Jia, Yingshuang Zhang, Jiangang Fu, Liangxiao Yuan, Zheng Li, Chang Liu, Di Zhao, Xiaobo Wang
更新时间: 2019-02-01
摘要: An absorbent, magnetic biochar supporting MgFe-Layered double hydroxides (MgFe-LDH) composites was synthesized to remove Pb²⁺ from the aqueous solution. The results of SEM, EDS, XRD, FT-IR, XPS, VSM and BET determinations showed that MgFe-LDH was successfully loaded on the magnetic biochar by hydrothermal synthesis. These characterizations also indicated that the adsorption of Pb²⁺ resulted from co-precipitation between interlayer anions, surface hydroxyl groups and Pb²⁺. The isotherms study revealed that the adsorption of Pb²⁺ on magnetic biochar/MgFe-LDH was well fitted to Langmuir model. The maximum adsorption capacity was 476.25 mg g^-1 at 25 °C. Kinetic and thermodynamic studies indicated that the adsorption process was a spontaneous endothermic reaction and limited by chemisorption. Owing to the simple synthesis, superior adsorption capacity, good magnetic properties and cyclic utilization, the magnetic biochar/MgFe-LDH is a promising adsorbent for removing Pb²⁺ from aqueous solution.
图文摘要:

26243. 题目: Biodegradation of methylene blue dye in a batch and continuous mode using biochar as packing media
文章编号: N19020104
期刊: Environmental Research
作者: Vikash Bharti, Kumar Vikrant, Mandavi Goswami, Himanshu Tiwari, Ravi Kumar Sonwani, Jechan Lee, Daniel C.W. Tsang, Ki-Hyun Kim, Mohd Saeed, Sunil Kumar, Birendra Nath Rai, Balendu Shekher Giri, Ram Sharan Singh
更新时间: 2019-02-01
摘要: Bacterial species for metabolizing dye molecules were isolated from dye rich water bodies. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting methylene blue (MB) batch degradation studies with the bacterial strains using NaCl-yeast as a nutrient medium. The most suitable bacterial species was Alcaligenes faecalis (A. faecalis) according to 16 S rDNA sequencing. Process parameters were optimized and under the optimum conditions (e.g., inoculum size of 3 mL, temperature of 30 °C, 150 ppm, and time of 5 days), 96.2% of MB was removed. Furthermore, the effectiveness for the separation of MB combining bio-film with biochar was measured by a bio-sorption method in a packed bed bioreactor (PBBR) in which microbes was immobilized. The maximum MB removal efficiencies, when tested with 50 ppm dye using batch reactors containing free A. faecalis cells and the same cells immobilized on the biochar surface, were found to be 81.5 and 89.1%, respectively. The PBBR operated in continuous recycle mode at high dye concentration of 500 ppm provided 87.0% removal of MB through second-order kinetics over 10 days. The % removal was found in the order of PBBR>Immobilized batch>Free cell. The standalone biochar batch adsorption of MB can be described well by the pseudo-second order kinetics (R² ≥ 0.978), indicating the major contribution of electron exchange-based valence forces in the sorption of MB onto the biochar surface. The Langmuir isotherm suggested a maximum monolayer adsorption capacity of 4.69 mg g^-1 at 40 °C which was very close to experimentally calculated value (4.97 mg g^-1). Moreover, the Casuarina seed biochar was reusable 5 times.

26244. 题目: Impact of Dissolved Organic Matter on Mercury and Methylmercury Sorption to Activated Carbon in Soils: Implications for Remediation
文章编号: N19020103
期刊: Environmental Science: Processes Impacts
作者: Grace Schwartz, James Sanders, Alyssa McBurney, Steven S Brown, Upal Ghosh, Cynthia Gilmour
更新时间: 2019-02-01
摘要: Activated carbon (AC) amendments have shown promise in reducing inorganic mercury (Hg) and methylmercury (MeHg) risk in contaminated soils. However, the effectiveness of AC in Hg and MeHg immobilization has varied among studies, suggesting that site biogeochemistry might dictate efficacy. In this study, we examine the effect of dissolved organic matter (DOM) on MeHg and Hg partitioning to AC. We evaluated the impact of Suwannee River Humic Acid (SRHA) on AC partitioning directly using an isotherm approach, and also evaluated DOM impacts on AC sorption in an estuarine marsh soil using slurry microcosms. Aqueous partition coefficients for Hg-SRHA and MeHg-SRHA complexes to AC (KAC) were one to two orders of magnitude lower than those for chloride complexes and more closely resembled the KAC of SRHA. In anaerobic, sulfidic soil slurries, we found that AC significantly reduced porewater concentrations of both ambient MeHg and a fresh Me199Hg spike and that the addition of up to 60 mg/L SRHA did not reduce AC efficacy. For inorganic Hg (both ambient Hg and fresh 201Hg spike), AC was also effective in reducing porewater concentrations, but SRHA reduced the magnitude of KAC in a concentration-dependent manner. We hypothesize that SRHA impacted Hg KAC in soils by interfering with HgS precipitation. For both Hg and MeHg, the KAC for sulfide species appears stronger than for chloride or SRHA species. This study highlights the need for site-specific evaluation of AC efficacy and the value in developing biogeochemical models of AC performance for Hg.

