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25981. 题目: Catalytic ozonation of humic acid in water with modified activated carbon: Enhancement and restoration of the activity of an activated carbon catalyst
文章编号: N19021911
期刊: Journal of Environmental Management
作者: Jing Feng, Bo Xing, Honglin Chen
更新时间: 2019-02-19
摘要: Catalytic ozonation of organic compounds in water is an important research area for addressing the current pollution crisis. The objective of the present study was to find a modification method for enhancing and restoring the activity of the activated carbon (AC) catalyst applied in the catalytic ozonation of the humic acid (HA) aquatic contaminant. A three-step treatment consisting of an initial thermal treatment, oxidation treatment, and further thermal treatment increased the amount of surface hydroxyl groups (COH) of AC while reducing the amounts of other surface groups, such as basic, carboxyl, lactone, and carbonyl groups. The obtained ACN2O2N2 shows better catalytic performance for HA ozonation than virgin AC, and the COD removal improved from 71% to 96% after reacting for 10 min. This modification method could also restore the catalytic activity of used ACN2O2N2, as the COD removal improved from 74% to 97% after reacting 10 min. The apparent first-order rate constant (kapp) was obtained by fitting the evolution of TOC. The regression analyses of the relationships between the kapp and the surface chemical properties, textural properties, and degree of AC graphitization showed that the increase in the amount of COH was the main factor driving the enhancement and restoration of the AC catalyst activity.
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25982. 题目: Paleoenvironmental changes during the late Albian oceanic anoxic event 1d: An example from the Capacho Formation, southwestern Venezuela
文章编号: N19021910
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: María-Emilia Rodríguez-Cuicas, Jean-Carlos Montero-Serrano, Grony Garbán
更新时间: 2019-02-19
摘要: The late Albian–early Cenomanian oceanic anoxic event 1d (OAE-1d; ~103 to 99.5 Ma) represents a global interval of enhanced organic carbon burial due to widespread oxygen deficiency in the water column and/or increased primary productivity. The biostratigraphy and geochemistry of organic-rich sediments in the La Grita Member (Capacho Formation) in southwestern Venezuela were studied to document the paleoenvironmental conditions that governed the deposition of this succession during OAE-1d. Carbon-isotope (δ13Ccarb and δ13CCorg) chemostratigraphy and biostratigraphic constraints show that the La Grita Member spans the late Aptian period (Rotalipora appenninica Zone), and that OAE-1d is well recorded in this succession. A prominent increase in total organic carbon (TOC) values (up to 10%) is clearly recorded through the onset of OAE-1d, coinciding with a prominent change in overall redox-sensitive proxies suggesting that the La Grita Member sediments accumulated under anoxic (and possibly euxinic) bottom-water conditions in a partially restricted basin. The detrital proxies suggest that the greenhouse climate prevailing during OAE-1d induced significant acceleration of the hydrologic cycle and an increase in continental chemical weathering rates. Overall, the carbon and oxygen isotope records, TOC contents, as well as the detrital proxies show cyclic variation during the late Albian stage. These variations support the hypothesis that orbital forcing likely also modulated the equatorial monsoonal activity during the OAE-1d.
25983. 题目: Distinct methanotrophic communities exist in habitats with different soil water contents
文章编号: N19021909
期刊: Soil Biology and Biochemistry
作者: Liyan Zhang, Jonathan Adams, Marc G. Dumont, Yuntao Li, Yu Shi, Dan He, Jin-Sheng He, Haiyan Chu
更新时间: 2019-02-19
摘要: Aerobic methane oxidizing bacteria play a key role in controlling global climate by reducing methane (CH4) emissions in natural ecosystems. We studied the community assembly processes and co-occurrence interactions of soil methanotrophs in three habitats (an alpine meadow, a marsh meadow, and a marsh) from Qinghai-Tibetan Plateau. Methanotrophic communities and CH4 oxidation potentials varied considerably between the habitats, and the diversity of methanotrophs was significantly lower in marsh meadow than in the other two soils (P < 0.001). Methanotrophic bacterial diversity was significantly correlated with soil dissolved organic carbon (DOC), pH, total carbon (TC), and total nitrogen (TN), while methanotrophic community structure was mostly correlated with soil C/N, TC, soil moisture, and TN. Stochasticity dominated methanotrophic community assembly, and increased from 67.6% in the alpine meadow and 68.0% in the marsh meadow to 98.2% in the marsh. The natural connectivity of co-occurrence network was greater in the alpine meadow than in the other two habitats, suggesting a more stable network in the alpine meadow. Methanotroph diversity contributed to the sub-network topological differences and keystone species were identified such as USCγ, Methylobacter, and RPC-1. The results suggest the existence of distinct community assembly processes and co-occurrence patterns of soil methanotrophs among different habitats, which may ultimately enhance the understanding of factors influencing CH4 oxidation rates.
