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23641. 题目: Humification in extracellular polymeric substances (EPS) dominates methane release and EPS reconstruction during the sludge stabilization of high-solid anaerobic digestion
文章编号: N20031115
期刊: Water Research
作者: Yanfei Tang, Xiaohu Dai, Bin Dong, Yiqun Guo, Lingling Dai
更新时间: 2020-03-11
摘要: High-solid anaerobic digestion (HAD) can directly treat dewatered sewage sludge (total solid content ≥15%) with superior volume efficiency. Sludge stabilization during HAD is expected to achieve by throughout organic degradation and conversion towards methane-rich biogas release and humic formation. Sewage sludge is the combination of microbial zoogleas and theirs adsorption of organic and inorganic matter, in which the extracellular polymeric substances (EPS) account 60–80% of total sludge organic matter, inevitably participating most extracellular metabolic pathways. The interactions between EPS transformation and genetically annotated metabolic pathways were found in this research. In brief, noticing the highly cross-linked structures in EPS with major active components of humic substances (HS) and protein (PN), as PN hydrolysis and decomposition in EPS were enhanced in the high-solid anaerobic condition, the exposure of aromatic groups and sites in HS were considerable. HS release was the main factor shifting the electron exchange capacity and activity, which aided in energy metabolism of sludge microorganisms involved in redox reactions, especially the methanogenesis, thus in turn facilitating the PN degradation; Then, the screened humic groups and active protein derives might act as the beneficial precursors to regenerate neo-humic structures, whose significant bridging effect and signal role on stimulating amino acid biosynthesis, member transport and metallic complexation could further contribute to proteolytic condensation and EPS reconstruction. Hence, the in-depth sludge stabilization mechanism during HAD process was established for developing enlightening strategies.

23642. 题目: A new dynamic wetness index (DWI) predicts soil moisture persistence and correlates with key indicators of surface soil geochemistry
文章编号: N20031114
期刊: Geoderma
作者: Ming Li, Erika J. Foster, Phong V.V. Le, Qina Yan, Andrew Stumpf, Tingyu Hou, A.N. (Thanos) Papanicolaou, Kenneth M. Wacha, Christopher G. Wilson, Jingkuan Wang, Praveen Kumar, Timothy Filley
更新时间: 2020-03-11
摘要: Commonly, the topographic influence on soil hydrology is calculated as a Topographic Wetness Index (TWI), which often correlates with surface soil properties, such as carbon and nitrogen, across broad spatial scales. However, traditional TWI methods can be ineffective at capturing finer scale variations when depression filling approaches are used and they do not incorporate localized soil texture controls on infiltration. We developed a new Dynamic Wetness Index (DWI) that attempts to account for the persistence of soil moisture over time at the microtopographic scale (~1 m2) by including inputs of measured soil texture, and information from the Dhara modeling framework that incorporates canopy process and surface-subsurface hydrologic models. DWI and TWI values were correlated with measured soil geochemical properties across six study sites (four agricultural sites, one restored prairie, and one forest site) within the Upper Sangamon River Basin, in central Illinois, USA. Relative to TWI, DWI improved correlations with certain measured soil surface geochemistry (pH R = −0.53), δ13C R = 0.13, δ15N R = 0.44) and certain lignin phenols (vanillyl, cinnamyl/vanillyl, syringyl-vanillyl-cinnamyl/substituted fatty acids). DWI positively correlated with indicators of lignin oxidation, indicating that wetter soils have higher potential for lignin decomposition. In this small dataset, relative to TWI the data show DWI increased significance and decreased the range of correlations with soil moisture and certain surface soil geochemistry parameters driving plant chemistry decay and nitrogen cycling.