26245. 题目: Coupled iron and phosphorus release from seasonally hypoxic Louisiana shelf sediment
文章编号: N19020102
期刊: Estuarine, Coastal and Shelf Science
作者: Neha A. Ghaisas, Kanchan Maiti, John R. White
更新时间: 2019-02-01
摘要: Phosphorus (P) cycling in the coastal ocean along deltaic coastlines is predominantly controlled by river discharge and biogeochemical properties of the sediments. In the Louisiana shelf, sediment biogeochemistry is strongly influenced by seasonally-fluctuating bottom water O₂, which, can potentially transition the shelf sediments from being a sink to source of P. Sediment P fluxes determined using persistent anaerobic and aerobic intact core incubations were 11.46 ± 3.2 mg m⁻² d⁻¹ and 0.67 ± 0.16 mg m⁻² d⁻¹ respectively, indicating a 17 times greater P efflux from O₂-deprived sediments. During the transition from aerobic to anaerobic conditions, the high sedimentary O₂ consumption rate of 889 ± 33.6 mg m⁻² d⁻¹ resulted in a progressive decrease in the dissolved O₂ in the overlying water, leading to a sediment P flux of 7.2 ± 5.5 mg m⁻² d⁻¹, which was mostly driven by P release towards the end of the incubation when the overlying water became near anoxic. This P flux led to a 34.6% loss in sedimentary Fe-bound P during the two-day incubation period which underscores the importance of coupled FeP biogeochemistry and O₂ penetration depth in a coastal hypoxia setting. The high DIN: DIP ratio of river water (∼50:1; P limited) coupled with high potential release of P from the shelf sediments can further increase primary production, further exacerbating hypoxic conditions though increased organic matter (OM) deposition and subsequent decomposition.
图文摘要:

26246. 题目: Low-femtogram sensitivity analysis of polyaromatic hydrocarbons using GC-APLI-TOF mass spectrometry: Extending the target window for aromatic steroids in early Proterozoic rocks
文章编号: N19020101
期刊: Organic Geochemistry
作者: Arne Leider, Sigrid Richter-Brockmann, Benjamin J. Nettersheim, Christine Achten, Christian Hallmann
更新时间: 2019-02-01
摘要: Reading the molecular record of early life on Earth can be challenging as a consequence of the thermal decomposition of biomarker hydrocarbons during extended and deep sedimentary burial. Biomarkers that appear absent may still exist in concentrations far below the detection limit of regular analytical techniques. Hence thermal maturation and analytical limitations form a major hurdle for the unambiguous reconstruction of Earth’s earliest ecosystems. Specific degradation products of hopanes and steranes might still carry diagnostic value for the reconstruction of past biota when found in mature oils and sediment extracts, but their concentrations are often exceedingly low. We here report on the use of gas chromatography–time-of-flight-mass spectrometry with laser ionization at atmospheric pressure (GC-APLI-TOF-MS) for the identification and quantification of aromatic steroids. GC-APLI-TOF-MS analyses of a reference oil revealed that triaromatic steroids (TAs) can be detected with significantly higher sensitivity and selectivity compared to commonly used electron impact ionization GC-MS in selected ion monitoring mode, while the limit of detection for retene was as low as 25 fg on column. Paleoproterozoic (1.64 Ga) sedimentary rocks of the Barney Creek Formation yield the so far oldest unambiguous aromatic steroids. GC-APLI-TOF-MS applied to these rocks revealed the presence of TAs in even deeper parts of this succession, where they are represented by short chain homologues only. While the TA-I/(TA-I + TA-II) parameter is principally controlled by thermal degradation of longer chain homologues, the complete disappearance of TA-II already at 435-442 °C T_max, may point towards an uncommon thermal gradient in the Barney Creek Formation or towards other influencing factors. GC-APLI-TOF-MS proves to be a highly promising tool that might extend molecular geobiological approaches to older sedimentary basins that were hitherto precluded from organic geochemical approaches by their elevated thermal maturity.
图文摘要:

26247. 题目: Biological resources in the Sea of Okhotsk Large Marine Ecosystem: Their status and commercial use
文章编号: N19013110
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: V.p. Shuntov, O.a. Ivanov, E.p. Dulepova
更新时间: 2019-01-31
摘要: The ecosystem studies of biological resources in the Sea of Okhotsk Large Marine Ecosystem (LME), launched by the Pacific Research Fisheries Center (TINRO-Center) in the 1980s, are considered in this brief review. Quantitative data on biomass, distribution density and diet of plankton, benthos, nekton, and nektobenthos were collected annually on three to five integrated expeditions annually covering all seasons. These studies show that the biological capacity and the stock size of commercial aquatic species have always been underestimated. According to the latest estimates, the total organic matter produced annually ranges within 17.85–23.9 billion tons of wet weight, of which the primary production accounts for 63–78%. Production of other components is: microzooplankton, up to 2100.0 million t; bacterioplankton, to 5200.0 million t; euryphagous zooplankton (mainly euphausiids and copepods), to 2520.0 million t; predatory zooplankton, to 480.0 million t; zoobenthos, to 340.0 million t; nekton, to 22.7 million t; nektobenthos, to 2.2 million t; marine mammals and birds, 0.1 million t. The stock status of most species of fish and invertebrates are considered to be in good or satisfactory shape. Fishing is regulated based on the precautionary approach. The current annual commercial catch is 1.5–1.7 million tons. In the absence of harvesting of marine mammals, the populations of cetaceans, pinnipeds and sea otter have recovered.

26248. 题目: Seasonality of archaeal lipid flux and GDGT-based thermometry in sinking articles of high latitude oceans: Fram Strait (79° N) and Antarctic Polar Front (50° S)
文章编号: N19013109
期刊: Biogeosciences
作者: Eunmi Park, Jens Hefter, Gehard Fischer, Morten H. Iversen, Simon Ramondenc, Eva-Maria Nöthig, and Gesine Mollenhauer
更新时间: 2019-01-31
摘要: The relative abundance of individual archaeal membrane lipids, namely of glycerol dialkyl glycerol tetraethers (GDGTs) with the different number of cyclopentane rings, varies with temperature, which enabled their use as paleotemperature proxy. The first GDGT-based index in marine sediments called TEX₈₆ is believed to reflect mean annual sea surface temperature (maSST). The TEX₈₆^L is an alternative temperature proxy for low temperature regions (<15°C), where the original TEX₈₆ proxy suffers from scattering in a linear calibration with SSTs. However, TEX₈₆^L-derived temperatures still display anomalous estimates in polar regions. In order to elucidate the potential cause of the disagreement between TEX₈₆^L estimate and SST, we analyzed GDGT fluxes and TEX₈₆^L-derived temperatures in sinking particles collected with time-series sediment traps in high northern and southern latitude regions. At 1296m depth in the eastern Fram Strait (79°N), a combination of various transporting mechanisms for GDGTs might result in seasonally different sinking velocities for particles carrying these lipids, resulting in strong variability in the TEX₈₆^L signal. The similarity of flux weighted TEX₈₆^L temperatures from sinking particles and surface sediments implies an export of GDGTs without alteration during transport in the Fram Strait. The estimated temperatures correspond to temperatures in water depths of 30–80m, where nitrification might occur, indicating the favorable depth habitat of Thaumarchaeota. In the Antarctic Polar Front of the Atlantic sector (50°S), TEX₈₆^L-derived temperatures displayed warm and cold biases compared to satellite-derived SSTs at 614m depth, and its flux-weighted mean signal differs from the deep signal at 3196m. TEX₈₆^L-derived temperatures at 3196m depth and the surface sediment showed up to 7°C warmer temperatures relative to satellite-derived SST. Such a warm anomaly might be caused by GDGT contributions from Euryarchaeota, which are known to dominate archaeal communities in the circumpolar deep water of the Antarctic Polar Front. The other reason might be that a linear calibration is not appropriate for this frontal region. Of the newly suggested SST proxies based on hydroxylated GDGTs (OH-GDGTs), only those with OH-GDGT−0 and Crenarchaeol or the ring index (RI) of OH-GDGTs yield realistic temperature estimates in our study regions, suggesting that OH-GDGTs could be applied as a potential temperature proxy in high latitude oceans.