25984. 题目: Biomonitoring tools for biochar and biochar-compost amended soil under viticulture: Looking at exposure and effects
文章编号: N19021908
期刊: Applied Soil Ecology
作者: M. Prodana, A.C. Bastos, A. Amaro, D. Cardoso, R. Morgado, A.L. Machado, F.G.A. Verheijen, J.J. Keizer, S. Loureiro
更新时间: 2019-02-19
摘要: Benefits that biochar can bring to unirrigated vineyards are related mainly to soil chemistry, soil structure and water retention improvements. Little is still known about effects of biochar on soil biotic processes and organisms that mediate them. For a sustainable use of biochar in agriculture, alone or in combination with other soil amendments, there is a need for better understanding of soil-biochar-biota interactions, particularly in the long term. Here we applied an ecotoxicological monitoring programme to evaluate the effects of field plot-scale biochar and biochar-compost mixture into vineyard soil. Standard and well described laboratory bioassays were used, assessing the survival and reproduction of Folsomia candida and food consumption and biomass change of Porcellionides pruinosus. The present study examined the effects of biochar- and biochar-compost-enriched soil treatments in a commercial vineyard subjected to conventional pesticide management practices. We considered two sampling events, corresponding to: i) the time of initial application of fresh biochar and biochar-compost (T0); and ii) the 18 month-period after the application of the amendments (T18). Additionally, based on the time and rates of the pesticides application prior to the second sampling event, a theoretical exposure was estimated alongside with risk quotients. The risk quotients were elevated for certain active ingredients in the mixture (cyprodinil, propiconazole, copper oxychloride and copper sulfate). This corroborates the overall decrease in organisms' performance observed after they were exposed to the field-aged samples. The ecotoxicological response to the tested biochar and biochar-compost enriched soil was species-specific, time-dependent, and to some extent, treatment-dependent. The most sensitive endpoint obtained in the study was the reproduction output of F. candida. While freshly amended soil did not induce substantial changes on organisms' performance, the measured endpoints were significantly lower when the organisms were exposed to the treatments from the second sampling event which was subjected to various climatic factors and conventional pesticides. Regarding food consumption of P. pruinosus, and number of F. candida juveniles the effects were more pronounced in 40 t ha−1 biochar and biochar-compost amended treatments than in 4 t ha−1 treatment. Results of the study show that bioavailability of potentially toxic elements might not be prevented over time by the presence of biochar and biochar-compost in commercial vineyards that receive conventional plant protection products.
25985. 题目: Forest organic matter removal leads to long-term reductions in bacterial and fungal abundance
文章编号: N19021907
期刊: Applied Soil Ecology
作者: Ryan M. Mushinski, Terry J. Gentry, Thomas W. Boutton
更新时间: 2019-02-19
摘要: Intensive organic matter removal (OMR) associated with forest harvest has been shown to significantly affect soil physical, chemical, and biological properties; however, the influence on microbial abundance has been neglected, especially at depth and over time. We used quantitative PCR to assess the long-term impact of two different intensities of OMR, soil depth, seasonality, and their interactions on bacterial and fungal abundances 18 years post-harvest, relative to an unharvested control. Both bacterial and fungal community sizes were significantly reduced by intensive OMR, and these effects were largest in surface soil (0–10 and 10–30 cm), and largest in summer and spring. The response ratios for bacteria and fungi were not statistically different, indicating that both taxonomic groups were susceptible to long-term changes in soil properties induced by intensive OMR. Furthermore, we found that root biomass was significantly correlated to bacterial and fungal abundance in unharvested, low-intensity harvest, and high-intensity harvest stands throughout time and across soil depths, suggesting that the input of organic matter through root exudation and turnover are key to controlling microbial community size. These reductions in bacterial and fungal community sizes suggest that microbial community functions related to biogeochemical processes may be altered for decades post-harvest, with potential implications for forest productivity and ecosystem function during subsequent rotations.
