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25401. 题目: Effect of gasification biochar application on soil quality: Trace metal behavior, microbial community, and soil dissolved organic matter
文章编号: N18112418
期刊: Journal of Hazardous Materials
作者: Xiao Yang, Ana Tsibart, Hyungseok Nam, Jin Hur, Ali El-Naggar, Filip M.G. Tack, Chi-Hwa Wang, Young Han Lee, Daniel C.W. Tsang, Yong Sik Ok
更新时间: 2018-11-24
摘要: Compared to pyrolysis biochar (PBC), gasification biochar (GBC) differs in both composition and surface functionalities due to the use of an oxidizing purging gas. This work compares the effect of using PBC and GBC as soil amendments on the soil properties, trace metal bioavailability, soil microbial activity, and soil dissolved organic matter (DOM). Biochar-driven reduction of bioavailable metals does not necessarily result in a positive impact on the soil microbial growth. The DOM in the soil was strongly related to the soil microbial activity, as revealed by the strong correlation between the soil dehydrogenase activity (DHA) and soil dissolved organic carbon (r = 0.957, p < 0.01). Three identified fluorescent components (C1, C2, C3) in the soil DOM were closely associated with the soil microbial activity, for instance, with a clear positive correlation between the soil DHA and C1 (r = 0.718, p < 0.05) and a significant negative correlation between the total bacterial fatty acid methyl ester content and C3 (r = -0.768, p < 0.05). The bioavailability of Cd and Zn is not only related to the pH and surface functionalities of the biochar, but also to its aromatic carbon and inorganic mineral composition. This study further demonstrates that a fluorescence excitation-emission matrix coupled with parallel factor analysis is a useful tool to monitor changes in the soil quality after application of biochar, which is greatly relevant to the soil biota.
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25402. 题目: Assessment of biochar and zero-valent iron for in-situ remediation of chromated copper arsenate contaminated soil
文章编号: N18112417
期刊: Science of The Total Environment
作者: Hanna Frick, Stacie Tardif, Ellen Kandeler, Peter E. Holm, Kristian K. Brandt
更新时间: 2018-11-24
摘要: Chromated copper arsenates (CCA) have been extensively used as wood impregnation agents in Europe and North America. Today, CCA contaminated sites remain abundant and pose environmental risks that need to be properly managed. Using a TRIAD approach that combined chemical, ecotoxicological and ecological assessment of soil quality, we investigated the abilities of biochar and zero-valent iron (ZVI) to remediate CCA contaminated soil in a microcosm experiment. Soil samples from a highly contaminated CCA site (1364, 1662 and 540 μg g⁻¹ of As, Cu and Cr, respectively) were treated with two different biochars (fine and coarse particle size; 1% w w⁻¹) and ZVI (5% w w⁻¹), both as sole and as combined treatments, and incubated for 56 days at 15 °C. In general, bioavailable As (As_bio) and Cu (Cu_bio) determined by whole-cell bacterial bioreporters corresponded well to water-extractable As and Cu (As_water and Cu_water). However, in biochar treatments, only Cu_bio and not Cu_water was significantly reduced. In contrast, under ZVI treatments only Cu_water and not Cu_bio was reduced, demonstrating the value of complementing analytical with bacterial bioreporter measurements to infer bioavailability of elements to soil microorganisms. The combined fine particle size biochar and ZVI treatment effectively reduced water extractable concentrations of Cr, Cu, and As on site by 45%, 45% and 43% respectively, and led to the highest ecological recovery of the soil bacterial community, as measured using the [³H]leucine incorporation technique. We conclude that the combined application of biochar and ZVI as soil amendments holds promise for in-situ stabilization of CCA contaminated sites.