23643. 题目: Forest disturbances affect functional groups of macrofungi in young successional forests – harvests and fire lead to different fungal assemblages
文章编号: N20031113
期刊: Forest Ecology and Management
作者: Jari Kouki, Kauko Salo
更新时间: 2020-03-11
摘要: Fungal assemblages after a large-scale disturbance can be diverse and have functionally important roles in forests. However, fungi include several functional groups, and the responses of these groups to different forest disturbances is poorly understood. For example, ectomycorrhizal fungi may facilitate the establishment of a new tree cohort while saprotrophic fungi are able to decompose most of the dead organic material that result from the disturbance event. In this study, we examined how functionally different macrofungi respond to two major disturbances: fire (prescribed burning) and different intensities of timber harvest. We used large-scale field experiment where (1) fire and (2) harvest intensity were manipulated simultaneously in a factorial, replicated design. Three levels of harvests and an unharvested control were included, and sites were either burned or not. Fungi were surveyed before treatments in year 2000 and annually over three years (2001–2003) after the treatments. Fungi species were divided into ectomycorrhizal (ECM), saprophyte (SaM) and wood-associated fungi (WAM). The latter group mostly included Aphylloporoid wood-associated species (AWAM) and agarics. We observed also two biotrophic and one parasitic fungus but these were excluded from the assemblage-level analyses due to their rarity. Both number of sporocarps (fruiting bodies) and their biomass were measured. Fungal groups were affected by harvest and fire but the various fungal groups responded in different ways to the treatments. The ECM species were sensitive to timber harvests and disappeared from all the harvested sites. Fire in the unharvested sites did not negatively affect the ECM fungi. The SaM fungi responded quickly after disturbance, and their assemblage composition changed after fire and harvest. Species richness was reduced but fire promoted several pyrophilous SaM species, leading to major compositional changes in SaM species and the formation of distinct assemblages. The WAM species declined after harvests but fire tended to counteract the negative effects of timber harvesting. The results show that fungal groups respond in different ways to major disturbances in boreal forests. Early successional post-disturbance forests contribute to the maintenance of forest biodiversity, especially the specialist SaM species. However, the type of disturbance (fire or harvest) affect fungi in different ways. Understanding the assemblage dynamics of decomposer and other fungi is crucial when estimating how changes in forest disturbance regimes may affect nutrient and carbon cycling, as well as the maintenance of forest biodiversity.

23644. 题目: Estimation of total nitrogen and organic carbon contents in mine soils with NIR reflectance spectroscopy and various chemometric methods
文章编号: N20031112
期刊: Geoderma
作者: Anna Pudełko, Marcin Chodak
更新时间: 2020-03-11
摘要: Rapid analytical methods are needed to measure organic carbon (OC) and total nitrogen (Nt) contents in reclaimed mine soils. Near infrared spectroscopy (NIRS) with appropriate chemometric techniques could be used for OC and Nt monitoring in the mine soils. The aim of this study was to compare efficiency of NIR-based models developed using various chemometric approaches to predict OC and Nt contents in afforested mine soils. The studied approaches were: partial least square regression (PLSR), principal component regression (PCR) and artificial neural networks based on the entire spectral data (ANN), the principal components (PCA-ANN) and the latent variables (PLS-ANN) calculated from the spectral data. The samples (n = 90) of uppermost mine soil horizons (0–20 cm) were taken from the reclaimed dump of Bełchatów lignite mine (Poland) and measured for the OC content by dry combustion and for the Nt content by Kjehldahl method. The samples were air-dried, finely ground and their NIR spectra (1000 nm–2500 nm) were recorded. The models were developed using 60 samples while the remaining 30 samples were used for independent validation. All the tested chemometric approaches (except the ANN model for OC) yielded excellent models useful for quantitative estimations. The PLSR models were promising at the calibration stage (values of ratio of inter-quartile distance to standard error of prediction (RPIQC) were 7.00 and 4.22 for Nt and OC, respectively) however in the validation they performed less successfully (RPIQV = 3.08 for Nt and RPIQV = 2.75). The accuracy of ANN models based on the entire spectra was similar to PLSR or PCR models. However, the ANN based on reduced spectral data (PCA-ANN and PLS-ANN) performed distinctly better. The most accurate predictive models for the OC and Nt contents were obtained using PCA-ANN approach (RPIQV = 3.64 and 2.90, for Nt and OC, respectively). The results indicate that NIRS coupled with ANN based on the reduced spectral data can be successfully applied to measure the OC and Nt contents in mine soils.

23645. 题目: The comparison of dissolved organic matter in hydrochars and biochars from pig manure
文章编号: N20031111
期刊: Science of The Total Environment
作者: Chengfang Song, Shengdao Shan, Chao Yang, Cheng Zhang, Xiaoqing Zhou, Qi Ma, Kim Yrjälä, Huabao Zheng, Yucheng Cao
更新时间: 2020-03-11
摘要: Dissolved organic matter (DOM) has an important effect on soil fertility, activity of microorganisms and transport of contaminants. In this study, DOM released by the hydrochar and biochar prepared under various conditions from pig manure, was assessed using a combination of UV–Visible spectroscopy, fluorescence excitation-emission (EEM) spectrophotometry and 1H-nuclear magnetic resonance (1H NMR). The dissolved organic carbon (DOC) extracted from the hydrochar and biochar ranged from 3.34–11.96% and 0.38–0.48%, respectively, and the highest DOM was released by HCK0.5 (180 °C and 0.5% KOH). The aliphatic compounds were most common in DOM which mainly included three humic acid-like and one protein-like substance. The hydrochar-DOM had a larger molecular weight and lower aromaticity than biochar-DOM, but the effect of temperature on the DOM characteristics of hydrochar and biochar was opposite. The acidic treatment increased the content of functional groups containing oxygen and nitrogen in hydrochar-DOM, and alkaline treatment increased the content of aliphatic compounds. The results obtained are beneficial to select carbonation process and guide the rational application of hydrochar and biochar from pig manure in soil remediation field.

