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24581. 题目: Integrating metabolomics and physiological analysis to investigate the toxicological mechanisms of sewage sludge-derived biochars to wheat
文章编号: N19091706
期刊: Ecotoxicology and Environmental Safety
作者: Lulu Kong, Jingze Liu, Qian Han, Qixing Zhou, Junliang He
更新时间: 2019-09-17
摘要: Effects of sewage sludge biochars (SSBCs) on the growth of wheat and the specific toxicological mechanisms were investigated from a metabolic perspective for better ecological risk assessment. We observed that conversion of sludge to biochar remarkably changed the properties, and also caused a significant (p < 0.05) reduction of the toxicity towards wheat. Wheat growth under exposure to SSBCs was influenced by the pyrolysis temperature (300 °C, 500 °C and 700 °C), with root length being promoted by SSBCs prepared at higher temperatures (500 °C and 700 °C). In addition to the contaminants, including polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) detected in SSBCs, the morphological characteristics of biochars contributed substantially to the wheat growth. Metabolomics analysis revealed the remarkable differences in the metabolic profiles among the control (CK), SS300- and SS700-treated samples. The toxicological mechanisms involved were found to be associated with the regulation of metabolisms pathways of protein, fatty acids and carbohydrates, among which protein metabolism was most affected by SSBCs. This work presents an innovative concept that SSBCs produced at a proper temperature may minimize the toxic effects on plant growth by regulating the metabolic fluxes in vivo.

24582. 题目: Spectroscopic measurements and imaging of soil colour for field scale estimation of soil organic carbon
文章编号: N19091705
期刊: Geoderma
作者: Asa Gholizadeh, Mohammadmehdi Saberioon, Raphael A. Viscarra Rossel, Lubos Boruvka, Ales Klement
更新时间: 2019-09-17
摘要: Effective measurement and management of soil organic carbon (SOC) are essential for ecosystem function and food production. SOC has an important influence on soil properties and soil quality. Conventional SOC analysis is expensive and time-consuming. The development of spectral imaging sensors enables the acquisition of larger amounts of data using cheaper and faster methods. In addition, satellite remote sensing offers the potential to perform surveys more frequently and over larger areas. This research aimed to measure SOC content with colour as an indirect proxy. The measurements of soil colour were made at an agricultural site of the Czech Republic with an inexpensive digital camera and the Sentinel-2 remote sensor. Various soil colour spaces and colour indices derived from the (i) reflectance spectroscopy in the selected wavelengths of the visible (VIS) range (400–700 nm), (ii) RGB digital camera, and (iii) Sentinel-2 visible bands were used to train models for prediction of SOC. For modelling, we used the machine learning method, random forest (RF), and the models were validated with repeated 5-fold cross-validation. For prediction of SOC, the digital camera produced R² = 0.85 and RMSE_p = 0.11%, which had higher R² and similar RMSE_p compared to those obtained from the spectroscopy (R² = 0.78 and RMSE_p = 0.09%). Sentinel-2 predicted SOC with lower accuracy than other techniques; however, the results were still fair (R² = 0.67 and RMSE_p = 0.12%) and comparable with other methods. Using a digital camera with simple colour features was efficient. It enabled cheaper and accurate predictions of SOC compared to spectroscopic measurement and Sentinel-2 data.

24583. 题目: The chemical fingerprint of solubilized organic matter from eroded soils and sediments
文章编号: N19091704
期刊: Geochimica et Cosmochimica Acta
作者: Sandrine J. Matiasek, Peter J. Hernes
更新时间: 2019-09-17
摘要: Organic matter (OM) transfers between solid and water phases are critical components of OM cycling in surface waters as they contribute to compositional differences between dissolved OM (DOM) and particulate OM (POM). However, fractionation effects during such phase changes are not well-characterized, especially during the release of soluble OM from sediments and eroded soils. Agricultural practices alter the magnitude and timing of OM export and constitute a major source of sediment through soil erosion. This study assessed the elemental, biomolecular, and optical characteristics of DOM solubilized from sediments and soils in an agricultural watershed of northern California to trace compositional changes during OM flow from mobilized soils in streams. Relative to mineral-bound OM, solubilized DOM was nitrogen-poor (more than doubled C:N ratios) and depleted in amino acids and lignin (three- to six-fold decrease in carbon-normalized yields). Distinct fractionation patterns of individual amino acids and lignin phenols led to a more acidic pool of solubilized DOM that appeared substantially more degraded than its source POM, with decreased degradation index (DI) values and more than doubled molar contributions of non-protein amino acids and processing ratio (PR) values. Lignin composition also greatly differed in solubilized DOM compared to mineral-bound OM, with cinnamyl:vanillyl phenol ratios up to six-fold lower in solubilized lignin than in particulate lignin. Solubilized DOM generally resembled stream DOM more than its source POM and was chemically distinguishable from DOM leached from plants. Absorption coefficients and fluorescence peak intensities were strongly correlated with solubilized DOM concentrations and composition, while optical parameters established to characterize DOM origin and reactivity such as spectral slope, fluorescence index, and carbon-specific fluorescence intensities suggested unique compositional traits for solubilized DOM compared to stream DOM. This study therefore documented strong fractionation patterns during solubilization, linking eroded soil OM and stream DOM and highlighting a pathway that can account for compositional differences between DOM and POM in surface waters. A new amino acid parameter, the Solubilization Index (SI), was defined to capture the effects of solubilization processes on OM composition. SI values in solubilized DOM were up to an order of magnitude higher than in its source POM and were similar to SI values in stream DOM. Because the SI is based on empirical behaviors of individual amino acids, each tied to mechanistic interpretations, the SI is demonstrating a strong potential for mechanistic-driven research on the extent of phase changes in streamwater DOM.