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25403. 题目: Turn the potential greenhouse gases into biomass in harmful algal blooms waters: A microcosm study
文章编号: N18112416
期刊: Science of The Total Environment
作者: Hainan Ai, Yixi Qiu, Qiang He, Yixin He, Chun Yang, Li Kang, Huarui Luo, Wei Li, Yufeng Mao, Meijuan Hu, Hong Li
更新时间: 2018-11-24
摘要: Carbon sources are a critical requirement for the proliferation of algae and the occurrence of harmful algal blooms (HABs), but are often turned into methane (CH₄) after the collapse of severe HABs. Here, we attempt to remove HABs, reduce algal-derived CH₄ emissions, and repair the broken carbon biogeochemical cycle in aquatic systems using an integrated ecological approach including flocculation, capping, and submerged macrophyte induction, preliminary at a microcosm scale. This strategy sustainably reached 98% algal removal after 65 days of incubation and resulted in an aerobic microenvironment (ORP = +12 mv) at the sediment-water interface. The approach contributed to an approximate 60% decline in CH₄ released from the aquatic environment into the atmosphere jointly through assimilation of mineralized organic carbon by submerged macrophytes, production of carbon dioxide (CO₂) under aerobic conditions, and aerobic CH₄ oxidation. Some of the CO₂ produced in the aquatic phase contributed to inorganic carbon and formed the submerged macrophytes biomass. A combination of flocculation, capping, and submerged macrophyte incubation were significant contributors to altering the carbon budget and sealing nearly 99% of the carbon in the simulated ecosystem (the majority in sediment, followed by submerged macrophytes), providing a sustainable way to reuse algal-derived carbon and reduce CH₄ emissions.
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25404. 题目: Changes in surface soil organic carbon in semiarid degraded Horqin Grassland of northeastern China between the 1980s and the 2010s
文章编号: N18112415
期刊: CATENA
作者: Yuqiang Li, Xuyang Wang, Yinping Chen, Yongqing Luo, Jie Lian, Yayi Niu, Xiangwen Gong, Huan Yang, Peidong Yu
更新时间: 2018-11-24
摘要: Soil organic carbon (SOC) plays an important role in the global carbon cycle and in mitigating climate change. The Horqin Grassland is one of the largest grasslands in China and has undergone serious aeolian desertification in recent decades. We conducted the largest field inventory to date, with the highest density of soil sampling, and explored changes in SOC in the region over the 30-year gap between the 1980s and the 2010s. Our results indicated that the mean SOC density to a depth of 20 cm decreased from 2.58 to 2.21 kg C m⁻², while the total SOC storage decreased from 311.11 to 266.70 Tg C, at an average of 12.29 g C m⁻² yr⁻¹. We ranked the SOC densities by ecosystem as woodland > grassland > cropland > sandy land. The decreased SOC storage in the Horqin Grassland can be ascribed to a combination of increasing temperature, decreasing precipitation, an expansion of the areas of extremely severely desertified land and cropland, and shrinkage of the grassland area. Our results provide an important updated regional baseline for quantifying how SOC storage will respond to future climate change and anthropogenic activities. Our results will also help policy makers determine how to achieve sustainable development of agriculture, forestry, and animal husbandry based on carbon sequestration.

25405. 题目: A multi-factor weighted regression approach for estimating the spatial distribution of soil organic carbon in grasslands
文章编号: N18112414
期刊: CATENA
作者: SuiZi Wang, JiangWen Fan, HuaPing Zhong, YuZhe Li, HuaZhong Zhu, YuXin Qiao, HaiYan Zhang
更新时间: 2018-11-24
摘要: Soil organic carbon (SOC) plays an important role in global carbon cycling and is increasingly important to the ecosystem. An accurate SOC content map would significantly contribute to the proper application of ecological modeling. Therefore, there is a need to accurately estimate and map SOC content in grasslands. We evaluated various methods for estimating the SOC content of grasslands using field soil sampling data and auxiliary data in the pastoral area. The results showed that (1) SOC is affected by various factors, including geographic location, soil, topography, and climate. Single-variable SOC models account for 2%–72% of the variations in the grassland SOC. (2) Based on the correlation of environmental variables of SOC, normalized difference vegetation index, annual precipitation, annual average temperature, elevation, and moisture index were explored as critical auxiliary data to predict SOC content. We established multi-factor weighted regression model (MWRM). (3) We compared three spatial estimation methods, including inverse distance weighting, regression kriging, and MWRM, to determine a suitable method for SOC mapping. Our results indicate that among the three spatial estimation methods, MWRM provides the lowest prediction error (RMSE = 4.85 g/kg; MAE = 3.47 g/kg; MRE = 24.04%) and highest R² (0.89) and Lin's concordance (0.94) values in the spatial estimation at a 0–10 cm soil layer. (4) Therefore, we applied MWRM to predict SOC content at various layers, and its SOC content prediction in the topsoil (0–20 cm) is better than that in the subsurface (20–30 cm) and subsoil (30–40 cm). The SOC content spatial distribution demonstrated a similar pattern for each soil layer and the SOC content gradually decreased with increasing soil depth.

