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25281. 题目: Characterization of the extracellular polymeric substances (EPS) of Virgibacillus strains capable of mediating the formation of high Mg-calcite and protodolomite
文章编号: N19081514
期刊: Marine Chemistry
作者: Zulfa Ali Al Disi, Nabil Zouari, Maria Dittrich, Samir Jaoua, Hamad Al Saad Al-Kuwari, Tomaso R.R. Bontognali
更新时间: 2019-08-15
摘要: The origin of dolomite –a common mineral in the geological record– is the subject of an ongoing debate. Among different hypotheses, it has been proposed that extracellular polymeric substances (EPS) excreted by microbes include organic molecules that catalyze the incorporation of Mg in the carbonate mineral. However, limited information exists on the composition of the EPS produced by CaMg carbonate- forming microbes, which in turn hampers a precise understanding of their role in the mineralization mechanism. Here, we present the results of laboratory experiments in which we cultured different strains of microbes, characterized their EPS, and identified components associated with carbonate minerals with high mol% Mg. Two Virgibacillus strains known to mediate the formation of Mg-rich carbonates, as well as a strain of Bacillus licheniformis –a negative control that does not mediate mineral formation but produces EPS, were grown under different salinities and temperatures, which caused them to produce EPS with different compositions. The EPS were subsequently characterized by measuring total carbohydrate (TCHO) and total protein (TP) contents, as well as by Fourier-transform infrared spectroscopy (FTIR). At the tested conditions, we found that Mg-carbonates with a mol% Mg higher than 40% (i.e., potential dolomite precursor phases) formed exclusively in association with EPS rich in carbohydrates (TCHO > than 75% of the total mass). FTIR spectra of CaMg carbonate-forming strains were distinct from those of the non-mineral-forming strain in areas associated with the protein structures responsible for the formation of hydrogels, which contribute to hydration or dehydration of ionic clusters; further differences have been observed in the regions of phosphoryl functional groups. These results provide insight on which fraction of organic molecules and specific functional groups are, among the many constituents of EPS, important for mineral nucleation and incorporation of Mg into carbonate minerals, a crucial step for the formation of dolomite in natural environments.

25282. 题目: Interacting effects of plant invasion, climate, and soils on soil organic carbon storage in coastal wetlands
文章编号: N19081513
期刊: Journal of Geophysical Research: Biogeosciences
作者: Ren‐Min Yang
更新时间: 2019-08-15
摘要: Coastal wetland soils store large amounts of organic carbon, which is becoming vulnerable to environmental changes such as exotic species invasion and climate change. Soil organic carbon (SOC) is also related to soil biogeochemical factors. To understand the mechanisms of these changes in regulating SOC, it is necessary to characterize the direct and indirect effects of exotic species invasion, climate, and soil variables on SOC. We used a structural equation model to identify the key driving mechanisms of SOC storage to a depth of 1 m at 15 sites on the East China coast, where Spartina alterniflora Loisel. (S. alterniflora) invasion has significantly influenced SOC storage. The model revealed several patterns that are expected to explain the enhanced SOC storage. S. alterniflora invasion had a direct effect on SOC storage mainly due to its impacts on biomass production. Temperature had an important influence on SOC storage and the sub‐surface SOC content. SOC storage was also related to the interacting effects of S. alterniflora invasion and soil biogeochemical properties such as soil salinity, fine soil fraction, and bulk density. The relative contribution of SOC in the topsoil to SOC storage at a depth of 1 m decreased over time, while the contribution increased for the SOC below the surface. These results highlight the interactions among S. alterniflora invasion, climate, and soil properties in regulating SOC dynamics. Our results imply that the relative importance of vertical patterns to SOC storage associated with S. alterniflora invasion and temperature fluctuations will change over time.

25283. 题目: Bacterial Community on a Guyot in the Northwest Pacific Ocean Influenced by Physical Dynamics and Environmental Variables
文章编号: N19081512
期刊: Journal of Geophysical Research: Biogeosciences
作者: Qian Liu, Ying‐Yi Huo, Yue‐Hong Wu, Youcheng Bai, Yeping Yuan, Min Chen, Dongfeng Xu, Jun Wang, Chun‐Sheng Wang, Xue‐Wei Xu
更新时间: 2019-08-15
摘要: Bacterial communities in sediments of the Caiwei Seamount, a typical guyot located in the northwest Pacific Ocean, were investigated. A total of 727,879 16S ribosomal RNA gene sequences were retrieved from 8 sediment samples of the top (mean depth = 1407 m) and the base (mean depth = 5525 m) of the guyot through pyrosequencing of V6 hypervariable region, and clustered into 32,844 Operational Taxonomic Units. Abundant‐weighted UniFrac metric partitioned bacterial assemblies into two categories (the top community and the base community) by principal coordinates analysis, consisting with the grouping of sampling stations by environmental variables. Differences in depth and physicochemical properties of the surrounding environment (e.g. concentrations of dissolved oxygen and geochemical elements) between the top and the base of the guyot may cause this partition of bacterial communities, whereas the typical fluid flow around the guyot may potentially contribute to the bacterial dispersal and environmental homogeneity along the same layer, resulting in the similarity of bacterial community structure within the same region (the top or the base). The surface sediment on the top of the guyot harbored the bacterial communities with greater diversity and evenness, represented by Gamma‐ and Deltaproteobacteria involved in sulfur cycling. At the base of the guyot, Gammaproteobacteria related to sulfur‐oxidizing and Chloroflexi functioning in the decomposition of refractory organic matters dominated, suggesting the redox condition at the interface of the sediment and the water can influence bacteria‐mediated elemental cycling, eventually shaping the physicochemical and geological characteristics of a guyot.