24584. 题目: The pH optimum of soil exoenzymes adapt to long term changes in soil pH
文章编号: N19091703
期刊: Soil Biology and Biochemistry
作者: Jérémy Puissant, Briony Jones, Tim Goodall, Dana Mang, Aimeric Blaud, Hyun Soon Gweon, Ashish Malik, Davey L. Jones, Ian M. Clark, Penny R. Hirsch, Robert Griffiths
更新时间: 2019-09-17
摘要: Soil exoenzymes released by microorganisms break down organic matter and are crucial in regulating C, N and P cycling. Soil pH is known to influence enzyme activity, and is also a strong driver of microbial community composition; but little is known about how alterations in soil pH affect enzymatic activity and how this is mediated by microbial communities. To assess long term enzymatic adaptation to soil pH, we conducted enzyme assays at buffered pH levels on two historically managed soils maintained at either pH 5 or 7 from the Rothamsted Park Grass Long-term experiment. The pH optima for a range of exoenzymes involved in C, N, P cycling, differed between the two soils, the direction of the shift being toward the source soil pH, indicating the production of pH adapted isoenzymes by the soil microbial community. Soil bacterial and fungal communities determined by amplicon sequencing were clearly distinct between pH 5 and soil pH 7 soils, possibly explaining differences in enzymatic responses. Furthermore, β-glucosidase gene sequences extracted from metagenomes revealed an increased abundance of Acidobacterial producers in the pH 5 soils, and Actinobacteria in pH 7 soils. Our findings demonstrate that the pH optimum of soil exoenzymes adapt to long term changes in soil pH, the direction being dependent on the soil pH shift; and we provide further evidence that changes in functional microbial communities may underpin this phenomena, though new research is now needed to directly link change in enzyme activity optima with microbial communities. More generally, our new findings have large implications for modelling the efficiency of different microbial enzymatic processes under changing environmental conditions.

24585. 题目: ¹⁵N-amino sugar stable isotope probing (¹⁵N-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities
文章编号: N19091702
期刊: Soil Biology and Biochemistry
作者: Michaela K. Reay, Alice F. Charteris, Davey L. Jones, Richard P. Evershed
更新时间: 2019-09-17
摘要: Although amino sugars represent a major component of soil organic nitrogen (ON), the assimilation of nitrate (NO₃⁻ ) and ammonium (NH₄⁺) into amino sugars (AS) by soil bacteria and fungi represents a neglected aspect of the global N cycle. A deeper knowledge of AS responses to N fertiliser addition may help enhance N use efficiency (NUE) within agricultural systems. Our aim was to extend a sensitive compound-specific ¹⁵N-stable isotope probing (SIP) approach developed for amino acids to investigate the immobilization of inorganic N into a range of amino sugars (muramic acid, glucosamine, galactosamine, mannosamine). Laboratory incubations using ¹⁵N-ammonium and ¹⁵N-nitrate applied at agriculturally relevant rates (190 and 100 kg N ha⁻¹ for ¹⁵NH₄⁺ and ¹⁵NO₃⁻, respectively) were carried out to obtain quantitative measures of N-assimilation into the AS pool of a grassland soil over a 32-d period. Using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) we found that δ¹⁵N values for individual AS reflected differences in routing of the applied ammonium and nitrate. The contrasting N-assimilation dynamics of bacterial and fungal communities were demonstrated through determinations of percentage ¹⁵N incorporation into diagnostic AS. N-assimilation dynamics of the bacterial community were altered with the applied substrate whilst fungal N-assimilation dynamics were unaffected. Rates and fluxes of the applied N-substrates into the bacterial AS pool reflected known biosynthetic pathways for AS, with fungal glucosamine appearing to be biosynthetically further from the applied substrates than bacterial glucosamine due to different turnover rates. This sensitive and specific compound-specific ¹⁵N-SIP approach using AS, building on existing approaches with amino acids (AA), enables differentiation of N-assimilation dynamics within the microbial community and assessment of microbial NUE with agriculturally relevant fertilisation rates.