26249. 题目: Tracking multiple aromatic compounds in a full-scale coking wastewater reclamation plant: Interaction with biological and advanced treatments
文章编号: N19013108
期刊: Chemosphere
作者: Jing Ren, Jianfeng Li, Jianguo Li, Zuliang Chen, Fangqin Cheng
更新时间: 2019-01-31
摘要: Aromatic compounds are widely contained in coking wastewater (CWW), drawing great attention due to their potential risks to environment and human health. Integrated systems combining biological processes with advanced treatments are the current trend of CWW reclamation. However, the variations of aromatic composition throughout these processes are poorly understood. This study investigated the occurrence, fate and removal of aromatic compounds in a full scale CWW reclamation plant with eight treatment stages by gas chromatography–mass spectrometry and optical spectrum. The results showed that polycyclic aromatic hydrocarbons (PAHs), phenols and heterocyclic compounds accounted for 38.9%, 33.5% and 22.6% of the total organics in CWW, respectively. Among them, PAHs were more sensitive to anaerobic digestion, while phenols and heterocyclics had higher bioavailability in aerobic process. Although more than 90% DOC could be removed in biological processes, the bio-effluent was still brown in color, implying the residues of aromatics to the advanced treatments. The interaction between the bio-refractory organics and the advanced treatments suggested that multiple aromatic compounds were selectively removed along the treatment train. Specifically, coagulation, sand filtration, ultrafiltration, adsorption, nanofiltration and reverse osmosis were found to be highly related to the elimination of residual isoquinoline, phenol, cresol, fluoranthene, benzene and humic-like organics, correspondingly. Findings in this study indicated that adsorption was a key step for removing chromophoric PAHs with more aromatic rings, while fouling control in the end-point membrane systems should be focused on the elimination of BTEXs and humic-like substances.
图文摘要:

26250. 题目: Ca²⁺ complexation of dissolved organic matter in arid inland lakes is significantly affected by drastic seasonal change of salinity
文章编号: N19013107
期刊: Science of The Total Environment
作者: Daoyong Zhang, Qinghua Lin, Nana Xue, Pengfeng Zhu, Fan Zhang, Chang Ge, Chaojie Ma, Xiangliang Pan
更新时间: 2019-01-31
摘要: CaCO₃ precipitation is one of the most common and important geochemical processes in the arid inland waters and it can be significantly affected by interaction of DOM with Ca²⁺. Effects of the drastic seasonal change of water salinity on interaction of DOM with Ca²⁺ in the arid inland waters were completely unknown. In the present study, complexation of DOM with Ca²⁺ in the freshwater (0.5‰ salinity) and hypersaline water (70‰ salinity) were comparatively examined by excitation-emission matrix (EEM) fluorescence quenching titration and isothermal titration calorimetry (ITC). The complexation of DOM with Ca²⁺ was significantly influenced by the drastic change of salinity. The ITC complexation is exothermic at 0.5‰ salinity but turns to an endothermic process at 70‰ salinity. More energy is needed for the complex reaction between DOM and Ca²⁺ under the hypersaline condition than in the fresh water. Fluorescence quenching titration indicates that DOM has stronger binding ability toward Ca²⁺ in the freshwater than in the saline water, and more fractions of DOM in the freshwater are accessible to Ca²⁺ than in the saline water. Ca²⁺ complexation in the DOM is dominated by the tryptophan-like components at both salinities and the complexation of Ca²⁺ with fulvic acid-like components is ignorable. The findings is important for understanding the aquatic geochemical processes in some lakes that seriously affected by irrigation water use in the arid zone.
图文摘要:

26251. 题目: Long-term greenhouse vegetable cultivation alters the community structures of soil ammonia oxidizers
文章编号: N19013106
期刊: Journal of Soils and Sediments
作者: Xing Liu, Ying Zhang, Xiujuan Ren, Bihua Chen, Changwei Shen, Fei Wang
更新时间: 2019-01-31
摘要: Purpose: Continuous cropping obstacles derived from long-term intensive cultivation has severely affected the healthy development of greenhouse vegetable industry in China. The alterations in soil microbial communities are commonly thought to be the important reasons behind continuous cropping obstacles. However, little attention is focused on soil functional microorganisms, such as soil ammonia oxidizers, which convert NH₃ to NO₂⁻ in soils and play an important role in terrestrial ecosystem N cycling. Materials and methods: With the help of quantitative real-time PCR and high-throughput sequencing methods, this study investigated the effects of consecutive greenhouse vegetable cultivation on the abundances and community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB). Results and discussion: Continuous greenhouse production significantly affected soil physicochemical properties but slightly influenced on soil biochemical properties. Long-term greenhouse production significantly decreased soil potential nitrification rates. The abundances of AOA and AOB were insensitive to continuous greenhouse cultivation, whereas their community structures were significantly altered. A significant increase in average relative abundance of Nitrososphaerales Clade B4 in AOA community was observed after long-term greenhouse cultivation but just the opposite for Nitrososphaerales Clade Nitrososphaera. Increasing greenhouse cultivation years decreased the average relative abundance of Nitrosospira in AOB community, and their ecological niches were gradually occupied by Nitrosomonas; consequently, Nitrosomonas dominated AOB community under long-term greenhouse vegetable cultivation. Soil physicochemical properties, but not biological activity, were directly linked to the shifts of community structures of ammonia oxidizers. Moisture and total nitrogen significantly regulated AOA community structure, whereas organic matter and salinity mediated that of AOB. Conclusions: Our results demonstrated that consecutive greenhouse production obviously affected soil N turnover through altering community structures of nitrifiers, and soil functional microorganisms should be taken more attention when exploring the mechanisms for continuous cropping obstacles of greenhouse vegetable. The current study also highlights the fast adaptation of both AOA and AOB communities to complexly varied soil physicochemical environments.