25284. 题目: RECENT CHANGES IN SOIL PROPERTIES AND CARBON STOCKS IN FEN PEATLANDS ADJACENT TO OPEN‐PIT LIGNITE MINES
文章编号: N19081511
期刊: Land Degradation & Development
作者: Bartłomiej Glina, Piotr Gajewski, Mendyk Łukasz, Bogna Zawieja, Zbigniew Kaczmarek
更新时间: 2019-08-15
摘要: The simultaneous impact of climate change and human activities on soil organic carbon content (SOC) in peatlands is insufficiently recognized, especially in relation to peatlands affected by open‐pit mining. Given their importance in climate change feedback loops, long‐term observations of SOC changes in peatlands are essential. The aim of the study was to determine recent changes in the properties and SOC content/stock of agro‐managed fen peatlands located adjacent to open‐pit lignite mines. We studied two soil layers (0–20 and 20–40 cm) within 12 sampling plots in the Grójec Valley (Central Poland). Soil sample collection and field measurements took place in 2005 and again in 2015. The largest negative changes in soil properties (e.g. SOC content drop from 208–318 g kg^‐1 in 2005 to 125–263 g kg^‐1 in 2015 and SOC stock decrease from 12.1–16.2 kg m^‐2 in 2005 to 9.22–14.5 kg m^‐2 in 2015), as well as the largest variability of water table level were recorded in the northern part of the study area, affected by long‐term lignite mining (1982–2009). While such a strong changes were not observed in the plots from central and southern part of the valley (230–439 g kg^‐1 in 2005 and 228–396 g kg^‐1 in 2015; 11.5–29,2 kg m^‐2 in 2005 and 13.4–36.1 kg m^‐2, respectively). Our results showed that depletion of SOC content in lowland peatlands in the temperate climate zone (due to human activity and changeable weather conditions) will proceed unless we implement sustainable management practices or apply restoration plans at these sites.

25285. 题目: The viscosity behaviors of bacterial suspensions or extracellular polymeric substances and their effects on aerobic granular sludge
文章编号: N19081510
期刊: Environmental Science and Pollution Research
作者: Xilan Yang, Tianguang Xu, Pei Cao, Kai Qiao, Lei Wang, Tingting Zhao, Jianrong Zhu
更新时间: 2019-08-15
摘要: Although the viscosity behavior of bacteria and extracellular polymeric substances (EPS) in flocculent activated sludge (FAS) and aerobic granular sludge (AGS) has been investigated, no studies have explored the role of viscosity in microbial attachment in pure culture. This study investigated the viscosity behavior of bacteria and EPS. The results showed that bacteria and their EPS exhibited non-Newtonian fluid and shear-thinning behavior. The viscosity of bacteria and EPS was 1.55–3.80 cP and 1.10–2.40 cP, respectively, while the attachment of bacteria (optical density at 600 nm) was 0.1426–3.1015. Bacteria with high attachment secreted EPS with a higher viscosity (2.40 cP), whereas those with weak attachment expressed EPS with a lower viscosity (1.10 cP). Viscosity and microbial attachment or extracellular polysaccharide (PS) content were significantly positively correlated. PS content was the source of bacterial viscosity, and β-polysaccharide played a more important role in viscosity and microbial attachment than α-polysaccharide. Thus, viscosity plays a critical role in microbial attachment, and high viscosity and PS content result in high microbial attachment, which is beneficial to the granulation process of AGS.