25986. 题目: Distribution and release of phosphorus fractions associated with soil aggregate structure in restored wetlands
文章编号: N19021906
期刊: Chemosphere
作者: Hu Cui, Yang Ou, Lixia Wang, Haitao Wu, Baixing Yan, Yingxin Li
更新时间: 2019-02-19
摘要: Phosphorus, a dominating element responsible for eutrophication, is a potential limiting nutrient in wetland ecosystem. In this study, the release risk of phosphorus was evaluated by investigating the distribution of phosphorus fractions in different grain-sizes of soil aggregates in wetlands with restoration durations of 1, 2, 3, 5, 13 or 19 years. The results showed that the soil aggregate structure tended to be stable when paddy fields were changed into wetland, though aggregate structure first condensed fine-aggregates (<0.25 mm) into coarse-aggregates (>0.25 mm), which was then reversed until the process stabilized after 5 restoration years. With the exception of labile inorganic phosphorus (L-Pi), which continuously decreased within extended abandoned period, total phosphorus (TP), labile organic phosphorus (L-Po), moderately labile organic phosphorus (Ml-Po), iron-aluminum bound phosphorus (Fe·Al-P), calcium-magnesium bound phosphorus (Ca·Mg-P), humic phosphorus (Hu-P) and residual phosphorus (Re-P) concentrations presented a unimodal tendency with a peak at the 2nd or 3rd restoration year, respectively. TP, L-Pi, L-Po and Re-P tended to decrease with decreasing soil aggregate grain-size, and Ml-Po was enriched in small macro-aggregates (0.25–1 mm) and micro-aggregates (0.053–0.25 mm). Macro-aggregates carried Fe·Al-P and Ca·Mg-P. Adsorption isotherm simulation results demonstrated that the retention capacity for phosphorus of a restored wetland first increased and then decreased with extended abandonment period, and macro-aggregates showed a considerable capacity to retain phosphorus. Fe.Al-P and Hu-P had potential release risk with approximate amounts of 197.25–337.25 mg kg−1 and 131.28–185.72 mg kg−1, in associated with anaerobic environment and aggregate structure.
25987. 题目: Phosphorus chemical speciation and seasonal variations in surface sediments of the Maowei Sea, northern Beibu Gulf
文章编号: N19021905
期刊: Marine Pollution Bulletin
作者: Bin Yang, Jia-Bin Zhou, Dong-Liang Lu, Solomon Felix Dan, Dong Zhang, Wen-Lu Lan, Zhen-Jun Kang, Zhi-Ming Ning, Dong-Yang Cui
更新时间: 2019-02-19
摘要: This study presents the distribution, seasonal variations and factors influencing phosphorus (P) forms in surface sediments from the Maowei Sea. P forms were measured using the sequential extraction (SEDEX) procedures. Inorganic P (IP) was the predominant chemical form of total P (TP). Fe-bound P (FeP) was the main IP form. Sediment particle sizes, organic matter distribution, terrestrial input and aquaculture activity were responsible for the seasonal variations of different forms of P in sediment. In summer, the average proportions of P fractions in TP followed the order of organic P (OP) > Fe-P > authigenic P (CaP) > detrital P (De-P) > exchangeable P (Ex-P); in winter, the corresponding order was OP > Fe-P > De-P > Ca-P > Ex-P. The potential bio-available P accounted for 71.1 ± 4.9% and 70.6 ± 6.3% of TP in summer and winter, respectively. Sedimentary organic matter mainly came from land-based sources in winter.
25988. 题目: A large artificial dyke greatly alters partitioning of sulfate and iron reduction and resultant phosphorus dynamics in sediments of the Yeongsan River estuary, Yellow Sea
文章编号: N19021904
期刊: Science of The Total Environment
作者: Sung-Uk An, Jin-Sook Mok, Sung-Han Kim, Jae-Hoon Choi, Jung-Ho Hyun
更新时间: 2019-02-19
摘要: We investigated sediment geochemistry, partitioning of organic carbon (Corg) oxidation by iron reduction (FeR) and sulfate reduction (SR), and benthic phosphorus (P) release, together with the P speciation in the sediments to elucidate the P dynamics in two contrasting sediments (i.e., estuarine vs. limnetic) separated by a large dyke in the Yeongsan River estuary of the Yellow Sea. In the sediments of the Yeongsan River estuary (St. YE), SR dominated the Corg oxidation pathway, accounting for 81.7% of total anaerobic Corg oxidation. Under the SR-dominated condition, H2S derived from SR reacts quickly with iron oxides to form iron sulfides, which ultimately release the P bound to Fe(III) into the pore water. The enhanced benthic P flux (0.24 mmol m−2 d−1) at the YE site accounted for 80% of the P required for primary production in the water column. In contrast, in the limnetic sediments of the Yeongsan Lake (St. YL), where high levels of CH4 accumulated, most P was bound to Fe and Al, which resulted in a low benthic P flux (0.03 mmol m−2 d−1). The results suggest that the frequent discharge of relatively P-depleted freshwater into the estuary via the artificial dyke may result in relatively P-limiting conditions in estuarine ecosystems. As a result, benthic P release from the SR-dominated estuarine sediment is a significant internal source of P in the coastal ecosystem. Our results indicate that the construction of a large dyke at a river mouth greatly alters Corg oxidation pathways and P dynamics in coastal ecosystems.