26252. 题目: In situ and ex situ bioremediation of seleniferous soils from northwestern India
文章编号: N19013105
期刊: Journal of Soils and Sediments
作者: Shrutika L. Wadgaonkar, Alberto Ferraro, Yarlagadda V. Nancharaiah, Karaj S. Dhillon, Massimiliano Fabbricino, Giovanni Esposito, Piet N. L. Lens
更新时间: 2019-01-31
摘要: Purpose: Selenium (Se) toxicity or deficiency disorders are chiefly associated with Se concentration and speciation in soils. Elevated soil Se content may lead to contamination of water bodies and groundwaters due to the leaching caused by rainfall and irrigation. This study is focused on Se removal by in situ (biostimulation and bioaugmentation) and ex situ (soil washing) bioremediation as well as on its recovery. Materials and methods: In this research, in situ bioremediation of Se-rich soil collected from rice fields in Ludhiana, Northwest India was studied in microcosms. The effect of biostimulation was determined by amending soil with different organic sources (fermentable, non-fermentable, and non-hydrolysable electron donors). The effect of bioaugmentation was determined by adding anaerobic granular sludge to the microcosms. With regard to ex situ bioremediation, the Se-rich soil was leached with water and the resulting leachate was biologically treated in an upflow anaerobic sludge blanket (UASB) reactor using lactate as electron donor. The UASB reactor was operated for 78 days in different conditions of lactate (electron donor) dosing to achieve maximum Se removal and recovery as elemental Se(0) on the granular sludge. The effluent of the UASB reactor was regularly analyzed to determine Se removal efficiencies. Results and discussion: The effect of biostimulation and bioaugmentation showed no significant difference in terms of Se reduction profiles in the microcosms. This suggested that the indigenous Se-reducing microorganisms and oxidizable organic carbon present in the soil are sufficient for in situ soil bioremediation. During treatment of soil leachate in the UASB reactor, 90% Se removal was achieved irrespective of the lactate dosing and mineral salt medium composition of the reactor influent. Analysis of the granular sludge using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and powder X-ray diffraction (P-XRD) confirmed the presence of elemental Se on the granular sludge. The total Se concentration in the anaerobic granular sludge amounted to 43.5 (± 0.7) μg Se per gram of granular sludge. Conclusions: In situ bioremediation achieved Se reduction in the Se-rich soil investigated. However, risk of Se re-oxidation and leaching into groundwater after in situ remediation cannot be disregarded. In contrast, during ex situ treatment, effluent from the UASB reactor contained less than the USEPA guideline value 5 μg L⁻¹ Se. This study showed biological treatment of Se-rich soils is suitable for cleaning the soil, Se recovery, and environmentally acceptable effluent discharge of the soil washing leachate treatment.

26253. 题目: Impact of surfactant and dissolved organic matter on uptake of atrazine in maize and its mobility in soil
文章编号: N19013104
期刊: Journal of Soils and Sediments
作者: Bing Bing Tian, Jing Hua Zhou, Fei Xie, Qian Nan Guo, Ai Ping Zhang, Xin Qiang Wang, Qian Qian Yu, Na Li, Hong Yang
更新时间: 2019-01-31
摘要: Purpose: The purposes of this study were to investigate the activation and transport of atrazine in the presence of dissolved organic matter (DOM) and the surfactant (Triton X-100) and to understand interactions between DOM, Triton X-100, and atrazine. Materials and methods: Uncontaminated soils collected from Nanjing, China, along with DOM extracted from rice straw and Triton X-100 (TX-100), were used in the study. The sorption and desorption experiments were carried out using the standard batch equilibration analysis. Soil column leaching was conducted with soil samples packed into PVC columns. Soil thin-layer chromatography was performed using soil and water mixture spread on a 0.5–0.7-mm-thick layer over 20 × 10-cm glass plates. Atrazine accumulation in maize was determined by planting maize in plastic pots (1 L) containing 1 kg soil mixed with 1.0 mg kg⁻¹ atrazine. Soils were watered with different solutions, with the relative water content of 60%. Results and discussion: Using batch experiment and soil thin-layer chromatography, application of DOM and surfactant reduced sorption and increased desorption of atrazine in soil. In column experiment, DOM and surfactant significantly promoted the mobility of atrazine in soil and the total concentration of atrazine in leachate of the soil column. Accumulation of atrazine in both maize roots and shoots increased with the elevated concentration of surfactant, whereas the content of atrazine declined with the increase of the DOM concentration. Conclusions: Dissolved organic matter and TX-100 affected the partitioning and transport of atrazine in soil–water and soil–plant ecosystems.