25286. 题目: Sewage sludge composting under semi-permeable film at full-scale: Evaluation of odour emissions and relationships between microbiological activities and physico-chemical variables
文章编号: N19081509
期刊: Environmental Research
作者: T. Robledo-Mahón, M.A. Martín, M.C. Gutiérrez, M. Toledo, I. González, E. Aranda, A.F. Chica, C. Calvo
更新时间: 2019-08-15
摘要: In the present study, physico-chemical characteristics, heavy metals content, odour emissions, microbial enumeration and enzymatic activities were analysed during industrial scale composting of sewage sludge partially pre-treated to evaluate the effect of a combined system of semi-permeable film and aeration on these parameters. The results related to physico-chemical parameters showed a decrease in total organic carbon (TOC), organic matter (OM), total carbon (TC) along the process. Volatile solids (VS) were also reduced, reaching 36% at 120 days, which is above the limit according to the current legislation. Similarly, metal content was found to be an important variable in the evolution of enzymatic activity, while lead (Pb), zinc (Zn), and nickel (Ni) were the most influential. Moreover, heavy metals were found below the limit of type B compost quality or European class 2 at the end of the process, which is suitable for agriculture soil. The odorous impact generated during the hydrolytic stage was reduced to an average value of 4 ou_E/s. This suggests that, covered stage with the semi-permeable film, could be a viable solution to mitigate odour emissions. The highest temperature was reached at 10 days and it was favoured by semi-permeable film. Temperature promoted the presence of thermophilic bacteria and fungi and indicated an early biodegradation process mediated by microorganisms. Statistical analyses revealed a high correlation of physico-chemical variables with microbial activity. Thus, samples from the first 14 days were highly correlated with enzymatic activities such as β-glucosidase (Ac-βGlu), protease (Ac-Pr), and dehydrogenase (Ac-De), which have usually been involved in the hydrolysis of organic matter.

25287. 题目: Coupling carbon metabolism and dissolved organic carbon fluxes in benthic and pelagic coastal communities
文章编号: N19081508
期刊: Estuarine, Coastal and Shelf Science
作者: Luis G. Egea, Cristina Barrón, Rocío Jiménez–Ramos, Ignacio Hernández, Juan José Vergara, José Lucas Pérez–Lloréns, Fernando G. Brun
更新时间: 2019-08-15
摘要: The knowledge of the production and carbon transference dynamics between adjacent communities is essential to gain a better understanding on the role of coastal areas in the global carbon cycle. Here, we assess the carbon metabolism (through dissolved oxygen –DO– concentration) and the net dissolved organic carbon (DOC) fluxes for benthic (dominated by the seagrass Cymodocea nodosa, the rhizophytic green algae Caulerpa prolifera and unvegetated sediments) and pelagic plankton communities co–habiting the same shallow coastal area in Cadiz Bay, southern Spain. Both the seagrass and macroalgae meadows were highly autotrophic, but the carbon metabolism of C. prolifera community shifted seasonally from net autotrophic to net heterotrophic. Unvegetated benthic communities were slightly heterotrophic throughout the year, while plankton community was net autotrophic. This study reveals how the different components of the ecosystem (i.e. macrophyte, sediment or plankton community) may have a seasonal variability in the contribution to the NCP in shallow coastal areas. Moreover, our results suggest that pelagic communities can be essential to maintain autotrophy of coastal system during periods of low benthic productivity. Regarding DOC, benthic communities were net DOC producers, undergoing a marked seasonality with maximum net DOC production during summer. This indicated an extra carbon assimilation not usually contemplated in productivity studies, which entails an underestimation of gross production in these communities. A strong relationship between net DOC flux and net community production (NCP) was found for the three benthic communities. The plankton community was a net DOC consumer indicating a strong coupling between the benthic and pelagic compartments in the bay. When up–scaling our results to the whole bay, the NCP estimated for the benthos was 8800 ± 3770 Tons C y⁻¹, and the net DOC flux was 2465 ± 830 Tons C y⁻¹, which were mainly due to vegetated communities, indicating the importance of coastal vegetated benthic ones in the carbon metabolism and DOC fluxes.