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25989. 题目: Redox properties of compost-derived organic matter and their association with polarity and molecular weight
文章编号: N19021903
期刊: Science of The Total Environment
作者: Xiao-Song He, Chao Yang, Shao-Hong You, Hui Zhang, Bei-Dou Xi, Min-Da Yu, Si-Jia Liu
更新时间: 2019-02-19
摘要: Compost-derived dissolved organic matter (DOM), which has a wide distribution of molecular weight (MW) and polarity, has a potential application in the remediation of the contaminated soil due to its redox-active functional groups. Composting treatment can change the MW and polarity of the DOM through microbial transformation and degradation. However, the relationship between the redox properties of compost-derived DOM and its MW and polarity is still unclear. DOM was extracted from municipal solid wastes with different composting times in this study, and it was further fractionated into humic acids (HA), fulvic acids (FA) and hydrophilic (HyI) fractions based on its hydrophobicity and XAD-8 resin. Electron transfer capacities [including electron accepting capacities (EAC) and electron donating capacities (EDC)] of the HA, FA and HyI fractions and their associations with polarity and MW were studied. The results showed that the EAC of the HA, FA and HyI all increased after composting. The EDC of the HA and HyI exhibited an increasing trend as well, though that of the FA decreased remarkably after composting. The MW, polarity and redox-active functional groups of the HA, FA and HyI fractions were determined using high performance liquid chromatography and excitation-emission matrix fluorescence spectra coupled with parallel factor analysis. The result showed that the quinone-like groups were mainly detected in the medium MW and transphilic sub-fractions of the HA, FA and HyI, and were the main functional groups responsible for the EAC. The low MW sub-fractions, which consisted mainly of tyrosine-like matter, were the main functional components accounted for the EDC. The results advance our understanding of the influence of MW and polarity on the redox properties of organic substances, and facilitate to reveal the important redox-active functional groups when compost is utilized to remediate the contaminated soil.
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25990. 题目: Molecular weight-dependent spectral and metal binding properties of sediment dissolved organic matter from different origins
文章编号: N19021902
期刊: Science of The Total Environment
作者: Huacheng Xu, Li Zou, Dongxin Guan, Wentao Li, Helong Jiang
更新时间: 2019-02-19
摘要: The metal binding potential of dissolved organic matter (DOM) is highly related with its inherent properties such as molecular weight (MW). Here sediment DOMs with different origins, i.e., algae- and macrophyte-dominated sediment DOM (named as ASDOM and MSDOM, respectively), were size-fractionated into low MW (LMW-, <1 kDa) and high MW (HMW-, 1 kDa~0.45 μm) fractions, with the spectral and metal binding properties in different MW fractions exploring via total organic carbon, absorption spectroscopy, fluorescence parallel factor (PARAFAC) analysis, and Cu(II) titration techniques. The MSDOM contained more organic carbon, lower specific UV absorbance, lower fluorescence index, higher humification index, and lower biological index compared to the ASDOM. As for the MW-fractionated samples, the humic- and fulvic-like fluorophores were mainly distributed in the LMW-DOM, while the protein-like ones were located richly in the HMW-DOM. Thus, obvious MW- and origin-dependent heterogeneities in abundance and spectral properties were observed for sediment DOMs. One humic-like, one fulvic-like, and two protein-like fluorescent components were identified by PARAFAC analysis, with different components exhibiting different variable patterns in response to Cu(II) addition. Irrespective of sample sources, humic- and fulvic-like components had higher condition stability constants (logKM > 4.96) than protein-like components (logKM < 4.86). As for the MW-fractionated samples, the HMW-DOM, especially the HMW humic-/fulvic-like components, exhibited higher metal binding potential than the bulk and LMW counterparts. This study highlighted the importance of HMW-DOM in manipulating the behavior, fate, and bioavailability of heavy metals in lake sediments.
