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7601. 题目: Effects of tea plantation age on soil aggregate-associated C- and N-cycling enzyme activities in the hilly areas of Western Sichuan, China
文章编号: N18072108
期刊: CATENA
作者: Shengqiang Wang, Tingxuan Li, Zicheng Zheng
更新时间: 2018-07-21
摘要: Research on the changes of soil carbon (C)- and nitrogen (N)-cycling enzyme activities within aggregate fractions is essential for improving our understanding of soil organic matter (SOM) dynamics in agricultural ecosystems. However, the short- and long-term implications of the conversion of abandoned croplands to tea (Camellia sinensis L.) plantations on enzyme activities associated with aggregate fractions remains poorly understood. In the present study, we hypothesized that (i) the concentrations of soil organic C and total N would increase as the tea plantations continued to age, and (ii) the potential of SOM decomposition would differ with the stage of tea cultivation, as there would be significant changes in the activities of soil C- and N-cycling enzymes over time. The activities of β-glucosidase, invertase, urease, and protease were analyzed in different size fractions of soil aggregates that were collected from 0 to 20 cm depth in four tea plantations with the same cultivar (Sichuan tea) of various ages (16-, 23-, 31-, and 53-years) in the hilly areas of Western Sichuan, China. The aggregates were separated using a dry-sieving procedure into four fractions, namely, large (>2 mm), medium (2–1 mm), small (1–0.25 mm) macro-aggregates, and micro-aggregates (<0.25 mm). In the early stage (in the first 23-years), tea cultivation contributed to a significant increase in organic C and total N stocks in the whole-soil, and these changes were primarily reflected in the increases of such elements stocks in the large macro-aggregates. For example, the increase in organic C stock associated with large macro-aggregates in the early stage accounted for 99.64% of the increase in organic C stock in the whole-soil. In the later stage (after 23-years), however, the increases in organic C and total N stocks in the whole-soil were primarily reflected in the increases of such elements stocks in the small macro-aggregates. Meanwhile, soil C- and N-cycling enzyme activities associated with the large macro-aggregates were significantly increased in the first 23-years of tea cultivation. These results indicated that young tea plantations in the early stage had limitations with respect to the potential for SOM sequestration; however, as the tea plantations matured under the present system of management, the SOM sequestration has improved.

7602. 题目: Ameliorating some quality properties of an erosion-prone soil using biochar produced from dairy wastewater sludge
文章编号: N18072107
期刊: CATENA
作者: Seyed Hamidreza Sadeghi, Mohammad Hossein Ghavimi Panah, Habibollah Younesi, Hossein Kheirfam
更新时间: 2018-07-21
摘要: Land degradation due to decline in soil quality and wastewater pollution is a major challenge for ecosystems sustainability, worldwide. Hence, utilizing adaptable and multi-objective strategies is essential to address environmental challenges. To this end, we produced a biochar from air-dried dairy wastewater sludge (i.e., Kalleh Dairy Company, Iran) through pyrolysis process at 300–350 °C which led to reduction in initial heavy metals contents. The produced biochar was then used to improve the soil quality of a highly degradable soil. Some important nutrients and heavy metals of dairy wastewater and produced biochar were measured by acid digestion/ICP-MS. We then spread two rates of the biochar (400 and 800 g m-2) over the surface of the small-scale boxes (0.5 × 0.5 × 0.5-m) filled by an erosion-prone soil collected from the Chalus Watershed, Northern Iran, and left for 30 days. The carbon (C), nitrogen (N) and organic matter (OM) content, and also carbon/nitrogen (C/N) ratio of treated soil were measured to assess effect of the produced biochar on soil quality improvement. The results showed that some contents of the measured heavy metals (i.e., Pb, Ni, Al, Cr, Mn, Fe and Zn) in the produced biochar significantly (p < 0.01) reduced compared to those of the raw dairy wastewater. Additionally, application of two dosages of 400 and 800 g m-2 of biochar to the study soil increased C, N, OM and C/N of the soil at tunes of 2.67–5.5; 2–3 and 2.67–5.5 times, and 22–61%, respectively, in comparison with untreated soils (control). By and large, converting the wastewater as an environmental pollution source to biochar and using it as an eco-friendly soil amendment is a multi-objective and adaptive approach for the ecosystem management.
图文摘要:

7603. 题目: Effect of vegetation type and season on microbial biomass carbon in Central Himalayan forest soils, India
文章编号: N18072106
期刊: CATENA
作者: Kiran Bargali, Vijyeta Manral, Kirtika Padalia, S.S. Bargali, V.P. Upadhyay
更新时间: 2018-07-21
摘要: Soil microbial biomass is an important component of soil organic matter constituting from 2 to 5% of the soil organic carbon and play a significant role in the cycling of nutrients and overall organic matter dynamics. The present study assessed the effects of three forest types (Banj-oak forest, Chir-pine forest and Mixed oak-pine forest) on the soil physico-chemical properties and microbial biomass Carbon in Central Himalaya, India. The soil microbial biomass carbon was determined by chloroform fumigation extraction method. In the 2 year of study period, the soil microbial biomass carbon (Cmic) was significantly higher in Mixed oak-pine forest (681 ± 1.81–763 ± 1.82 μg g-1) than in the Banj-oak (518 ± 1.50–576 ± 1.73 μg g-1) and Chir-pine forest (418 ± 1.42–507 ± 2.05 μg g-1). Though insignificant, all the forest types showed distinct seasonal variations in microbial biomass carbon with a minimum value in winter season and maximum value in rainy season. The soil microbial quotients (Cmic to Corg) were higher in Chir-pine (2.52–4.18) and Banj-oak forest (2.26–4.02) than those reported in Mixed oak-pine forest (1.44–2.24). These results indicate that Mixed oak-pine forest is better in sustaining the soil microbial biomass and soil nutrients than Banj-oak and Chir-pine forest. It recommends that nutrients rich Mixed oak-pine forest should be preferred as a forest management practice to promote microbial diversity, their activities and soil quality enhancement in Central Himalayan forests.