23646. 题目: Decreasing underwater ultraviolet radiation exposure strongly driven by increasing ultraviolet attenuation in lakes in eastern and southwest China
文章编号: N20031110
期刊: Science of The Total Environment
作者: Yunlin Zhang, Kun Shi, Qichao Zhou, Yongqiang Zhou, Yibo Zhang, Boqiang Qin, Jianming Deng
更新时间: 2020-03-11
摘要: Underwater light attenuation plays an important role in modulating aquatic ecosystems and is considered a sentinel of climate change and human activity. However, knowledge of the long-term exposure of underwater ultraviolet radiation (UVR) in aquatic ecosystem is still very limited. We carried out extensive UVR measurements in different seasons in five lakes at different altitudes, collected long-term Secchi disk depth (SDD) data, developed the models between UVR diffuse attenuation coefficient (Kd) and SDD, and further assessed the long-term underwater UVR exposure. Observation results from five lakes including 259 samples showed large spatial variabilities of Kd(313) (UVB) from 0.83 to 5.91 m−1 and Kd(340) (UVA) from 0.51 to 4.67 m−1. Chromophoric dissolved organic matter (CDOM) absorption coefficients were significantly correlated with Kd(313) and Kd(340). Thus, the effects of climate change and human activity on CDOM abundance, source and composition may significantly alter UVR attenuation in aquatic environments. The long-term underwater UVR exposure, which was estimated from significant positive correlations between 1/SDD and Kd(313) and Kd(340), and incident UVR, significantly decreased in Lake Fuxianhu, Lake Erhai, and Lake Qiandaohu. The regime shift from clear water state to turbid state in Lake Erhai around 2001–2003 dramatically decreased underwater UVR exposure. In conclusion, increasing UVR attenuation played a more important role in determining underwater UVR exposure than decreasing incident UVR with the relative contributions of 89.9% and 87.7% in Lake Fuxianhu, 98.0% and 97.7% in Lake Erhai, 94.4% and 92.5% in Lake Qiandaohu for UVB and UVA exposure, respectively. This is the first study to elucidate the long-term trend of underwater UVR exposure considering both increasing UVR attenuation and decreasing incident UVR.

23647. 题目: Intensive land uses modify assembly process and potential metabolic function of edaphic bacterial communities in the Yellow River Delta, China
文章编号: N20031109
期刊: Science of The Total Environment
作者: Yuxan Zou, Jiaguo Yan, Shengwei Hou, Yujun Yi, Baoshan Cui
更新时间: 2020-03-11
摘要: Coastal reclamation is a global threat to natural ecosystems, disturbing biological community structure, diversity and ecological function through habitat conversion. We have limited insights into the changes brought about by coastal reclamation for different land-use types. We used the Yellow River Delta (YRD) as a model because it is a region with intensive land reclamation, and we investigated the structural and functional variations of bacterial communities and their relations to edaphic properties under different land-use types. Our results showed that the high soil organic carbon (SOC), nitrate concentrations and salinity were found in oil field, aquaculture pond and salt pan, respectively, and low values in natural wetland. Land use was found to have significant influence on bacterial community diversity. To investigate the phylogenetic conservation of specific traits, we analyzed the relationship between soil bacterial assembly processes and edaphic properties. Bacterial traits phylogenetically conserved, and differs in depth. Our findings suggest that SOC served as a deep trait due to it negative correlation with deeper branches of phylogenetic clustering, while nitrate functioned as a shallow trait due to its positive correlation with phylogenetic clustering at finer branches. Soil salinity acted as a complex trait effected on both finer and deeper branches. Further potential functional gene co-occurrence network analysis revealed that land reclamation induced shifts of metabolic function by altering the functional gene connectivity. We found that the photosynthesis pathway was enriched in hub modules related to oil field (OF), while methane metabolism was enriched in hub modules linked to sea cucumber pond (CP1). In addition, two-component systems (TCS) were enriched with nitrate, ammonia, SOC and salinity-related modules. Therefore, our study highlights the importance of integrating multi-function and multi-process identification and prediction of coastal diverse reclamation impacts on coastal ecosystems.