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25991. 题目: Simultaneous removal of natural organic matter and micro-organic pollutants from reverse osmosis concentrate using granular activated carbon
文章编号: N19021901
期刊: Water Research
作者: Shahzad Jamil, Paripurnanda Loganathan, Andrzej Listowski, Jaya Kandasamy, Chinu Khourshed, Saravanamuthu Vigneswaran
更新时间: 2019-02-19
摘要: Although reverse osmosis produces high quality reusable water from wastewater the rejected concentrate (ROC) poses potentially serious health hazards to non-target species. This is especially the case when it is disposed into aquatic environments due to the presence of high concentrations of dissolved natural organics, micro-organic pollutants (MOPs) and other pollutants. In batch and column studies we found that granular activated carbon (GAC) was very effective in simultaneously removing dissolved organic carbon (DOC) and 18 MOPs from ROC. The amounts of all DOC fractions adsorbed (0.01-3 mg/g) were much higher than those of the MOPs (0.01-2.5 μg/g) mainly because ROC contained larger concentrations of DOC fractions than MOPs. However, the partition coefficient which is a measure of the adsorbability was higher for most of the MOPs (0.21-21.6 L/g) than for the DOC fractions (0.01-0.45 L/g). The amount of DOC fraction adsorbed was in the order: humics > low molecular weights > building blocks > biopolymers (following mostly their concentrations in ROC). The partition coefficient was in the order: low molecular weights > humics > building blocks > biopolymers. The MOPs were classified into four groups based on their hydrophobicity (log Kow) and charge. The four positively charged MOPs with high hydrophobicity had the highest amounts adsorbed and partition coefficient, with 95-100% removal in the GAC column. The MOPs that are negatively charged, regardless of their hydrophobicity, had the lowest amounts adsorbed and partition coefficient with 73-94% removal.
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25992. 题目: Insights into the relationship between colony formation and extracellular polymeric substances (EPS) composition of the cyanobacterium Microcystis spp
文章编号: N19021809
期刊: Harmful Algae
作者: Man Xiao, Ming Li, Pengfei Duan, Zhi Qu, Haiming Wu
更新时间: 2019-02-18
摘要: Extracellular polymeric substances (EPS) were considered as fundamental substances in colony formation; however, the understanding of EPS composition remains limited. This study analyzed the content and composition of EPS fractions (soluble EPS, loosely bound EPS, and tightly bound EPS) of four Microcystis species from laboratory cultures in both unicellular and colonial morphologies, as well as colonies collected during Microcystis blooms, using fluorescence excitation - emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC). This method enables to make insight into protein-like and humic acid-like components but cannot detect polysaccharides. The EPS was successfully categorized into three humic acid-like components (C1 – C3) and a protein-like component (C4). Component C1 was discovered to be involved in colony formation and colony size growth of Microcystis. EPS content varied among Microcystis morphospecies, such as M. aeruginosa, M. wesenbergii and M. ichthyoblabe, and this was significantly affected by the environmental constraints rather than the morphospecies. The proportion of C1 relating to larger colony size was negatively correlated to temperature and concentrations of TN and TP. The tightly bound EPS directly promoted colony formation, but the soluble EPS or loosely bound EPS alone did not induce colony formation in Microcystis. These results advanced the current knowledge on the chemical materials involved in the colony formation of Microcystis and provided new clues in unicellular-multicellular transformation as well as colonial morphology changes in Microcystis.