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25288. 题目: Changes in soil organic carbon and nutrient stocks in conventional selective logging versus reduced-impact logging in rainforests on highly weathered soils in Southern Cameroon
文章编号: N19081507
期刊: Forest Ecology and Management
作者: Rodine Tchiofo Lontsi, Marife D. Corre, Oliver van Straaten, Edzo Veldkamp
更新时间: 2019-08-15
摘要: Although disturbances associated with selective logging can cause pronounced changes in soil characteristics and nutrient stocks, such information is very limited for highly weathered soils in Africa. We assessed the effects of reduced impact logging (RIL, with a 30-year rotation management plan) and conventional logging (CL, without a management plan) on physical and biochemical characteristics of Ferralsol soils that developed on pre-Cambrian rocks in rainforests of Cameroon. Five to seven months after the logging operations were completed, we mapped the CL and RIL sites and quantified the disturbed areas: felling gaps, skidding trails, logging decks and roads. We selected four replicate plots at each site that encompassed these four disturbed strata and an adjacent undisturbed area as the reference. At each disturbed stratum and reference area per plot, we took soil samples down to 50 cm, and quantified soil physical and biochemical characteristics. Nutrient exports with timber harvest were also quantified.The logging intensity was very low with removals of 0.2 and 0.3 tree per hectare, and the ground area disturbed accounted only 5.2% and 4.0% of the total area in CL and RIL, respectively. In terms of area disturbance for each harvested tree, CL had 753 m² tree⁻¹ more affected ground area than RIL. Roads and logging decks were the most affected by logging operations, where effective cation exchange capacity, soil organic carbon (SOC), total nitrogen (N), Bray-extractable phosphorus (P) and exchangeable aluminum decreased whereas pH, ¹⁵N natural abundance and exchangeable manganese increased compared to the undisturbed reference area (P < 0.01–0.04). The disturbed area showed overall reductions of 21–29% in SOC, N and P stocks relative to the reference areas (P = 0.02–0.07). The amounts of C, N, P and base cations exported with harvested timber were only 0.4–5.9% of the changes in stocks of these elements in the disturbed strata. Nutrient reductions in the soil and exports through timber harvest were comparable between CL and RIL, after one logging event in this very low intensity logging systems. Our results suggest that unplanned operations together with frequent re-logging inherent to CL can increase area damage and enhance changes in SOC and nutrients as opposed to RIL, which may affect the recovery of the succeeding vegetation.

25289. 题目: Soil microaggregate size composition and organic matter distribution as affected by clay content
文章编号: N19081506
期刊: Geoderma
作者: Steffen A. Schweizer, Franziska B. Bucka, Markus Graf-Rosenfellner, Ingrid Kögel-Knabner
更新时间: 2019-08-15
摘要: Aggregation assembles different size mixtures of soil particles into a larger architecture. Such mixtures impede resolving which particles build aggregates and how these control the accumulation of soil organic matter (OM). Here we present an approach to differentiate the size distributions of soil fractions in the size range of microaggregates (<250 μm) from their dispersible particle-size distribution using dynamic image analysis. This approach enabled us to differentiate the magnitude and preferential size ranges of aggregates and non-aggregated particles. Wet sieving was used to isolate free microaggregate-sized fractions. Larger soil structures >250 μm were sonicated to isolate occluded size fractions <250 μm. To investigate the impact of soil texture, we analyzed topsoil samples of an arable site on Cambisol soils with a gradient in clay content of 16–37% and organic carbon concentrations of 10–15 g kg⁻¹. Our results demonstrate how soil texture governs aggregate size distributions: most water-stable microaggregates were found to be of approximately 30 μm diameter, independent of the clay content gradient. High-clay soils contain more water-stable macroaggregates (>250 μm) and larger microaggregates in the 50–180 μm size range. The low-clay soils, on the other hand, contained more non-aggregated sand-sized particles >100 μm which probably hampered the buildup of larger aggregates. The size distribution of particles <100 μm in size fractions <250 μm showed a similar prevailing soil texture pattern, with approximately 24% clay, 59% silt, and 17% sand-sized particles at all clay contents. In contrast to the prevailing texture pattern along the clay content gradient, 4% more clay-sized particles helped build up water-stable macroaggregates. In the low-clay soils, the aggregates were smaller and the size fractions <53 μm had higher OM concentrations. This indicates that the low-clay soils held most of their OM in smaller microaggregates. Such arrangement of OM in smaller microaggregates demonstrates that soil texture may control OM stabilization mostly indirectly via the distribution of OM in different aggregate fractions. The occlusion of microaggregates in larger structures led to lower alkyl:O/N-alkyl ratios in ¹³C nuclear magnetic resonance (NMR) spectroscopy, indicating increased preservation.

25290. 题目: Modified biochar for phosphate adsorption in environmentally relevant conditions
文章编号: N19081505
期刊: Chemical Engineering Journal
作者: Yimin Huang, Xinqing Lee, Matteo Grattieri, Mengwei Yuan, Rong Cai, Florika C. Macazo, Shelley D. Minteer
更新时间: 2019-08-15
摘要: Herein, we explored the modification of wheat straw biochar with chitosan, quaternary ammonium salt, and lanthanum for enhanced phosphate removal in environmentally relevant conditions. Specifically, a new amine protected cross-linking method was utilized to modify the absorbent material for maximum adsorption capacity, reaching 109 ± 4 mg P g⁻¹. The high phosphate removal performance of the composite was not significantly affected in a broad range of temperature (15–45 °C) and pH (2.5–7). 30 min allowed reaching a 100% adsorption equilibrium for 100 mg P L⁻¹, and 93% for 25 mg P L⁻¹, thus, significantly reducing the treatment time compared to previous reports. The highest partition coefficient 172.1 mg g⁻¹ μM⁻¹ was obtained at a concentration of 25 mg L⁻¹, and the phosphorus removal rate was as high as 99.98%, indicating La/GTB have great adsorption performance at low phosphate concentration. The adsorption mechanisms of the composite are extensively described, where electrostatic interaction, ligand exchange, and Lewis acid-base interaction contribute to the process. All of the above-mentioned advantages make the prepared composite of great interest for the development of materials for on-site phosphate removal.