23648. 题目: Does terracing enhance soil organic carbon sequestration? A national-scale data analysis in China
文章编号: N20031108
期刊: Science of The Total Environment
作者: Die Chen, Wei Wei, Stefani Daryanto, Paolo Tarolli
更新时间: 2020-03-11
摘要: Terracing practice is expected to reserve soil organic carbon (SOC) pools, which are the key components for maintaining soil fertility and land productivity. In China such practice is widespread from center to south since ancient time. In this work, to reveal the spatial-temporal variation characteristics of SOC under different terraced sites in China, we conducted a meta-analysis on 78 studies regarding terracing effects on SOC sequestration. The between-group heterogeneity analysis indicated that terracing land use, age, climatic background, and slope gradient were critical factors for SOC sequestration, while terracing structure and soil depth were not. Overall, for China's landscapes, terracing increased SOC sequestration by 32.4% on average. Relative to other terracing structures, level ditches and half-moon terraces receive more rainwater and fertile topsoil from upper slopes due to their specific concave structures. Terracing in those areas with lower temperatures and less precipitation showed higher SOC sequestration. The extent of SOC sequestration due to terracing was primarily determined by land use type. Reforestation terraces could increase SOC sequestration markedly by eliminating water erosion and related soil carbon loss. The terracing aged 1–2 years leads to a decrease of 6.4% averagely on SOC sequestration, likely because the breakdown of soil aggregates through soil excavation and redistribution improves the decomposition of SOC. Furthermore, terracing aged over five years was more effective on SOC sequestration. Since this study offered a useful synthesis on multiple terracing factors affecting soil carbon in China, it can help to provide a wiser utilization and management of terracing to maximize SOC sequestration, and to make better terracing practices in the context of global change.

23649. 题目: Removal of organic and inorganic matters from secondary effluent using resin adsorption and reuse of desorption eluate using ozone oxidation
文章编号: N20031107
期刊: Chemosphere
作者: Qimeng Li, Xiang Li, Jing Sun, Haiou Song, Ji Wu, Guoxiang Wang, Aimin Li
更新时间: 2020-03-11
摘要: This study aimed to compare the effectiveness of MAER and L20 resin for the adsorption treatment of secondary effluent, and evaluate the applicability of ozone oxidation for the reuse of desorption eluate. Bench-scale adsorption experiments showed that the MAER resin exhibited higher efficiency than L20 resin in removal of COD within 600 treated bed volumes (BV), which declined from 32.5% to 14.1% in the first and sixth treatment loading of 100 BV. On the other hand, the L20 resin displayed obviously higher removal efficiency of total nitrogen (TN) than MAER resin within 600 BV, which dropped from 74.6% to 9.8% at the same condition. The ozone oxidation treatment could achieve desirable reuse of desorption eluate, although its chemical oxygen demand (COD) concentration increased gradually in line with the reuse numbers. The uptake of COD, TN and total phosphorus declined steadily by using ozone treated eluate as the regenerant in successive adsorption-desorption cycles, but increased obviously with a new batch of regenerant. Overall, the resin adsorption could efficiently remove organic and inorganic matters from secondary effluent, while the treatment loop including desorption eluate oxidation and eluate reuse could markedly enhance the concentration ratio of treated effluent.

23650. 题目: Impact of Soil Biochar Incorporation on the Uptake of Heavy Metals Present in Wastewater by Spinach Plants
文章编号: N20031106
期刊: Water, Air, & Soil Pollution
作者: Christopher Nzediegwu, Shiv Prasher, Eman Elsayed, Jaskaran Dhiman, Ali Mawof, Ramanbhai Patel
更新时间: 2020-03-11
摘要: The effect of plantain peel biochar on the uptake of six heavy metals (Cd, Cr, Cu, Fe, Pb and Zn) in spinach (Spinacia oleracea L.) irrigated with untreated wastewater was investigated in nine outdoor lysimeters (0.45 m diameter × 1.0 m height) arranged in a completely randomised design with three replicates. The lysimeters were packed with sandy soil (bulk density 1.35 Mg m−3) and brought to field capacity 1 day before starting the experiment. Biochar (1% w/w) was mixed in the top 0.10 m of soil under biochar amendment. Spinach were planted in each lysimeter, irrigated (every 10 days for 4 times in total), harvested (harvest 1 and harvest 2) and analysed for the heavy metals. Spinach leaves accumulated more heavy metals than the roots and stems. Biochar amendment did not affect the translocation of heavy metals (Cd, Cu, Cr, Fe and Pb) to spinach leaves, possibly due to competition with other compounds in the soil solution. However, the biochar amendment improved CEC and increased the pH of soils which resulted in a 42% reduction of translocation of Zn in spinach leaves. Assuming daily spinach consumption of 200 g per person, Zn in spinach grown in soil amended with biochar would be below the provisional maximum tolerable daily intake limit for adults (20 mg) as prescribed by WHO/FAO/IAEA. Consumption of spinach grown with wastewater in soil without biochar amendment may not be safe because of Zn toxicity. Likewise, the concentration of Cd, above CODEX permissible levels in the spinach leaves and eleven times higher in wastewater than freshwater irrigation, raises a concern for consumers in developing countries where untreated wastewater is often used for irrigation.