25993. 题目: Waste-to-resources: Exploratory surface modification of sludge-based activated carbon by nitric acid for heavy metal adsorption
文章编号: N19021808
期刊: Waste Management
作者: Loretta Y. Li, XuDong Gong, Otman Abida
更新时间: 2019-02-18
摘要: Sewage sludge has the potential to be utilised as a sorbent for dissolved pollutant removal. This study investigated metal removal efficiency of carbonised sewage sludges obtained via pyrolysis at 500 °C: biochar/carbonised sludge (CS), ZnCl2-activated sludge-based active carbon (SBAC), and three SBACs modified by nitric acid at different concentration and temperature (MSBACs). Batch adsorption kinetic tests indicated that the Pb2+ adsorption equilibrated in <5 min. Efficiencies of these sludge-based sorbents for Pb2+ adsorption followed the order MSBAC > SBAC > CS. Metal leachabilities were low or negligible for the SBAC and MSBACs. A comparison of 5-min adsorption of the best-performing MSBAC with different sorbents indicates that performance followed the trend MSBAC > grundite (illite) > zeolite (clinoptilolite) > commercial activated carbon (CAC) > kaolinite > perlite. Furthermore, MSBAC achieved 98.9%, 42.6%, and 34.6% removal of Cu, Zn, and Al, respectively, from spiked natural acid rock drainage in <5 min. The modified sludge-based activated carbon is an effective and sustainable sorbent for removing metals from aqueous environments.
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25994. 题目: A soil‐quality index for soil from Mediterranean forests
文章编号: N19021807
期刊: European Journal of Soil Science
作者: Manuela Andrés‐Abellán, Consolación Wic‐Baena, Francisco R. López‐Serrano, Francisco A. García‐Morote, Eduardo Martínez‐García, Marta I. Picazo, Eva Rubio, Jose L. Moreno‐Ortego, Felipe Bastida‐López, Carlos García‐Izquierdo
更新时间: 2019-02-18
摘要: Treatments involving vegetation thinning have become more frequent in Mediterranean forest ecosystems. Under extreme climate conditions, this practice can affect the balance between physicochemical, microbiological and biochemical soil properties, modifying the soil quality and the ability of these forest ecosystems to regenerate. The aim of this study was to use principal component analysis (PCA) to develop a multivariable soil‐quality index (SQI) applicable to the Mediterranean forest ecosystems of the Cuenca mountain range in Central‐Eastern Spain. To achieve this, seven physicochemical properties (moisture, pH, electrical conductivity, carbonate, total organic carbon, total nitrogen and available phosphorus) and six microbiological properties (basal respiration and microbial biomass carbon, as well as the activity of dehydrogenase, urease, phosphatase and β‐glucosidase enzymes) were measured seasonally between 2011 and 2012. Soil samples were obtained from seven unmanaged and undisturbed forest areas and these data were used to create the SQI. Subsequently we applied this SQI to soil samples from other forests in the Cuenca mountain range which had been affected by different thinning treatments. Our analysis showed that the greater was the canopy present in these treated forests, the larger were the average values for all 13 variables. The smallest SQI values were in areas that had been intensively thinned. Therefore, our results suggest that this SQI is an important tool for the development of appropriate measures to maintain the quality of forest soil in Spanish Mediterranean forest ecosystems.
25995. 题目: Identification of secondary fatty alcohols in atmospheric aerosols in temperate forests
文章编号: N19021806
期刊: Biogeosciences
作者: Yuzo Miyazaki, Divyavani Gowda, Eri Tachibana, Yoshiyuki Takahashi, and Tsutom Hiura
更新时间: 2019-02-18
摘要: Fatty alcohols (FAs) are major components of surface lipids (waxes) and can act as surface-active organic aerosols in the atmosphere, influencing chemical reactions, particle lifetimes, and the formation of cloud droplets and ice nuclei. However, studies on the composition and source of the FAs in atmospheric aerosols are very limited. In this study, we identified five secondary FAs (SFAs) with C27 and C29 from aerosol samples collected throughout one year at two different deciduous forest sites in Japan. Fatty diols, such as n-heptacosan-5,10-diol, were identified in atmospheric aerosols for the first time. Among the identified SFAs, n-nonacosan-10-ol was the most abundant compound, followed by n-nonacosan-5-10-diol at both of the forest sites. Concentrations of the SFAs exhibited distinct seasonal variation, with pronounced peaks during the growing season at each forest site. The SFAs showed significant correlation with sucrose, which is used as a molecular tracer of pollen. A significant fraction of the SFAs was attributed to the submicrometer particles in the growing season. The results indicate that they originated mostly from plant wax and could be used as useful tracers for primary biological aerosol particles.