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25291. 题目: Bacterioplankton community in response to biological filters (clam, biofilm, and macrophytes) in an integrated aquaculture wastewater bioremediation system
文章编号: N19081504
期刊: Environmental Pollution
作者: Betina Lukwambe, Li Zhao, Regan Nicholaus, Wen Yang, Jinyong Zhu, Zhongming Zheng
更新时间: 2019-08-15
摘要: Integrated systems with appropriate bio-filters can be used to treat aquaculture effluents. However, the information on bio-filters that alters the ecological functions of the bacterioplankton community (BC) in biodegradation of the aquaculture effluents remains controversial. In this study, we implemented a comprehensive restoration technology combined with bio-filters [biofilm, clam (Tegillarca granosa), and macrophytes (Spartina anglica)] to investigate their influence on the stability of the BC and nutrient removal. We found that the diversity of BC was linked with biogeochemical factors in processing and upcycling nitrogen-rich effluents into high-value biomass. The BC exhibited significant distinct patterns in the bio-filter areas. Potential biomarkers for constrained harmfully algae-bacteria (Nitriliruptoraceae, Bacillales, and Rhodobacteraceae) and nutrient removal were significantly higher in the bio-filters areas. The bio-filters significantly promoted the restoration effects of N and P balance by reducing 82.34% of total nitrogen (TN) and 81.64% of total phosphorus (TP) loads at the water interface. The main mechanisms for TN and TP removal and nutrient transformation were achieved by assimilation and absorption by the emergent macrophytes (Spartina anglica). The bio-filters significantly influenced the biodegradability and resolvability of particulate organic matter through ammonification, nitrification, and denitrification of microbes, which meliorated the nutrient removal. Beside bio-filter effects, the BC was significantly controlled by abiotic factors [nitrate (NO₃⁻-N), dissolved oxygen (DO), total nitrogen (TN), and water temperature (WT)], and biotic factors (chlorophyll ɑ and green algae). Our study revealed that the co-existence system with bio-filters may greatly improve our understanding on the ecological functions of the BC in aquaculture systems. Overall, combined bio-filters provide an opportunity for the development of efficient and optimized aquaculture wastewater treatment technology.
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25292. 题目: Bacterial community rather than metals shaping metal resistance genes in water, sediment and biofilm in lakes from arid northwestern China
文章编号: N19081503
期刊: Environmental Pollution
作者: Wenjuan Song, Ran Qi, Li Zhao, Nana Xue, Liyi Wang, Yuyi Yang
更新时间: 2019-08-15
摘要: Lakes in arid northwestern China are valuable freshwater resources that drive socioeconomic development. Environmental pollution can significantly influence the composition of microbial communities and the distribution of functional genes in lakes. This study investigated heavy metal pollution to identify possible correlations with metal resistance genes (MRGs) and bacterial community composition in water, sediment and biofilm samples from Bosten Lake and Ebi Lake in northwestern China. High levels of zinc were detected in all samples. However, the metals detected in the sediment samples of both lakes were determined to be at low risk levels according to an ecological index. The mercury resistance gene subtype merP had the greatest average abundance (4.61 × 10⁻³ copies per 16S rRNA) among all the samples, followed by merA and merC. The high abundance of merA in the pelagic zone rather than in benthic sediment suggests that the pelagic microbial community was important in mercury reduction. Proteobacteria were the main phylum found in the microbial communities in all samples. However, microbial communities in most of the water, sediment and biofilm samples had different compositions, indicating that the habitat niche plays an important role in shaping the bacterial communities in lakes. The microbial community, rather than the heavy metals, was the main driver of MRG distribution. The abundances of some bacterial genera involved in the decomposition of organic matter and the terrestrial nitrogen cycle were negatively correlated with heavy metals. This result suggests that metal pollution can adversely affect the biogeochemical processes that occur in lakes.