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24586. 题目: Using UV/H₂O₂ pre-oxidation combined with an optimised disinfection scenario to control CX₃R-type disinfection by-product formation
文章编号: N19091701
期刊: Water Research
作者: Shunke Ding, Feifei Wang, Wenhai Chu, Chao Fang, Yang Pan, Shan Lu, Naiyun Gao
更新时间: 2019-09-17
摘要: The effects of UV/H₂O₂ pre-oxidation or disinfection methods on the formation of partial disinfection by-products (DBPs) have been studied previously. This study assessed the effect of UV/H₂O₂ pre-oxidation combined with optimisation of the disinfection method on the formation of six classes of CX₃R-type DBPs, including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetaldehydes (HALs), haloacetonitriles (HANs), halonitromethanes (HNMs), and haloacetamides (HAMs). Experimental results showed that a simulated distribution system (SDS) in-situ chloramination or pre-chlorination followed by chloramination effectively decreased total CX₃R-type DBP formation by 51.1–63.5% compared to SDS chlorination, but little reduction in DBP-associated toxicity was observed. The dominant contributors to the calculated toxicity were HANs and HALs. UV/H₂O₂ pre-oxidation was able to destroy the aromatic and dissolved organic nitrogen components of natural organic matter. As a consequence, THM, HAA, and HAL formations increased by 49.5–55.0%, 47.8–61.9%, and 42.0–67.1%, respectively, whereas HAN, HNM, and HAM formations significantly decreased by 52.1–83.6%, 42.9–87.3%, and 74.1–100.0%. UV/H₂O₂ pre-oxidation increased total CX₃R-type DBP formation, during SDS chlorination, whereas SDS in-situ chloramination or pre-chlorination followed by chloramination of UV/H₂O₂-treated water produced lower total CX₃R-type DBPs than water without UV/H₂O₂ pre-oxidation. Nevertheless, the DBP-associated toxicity of water with UV/H₂O₂ pre-oxidation was substantially lower than the toxicity for water without UV/H₂O₂ pre-oxidation, decreased by 24.1–82.7%. HALs followed by HANs contribute to major toxic potencies in UV/H₂O₂ treated water. The best DBP concentration and DBP-associated toxicity abatement results were achieved for water treated by UV/H₂O₂ coupled with in-situ chloramination treatment.
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24587. 题目: Recent onset of eutrophication in Lake Izabal, the largest water body in Guatemala
文章编号: N19091604
期刊: Journal of Paleolimnology
作者: Jonathan Obrist-Farner, Mark Brenner, Jason H. Curtis, William F. Kenney, Carlo Salvinelli
更新时间: 2019-09-16
摘要: Recent human population growth has contributed to the degradation of environmental resources in Guatemala. Since 1900, the population of the country grew from < 1 to > 17 million inhabitants. The watershed of Lake Izabal, eastern Guatemala, also experienced rapid population growth, and with it, development of intensive agriculture in areas adjacent to the lake. These recent demographic and land-use changes altered anthropogenic nutrient inputs to the water body, through delivery of raw sewage, and agricultural practices that include excessive use of fertilizers. Currently, Lake Izabal is marked by frequent algal blooms and associated fish-kill events. It also hosts a number of invasive, and in some cases, exotic plant and animal species. We used data from a sediment core collected in the western end of the lake to link past anthropogenic activities in the watershed to the deterioration of water quality and shifts in aquatic ecosystem functioning. We measured total organic carbon (TOC), total nitrogen (TN), and δ13C and δ15N of organic matter in a 137Cs- and 14C-dated sediment core from the Polochic Delta in Lake Izabal to infer past limnological changes. The core chronology indicates that 505 cm of sediment accumulated in only the last 370 years (~ 1.4 cm a−1). TOC and TN concentrations increased since about 1950, a time during which the TOC:TN ratio decreased, indicating a relatively greater contribution of phytoplankton to the sediment organic matter. Stratigraphic shifts in δ13C and δ15N indicate recent increasing inputs of raw sewage and fertilizer to the lake during the same time period. Lake Izabal, like many other water bodies in Guatemala, is starting to undergo cultural eutrophication, which probably accounts for the frequent algal blooms, proliferation of invasive species (e.g. Hydrilla verticillata), and decline in fish abundance.