25406. 题目: Assessment of spatial hybrid methods for predicting soil organic matter using DEM derivatives and soil parameters
文章编号: N18112413
期刊: CATENA
作者: Panagiotis Tziachris, Vassilis Aschonitis, Theocharis Chatzistathis, Maria Papadopoulou
更新时间: 2018-11-24
摘要: This paper assesses hybrid spatial models with the use of auxiliary variables based on machine learning algorithms for predicting soil Organic Matter (OM) content in Kastoria area (Greece). The machine learning methods that are used are random forests (RF) and gradient boosting (GB), also called ensemble methods, which combine multiple Classification and Regression Trees (CART). Overall, the different methods evaluated in the current study are Ordinary Kriging (OK), Regression Kriging (RK), Random Forest (RF), Random Forest Kriging (RFK), Gradient Boosting (GB) and Gradient Boosting Kriging (GBK). According to the findings of the study, machine learning methods (RF and GB) improve the prediction accuracy. The improvement ranged from 6% to 9% for RMSE, 47% to 250% for R² and 4% to 11% for MAE. Moreover, the introduction of residuals' kriging (hybrid methods), increases the accuracy of predictions furthermore (from 1% to 34%). It is also interesting that the measured collocated soil parameters that are used as auxiliary variables have consistently more influence (increased Pearson correlation coefficient for MLR and importance for RF and GB) than the environmental parameters. The main reason could be the flat terrain and the rather homogenous study area that minimizes the effect of topography on the soils. Therefore, topography and spatial characteristics of an area should be considered in design phase, in order to choose the appropriate secondary information in soil parameters' prediction.

25407. 题目: Spatiotemporal variations in the summer hypoxia in the Bohai Sea (China) and controlling mechanisms
文章编号: N18112412
期刊: Marine Pollution Bulletin
作者: Qinsheng Wei, Baodong Wang, Qingzhen Yao, Liang Xue, Junchuan Sun, Ming Xin, Zhigang Yu
更新时间: 2018-11-24
摘要: Based on field observations in the summer of 2006 and long-term series data, this paper investigates the spatiotemporal variations of hypoxia and associated physical-biogeochemical driving mechanisms in the Bohai Sea (BS), China. Results show that the benthic hypoxic zone is mainly distributed in the “V”-shaped trough region in the western BS, and it tends to form two hypoxic centers which generally correspond to the bottom cold-water core. The regional difference in the intensity of stratification has a significant impact on the spatial distribution of hypoxia. The relatively weak stratification and the mesoscale anticyclonic eddy in the central shoal of the BS weaken the connectivity between the southern and northern hypoxic zones. Organic matter decomposition contributes to hypoxia and results in corresponding nutrient pool with a “dual (southern and northern)-core” structure. Intensified eutrophication is the main drive for decreasing in bottom dissolved oxygen and expansion of hypoxic zone in the BS.
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25408. 题目: Mobility of Pb, Zn, Ba, As and Cd toward soil pore water and plants (willow and ryegrass) from a mine soil amended with biochar
文章编号: N18112411
期刊: Journal of Environmental Management
作者: Marie-Paule Norini, Hugues Thouin, Florie Miard, Fabienne Battaglia-Brunet, Pascale Gautret, Régis Guégan, Lydie Le Forestier, Domenico Morabito, Sylvain Bourgerie, Mikael Motelica-Heino
更新时间: 2018-11-24
摘要: Mine soils often contain metal(loid)s that may lead to serious environmental problems. Phytoremediation, consisting in covering the soil with specific plants with the possible addition of amendments, represents an interesting way of enhancing the quality of mine soils by retaining contaminants and reducing soil erosion.In order to study the effect of an assisted phytoremediation (with willow and ryegrass) on the properties of soil pore water (SPW), we investigated the impact of amendment with biochar (BC) combined with the planting of willow and ryegrass on the behavior of several metal(loid)s (Pb, Zn, Ba, As, and Cd) in a mine soil. Data on the physicochemical parameters and concentrations of the different metal(loid)s in both SPW and in plant tissues of willow and ryegrass highlight the importance of BC for SPW properties in terms of reductions in soluble concentrations of Pb and Zn, although there was no effect on the behavior of As and Cd. BC also increased soluble concentrations of Ba, probably related to ion release by the BC. By improving major ions available in mine soil, BC improved the lifetime of plants and enhanced their growth. Plant development did not appear to significantly affect the physicochemical parameters of SPW. Willow and ryegrass growing on soil with BC incorporated Cd and Ba into their tissues. The influence of plants on the behavior of metal(loid)s was noticeable only for ryegrass growing in soil with 2% BC, where it modified the behavior of Pb and Ba.