23651. 题目: Effect of aluminum modification of rice straw–based biochar on arsenate adsorption
文章编号: N20031105
期刊: Journal of Soils and Sediments
作者: Xian He, Jun Jiang, Zhineng Hong, Xiaoying Pan, Ying Dong, Renkou Xu
更新时间: 2020-03-11
摘要: Purpose To evaluate the adsorption capacity of aluminum-modified biochars for arsenate (As(V)) and the effect of the biochars on As(V) adsorption by acidic Ultisols.Materials and methods Rice straw was collected from Yingtan, Jiangxi Province. Rice straw and the biochar derived from rice straw were both treated with aluminum (Al) to prepare two kinds of Al-modified biochars. An Ultisol was collected from Jinxian, Jiangxi Province, and an indoor incubation was used to prepare biochar-ameliorated soil. Zeta potential and Fourier transform infrared spectroscopy (FTIR) were used to characterize the effects of Al modification on surface charge and functional groups of the biochars. The batch method was used to investigate the adsorption and desorption of As(V) by the biochars and the soil. Arsenic in equilibrium solution was determined using hydride generation–atomic fluorescence spectrometry. Results and discussion The yield of biochar derived from Al-treated rice straw was significantly greater than that of the biochar from untreated rice straw. The Al content of Al-treated biochar from rice straw was higher than that of biochar derived from Al-treated rice straw. Modification did not change the morphology of Al oxide on biochar. Zeta potential of the two modified biochars changed to a positive value compared with that of unmodified biochar, and more change in zeta potential was observed for the Al-treated biochar from rice straw than that of biochar derived from Al-treated rice straw. After As(V) was adsorbed by the two modified biochars, new absorption peaks were found in the FTIR spectra from the biochars at 892 cm−1 (biochar from Al-treated rice straw) and 884 cm−1 (Al-treated biochar from rice straw). The peaks suggested that a chemical bond was formed between As(V) and Al on biochars during As(V) adsorption. The two Al-modified biochars adsorbed much more As(V) than the unmodified biochar. The desorption of adsorbed As(V) in the modified biochars was very low, which indicated that specific adsorption was the dominant mechanism for As(V) adsorption. The addition of modified biochar promoted the adsorption of As(V) by the Ultisol. Moreover, Al-treated biochar from rice straw enhanced As(V) adsorption by the soil more than the biochar derived from Al-treated rice straw. Conclusions Compared with the effect of adding unmodified biochar, adding either of the two Al-modified biochars significantly enhanced the adsorption of As(V) by the Ultisol. Therefore, Al-modified biochar can be used to immobilize As(V) in arsenic-contaminated soils, especially in acidic soils.

23652. 题目: Effect of ageing process on bisphenol A sorption and retention in agricultural soils amended with biochar
文章编号: N20031104
期刊: Environmental Science and Pollution Research
作者: Junguang Liu, Lingling Liu, Yuehong Shu, Shaojun Jiang, Renlong Huang, Zhenzhen Jia, Dongyang Wei
更新时间: 2020-03-11
摘要: The ageing of biochar and organic pollutant itself in soils can both influence the retention of organic pollutant in field soils. In this study, column experiments were adopted to determine the effect of ageing process on bisphenol A (BPA) sorption and retention in two typical Chinese agricultural soils with lychee branch biochar added. The effect of biochar ageing on soil organic matter (SOM) was specially investigated. Experimental results showed that the addition of biochar significantly increased the condensation and rigid of SOM, which could further increase with biochar ageing in soils. As a result, the addition of biochar significantly increased BPA sorption capacity (5.86 times and 3.30 times) and retention rate (13.60 times and 4.47 times) in fluvo-aquic soil and phaeozem respectively, while BPA sorption capacity and retention rate decreased obviously after biochar ageing in the two soils for 2 months as compared with the freshly incorporated biochar treatments, which may be attributed to the surface coverage and/or pore blockage of some sorption sites owning to DOC. With biochar incorporated, 2 months of BPA ageing increased BPA retention rate by about 4.50 times in both soils as compared with BPA newly spiked treatments. The results of this study could provide important parameters for prediction and control of organic pollutants such as BPA in soils.