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25293. 题目: Transformation of atenolol by a laccase-mediator system: Efficiencies, effect of water constituents, and transformation pathways
文章编号: N19081502
期刊: Ecotoxicology and Environmental Safety
作者: Yiping Feng, Mengyao Shen, Zhu Wang, Guoguang Liu
更新时间: 2019-08-15
摘要: In this study, we investigated the transformation of atenolol (ATL) by the naturally occurring laccase from Trametes versicolor in aqueous solution. Removal efficiency of ATL via laccase-catalyzed reaction in the presence of various laccase mediators was examined, and found that only the mediator 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO) was able to greatly promote ATL transformation. The influences of TEMPO concentration, laccase dosage, as well as solution pH and temperature on ATL transformation efficiency were tested. As TEMPO concentrations was increased from 0 to 2000 μM, ATL transformation efficiency first increased and then decreased, and the optimal TEMPO concentration was determined as 500 μM. ATL transformation efficiency was gradually increased with increasing laccase dosage. ATL transformation was highly pH-dependent with an optimum pH of 7.0, and it was almost constant over a temperature range of 25–50 °C. Humic acid inhibited ATL transformation through competition reaction with laccase. The presence of anions HCO₃⁻ and CO₃²⁻ reduced ATL transformation due to both anions enhanced solution pHs, while Cl⁻, SO₄²⁻, and NO₃⁻ at 10 mM showed no obvious influence. The main transformation products were identified, and the potential transformation pathways were proposed. After enzymatic treatment, the toxicity of ATL and TEMPO mixtures was greatly reduced. The results of this study might present an alternative clean strategy for the remediation of ATL contaminated water matrix.
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25294. 题目: A review of arsenic interfacial geochemistry in groundwater and the role of organic matter
文章编号: N19081501
期刊: Ecotoxicology and Environmental Safety
作者: Jinli Cui, Chuanyong Jing
更新时间: 2019-08-15
摘要: Recent discoveries on arsenic (As) biogeochemistry in aquifer-sediment system have strongly improved our understanding of As enrichment mechanisms in groundwater. We summarize here the research results since 2015 focusing on the As interfacial geochemistry including As speciation, transformation, and mobilization. We discuss the chemical extraction and speciation of As in environmental matrices, followed by As redox change and (im)mobilization in typical minerals and aquifer system. Then, the microbial-assisted reductive dissolution of Fe (hydr)oxides and As transformation and liberation are summarized from the aspects of bacterial isolates, microbial community and gene analysis by comparing As rich groundwater cases worldwide. Finally, the potential effect of organic matter on As interfacial geochemistry are addressed in the aspects of chemical interactions and microbial respiring activities for Fe and As reductive release.

25295. 题目: The influence of dissolved organic matter on the marine production of carbonyl sulfide (OCS) and carbon disulfide (CS&lt;sub&gt;2&lt;/sub&gt;) in the Peruvian upwelling
文章编号: N19081406
期刊: Ocean Science
作者: Sinikka T. Lennartz, Marc von Hobe, Dennis Booge, Henry C. Bittig, Tim Fischer, Rafael Gonçalves-Araujo, Kerstin B. Ksionzek, Boris P. Koch, Astrid Bracher, Rüdiger Röttgers, Birgit Quack, Christa A. Marandino
更新时间: 2019-08-14
摘要: Oceanic emissions of the climate-relevant trace gases carbonyl sulfide (OCS) and carbon disulfide (CS2) are a major source to their atmospheric budget. Their current and future emission estimates are still uncertain due to incomplete process understanding and therefore inexact quantification across different biogeochemical regimes. Here we present the first concurrent measurements of both gases together with related fractions of the dissolved organic matter (DOM) pool, i.e., solid-phase extractable dissolved organic sulfur (DOSSPE, n=24, 0.16±0.04 µmol L−1), chromophoric (CDOM, n=76, 0.152±0.03), and fluorescent dissolved organic matter (FDOM, n=35), from the Peruvian upwelling region (Guayaquil, Ecuador to Antofagasta, Chile, October 2015). OCS was measured continuously with an equilibrator connected to an off-axis integrated cavity output spectrometer at the surface (29.8±19.8 pmol L−1) and at four profiles ranging down to 136 m. CS2 was measured at the surface (n=143, 17.8±9.0 pmol L−1) and below, ranging down to 1000 m (24 profiles). These observations were used to estimate in situ production rates and identify their drivers. We find different limiting factors of marine photoproduction: while OCS production is limited by the humic-like DOM fraction that can act as a photosensitizer, high CS2 production coincides with high DOSSPE concentration. Quantifying OCS photoproduction using a specific humic-like FDOM component as proxy, together with an updated parameterization for dark production, improves agreement with observations in a 1-D biogeochemical model. Our results will help to better predict oceanic concentrations and emissions of both gases on regional and, potentially, global scales.