25409. 题目: Factors affecting the sorption of halogenated phenols onto polymer/biomass-derived biochar: Effects of pH, hydrophobicity, and deprotonation
文章编号: N18112410
期刊: Journal of Environmental Management
作者: Seok-Young Oh, Yong-Deuk Seo
更新时间: 2018-11-24
摘要: High-performance biochar synthesized via co-pyrolysis of a polymer and rice straw (RS) was evaluated as a sorbent for ionizable halogenated phenols. Compared with RS-derived biochar, the sorption of 2,4-dichlorophenol (DCP), 2,4-dibromophenol (DBP), and 2,4-difluorophenol (DFP) onto polymer/RS-derived biochar was significantly enhanced by the properties of biochar changing due to polymer residues. According to Langmuir sorption isotherm model maximum sorption capacities for DCP, DBP, and DFP were 25.5–27.8, 22.1–26.5, and 11.5–13.3 mg/g, respectively, 3–5 times higher than those of RS-derived biochar. The removal of the polymer residues and increasing aromaticity of polymer/RS-derived biochar at elevated pyrolysis temperatures affected the sorption capacity of halogenated phenols. The surface charge of biochar and deprotonation of the halogenated phenols according to the solution pH were other factors responsible for sorption onto polymer/RS-derived biochar. Competition with other halogenated phenols, Zn²⁺, and Cu²⁺ implied that similar sorption mechanisms existed and that surface complexation and electron donor-acceptor interactions were involved in sorption onto polymer/RS-derived biochar. Our results suggest that co-disposal of thermoplastic and biomass wastes through pyrolysis may be an effective option to produce high-performance upgraded biochar as a sorbent for various types of contaminants.
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25410. 题目: Effect of biochar on heavy metal accumulation in potatoes from wastewater irrigation
文章编号: N18112409
期刊: Journal of Environmental Management
作者: Christopher Nzediegwu, Shiv Prasher, Eman Elsayed, Jaskaran Dhiman, Ali Mawof, Ramanbhai Patel
更新时间: 2018-11-24
摘要: In many developing countries water scarcity has led to the use of wastewater, often untreated, to irrigate a range of crops, including tuber crops such as potatoes (Solanum tuberosum L.). Untreated wastewater contains a wide range of contaminants, including heavy metals, which can find their way into the edible part of the crop, thereby posing a risk to human health. An experiment was undertaken to elucidate the fate and transport of six water-borne heavy metals (Cd, Cr, Cu, Fe, Pb and Zn), applied through irrigation water to a potato (cv. Russet Burbank) crop grown on sandy soil, having either received no biochar amendment or having top 0.10 m of soil amended with 1% (w/w) plantain peel biochar. A non-amended control, irrigated with tap water, along with the two contaminated water treatments were replicated three times in a completely randomized design carried out on nine outdoor PVC lysimeters of 1.0 m height and 0.45 m diameter. The potatoes were planted, irrigated at 10-day intervals, and leachate then collected. Soil samples collected two days after each irrigation showed that all heavy metals accumulated in the surface soil; Fe, Pb and Zn were detected at 0.1 m depth, while only Fe was detected at 0.3 m depth. Heavy metals were not detected in the leachate. Tested individually, all portions of the potato plant (tuber flesh, peel, leaf, stem and root) bore heavy metals. Biochar-amended soil significantly reduced only Cd and Zn concentrations in tuber flesh (69% and 33%, respectively) and peel compared to the non-amended wastewater control (p < 0.05). Heavy metal concentrations were significantly lower in the tuber flesh than in the peel, suggesting that when consuming potatoes grown under wastewater irrigation, the peel poses a higher health risk than the flesh.