23653. 题目: Microplastic identification and quantification from organic rich sediments: A validated laboratory protocol
文章编号: N20031103
期刊: Environmental Pollution
作者: P. Vermeiren, C. Muñoz, K. Ikejima
更新时间: 2020-03-11
摘要: Plastic pollution presents a global environmental concern with potentially widespread ecological, socio-economic and health implications. Methodological advances in microplastic extraction, quantification and identification from sediments have been made. However, integrating these fragmentary advances into a holistic, cost-effective protocol and applying it to organic rich sediments with fine grain size remains a challenge. Nonetheless, many hot spots of microplastic contamination such as harbour and estuarine sediments are characterised by such sediments. We conducted a series of experiments to integrate methodological advances, and clarify their applicability to organic rich sediments with fine grain size. The resulting protocol consisted of three stages. First, pre-treatment with Fenton's reagent was found to be efficient in reducing organic matter content, compatible with later Fourier Transform-Infrared Spectroscopy (FT-IR) for polymer identification, although it did affect the size of polyethylene (PE) and polyethylene terephthalate (PET). Secondly, a novel density separation column with a top overflow (the OC-T) obtained recovery rates above 90% for microplastics present in a ZnCL2 solution. Finally, automated epifluorescence microscopic image analysis of Nile Red stained filters with selected validation of polymer identities using FT-IR revealed 91.7% of stained particles to be plastics. A case study on estuarine sediments demonstrated a high extraction efficiency with quantification possible down to 125 μm and detection possible down to 62.5 μm. This makes this protocol suitable for large scale monitoring of microplastics in sediments of estuarine origin provided polymer specific recovery rates, background contamination and uncertainty in Nile Red identification is accounted for. Subject to further validation, the protocol could also offer a solution to similar organic rich sediments with fine grain size, such as some soils and sludge, to improve our ability to conduct cost-effective, large scale monitoring of microplastic contamination.

23654. 题目: Assessing the effectiveness of riparian buffers for reducing organic nitrogen loads in the Coastal Plain of the Chesapeake Bay watershed using a watershed model
文章编号: N20031102
期刊: Journal of Hydrology
作者: Sangchul Lee, Gregory W. McCarty, Glenn E. Moglen, Xia Li, Carlington W. Wallace
更新时间: 2020-03-11
摘要: Riparian buffers are an important conservation practice to mitigate water quality degradation in the Coastal Plain of the Chesapeake Bay watershed (CBW). Although forested and grassed riparian buffers have been implemented in this region through government programs, the impacts of riparian buffers on water quality have been rarely examined. The objective of this study was to assess the long-term effects of riparian buffers to improve water quality in the Coastal Plain of the CBW. A watershed model, Soil and Water Assessment Tool (SWAT), was employed for this study. Considering impacts of model uncertainty (i.e., equifinality) on the effectiveness of riparian buffers, we adopted all parameter sets that produced acceptable simulation results. Multiple riparian buffer implementation scenarios were developed to generate the baseline condition on total organic nitrogen (TON) loads without riparian buffers and examine variation of TON loads with areal coverage of riparian buffers. Through the calibration processes, a total of 235 acceptable parameter sets were identified and used to simulate TON loads. The simulation results indicated that riparian buffers significantly reduce TON loads. Without riparian buffers, annual TON loads from the 220 km2 study watershed were 18 to 34 metric tons, but declined to 8 to 21 metric tons with riparian buffers. The effectiveness of riparian buffers on reducing annual TON loads increased from 17% to 45% with an increase in the extent of riparian buffer implementation. The effectiveness of riparian buffers tended to be higher during early spring than other seasons as high soil water conditions promote occurrence of surface water flow and thus TON loads. Riparian buffers were more efficient on croplands than other land use types due to high soil nutrient levels caused by fertilizer applications. The effectiveness of riparian buffers differed considerably by parameter set. Thus, efforts to consider model uncertainty are important to provide better insight into the impacts of conservation practices. This study supports ongoing riparian buffer programs for the Mid-Atlantic Coastal Plain by demonstrating the effectiveness of riparian buffers and informing implementation guidelines.

23655. 题目: The ratio of H/C is a useful parameter to predict adsorption of the herbicide metolachlor to biochars
文章编号: N20031101
期刊: Environmental Research
作者: Lan Wei, Yufen Huang, Lianxi Huang, Yanliang Li, Qing Huang, Guizhi Xu, Karin Müller, Hailong Wang, Yong Sik Ok, Zhongzhen Liu
更新时间: 2020-03-11
摘要: Biochar adsorbent was produced by pyrolyzing traditional Chinese medicinal herb residue at 300, 500 and 750 °C (referred to as biochar-300, biochar-500 and biochar-750). Basic physical and chemical analyses, Fourier transform infrared spectroscopy (FT-IR), and thermodynamic analyses were performed to elucidate adsorption and properties of biochar. Biochar adsorption capacity of herbicide metolochlor, as measured by batch-type adsorption experiments by Freundlich constant Kf (mg1−n Ln kg−1), followed the order: biochar-750 > biochar-300 > biochar-500. Thermodynamic analysis suggested that adsorption of metolachlor on biochar was a spontaneous process. The adsorption isotherm for the biochar produced at the highest pyrolysis temperature was characteristic for adsorption process driven by a high surface area of biochar (85.30 m2 g−1), while the adsorption process for the biochar produced at the lowest temperature was controlled by its higher content of organic matter (39.06%) and abundant functional groups. The FT-IR spectra also showed that the biochar prepared at the lowest temperature had the highest number of surface groups. In general, pore-filling induced by the large surface area of the biochar was the dominant adsorption mechanism. When the H/C value was >0.5, the adsorption mechanism of biochar was dominated by surface chemical bond, while pore-filling played a major role when the H/C value was <0.5.