25296. 题目: Organic and chemical amendments positively modulate the bacterial proliferation for effective rhizoremediation of PCBs-contaminated soil
文章编号: N19081405
期刊: Ecological Engineering
作者: Ayesha Hayat, Imran Hussain, Gerhard Soja, Mazhar Iqbal, Naeem Shahid, Jabir Hussain Syed, Sohail Yousaf
更新时间: 2019-08-14
摘要: Polychlorinated Biphenyls (PCBs) are xenobiotic chlorinated aromatic compounds with high toxicity to both fauna and flora. PCBs can enter the environment through close interactions of multiple environmental matrices such as sediments, soils, water and food web. Biogeochemical cycle of PCBs can transport them far from their initial source of production. The present study aims to investigate the effects of organic and chemical amendments during rhizoremediation of PCBs in aged contaminated soil. Italian ryegrass (Lolium multiflorum) was grown in PCB-contaminated soil, whereas different combinations of two biochar (i.e., beech woodchip and green garden waste) and a surfactant (i.e., sodium dodecyl sulfate) were applied to assess the removal efficiency. The overall system’s performance was evaluated based on plant growth, PCBs degradation, and proliferation of PCBs degrading bacteria after 5-months of sowing of ryegrass. We found that PCBs removal was significantly high in the vegetated soils as compared to the un-vegetated soils. Maximum removal (85% of total PCBs load) was observed in the presence of green garden waste biochar whereas less removal was observed with the surfactant application. The observations on PCBs degrading bacteria and plant growth parameters were consistent with the degradation scheme, which suggest the potential role of bacteria in the overall degradation process. We conclude that appropriate combinations of vegetation, soil amendments, and PCB degrading bacteria can help to improve the degradation of PCBs impacted soils.
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25297. 题目: Radiolysis as a source of ¹³C depleted natural gases in the geosphere
文章编号: N19081404
期刊: Organic Geochemistry
作者: Renzo C. Silva, Lloyd R. Snowdon, Haiping Huang, Michael Nightingale, Veith Becker, Stephen Taylor, Bernhard Mayer, Jon H. Pedersen, Rolando di Primio, Steve Larter
更新时间: 2019-08-14
摘要: Is natural radioactivity a significant agent of hydrocarbon gas generation from sedimentary organic matter Laboratory gamma radiation of dead crude oil (no solution gas) yields wet hydrocarbon gases depleted in ¹³C: δ¹³C CH₄ (-75‰ to -65‰), δ¹³C C₂H₆ (-52‰ to -45‰), δ¹³C C₃H₈ (-42‰ to -37‰) and δ¹³C C₄H₁₀ (-35‰ to -32‰). Although laboratory irradiation dose rates are orders of magnitude higher than those in geological settings, radiolytic transformations occur at total radiation doses equivalent to those in natural geological settings over many millions of years. Radiolysis generates wet gases with isotopic signatures that might be interpreted as “biogenic” if only the methane carbon isotope ratio is considered. We examine situations where such gases may be quantitatively significant.

25298. 题目: Palaeoenvironments, flora, and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head, Australia
文章编号: N19081403
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Shreya Misra, Neerja Jha, Alan Stebbins, Michael Brookfield, Robyn Hannigan
更新时间: 2019-08-14
摘要: The Permian-Triassic boundary section at Wybung Head, eastern Australia shows a rapid change from humid coal-bearing lowland braided stream through a thin clay and coal breccia and paleosols to semi-arid silty floodplain deposits. Identifiable plant remains and total organic matter disappear above the coal and clay breccia. Three characteristic palynofacies accumulated in a range from oxic to sub-oxic to anoxic conditions. The dominance of opaque phytoclasts in the entire sequence reflects deposition under oxic conditions, especially in the sequence lying above the Birdie Coal, the result of fluctuating water tables, high energy and desiccating conditions. In the Birdie Coal, however, at certain horizons, a water-saturated environment favored the preservation of organic matter such as pollen, spores, and structured organic matter. This latest Permian paleovegetation was dominated by opportunistic understory spore-bearing plants, with a canopy of pollen-bearing glossopterids, conifers and cordaitales. Total organic carbon drops from >30% in the coal, through <5% in the breccia to <1% in the paleosols and silts. The organic δ¹³C values are constant at ~ −25.5‰ in the coal and coal breccia, but then decrease to less than −27‰ in the paleosols and silts. These results confirm the rapid sedimentary, floral and organic carbon isotope changes across the non-marine Permian-Triassic boundary in eastern Australia. Our δ¹³C_org values suggest a significant and sustained negative δ¹³C_org excursion, with a magnitude of about 3‰, above the Birdie Coal. Unlike δ¹³C_org, there is no clear trend in δ¹⁵N_org values. The low C/N ratios of 10 and less, of the samples above +55 cm, are only found in modern burned soils with low bacteria/fungi ratios or in decaying wood. There is no obvious fungal spike in the Wybung Head section, may have been destroyed during the formation of this soil B horizon, as elsewhere a global fungal spike layer marks an interval of decreased terrestrial biomass and decaying vegetation associated with the Permian-Triassic crisis and boundary. Two negative excursions in the uppermost Permian and lowest Triassic can be correlated throughout Gondwana.