26254. 题目: Effects of water and organic manure coupling on the immobilization of cadmium by sepiolite
文章编号: N19013103
期刊: Journal of Soils and Sediments
作者: Yiyun Liu, Yingming Xu, Xu Qin, Lijie Zhao, Qingqing Huang, Lin Wang
更新时间: 2019-01-31
摘要: Purpose: Natural sepiolite (SP) has proven effective on the in-situ immobilization remediation of Cd-contaminated soils. But the practical remediation effect may largely influenced by water management and the application of organic manure. The effects of chicken manure (CM) on SP-amended soils were investigated under normal and saturated water conditions using a pot experiment with Brassica campestris L. Materials and methods: Cd-contaminated paddy soils were amended with CM, SP, and CM + SP with no amendment as control. The amount of sepiolite was 0.5% (w/w, the same below) either in SP or CM + SP amended soils, while the amount of CM was 0.5, 1.0, and 2.0% in CM and CM + SP-amended soils. The plant metal contents, fresh weight, and soluble sugar content of plant edible parts were measured on harvest. Soil Cd was extracted by diethylenetriaminepentaacetic acid (DTPA) and HCl to estimate the mobility of heavy metal. Soil pH and dissolved organic matter (DOM) of rhizosphere soil were determined. The electronegative charges of soils were also measured using the zeta potential. Results and discussion: The application of CM and increasing soil moisture on SP-amended soil increased plant growth to a greater extent than the application of SP alone. The application of CM along with the increase of soil moisture decreased Cd uptake and translocation in plants grown on SP-amended soil compared to the application of SP alone. Cd content of edible plant parts reached a minimum of 0.24 mg kg⁻¹ with the application of 2.0% CM on SP-amended soils under water-saturated conditions, which was approximately 50% lower than the Cd concentration found when applying SP alone. Conclusions: The results of this study suggest that the application of sepiolite on Cd contaminated soil can effectively reduce Cd uptake by B. campestris L., and the addition of CM combined with effective water management also appears to further reduce Cd absorption and accumulation.

26255. 题目: Biochar reduced soil extractable Cd but increased its accumulation in rice ( Oryza sativa L.) cultivated on contaminated soils
文章编号: N19013102
期刊: Journal of Soils and Sediments
作者: Honghong Li, Yong Yu, Yanhui Chen, Yunyun Li, Mingkuang Wang, Guo Wang
更新时间: 2019-01-31
摘要: Purpose: This study focused on the effects and mechanisms of biochar amendment to Cd-contaminated soil on the uptake and translocation of Cd by rice under flooding conditions. Materials and methods: Pot and batch experiments were conducted using Cd-contaminated soil collected from a field near an ore mining area and a cultivar of Oryza sativa ssp. indica. Biochar derived from rice straw under anaerobic conditions at 500 °C for 2 h was mixed with the soil at the rate of 0, 2.5, and 5%. Results and discussion: The application of 5% biochar reduced CaCl₂-extractable soil Cd by 34% but increased Cd concentration in brown rice by 451%. Biochar amendment decreased water-soluble Fe²⁺ in soils and formation of Fe plaques on roots and weakened the Fe²⁺-Cd²⁺ competition at adsorption sites on the root surface. Biochar increased water-soluble Cd in the soil and consequently Cd uptake by rice roots by releasing water-soluble Cl⁻. Biochar application also reduced the proportion of cell wall-bound Cd in the root, which caused easier Cd translocation from the cortex to the stele in the root and up to the shoot. Conclusions: Rice straw biochar (with high concentration of water-soluble Cl⁻) reduced CaCl₂-extractable soil Cd but increased Cd concentration in rice under flooding condition.