23656. 题目: Sedimentary environment and organic matter accumulation of Neoproterozoic black shale in the North China Craton: A case study of the Tonian Baishugou Formation in the Luonan area
文章编号: N20031007
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Suyun Hu, Kun Wang, Tongshan Wang, Tao Yang, Ping Luo, Shuyuan Shi, Shaoyong Wang, Jian Su
更新时间: 2020-03-10
摘要: With acceleration of oil exploration near the source in the petroleum industry, black shales (BS) play an increasingly important role in oil and gas exploration. Meso-Neoproterozoic BS are well developed in the North China Craton (NCC), China, many of which are identified as potential hydrocarbon source rocks. Although BS from the Mesoproterozoic Era has been widely investigated, few studies were focused on the Neoproterozoic BS so far. Based on petrology and geochemistry analysis, the sedimentary environment, provenance and organic matter accumulation of two BS layers in the Tonian Baishugou Formation from Sujiacun section, Luonan Area, southern NCC were investigated. It suggests that the lower BS (LB) was deposited in a shallow and non-stratified cratonic-interior sea environment with unstable dysoxic or suboxic conditions. The seawater salinity increased from brackish to marine facies conditions due to the decrease of runoff caused by climate cooling. The Upper BS (UB) was deposited in an open paleomarine environment with stable suboxic conditions and brackish salinity in continuously humid and hot paleoclimate. Both BS were derived from granitoids formed by the ca.2.5 Ga collisional-thermal events in the NCC. The OM accumulation rate of UB is higher than that of UB while LB records lower OM loss rate. On these bases, two developmental modes for the BS from the Baishugou Formation were established.

23657. 题目: A magnetic macro-porous biochar sphere as vehicle for the activation and removal of heavy metals from contaminated agricultural soil
文章编号: N20031006
期刊: Chemical Engineering Journal
作者: Yonglin Liu, Jianfei Huang, Huijuan Xu, Yulong Zhang, Tian Hu, Wenzhao Chen, Hanjian Hu, Jinhua Wu, Yongtao Li, Gangbiao Jiang
更新时间: 2020-03-10
摘要: Remediation of contaminated agricultural soils focused on fixing heavy metals in soils to reduce their bioavailability. However, with the influence of pH, redox potential, and microorganism in the soils, heavy metals were likely to be released from a fixed state. The study aims to investigate magnetic porous biochar spheres and their roles in in situ sorption and removal of heavy metal from the contaminated agricultural soil. The magnetic biochar spheres were prepared using alginate and FeCl3 through a one-step gelation to obtain alginate-Fe3+ gel and subsequently pyrolyzed. Results of Ultraviolet–visible spectrophotometer, X-ray diffraction and Fourier transform infrared spectrometer showed the decomposition of alginate and the formation of Fe3O4 and FeCl2 hydrates nanoparticles on the spheres when the spheres were pyrolyzed at 300 °C. Scanning electron microscope image showed that the CFe300 sphere has a macro-porous structure. The CFe300 sphere exhibited good adsorption capacity of hexavalent chromium from aqueous solution. The CFe300 sphere decreased the bioavailable and total cadmium (II) concentrations from 1.55 ± 0.08 to 0.32 ± 0.04 mg/kg and from 2.81 ± 0.02 to 1.39 ± 0.06 mg/kg, respectively. Moreover, the CFe300 sphere decreased bioavailable and total arsenate (V) concentrations from 1.26 ± 0.003 to 0.85 ± 0.01 mg/kg and from 60.23 ± 0.39 to 27.34 ± 0.94 mg/kg, respectively. Subsequently, addition of water into the soil induced the spheres to leave the soil and float on the surface of soil/water mixture. Thus, the magnetic biochar spheres can be much easier to separate from the soil using magnets.