24588. 题目: Soil moisture as a key factor in carbon release from thawing permafrost in a boreal forest
文章编号: N19091603
期刊: Geoderma
作者: Xiaoyan Song, Genxu Wang, Fei Ran, Kewei Huang, Juying Sun, Chunlin Song
更新时间: 2019-09-16
摘要: The feedback between the atmosphere and permafrost soils containing large carbon stocks is currently considered the most important carbon-cycle feedback, but it is missing from climate models due to many uncertainties. Knowledge of how differences in post-thaw hydrological conditions affect carbon (C) release is critical for predicting permafrost feedback, but this knowledge remains limited. In this study, permafrost and active layer soils from the southern margin of the Eurasian boreal permafrost region in Northeast China were collected and incubated under experimentally modified moisture to monitor their CO₂ and CH₄ productions under simulated natural, drier and flooded conditions. We also characterized soil properties related to soil organic carbon (SOC) quality and microbial activities to determine their relations with measured C productions. We found that permafrost had higher C release per gram of SOC basis (C vulnerability) than the active layer, which suggested that there would be a high risk for C emissions in the permafrost region when permafrost thaws in the warming future. However, hydrological conditions following the permafrost thaw control these emissions. Permafrost C decomposed in relatively aerobic upland systems had higher C emissions than that decomposed in anaerobic wetland environments. Our results suggest a greater climate forcing of C release in aerobic than anaerobic conditions, but there are some uncertainties resulting from the unknown long-term CH₄ production rates. Moreover, we found that the aerobic C production in permafrost after thawing could be constrained by water stress, suggesting that previous predictions based on soil incubations at natural soil moisture might overestimate the aerobic permafrost C release.

24589. 题目: Dramatic enhancement effects of l-cysteine on the degradation of sulfadiazine in Fe³⁺/CaO₂ system
文章编号: N19091602
期刊: Journal of Hazardous Materials
作者: Jian Lu, Tenghao Wang, Yi Zhou, Changzheng Cui, Zhimin Ao, Yanbo Zhou
更新时间: 2019-09-16
摘要: Excessive sulfonamides accumulated in soil and groundwater seriously menace the ecological environment and human health. The performance of a Fenton-like system applying Fe³⁺ and calcium peroxide (CaO₂) in the presence of l-cysteine(l-cys) for sulfadiazine (SDZ) degradation was investigated. Compared with other chelating agents such as citric acid, butyric acid and Ethylenediaminetetraacetic acid, l-cys could effectively promote the SDZ removal in Fe³⁺/CaO₂ system. With the addition of 0.5 mM l-cys, the SDZ degradation increased from 2.14% to 66.53% in 60 min. High concentration of HCO₃⁻ inhibited the degradation of SDZ while slightly negative effects on SDZ degradation were observed in the presence of Cl⁻ or humic acid (HA) in l-cys/Fe³⁺/CaO₂ system. Electron paramagnetic resonance (EPR) analysis and radicals scavenge tests affirmed the generation of OH and O₂- in l-cys/Fe³⁺/CaO₂ system. Possible degradation pathway of SDZ was speculated and the toxicity of SDZ intermediates was further evaluated. l-cys could enhance the reduction of Fe³⁺ to Fe²⁺ and reduced the Fe³⁺ precipitation due to the l-cys could form stable complexes with Fe³⁺. l-cys/Fe³⁺/CaO₂ system exhibited high mineralization ability. Overall, these results indicated that l-cys is a promising chelating agent for sulfadiazine wastewater treatment.
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24590. 题目: Bacillus cereus s-EPS as a dual bio-functional corrosion and scale inhibitor in artificial seawater
文章编号: N19091601
期刊: Water Research
作者: Shunling Li, Qing Qu, Lei Li, Ke Xia, Yan Li, Tingting Zhu
更新时间: 2019-09-16
摘要: In this study, soluble extracellular polymeric substances (s-EPS) secreted by Bacillus cereus (B. cereus) were studied as a novel, dual bio-functional corrosion and scale inhibiting material, in artificial seawater. Static tests showed that the scale inhibition efficiency (SI%) was close to 87.60% for CaCO₃ at the concentration of 80 mg/L s-EPS. Electrochemical technique results showed that s-EPS inhibition efficiencies, in relation to 316L stainless steel (SS), and at the concentration of 40 mg/L, reached 91.05% at 10 d and 91.16% at 30 d, respectively. The high anti-scale and anti-corrosion performance of s-EPS was related to their chelating, adsorption, and biomineralization abilities. s-EPS integrated with metal ions on the SS surface, resulting in formation of a thin but dense biomineralized film, which exhibited lasting corrosion resistance. Meanwhile, s-EPS controlled the kinetic pathway of CaCO₃ biomineralized nucleation and crystal growth, which inhibited CaCO₃ crystal precipitation. This finding suggests that B. cereus s-EPS may offer a green, sustainable, and economic strategy for anti-corrosion and anti-scale application in industry.