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25411. 题目: Sorption of uranyl ions on TiO₂: Effects of pH, contact time, ionic strength, temperature and HA
文章编号: N18112408
期刊: Journal of Environmental Sciences
作者: Jingjing Wang, Bihong He, Xiaoyan Wei, Ping Li, Jianjun Liang, Shirong Qiang, Qiaohui Fan, Wangsuo Wu
更新时间: 2018-11-24
摘要: Sorption of U(VI) onto TiO₂ as functions of pH, ionic strength, contact time, soil humic acid (SHA), solid-to-liquid ratio and temperature was studied under ambient conditions using batch and spectroscopic approaches. The sorption of U(VI) on TiO₂ was significantly dependent on pH and ionic strength. The presence of SHA slightly enhanced the sorption of U(VI) on TiO₂ below pH 4.0, while it inhibited U(VI) sorption in the higher pH range. U(VI) sorption on TiO₂ was favored at high temperatures, and the sorption process was estimated to be endothermic and spontaneous. Reduction of U(VI) to lower valent species was confirmed by X-ray photo-electron spectroscopy analysis. It is very interesting to find that U(VI) sorption on TiO₂ was promoted in solutions with higher back-ground electrolyte concentrations. In the presence of U(VI), higher back-ground electrolyte made more TiO₂ particles aggregate through (001) facets, leading more (101) facets to be exposed. Therefore, the reduction of U(VI) was enhanced by the exposed (101) facets and more U(VI) removal was observed.
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25412. 题目: Use of polymeric sub-micron ion-exchange resins for removal of lead, copper, zinc, and nickel from natural waters
文章编号: N18112407
期刊: Journal of Environmental Sciences
作者: Audrey Murray, Banu Örmeci
更新时间: 2018-11-24
摘要: This research investigated the removal capacity of polymeric sub-micron ion-exchange resins (SMR) for removal of lead, copper, zinc, and nickel from natural waters in competition with natural organic matter (NOM). Polymeric SMR particles were created and tested to ensure that they were adequately dispersed in the solution. They removed little NOM (10% or less) from river water and wastewater, indicating that competition from NOM was not a major concern. SMR were able to remove 82% ± 0.2% of lead, 46% ± 0.6% of copper, 55% ± 20% of zinc, and 17% ± 2% of nickel from river water spiked with 500 μg/L of each. Similarly, in wastewater, they were able to remove 86% ± 0.1% of lead, 38% ± 0.8% of copper, 28% ± 1% of zinc, and 11% ± 1% of nickel.
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25413. 题目: Relationship between heavy metals and dissolved organic matter released from sediment by bioturbation/bioirrigation
文章编号: N18112406
期刊: Journal of Environmental Sciences
作者: Yi He, Bin Men, Xiaofang Yang, Yaxuan Li, Hui Xu, Dongsheng Wang
更新时间: 2018-11-24
摘要: Organic matter (OM) is an important component of sediment. Bioturbation/bioirrigation can remobilize OM and heavy metals that were previously buried in the sediment. The remobilization of buried organic matter, thallium (Tl), cadmium (Cd), copper (Cu) and zinc (Zn) from sediment was studied in a laboratory experiment with three organisms: tubificid, chironomid larvae and loach. Results showed that bioturbation/bioirrigation promoted the release of dissolved organic matter (DOM) and dissolved Tl, Cd, Cu and Zn, but only dissolved Zn concentrations decreased with exposure time in overlying water. The presence of organisms altered the compositions of DOM released from sediment, considerably increasing the percentage of fulvic acid-like materials (FA) and humic acid-like materials (HA). In addition, bioturbation/bioirrigation accelerated the growth and reproduction of bacteria to enhance the proportion of soluble microbial byproduct-like materials (SMP). The DOM was divided into five regions in the three-dimensional excitation emission matrix (3D-EEM), and each part had different correlation with the dissolved heavy metal concentrations. Dissolved Cu had the best correlation with each of the DOM compositions, indicating that Cu in the sediment was in the organic-bound form. Furthermore, the organism type and heavy metal characteristics both played a role in influencing the remobilization of heavy metal.