23658. 题目: Changes in soil organic carbon and total nitrogen as affected by primary forest conversion
文章编号: N20031005
期刊: Forest Ecology and Management
作者: Fei Gao, Xiaoyang Cui, Ying Sang, Jinfeng Song
更新时间: 2020-03-10
摘要: Numerous studies have addressed the effects of forest conversion on soil organic carbon (SOC) and total nitrogen (TN); however, knowledge of SOC and TN stocks and SOC stability after primary forest conversion to secondary forest is still lacking. Such an understanding is critical for the accurate estimation of the potential of forest soils to act as carbon sinks. To learn more about the changes in SOC and TN stocks and SOC stability after primary forest conversion, we used a strict paired-plots method and measured bulk-soil and aggregate-associated OC and TN as well as four SOC stability indices, i.e., heterotrophic respiration, alkyl/O-alkyl C ratio, aggregate-occluded OC, and mineral-associated OC, in paired primary and secondary forest plots in Liangshui National Nature Reserve, Heilongjiang Province, Northeast China. The SOC and TN stocks at the 0–15 cm depth significantly increased with the conversion of primary to secondary forest, by 17.11 Mg ha−1 and 2.91 Mg ha−1, respectively, which was mainly due to increases in soil aggregate (>0.053 mm)-associated OC and TN concentrations. The primary forests dominated by conifer tree species had more low-quality plant OC in the organic layer (i.e., higher amounts of litter and forest floor and higher litter C/N ratio), while the secondary forests composed of broadleaf tree species with higher litter and fine root TN and lower C/N ratios accumulated more stable OC (as indicated by the reduced respiration per g of SOC and the greater proportion of aggregate-occluded OC) and TN in the mineral soil. We did not observe significant differences in the alkyl/O-alkyl C ratio or the proportion of mineral-associated OC (<50 µm) between the two forest types, reflecting the insensitivity of some stability indicators to decadal-scale shifts in primary forest conversion. Tree species-specific differences in litter and fine root traits (i.e., C and N) might be the main driving factors affecting the accumulation and stability of SOC and TN. Thus, it is important to identify and select tree species that are beneficial for the sequestration of OC in mineral soil for forest management or afforestation from the perspective of ecosystem carbon sequestration.

23659. 题目: Spirulina hydrothermal carbonization: effect on hydrochar properties and sulfur transformation
文章编号: N20031004
期刊: Bioresource Technology
作者: Zhiming Zhang, Yong Zhao, Tengfei Wang
更新时间: 2020-03-10
摘要: The effect of hydrothermal carbonization (Htc) on the hydrochar properties and sulfur conversion for microalgae was investigated. The sulfur species and distribution in solid and aqueous products produced from different temperature (180-300°C) were evaluated. Results suggested that varying temperature significantly influenced the elemental composition, functional groups of hydrochar, and the sulfur species in the products. With temperature increased, the hydrochar had increased aromatic structure with low H/C and O/C ratio, and more conversion of organic sulfur into liquid as SO42--S, which acquired the highest concentration (293.31 mg/L) at 300°C. The thiophene-S, aromatic-S, and thiazole-S accounted for the main sulfur species in bio-oil, while components of thiophene-S and thiazole-S were decreased at high temperature. In addition, elevated temperature resulted in more sulfur forms (i.e. thiophene) in hydrochar and formation of more inorganic-S species like sulfate.

23660. 题目: Modeling oxygen and organic matter concentration in the intensive rainbow trout (Oncorhynchus mykiss) rearing system
文章编号: N20031003
期刊: Environmental Monitoring and Assessment
作者: Firouzeh Hosseini Galezan, Mohammad Reza Bayati, Omid Safari, Abbas Rohani
更新时间: 2020-03-10
摘要: Dissolved oxygen (DO) as one of the most fundamental parameters of water quality plays a vital role in aquatic life. This study was conducted to predict DO, biological oxygen demand (BOD), and chemical oxygen demand (COD) in an intensive rainbow trout rearing system with different biomass (B). The multilayer perceptron (MLP) and the radial basis function (RBF) neural networks were employed for evaluating the impacts of food parameters (crude protein (CP), consumed feed (CF)), fish parameters (different values of B, and weight gain (WG)), and water quality parameters including temperature (T) and flow rate (Q) on variation of DO, BOD, and COD concentrations. This study's results showed that although both MLP and RBF neural networks are capable to estimate DO, BOD, and COD concentrations, RBF neural network showed better performance compared to MLP neural network. The results of sensitivity analysis indicated that the parameter CF has the highest effect on DO concentration estimation. Independent variables CF, CP, WG, and B showed the highest to the lowest rank of impacts on BOD estimation, respectively. The results also illustrated a decreasing trend of the effects on the estimation error of COD changes simulation by all independent variables, including B, T, WG, CF, CP, and Q, respectively. RBF neural network based on better stability and generalization ability with average root mean square error (RMSE) and mean absolute percentage error (MAPE) values of less than 0.12 and 3% was superior to MLP in DO, BOD, and COD concentration prediction. Moreover, CF was identified as the most effective factor in estima12tion process. Based on the present study results, there are direct relationships between DO, BOD, and COD concentrations and water quality parameters, fish parameters, and food parameters. Food parameters relative to fish and water quality parameters imposed the greatest effects. Improvement in feeding process such as application of intelligence feeding methods and change in fish diet and feeding time can considerably reduce losses in production system.