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24591. 题目: Hydrogeomorphic controls on soil carbon composition in two classes of subalpine wetlands
文章编号: N19091511
期刊: Biogeochemistry
作者: Ellen E. Daugherty, Georgina A. McKee, Robert Bergstrom, Sarah Burton, Céline Pallud, Robert M. Hubbard, Eugene F. Kelly, Charles C. Rhoades, Thomas Borch
更新时间: 2019-09-15
摘要: Wetlands play a vital role in terrestrial carbon (C) sequestration, but the sensitivity of their C stocks to disturbance remains uncertain, requiring enhanced understanding of the processes that govern C storage and removal. The unique conditions in wetlands from different hydrogeomorphic (HGM) classes likely regulate the cycling, storage and vulnerabilities of wetland soil C stocks. To determine how differences in hydrogeomorphic setting influence soil organic carbon (SOC) processing, we compared C content and composition between depressional and slope wetlands located in the Colorado Rocky Mountains. Isolated depressional wetlands were characterized by seasonally declining water tables, slow discharge, high clay content, and thick organic horizons. Slope wetlands received perennial groundwater inputs and had coarser soil textures and thinner organic horizons. Seasonal snowmelt inputs coupled with low hydrologic discharge and higher clay content in depressional wetlands were predicted to sustain anoxic conditions, leading to high SOC content and chemically reduced C compounds. Depressional wetland soils had higher SOC content at depth and higher porewater DOC concentrations compared to slope wetland soils. Solid-state ¹³C nuclear magnetic resonance spectroscopy demonstrated that aliphatic compounds were the dominant SOC component in depressional wetlands compared to aromatic C forms in the slope wetlands. The higher prevalence of aliphatic carbon in depressional wetland soils suggests that stored SOC is protected by anaerobic conditions to a greater extent than in the slope wetlands, and that this SOC may be more vulnerable to drying and oxic conditions associated with wetland drainage and climate change.

24592. 题目: Effect of soil pH and organic matter content on heavy metals availability in maize ( Zea mays L.) rhizospheric soil of non-ferrous metals smelting area
文章编号: N19091510
期刊: Environmental Monitoring and Assessment
作者: Shengnan Hou, Na Zheng, Lin Tang, Xiaofeng Ji, Yunyang Li
更新时间: 2019-09-15
摘要: Maize plant tissues and rhizosphere soil were collected from an agricultural area around the Huludao Zinc Plant in Liaoning Province, China, to investigate the effects of soil pH and organic matter content on heavy metal concentration and accumulation in different types of maize tissues. The mean pH of the soil samples was 7.02 (range 5.74–7.86), and the mean organic matter content was 31.03 g kg⁻¹ (range 18.80–52.20 g kg⁻¹). The average Cu, Zn, Pb, and Cd contents in soil were 2.92, 6.72, 7.95, and 16.28 times greater than the corresponding background values, respectively. The geo-accumulation index indicated that the soils were uncontaminated to moderately contaminated by Cu, moderately to strongly contaminated by Pb and Zn, and strongly contaminated by Cd. The average available Cu, Pb, Zn, and Cd contents in the soil samples were 16.34, 6.997, 69.77, and 0.190 mg kg⁻¹, respectively, while their bioavailability coefficients were 28.53%, 1.65%, 40.44%, and 10.83%, respectively. The respective mean Pb and Cd concentrations in grain samples were 0.341 and 0.342 mg kg⁻¹, which exceeded the maximum concentrations permitted by the Chinese National Standard. Thus, the maize grain is not safe for consumption and poses potential risks to human health. With the exception of Cu, the combined effect of pH and organic matter content had a stronger influence on the availability of heavy metals in soil compared with either factor alone. Cd uptake in maize plant tissues was affected by the combination of soil pH, organic matter content, and bioavailable Cd content in soil; however, the combination of these three factors had only slight effects on Cu, Zn, and Pb absorption in maize tissues.