25299. 题目: Effects of soil organic residue amendment on losses of dissolved organic carbon, P, Cu and Zn via surface runoff from arable soils
文章编号: N19081402
期刊: Soil and Tillage Research
作者: Pu Shi, Rainer Schulin
更新时间: 2019-08-14
摘要: Dissolved organic carbon (DOC) constitutes the largest carbon pool in surface waters, with soil being its main source via surface and subsurface runoff. Amendment with organic residues can reduce soil erosion and surface runoff, but little is known how this affects the amount and composition of DOC losses via surface runoff and the associated transfer of nutrients and pollutants. In this study, artificial rainfall experiments were conducted on three pairs of soil runoff plots with contrasting organic matter management. A mixture of grass and wheat straw residues was incorporated into the topsoil of one plot in each pair (OI treatment) but not into the other (control). Artificial rainfall was applied onto both treatments at an intensity of 49.1 mm h⁻¹, and surface runoff samples were collected at designated time steps for analysis of DOC, total dissolved phosphorus (TDP), copper (TDCu) and zinc (TDZn) concentrations, as well as for characterization of DOC by UV–vis absorbance (SUVA₂₅₄ and E2:E3) and fluorescence spectroscopy (FI) indexes. The organic amendment reduced the loss rates of DOC, TDP, TDCu and TDZn by reducing surface runoff, although increasing the concentrations of DOC, TDP and TDCu. Regardless of the treatment, DOC, TDP and TDCu concentrations were always maximal at the onset of runoff and then continuously decreased after the initial flush. The observed relationships of TDP and TDCu concentrations with DOC indicate that the export of “dissolved” P and Cu primarily occurred in DOC-bound form, while the concentration of TDZn was not correlated with that of DOC. Surface runoff from the amended soils generally contained more hydrophilic and low molecular weight DOC (as indicated by low SUVA₂₅₄ and high E2:E3 and FI values), particularly at high DOC concentrations. The ratio between TDCu and DOC concentration showed a positive relationship to DOC aromaticity (as indicated by SUVA₂₅₄ values) in the OI treatment. The results indicate that organic amendment can reduce total rates of dissolved element losses with surface runoff, but attention should also be paid to the composition of lost DOC and the concentrations of DOC-associated solutes.

25300. 题目: Effects of fertilization and straw return methods on the soil carbon pool and CO₂ emission in a reclaimed mine spoil in Shanxi Province, China
文章编号: N19081401
期刊: Soil and Tillage Research
作者: Jianhua Li, Hua Li, Qiang Zhang, Hongbo Shao, Chunhua Gao, Xunzhong Zhang
更新时间: 2019-08-14
摘要: Reclaimed soil is similar to an “empty cup” with a large carbon (C) sequestration potential. Agricultural management practices strongly influence C storage and soil carbon dioxide (CO₂) emission. The objective of this study was to identify the effects of fertilization and straw return methods on the soil C pool and CO₂ emission in a reclaimed mine spoil. Thus, we studied the effects of four fertilization treatments [chemical fertilizer (NP), manure (M), 50% M plus 50% NP (NPM), and unfertilized control (CK)] and three straw return methods [no straw return (no straw), return of straw mixed with soil (straw mixing), and return of straw to the surface of the soil (straw mulching)] in a mine reclamation region by examining changes in the soil C pool and CO₂ emission. The soil C pool was evaluated by acid hydrolysis, considering three pools: (a) labile pool I (LP I), obtained by hydrolysis with 5 N H₂SO₄ at 105 °C for 30 min; (b) labile pool II (LP II), obtained by hydrolysis with 26 N H₂SO₄ at room temperature overnight, followed by 2 N H₂SO₄ at 105 °C for 3 h; and (c) the recalcitrant pool, measured as the unhydrolyzed residue. The CO₂ emission/C sequestration and CO₂ emission/grain yield ratios were used as indicators of C emission. Compared with the CK, the NPM treatment was the most efficient among the fertilization treatments in increasing grain yield (136%) and C sequestration (311%) and reducing the CO₂ emission/C sequestration (62%) and CO₂ emission/grain yield (32%) ratios. The straw mixing treatment had more soil organic carbon (SOC), a larger LP I and LP II, and more C sequestration than the other straw return treatments. The addition of manure resulted in a higher distribution rate of new organic C to the labile C pool (73–78%) than the addition of inorganic fertilizer (45%). Soil C emissions were mainly concentrated in the maize growing season, accounting for more than 80% of the total annual C emissions. LP I, LP II and CO₂ emission were significantly positive correlated with SOC and yield. Therefore, soil C pools and CO₂ emissions are significantly influenced by fertilization regimes and straw return methods, which should be used to important indicators to estimate the C balance in agro-ecosystems during the process of mine spoil reclamation.