25996. 题目: Is the content and potential preservation of soil organic carbon reflected by cation exchange capacity? A case study in Swiss forest soils
文章编号: N19021805
期刊: Biogeosciences
作者: Emily F. Solly, Valentino Weber, Stephan Zimmermann, Lorenz Walthert, Frank Hagedorn, and Michael W. I. Schmidt
更新时间: 2019-02-18
摘要: The content of organic carbon (C) in soils is not stable, but depends on a number of environmental variables and biogeochemical processes that actively regulate its balance. An improved identification of the environmental variables that can be used as predictors of soil organic C (SOC) content is needed to reduce uncertainties of how the soil C reservoir will respond to environmental change. Although several simulations rely on the amount of clay to reproduce changes in the balance of SOC, recent efforts have suggested that other soil physicochemical properties may serve as better predictors. Here we tested whether the effective cation exchange capacity (CEC eff.), may be a more suitable predictor of the content and potential preservation of SOC as compared to the mere quantification of clay-size particles. We further assessed how various climatic, vegetation and edaphic variables explain the variance of SOC content across different soil depths and soil pH classes. A set of more than 1000 forest sites across Switzerland, spanning a unique gradient of mean annual precipitation (636–2484 mm), altitude (277–2207 m a.s.l), pH (2.8–8.1) and representing different geologies and soil orders was used as a case study for this linear model analysis. Our results showed that CEC eff. has the largest explanatory potential of SOC content (35 % of response variance in the complete mineral soil profile) as compared to the amount of clay (which only explained 7 % of the response variance in the complete mineral soil profile) and other environmental variables. CEC eff. is strongly linked to SOC especially in the top mineral soil (0–30 cm depth) with the larger presence of organic matter. At deeper soil depths most of the variance in SOC is instead explained by climate, which in Switzerland is related to a greater weathering activity and translocation of organic C through leaching with increasing mean annual precipitation. We further observed soil pH to have a complex influence on SOC content, with CEC eff. being a dominant variable controlling SOC content at pH > 4.5 in the upper mineral soil and pH > 6 in the subsoil. Since CEC eff. is an edaphic property which is intimately associated to both the conditions that shaped the soil and the current edaphic physicochemical conditions, these findings indicate that considering CEC eff. as an integrative proxy for the potential preservation of SOC and its alteration could improve future predictions of how the soil C reservoir will feed back to environmental change.
25997. 题目: Effects of organic ligands and background electrolytes on barite dissolution
文章编号: N19021804
期刊: Geochimica et Cosmochimica Acta
作者: Bingjie Ouyang, Devon Renock, Denise M. Akob
更新时间: 2019-02-18
摘要: Barite dissolution rates and features were investigated under conditions that combine a variety of organic ligands with different background electrolyte solutions. The organic ligands included low molecular weight organic compounds (LMWO) that can be produced by halophilic bacteria and are common in natural environments, as well as synthetic chelators that were previously studied in barite dissolution. Background electrolyte solutions included deionized water, 0.72 M NaCl and 2 M NaCl solutions designed to simulate freshwater, seawater, and brine fluids, respectively. Barite dissolution rates and corresponding rate constants normalized for saturation states were calculated for most experiments. Equal or lower rates and rate constants for pure LMWO relative to controls at all background electrolyte concentrations and pH values indicated that LMWO do not promote barite dissolution. Synthetic chelators showed higher rates and rate constants at pH 10 at static conditions than controls, indicating enhanced barite dissolution. Distinctive etch pit morphologies on the barite (0 0 1) face were observed in the presence of synthetic chelators, suggesting a direct contact dissolution mechanism by synthetic chelators. The effect of synthetic chelators on barite dissolution was significantly reduced in the presence of 2 M NaCl and/or at pH 6.5 due to salting out effects. Under hypersaline conditions, barite dissolution rates and rate constants by bacterial activities were up to four times higher than those of synthetic chelators. The wide range of conditions studied in this work provides insights into prediction of barite dissolution behavior in various natural environments as well as in industrial treatment procedures.