24593. 题目: Colloidal transport of carbon and metals by western Siberian rivers during different seasons across a permafrost gradient
文章编号: N19091509
期刊: Geochimica et Cosmochimica Acta
作者: Ivan V. Krickov, Oleg S. Pokrovsky, Rinat M. Manasypov, Artem G. Lim, Liudmila S. Shirokova, Jerome Viers
更新时间: 2019-09-15
摘要: In contrast to fairly good knowledge of dissolved (< 0.45 µm) and particulate (> 0.45 µm) fluxes of carbon, nutrients and metals from the land to the ocean, colloidal (1 kDa - 0.45 µm) forms of solutes are rarely quantified. This is especially true for Siberian rivers draining into the Arctic Ocean: because of organic-rich soils, colloidal fractions of elements are high and may sizably impact coastal biological processes. However, the main environmental parameters such as seasons, river size, climate, permafrost distribution and landscape parameters of the watershed controlling colloidal distribution of organic carbon (OC) and metals remain totally unknown. Here we used on-site centrifugation combined with ultrafiltration via 3, 30 and 100 kDa pore size membranes and 1 kDa dialysis to characterize colloidal size fractionation of OC and metals in 32 western Siberian rivers, ranging in size from 10 to 150,000 km² watershed area, across a climate and permafrost gradient (from absent to continuous permafrost). The dominant forms of OC and metals was low molecular weight LMW_{< 3 kDa} fraction and medium molecular weight (MMW_{3kDa-30 kDa}) colloids. The LMW_{< 3 kDa} fraction of OC increased in the order spring < autumn < summer, following progressive replacement of allochthonous medium and high molecular weight colloids in spring by autochthonous LMW organic ligands in summer; the latter possibly occurred due to exometabolites of plankton and periphyton. The LMW OC fraction became low again in autumn, presumably due to appearance of allochthonous DOM washed out by autumn rains from peat soil at maximum thawing depth. The size of the watershed had subordinate influence on colloidal distribution compared to seasons. The effect of landscape parameters of the watershed on the colloidal status of solutes was subordinate to seasonal and permafrost-zone controls. Overall, the ongoing environmental changes in WSL will likely decrease the proportion of mineral (Fe, Al - bearing) colloids of C and trace metals exported by rivers to the Kara Sea. As a result, the flux of dissolved C, micro-nutrients and metal toxicants may become increasingly bioavailable to coastal aquatic biota.

24594. 题目: Short communication on “Differentiating with fluorescence spectroscopy the sources of dissolved organic matter in soils subjected to drying” [Zsolnay et al. Chemosphere 38, 45–50, 1999]
文章编号: N19091508
期刊: Chemosphere
作者: Susanne Halbedel, Peter Herzsprung
更新时间: 2019-09-15
摘要: This article is a short, but very important comment to the often used humification index (HIX), assumed to indicate the degree of biochemical degradation of dissolved organic matter in water samples. HIX is commonly calculated by dividing the fluorescence intensity detected at longer wave lengths by the intensity detected at shorter wavelengths.However, we found typos in the original article that affect the used equation directly and thus the results. We compared the different ways to calculate HIX and found a strong correlation between all results. Nevertheless, we recommend to use only equation 1, especially if data from different studies should be compared.

24595. 题目: Predicting the sorption of azithromycin and levofloxacin to sediments from mineral and organic components
文章编号: N19091507
期刊: Environmental Pollution
作者: Seiya Hanamoto, Fumiaki Ogawa
更新时间: 2019-09-15
摘要: Despite the strong association of azithromycin (AZM), a macrolide antibiotic, and levofloxacin (LVF), a quinolone antibiotic, to sediment, sorption data are scarce. We conducted sorption experiments with eight river sediments, their major clay minerals (illite and chlorite), a highly negatively charged clay mineral (montmorillonite), and an organic-matter-rich soil (Andosol). The sorption of AZM and LVF to the sediments was influenced by the concentration and type of coexisting inorganic cations as much as by reported organic cations. In addition, their linear sorption coefficients (K_d) to sediments were correlated with cation exchange capacity (CEC) but not organic carbon content, so cation exchange is the dominant sorption mechanism. Multiple linear regression analysis showed improved prediction of sediment K_d from CEC contributed by minerals and organic matter for AZM, but not for LVF. K_cec (= K_d/CEC) values of AZM were 2–3 orders of magnitude higher on minerals than on Andosol, but those of LVF ranged within a factor of 4. Therefore, mineral and organic components need to be separated in estimating AZM sorption to sediments. Sediment K_d values of AZM and LVF were satisfactorily predicted by a cation-exchange-based model using individual K_cec values on illite, chlorite, and Andosol (mean absolute error of 0.57 and 0.22 log units, respectively). K_cec values on montmorillonite and chlorite ranged within a factor of about 3 from those of illite for both antibiotics, and K_cec differences by mineral type would generally be negligible in model estimation. Because AZM was sorbed mostly to minerals in sediments, the model and sorption data can be applicable to various soils or sediments. Overall, the trend of LVF sorption corresponds to reported sorption of other organic cations, whereas remarkably higher AZM K_cec to minerals than to Andosol is attributable to its large lactone ring, higher molecular weight, or two charged amines.