26256. 题目: Assessment of the retardation of selected herbicides onto Danube sediment based on small column tests
文章编号: N19013101
期刊: Journal of Soils and Sediments
作者: Anita Leovac Maćerak, Ivana Ivančev-Tumbas, Hilmar Börnick, Gordana Ilić, Marijana Kragulj Isakovski, Snežana Maletić
更新时间: 2019-01-31
摘要: Purpose: This study utilizes column tests to investigate the retardation of certain herbicides with different hydrophobicities (atrazine, alachlor and trifluralin) during transport through surface Danube sediment. The influence of water matrix on the retardation factor R_d and Freundlich constant K_f is investigated. The results are compared with batch tests to establish whether different methodologies result in similar or different conclusions. Materials and methods: A stainless steel column was filled with natural Danube sediment. Three water matrices were investigated: synthetic, Danube surface, and deep groundwater rich in natural organic matter (NOM). The goal was to examine whether different water matrices would result in changes in the R_d and corresponding K_f values. After a tracer experiment, single herbicide solutions were tested in the three water matrices. Herbicides were analyzed by gas chromatography coupled with electron capture detector (GC/ECD). Retardation factors obtained in the column experiments were calculated using Transmod software (version 2.2). The K_f values calculated were compared with the values obtained in previous batch experiments. Results and discussion: A breakthrough curve (BTC) for trifluralin could not be obtained during the experiment. Atrazine R_d values were almost the same in the natural matrices (54 and 55 for the ground and surface waters, respectively), and lower in the synthetic water (40). Alachlor R_d values in the three water matrices were very similar (30–35). The corresponding K_f values for alachlor (8.47–17.4) were lower than those of atrazine (13.5–27.9). These results differ from those obtained by earlier batch tests, which showed similar K_f values for both atrazine (4.4–9.2) and alachlor (4.43–10.35) in all three matrices. In contrast to the results observed during the batch tests, the column tests exhibited higher K_f values in the natural water matrices than the synthetic water, possibly due to the influence of dissolved organic carbon on herbicide sorption. Conclusions: Of the three herbicides investigated, the smallest retardation was observed for alachlor. This was unexpected given the relative hydrophobicities of alachlor and atrazine. The potential risk of transport through the sediment may therefore be greater for alachlor than the other two herbicides. This was indicated neither by the batch tests nor from the K_oc–K_ow estimations. Both herbicides exhibited similar K_d and K_f values in the batch tests, and lower values in the natural water matrices. In comparison, the column tests showed higher K_f values, with higher values in the natural matrices than in the synthetic water matrix.

26257. 题目: The ballast effect of lithogenic matter and its influences on the carbon fluxes in the Indian Ocean
文章编号: N19013020
期刊: Biogeosciences
作者: Tim Rixen, Birgit Gaye, Kay-Christian Emeis, Venkitasubramani Ramaswamy
更新时间: 2019-01-30
摘要: Data obtained from long-term sediment trap experiments in the Indian Ocean in conjunction with satellite observations illustrate the influence of primary production and the ballast effect on organic carbon flux into the deep sea. They suggest that primary production is the main control on the spatial variability of organic carbon fluxes at most of our study sites in the Indian Ocean, except at sites influenced by river discharges. At these sites the spatial variability of organic carbon flux is influenced by lithogenic matter content. To quantify the impact of lithogenic matter on the organic carbon flux, the densities of the main ballast minerals, their flux rates and seawater properties were used to calculate sinking speeds of material intercepted by sediment traps. Sinking speeds in combination with satellite-derived export production rates allowed us to compute organic carbon fluxes. Flux calculations imply that lithogenic matter ballast increases organic carbon fluxes at all sampling sites in the Indian Ocean by enhancing sinking speeds and reducing the time of organic matter respiration in the water column. We calculated that lithogenic matter content in aggregates and pellets enhances organic carbon flux rates on average by 45% and by up to 62% at trap locations in the river-influenced regions of the Indian Ocean. Such a strong lithogenic matter ballast effect explains the fact that organic carbon fluxes are higher in the low-productive southern Java Sea compared to the high-productive western Arabian Sea. It also implies that land use changes and the associated enhanced transport of lithogenic matter from land into the ocean may significantly affect the CO2 uptake of the organic carbon pump in the receiving ocean areas. ]]>

26258. 题目: Enhanced mineralization of sedimentary organic carbon induced by excess carbon from phytoplankton in a eutrophic plateau lake
文章编号: N19013019
期刊: Journal of Soils and Sediments
作者: Changchun Huang, Zhili Chen, Yan Gao, Yang Luo, Tao Huang, Axing Zhu, Hao Yang, Benjun Yang
更新时间: 2019-01-30
摘要: Purpose: Large additions of organic carbon (OC) have been introduced into the carbon cycle of lakes from algae during the process of lake eutrophication. The impact of eutrophication on OC burial and CO₂ fixing has been widely studied; however, there is still a gap regarding the impact of excess OC from algae on sedimentary OC mineralization. In this study, we aim to fill this gap by analyzing in situ measurements. Materials and methods: Three pairs of sediment cores collected from a plateau lake (Dianchi Lake) in 2006 and 2014 were used to estimate the accumulation loss rate (ALR) of OC (and thus the total mineralization rate) in the sediment. n-Alkanes, measured from the same sedimentary cores, were used to identify the source of OC. An OC mineralization experiment in a laboratory was used to confirm the enhanced effect of excess phytoplankton carbon on ALR and reveal the potential influence of microorganisms. Results and discussion: The results indicate that the sedimentary core (core 3), with high excess OC from algae (located in an algal bloom area), possessed a higher ALR (85.66%) and a higher attenuation coefficient (0.078), indicating the low burial efficiency and short mineralization duration of OC. Sedimentary core 1, controlled by terrestrial OC, had a relatively lower ALR (64.60%) and lower attenuation coefficient (0.029), indicating a high burial efficiency and long period of OC mineralization. The mineralization of OC in core 2 was impacted by terrestrial and endogenous OC, with an ALR of 72.00% and attenuation coefficient of 0.064, which is between that of cores 1 and 3. Excess OC from algae corresponded to an increase in ALR by 32.60% when comparing core 1 to core 3. The increased ALR and attenuation coefficient could be caused by excess OC from algae. Conclusions: Sedimentary OC mineralization indicates that the ALR with dominantly allochthonous OC (64.60%) is much lower than that controlled by autochthonous OC (85.66%). Excess OC from phytoplankton increases the mineralization of OC: not only via increased ALR but also increased mineralization speed. The laboratory experiment on the mixture of algae and sediment suggested that excess phytoplankton OC increased the emission of CO₂ by 20–70% (mineralization rate).