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25414. 题目: Effects of redox potential on soil cadmium solubility: Insight into microbial community
文章编号: N18112405
期刊: Journal of Environmental Sciences
作者: Delong Meng, Juan Li, Tianbo Liu, Yongjun Liu, Mingli Yan, Jin Hu, Xiaoqi Li, Xueduan Liu, Yili Liang, Hongwei Liu, Huaqun Yin
更新时间: 2018-11-24
摘要: Understanding the role of microbes in the solubility of cadmium (Cd) is of fundamental importance for remediation of Cd toxicity. The present study aimed to identify the microbes that involved in regulating Cd solubility and to reveal possible mechanisms. Therefore, microbial communities were investigated through high-throughput sequencing approach, the molecular ecological network was constructed and metagenomes were predicted. Our results indicated that redox conditions affected both the solubility of soil Cd and the microbial communities. Anaerobic microbes, such as Anaerolineaceae, did not only play important roles in shaping the microbial community in soils, but might also be involved in regulating the Cd solubility. Two possible mechanisms that how Anaerolineaceae involved in Cd solubility are (1) Anaerolineaceae are important organic matter degraders under anoxic conditions and (2) Anaerolineaceae can co-exist with methane metabolism microbes, while methane metabolism promotes the precipitation of soluble Cd. Thus, application of Anaerolineaceae in bioremediation of soil Cadmium contamination is a potential approach. The study provided a novel insight into the role of microbial community in the regulation of Cd solubility under different redox conditions, and suggested a potential approach for the remediation of soil Cd contamination.
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25415. 题目: Characterization of dissolved organic matter and membrane fouling in coagulation-ultrafiltration process treating micro-polluted surface water
文章编号: N18112404
期刊: Journal of Environmental Sciences
作者: Fan Bu, Baoyu Gao, Qinyan Yue, Xue Shen, Wenyu Wang
更新时间: 2018-11-24
摘要: Coagulation–ultrafiltration (C–UF) is widely used for surface water treatment. With the removal of pollutants, the characteristics of organic matter change and affect the final treatment efficiency and the development of membrane fouling. In this study, we built a dynamic C–UF set-up to carry out the treatment of micro-polluted surface water, to investigate the characteristics of dissolved organic matter from different units. The influences of poly aluminum chloride and poly dimethyldiallylammonium chloride (PDMDAAC) on removal efficiency and membrane fouling were also investigated. Results showed that the dosage of PDMDAAC evidently increased the UV₂₅₄ and dissolved organic carbon removal efficiencies, and thereby alleviated membrane fouling in the C–UF process. Most hydrophobic bases (HoB) and hydrophobic neutral fractions could be removed by coagulation. Similarly, UF was good at removing HoB compared to hydrophilic substances (HiS) and hydrophobic acid (HoA) fractions. HiS and HoA fractions with low molecule weight accumulated on the surface of the membrane, causing the increase of transmembrane pressure (TMP). Membrane fouling was mainly caused by a removable cake layer, and mechanical cleaning was an efficient way to decrease the TMP.
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25416. 题目: Profile stock of soil organic carbon and distribution in croplands of Northeast China
文章编号: N18112403
期刊: CATENA
作者: Meng Li, Xiaozeng Han, Shuli Du, Lu-Jun Li
更新时间: 2018-11-24
摘要: Soil organic carbon (SOC) stock is one of the most important carbon (C) reservoirs on the Earth and plays a vital role in the global climate change. However, SOC stock at a regional scale is still uncertain due to the lack of soil bulk density data, differences in sample depth, geography, and soil properties. Based on data from 78 soil profiles, we estimated SOC density (SOCD) and its distribution at 0–100 cm depth of croplands in three typical Counties (Lindian, Hailun and Baoqing Counties) in Northeast China. Soil organic carbon content and variations significantly decreased with increased soil depth. The SOCD in 100-cm depth ranged from 52.3 to 323.1 Mg ha⁻¹, with an average of 163.6 Mg ha⁻¹. The SOCD in the top 20 cm accounted for 32.8% of that in 100 cm soil profile. A good mathematical equation between SOCD of 0–20 cm and 0–100 cm would be a useful tool to estimate SOCD in soil profiles. In addition, soil depth, bulk density, soil pH, and elevation were significantly correlated with SOC content. Regression of SOC in the data set to individual factors (soil depth, BD, soil pH, clay content, and elevation) is relevant to understand how C changes over time and depth.