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24596. 题目: Biofilm characteristics, microbial community structure and function of an up-flow anaerobic filter-biological aerated filter (UAF-BAF) driven by COD/N ratio
文章编号: N19091506
期刊: Science of The Total Environment
作者: Hexi Zhou, Guoren Xu
更新时间: 2019-09-15
摘要: The biofilm characteristics, microbial community structure and function in a lab-scale up-flow anaerobic filter-biological aerated filter (UAF-BAF) driven by COD/N ratio were investigated. Results showed that the TN removal rate of system reduced from 68.7% to 50.6% with COD/N ratio ranging from 10 to 3. Biofilm characteristics analysis indicated that the biomass, biofilm thickness, polysaccharide and protein contents in extracellular polymeric substance and dehydrogenase activity from biofilm in the UAF-BAF declined with the decrease of COD/N ratio. The biofilm structure visualized by confocal laser scanning microscopy displayed that the total cells and EPS content decreased as the COD/N ratio downshifted. 16S rRNA sequencing illustrated that Zoogloea and Pleomorphomonas were the major contributors to TN removal in the UAF, with dramatically decreasing abundance. Functional prediction indicated that the genes involved in nitrogen metabolism and nitrate reductase (EC 1.7.99.4) also decreased, which was responsible for the decrease of TN removal. This study provided insights into understanding of the biofilm structure and underlying ecological function in the UAF-BAF, which would help to regulate wastewater biofilm and improve process performance.
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24597. 题目: Spatiotemporal variations of spectral characteristics of dissolved organic matter in river flowing into a key drinking water source in China
文章编号: N19091505
期刊: Science of The Total Environment
作者: Huan Zhang, Kangping Cui, Zhi Guo, Xiaoyang Li, Juan Chen, Zhaoguo Qi, Siyuan Xu
更新时间: 2019-09-15
摘要: The characteristics of dissolved organic matter (DOM) in inflowing river, flowing into drinking water, have profound influences on the quality and safety of water. Here, ultraviolet–visible (UV–vis) spectroscopy and three-dimensional fluorescence (EEM) spectroscopy were combined to investigate the spatiotemporal variations of DOM in Nanfei River flowing into Chaohu Lake in China. 24 water samples and 24 surface sediments samples (including dry-to-wet transition season and wet season in 2018) were collected from different types of outlets. Parallel factor analysis (PARAFAC) model and correlation analysis were conducted to identify the primary sources of DOM. Two humic-like components (C1 235–250 nm/385–430 nm and C3 255–270 nm/455–510 nm) and one tryptophan-like component (C2 270–290 nm/320–350 nm) were effectively identified by PARAFAC model. The results showed DOM concentration presented significant spatiotemporal variations. The concentration was much lower in water than in surface sediments in dry-to-wet transition season, but higher in the wet season. Fluorescence index (FI), biological index (BIX) and humification index (HIX) were used to judge characteristic of DOM origination. These indexes indicated that, DOM in Nanfei River had both the characteristics of humus and autogenous, but neogene autogenic feature was stronger, which was largely due to mixture of water, resuspension and desorption of DOM in sediments and photochemical degradation. In addition, the characteristic parameter of molecular mass of DOM (the values of M) had an obvious linear relationship with the fluorescence intensity ratio of fulvic acid-like to humic acid-like (C1/C3), indicating that macromolecular substances could be removed by adding or improving membrane treatment. These provided technical support for improving quality and comprehensive treatment of drinking water sources.