25998. 题目: Rice straw- and rapeseed residue-derived biochars affect the geochemical fractions and phytoavailability of Cu and Pb to maize in a contaminated soil under different moisture content
文章编号: N19021803
期刊: Journal of Environmental Management
作者: Abdus Salam, Sabry M. Shaheen, Saqib Bashir, Imran Khan, Jianxu Wang, Jörg Rinklebe, Fazal Ur Rehman, Hongqing Hu
更新时间: 2019-02-18
摘要: Management of toxic elements contaminated upland and wetland soils using biochar is of great concern from both agricultural and environmental points of view. The impact of rice straw- and rapeseed residue-derived biochars produced under 300 °C and 550 °C (added to the soil at 2% and 5%; w/w) on the geochemical fractions, phytoavailability, and uptake of Cu and Pb in a contaminated mining soil under different moisture contents (80%, 60%, and 40% of soil field capacity) was investigated in a greenhouse pot experiment using maize. The higher rate of rice straw-derived biochar pyrolyzed at 550 °C caused a significant reduction in the mobile (soluble + exchangeable) fraction of Cu (59.42%) and Pb (75.4%) and increased the residual fractions of Cu (37.8%) and Pb (54.7%) in the treated soil under the highest moisture content (80%) as compared to the untreated soil. Therefore, this biochar significantly decreased the phytoavailability (CaCl2-extractable form) of Cu by 59.5% and Pb by 67.6% under the highest moisture content. Also, at the same moisture level (80%), the higher rate of rapeseed residue-derived biochar pyrolyzed at 550 °C decreased significantly the phytoavailability of Cu by 46.5% and Pb by 60.52% as compared to the untreated soil. The 5% rate of the higher temperature pyrolyzed rice straw and rapeseed biochars decreased the uptake of Cu and Pb by the roots and shoots of maize up to 51% for Cu and 45% for Pb. Immobilization of Cu and Pb in the biochar-treated soil at 80% moisture content may possibly due to the associated increase of soil pH and poorly-crystalline Fe oxides content, and/or the metals precipitation with sulfides. These results indicated that application of high temperature pyrolyzed rice straw- and rapeseed residue-derived biochars at 5% could immobilize Cu and Pb and decrease their uptake by maize under high levels of moisture content; consequently, they can be used for phyto-management of Cu and Pb contaminated wetland soils.
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25999. 题目: Optimizing biomethane production of mesophilic chicken manure and sheep manure digestion: Mono-digestion and co-digestion kinetic investigation, autofluorescence analysis and microbial community assessment
文章编号: N19021802
期刊: Journal of Environmental Management
作者: Liuying Song, Dunjie Li, Xiangyunong Cao, Yu Tang, Rutao Liu, Qigui Niu, Yu-You Li
更新时间: 2019-02-18
摘要: Optimization of mesophilic methane production from Chicken manure (CM) and Sheep manure (SM) at total solid (TS) of 8% and 1.6% were obtained by sequence tests in mono-digestion. However, the positive synergy of co-digestion with an optimum CM/SM of 2.5 (310 mLCH4/gVSadded) resulted in a high hydrolytic capacity and methane production. The modified Gompertz model (R2 > 0.98) and modified Aiba model (R2 > 0.88) illustrated co-digestion significantly improved the methane generation rate with strong ammonia tolerance. Dissolved Organic Matter (DOM) variation in response to the metabolic rate of microbial community illustrated that the SMP-like and protein-like components half-split by EEM–PARAFAC were significantly negative corresponded to bio-methane production. Moreover, the canonical correlation analysis (CCA) resulted a significant difference between the substrate and DOM composition. Potential functional metabolic illustrated statistically significance difference between mono and co-digestion, however, Methanosaeta and Syntrophobacter predominated the syntrophic methanogenesis. The constructed complex metabolic cooperation caused the co-digestion stable and high efficiency.
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26000. 题目: Wheat straw biochar reduces environmental cadmium bioavailability
文章编号: N19021801
期刊: Environment International
作者: Liqiang Cui, Matt R. Noerpel, Kirk G. Scheckel, James A. Ippolito
更新时间: 2019-02-18
摘要: Cadmium contamination in waters and soils can lead to food chain accumulation and ultimately deterioration in human health; means for reducing bioavailable Cd are desperately required, and biochars may play a role. Long-term (240 d) lab incubation experiments were utilized to explain wheat straw-derived biochar effects on Cd sorption and decreasing Cd bioavailability in soils and solutions (0, 5, and 15% biochar as wt:wt or wt:vol, respectively), and to identify Cd forms present using both the European Community Bureau of Reference (BCR) chemical sequential extraction procedure and synchrotron-based X-ray absorption spectroscopy (XAS). Biochar Cd removal was up to ~90% from Cd-containing solutions and contaminated soil as compared to the control. Based on the wet chemical sequential extraction procedure in conjunction with XAS, biochar application promoted the formation of (oxy)hydroxide, carbonate, and organically bound Cd phases. As a material, biochar may be promoted as a tool for reducing and removing bioavailable Cd from contaminated waters and soils. Thus, biochar may play a role in reducing Cd bioaccumulation, trophic transfer, and improving environmental quality and human health.