25417. 题目: Spatial heterogeneity and affecting factors of litter organic carbon and total nitrogen over natural spruce-fir mixed forests in northeastern China
文章编号: N18112402
期刊: CATENA
作者: Qianqian Qin, Haiyan Wang, Xiang Li, Yalin Xie, Xiangdong Lei, Yonglin Zheng, Dandan Yang, Fuzeng Wang
更新时间: 2018-11-24
摘要: Litter, as the basic carrier of nutrients, is a link between plants and soil in nutrient cycling and plays a major role in maintaining soil fertility and promoting material cycling and nutrient balance in forest ecosystems. The present study used geostatistics to investigate the spatial heterogeneity of organic carbon (OC) and total nitrogen (TN) in litter and their influencing factors, over four representative 1-ha natural spruce-fir mixed stands in Jilin Province, China. Our results showed that forest litter OC and TN varied in the four stands with an average OC concentration ranging from 378 to 453 g·kg⁻¹ and average TN concentration ranging from 16.4 to 21.8 g·kg⁻¹. The nugget-to-sill values were <25%, revealing that litter OC and TN had a strong spatial autocorrelation. Spatial distributions were estimated using ordinary kriging and showed a distinct strip and patch as the gradient changed. The fractal dimension of litter OC concentration was higher than that of litter TN. This indicated that litter OC had a more complex spatial pattern, whereas litter TN exhibited a better structure and stronger spatial dependence. Stand characteristics (i.e., species number, stem number, biodiversity indices, proportion of conifer species and stems), together with litter properties (i.e., litterfall, litter moisture content and total phosphorous concentration), affected the spatial variation in litter TN concentration, but they had no significant effects on litter OC. Therefore, this study demonstrated the feasibility of using geostatistics to predict litter nutrient concentrations at small scales and provided a theoretical basis for large-scale monitoring of biogeochemical cycles and disturbances in forest ecosystems.

25418. 题目: Pleistocene periglacial imprinting on polygenetic soils and paleosols in the SW Italian Alps
文章编号: N18112401
期刊: CATENA
作者: Michele E. D'Amico, E. Pintaldi, M. Catoni, M. Freppaz, E. Bonifacio
更新时间: 2018-11-24
摘要: Because of extensive Pleistocenic glaciations, which erased most of the previously existing soils, slope steepness and climatic conditions favoring soil erosion, most soils observed in the Alps (and in other mid-latitude mountain ranges) have developed during the Holocene or Late Glacial period. However, in few sites, particularly in the outermost sections of the Alpine range, Pleistocene glaciers covered only small and scattered surfaces, and ancient soils could be preserved for long periods on stable surfaces. In many cases, these soils retain good memories of Quaternary periglacial activity, which have never been characterized on the Alpine range. Based on both geomorphological and pedological interpretations, this work aims to investigate these environments, providing, therefore, new evidences to support paleoclimate reconstructions on the Alps.We described and sampled soils on stable surfaces in the Upper Tanaro valley, Ligurian Alps (Southwestern Piemonte, Italy). The sampling sites were between 600 and 1600 m a.s.l., under present day lower montane Ostrya carpinifolia, montane Fagus sylvatica forests or montane heath/grazed grassland, on quartz-rich substrata.The surface morphology often showed strongly developed fossil periglacial morphologies such as large-scale patterned ground, blockfields/blockstreams or solifluction sheets.The soils preserved in such Quaternary periglacial landforms normally showed stratification of different layers (units), separated by structural discontinuities, evidencing different depositional settings and different pedogenic development degree. A strong cryogenic granulometric sorting characterized all the observed soils/paleosols, with silt-enriched horizons and lateral differentiation of sand- and stone-rich parts and fine enriched ones; organic matter was irregularly distributed at depth as a result of past cryoturbation. Compact and dense layers with strong platy/lenticular structural aggregation, wedge casts and large-scale cryoturbations were described below fixed depths in all soil profiles.Thus, surface morphology and soil properties suggest the presence of permafrost during cold Pleistocene phases, with two main active layer thicknesses at 60–120 and 100–160 cm depths respectively.