26259. 题目: Wetland floodplain flux: temporal and spatial availability of organic matter and dissolved nutrients in an unmodified river
文章编号: N19013018
期刊: Biogeochemistry
作者: Carla L. Atkinson, Brian C. van Ee, YueHan Lu, Wenli Zhong
更新时间: 2019-01-30
摘要: River ecosystem dynamics are strongly regulated by the surrounding watershed. The availability and sources of energy and nutrient resources that drive these systems are controlled by topography, climate, geology, and position in the watershed. Here we examined particulate and dissolved organic matter (POM and DOM, respectively) and nutrient concentrations across an entire watershed during multiple flow regimes in an unregulated, low gradient river with extensive floodplain forests. The objectives of the study were to: (1) determine the influence of watershed position and floodplain connectivity on POM, DOM, and nutrient concentrations; (2) examine the influence of flow variability on POM, DOM, and nutrient concentrations; and (3) develop an empirical rating curve to predict POM, DOM, and nutrient transport and flux. We sampled POM, DOM, and nutrient concentrations (ammonia, nitrate, nitrite and soluble reactive phosphorus) at ten sites across the Sipsey River watershed that varied in their degree of connectivity to the floodplain over a two-year period. Both watershed position and flow regime influenced POM, DOM, and nutrient concentrations. In particular, a large floodplain swamp in the middle of the watershed, the Sipsey Swamp, strongly controlled the relative availability of particulate and dissolved materials in the water. In the headwaters, there was a greater proportion of particulate material in suspension relative to dissolved carbon. While in the downstream reaches, both within and downstream of the Sipsey Swamp, DOC accompanied by greater molecular mass and more aromatic DOM was in greater quantity than particulate materials at high flows. Nutrient concentrations in the stream water tended to decline through the floodplain swamp across all flow conditions and tended to be lower in high flows. We demonstrate that floodplains can disrupt the upstream–downstream continuum by supplying a large quantity of allochthonous organic matter. Using long-term data we estimated the total annual flux of DOC and nitrate to range between 1221–6500 and 24–35 tonnes per year, respectively, between 2007 and 2017 with the highest flux rates occurring during high flow periods. Our study shows the complex dynamics of a natural floodplain river system and generally supports the flood pulse concept by highlighting the importance of wetland complexes and floodplain connectivity on material and nutrient transport. Description of organic matter and nutrient dynamics in natural low gradient rivers is critical to understanding production of organisms, food webs and ecosystem processes in the face of climate and land use changes.

26260. 题目: Mixed heavy metals removal from wastewater by discarded mushroom-stick biochar: adsorption properties and mechanisms
文章编号: N19013017
期刊: Environmental Science: Processes Impacts
作者: Xinhua Wang, Xin Li, Guangqing Liu, Yufei He, Chang Chen, Xiaoying Liu, Gang Li, Yiqin Gu, Yuqing Zhao
更新时间: 2019-01-30
摘要: Abstract The physicochemical, morphology properties and the sorption capacities of discarded mushroom-stick biochar (DMB) prepared under different pyrolysis temperatures from 300 °C to 800 °C were explored. Results showed that the yield and surface oxygen-containing group of DMB prepared at 300 °C (DMB3) were higher than that of DMB prepared at higher pyrolysis temperature (DMB5 and DMB8), while the DMB prepared at 800 °C (DMB8) had higher pH, mineral elements, ash content, aromaticity, and polarity. Therefore, the heavy metal adsorption capacity of DMB3 was higher than DMB5, while the maximal sorption capacities of Pb2+, Cu2+, Cd2+, and Ni2+ (21.0, 18.8, 11.2, and 9.8 mg•g−1) were obtained by DMB8. Adsorption kinetics and sorption isotherms data were fitted more well by pseudo second order and Langmuir models, thereby indicating that the heavy metal adsorption by DMB was monolayer and rapid adsorption. Based on the contribution percentage parameters of diverse heavy metal sorption mechanisms, mineral precipitation and ion exchange were the two dominant mechanisms of heavy metal adsorption by DMB. This study provided a promising way not only to recycle the discarded mushroom-sticks into feasible heavy metal adsorbents, but also for potential utilization of agriculture waste.