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24598. 题目: Dissolved organic matter in the deep TALDICE ice core: A nano-UPLC-nano-ESI-HRMS method
文章编号: N19091504
期刊: Science of The Total Environment
作者: Roberta Zangrando, Veronica Zanella, Ornela Karroca, Elena Barbaro, Natalie M. Kehrwald, Dario Battistel, Elisa Morabito, Andrea Gambaro, Carlo Barbante
更新时间: 2019-09-15
摘要: Trace organic compounds in deep ice cores supply important paleoclimatic information. Untargeted analyses of dissolved organic matter provide an overview of molecular species in ice samples; however, sample volumes usually required for these analyses are generally not available from deep ice cores. Here, we developed an analytical method using a nano-UPLC-nano-ESI-HRMS to detect major molecular species in ice cores. Samples (4 μL) from the TALos Dome Ice CorE (TALDICE), allowed investigating molecular species across a range of depths including during glacial and interglacial periods. We detected 317 chemical species that were tentatively assigned to fatty acids, hydroxy fatty acids and their degradation products (oxo-fatty acids and dicarboxylic acids), as well as oxidation byproducts of isoprene and monoterpenes. These compounds indicate that the main sources of the organic fraction are microbes as well as primary and secondary aerosols. Interglacial samples encompass a wide range of species including compounds from the oxidation of isoprene and monoterpenes as well as unsaturated fatty acids, while the glacial samples contained less diverse species. This difference may be due to decreased temperatures during the glacial period inhibiting terrestrial vegetation growth and increasing the sea ice extent, thereby weakening the emission sources.
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24599. 题目: Influence of land use and rainfall on the optical properties of dissolved organic matter in a key drinking water reservoir in China
文章编号: N19091503
期刊: Science of The Total Environment
作者: Yu Shi, Liuqing Zhang, Yuanpeng Li, Lei Zhou, Yongqiang Zhou, Yunlin Zhang, Changchun Huang, Hengpeng Li, Guangwei Zhu
更新时间: 2019-09-15
摘要: The concentration, source and composition of dissolved organic matter (DOM) in aquatic ecosystems are associated with land use and hydrological connectivity between terrestrial and aquatic systems. However, direct evidence of the effects of rainfall and land use on the variability of DOM in aquatic ecosystems is very limited. In this study, chromophoric DOM (CDOM) absorption and fluorescence spectroscopy were used to elucidate how rainfall and land use affect the variability of CDOM in the watershed of Lake Tianmu, a key drinking water reservoir in the Yangtze River Delta. The mean values of the fluorescence intensity (F_max) of parallel factor analysis-derived humic-like components (C1, C3, C6) and tryptophan-like components C5 were higher in the southeastern inflowing river mouths than those downstream of the lake outlet regions. The upstream tributaries were mainly dominated by humic-like materials, while the lake was mainly dominated by protein-like materials. The F_max values of four humic-like components and two tryptophan-like components all increased significantly as the %woodland decreased, but %anthropogenic land use (%cropland + %urban construction area) increased. The F_max of the humic-like components at the inflowing tributaries and the lake increased with increasing rainfall during storm events, and the value was especially pronounced at the inflowing river mouths. We concluded that land use and hydrological conditions play an important role in influencing the CDOM source and optical composition, and these findings provide insights for the understanding of aquatic ecosystem metabolism and reservoir water quality management.
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24600. 题目: Biochar-induced metal immobilization and soil biogeochemical process: An integrated mechanistic approach
文章编号: N19091502
期刊: Science of The Total Environment
作者: Ali El-Naggar, Mi-Hee Lee, Jin Hur, Young Han Lee, Avanthi Deshani Igalavithana, Sabry M. Shaheen, Changkook Ryu, Jörg Rinklebe, Daniel C.W. Tsang, Yong Sik Ok
更新时间: 2019-09-15
摘要: The nature of biochar-derived dissolved organic matter (DOM) has a crucial role in the interactions between biochar and metal immobilization, carbon dynamics, and microbial communities in soil. This study utilized excitation–emission matrix coupled with parallel factor analysis (EEM-PARAFAC) modeling to provide mechanistic evidence of biochar-induced influences on main soil biogeochemical processes. Three biochars produced from rice straw, wood, and grass residues were added to sandy and sandy loam soils and incubated for 473 d. Microbial and terrestrial humic-like fluorescent components were identified in the soils after incubation. The sandy loam soil exhibited a higher DOM with microbial sources than did the sandy soil. All biochars reduced Pb bioavailability, whereas the rice straw biochar enhanced the As bioavailability in the sandy loam soil. The biochar-derived aliphatic-DOM positively correlated with As bioavailability (r = 0.82) in the sandy loam soil and enhanced the cumulative CO₂-C (r = 0.59) in the sandy soil. The promoted cumulative CO₂-C in the sandy soil with all biochars correlated with the enhanced microbial communities, in particular, gram-positive (r = 0.59) and gram-negative (r = 0.59) bacteria. Our results suggest that the integration of EEM-PARAFAC with spectroscopic indices could be useful for a comprehensive interpretation of the soil quality changes in response to the application of biochar.
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