25419. 题目: Punching above their weight: Large release of greenhouse gases from small agricultural dams
文章编号: N18112309
期刊: Global Change Biology
作者: Quinn R. Ollivier, Damien T. Maher, Chris Pitfield, Peter I. Macreadie
更新时间: 2018-11-23
摘要: Freshwater ecosystems play a major role in global carbon cycling through the breakdown of organic material and release of greenhouse gases (GHGs). Carbon dioxide (CO2) and methane (CH4) emissions from lakes, wetlands, reservoirs and small natural ponds have been well studied, however, the GHG emissions of highly abundant, small‐scale (<0.01 km2) agricultural dams (small stream and run‐off impoundments) are still unknown. Here, we measured the diffusive CO2 and CH4 flux of 77 small agricultural dams within south‐east Australia. The GHG emissions from these waterbodies, which are currently unaccounted for in GHG inventories, amounted to 11.12 ± 2.59 g CO2‐equivalent m2/day, a value 3.43 times higher than temperate reservoir emissions. Upscaling these results to the entire state of Victoria, Australia, resulted in a farm dam CO2‐equivalent/day emission rate of 4,853 tons, 3.1 times higher than state‐wide reservoir emissions in spite of farm dams covering only 0.94 times the comparative area. We also show that CO2 and CH4 emission rates were both significantly positively correlated with dissolved nitrate concentrations, and significantly higher in livestock rearing farm dams when compared to cropping farm dams. The results from this study demonstrate that small agricultural farm dams can be a major source of greenhouse gas emissions, thereby justifying their inclusion in global carbon budgets.

25420. 题目: LONG-TERM FERTILIZATION EFFECTS ON 13 C NATURAL ABUNDANCES, SOIL AGGREGATION AND DEEP SOIL ORGANIC CARBON SEQUESTRATION IN AN ALFISOL
文章编号: N18112308
期刊: Land Degradation & Development
作者: Avijit Ghosh, Ranjan Bhattacharyya, B.K. Aggarwal, P. Mahapatra, D.K. Shahi, Geeta Singh, R. Agnihorti, Ravi Sawlani, C. Sharma
更新时间: 2018-11-23
摘要: While the ¹³C (¹³Carbon) natural abundance method is used to study soil C dynamics, scanty information is available on long‐term fertilization effects on soil C sequestration rates along with δ¹³C in surface (0‐30 cm) and deep (30‐90 cm) soil layers and their relationships with crop productivities in sub‐tropics. Hence, soil aggregation, δ¹³C in bulk soils and aggregates, C pools and sequestration rates were studied in an Indian Alfisol under a 43‐year old wheat (Triticum aestivum L.)‐based cropping system. Treatments were: no mineral fertilizer and no manure (unfertilized control; UC), 100% recommended dose of nitrogen (N), 100% N and 100% recommended phosphorus (NP), 100% N, 100% P and 100% recommended potassium (NPK), NPK + lime (NPKL), 150% recommended NPK (1.5NPK), and NPK + farmyard manure (FYM) at 10 Mg ha^‐1 (NPKF). Plots with NPKF contained 50% higher soil organic C (SOC) than NPKL in surface soil (0‐15 cm layer). In the 0‐90 cm profile, SOC accumulation and sequestration rates in NPKF were ~0.15 and 0.11 Mg ha^‐1 year^‐1 higher than NPKL plots, respectively. The NPKF plots had higher glomalin‐related soil protein and greater recalcitrant C than NPKL, 1.5NPK and NPK in surface soil. The NPKF plots had higher δ¹³C values within bulk soils and their aggregates than NPKL and NPK. There were significant correlations between deep soil C sequestration rates with mean crop productivities and δ¹³C with deep soil C sequestration rates. Overall, NPKF application had largest surface and deep soil C sequestration with highest crop productivity and hence is recommended.