7604. 题目: Factors that influence soil total phosphorus sources on dam fields that are part of ecological construction programs on the Loess Plateau, China
文章编号: N18072105
期刊: CATENA
作者: Yuting Cheng, Peng Li, Guoce Xu, Zhanbin Li, Kunxia Yu, Shengdong Cheng, Binhua Zhao, Feichao Wang
更新时间: 2018-07-21
摘要: Terraces and check-dam construction are widely used to control soil and water on the Loess Plateau, China. However, it is not known whether dam fields behave as soil phosphorus sources or sinks. This study quantitatively assessed the effects of check-dam and terrace construction on soil total phosphorus (STP). It also investigated the factors that influenced STP. A total of 1010 soil samples (five land uses and five soil depths) were collected in a small watershed on the Loess Plateau. The probability density function of the Weibull distribution was used to analyze the STP sources on the dam field land. The results showed that the highest STP concentration was recorded in the dam field land. Furthermore, the STP concentration mean values for the five land-use types decreased in the following order: dam field > terraced land > grassland > forestland > sloping cropland. The highest clay content value was also recorded in the dam field land. Soil total phosphorus was significantly and positively correlated to soil organic carbon (SOC), but negatively correlated to sand content (P < 0.01) in all areas. Across the entire soil profile down to 60 cm depth, the STP levels for the five land-uses were dam field, 2.78 kg/m2; terrace, 2.86 kg/m2; grassland, 2.98 kg/m2; forestland, 2.84 kg/m2; and sloping cropland, 2.83 kg/m2. The percentage contributions made by the four land use types to the soil total phosphorus deposited in the dam field were 50% (sloping cropland), 33% (grassland) and 17% (forestland). Therefore, check dam constructions behave as a sink for soil phosphorus on the Loess Plateau, China.

7605. 题目: Soil carbon sequestration potential as affected by soil physical and climatic factors under different land uses in a semiarid region
文章编号: N18072104
期刊: CATENA
作者: Elham Alidoust, Majid Afyuni, Mohammad Ali Hajabbasi, Mohammad Reza Mosaddeghi
更新时间: 2018-07-21
摘要: Carbon (C) sequestration in soil is recognized as a possible solution for climate change mitigation. Different land uses may alter carbon sequestration in soil. In the semiarid regions of central Iran, during the last decades, land use changes from native cover to farmlands have altered the C sink role of soil to a source of CO2 emission to the atmosphere. This study was conducted to evaluate and compare changes and the potential of soil organic carbon (SOC) sequestration from 1988 to 2014, under different land uses, in western central Iran (Lordegan). The land uses included pasture, forest, rain-fed, and irrigated farmlands. Soil (450 samples) from 50 points across the study basin (390 km2) was collected in three depth increments (0–5, 5–15 and 15–30 cm) during three sampling times (June and November 2014, and June 2015). Mean SOC concentrations in the pasture, forest, rain-fed and irrigated farmlands were 10.3, 20.2, 9.2 and 10.1 g kg-1, respectively. The SOC concentration in the forest soil was significantly greater than the other land uses, and any reduction in forestland area would lead to the SOC stock decline. About 1390 Gg organic carbon was found to be stored in the top 0–30 cm depth of the study area. Comparing land use maps between 1988 and 2014 indicated an alteration in the relative contribution of each land use across the study area leading to SOC stock reduction by 100 Gg carbon during this period. The results showed that all studied soils comprised non-complexed clay, suggesting a considerable potential capacity for sequestering carbon. The results also indicated that the SOC controlling factors varied considerably among different land uses and soil depths. Mean weight diameter of aggregates (MWD), bulk density, clay and sand content, and altitude were identified as the important controlling variables by the stepwise multiple linear regression analysis.

7606. 题目: Soil surface quality assessment in rangeland ecosystems with different protection levels, central Iran
文章编号: N18072103
期刊: CATENA
作者: Azita Molaeinasab, Hossein Bashari, Mostafa Tarkesh Esfahani, Mohammad Reza Mosaddeghi
更新时间: 2018-07-21
摘要: This study aimed to evaluate the application of landscape function analysis (LFA) and some soil quality indicators for the assessment of the structure and function of Steppe rangelands in arid regions of Ghamishloo National Park, Isfahan, central Iran. Three zones with different protection levels/grazing intensities, including a national park with wild herbivores, a peripheral protected area where both livestock and wild herbivores were present, and an adjacent grazing-free area where wild herbivores were absent, were selected. Eleven soil surface indicators were assessed to measure soil stability, infiltration, and nutrient cycling indices in various zones. Eighty-seven soil samples were collected in the study area and their characteristics, including pH, electrical conductivity (EC), total nitrogen, phosphate, soil organic carbon (SOC), particulate organic matter (POM), microbial respiration, and mean weight diameter (MWD), were measured. The results showed that although structural attributes (patch area index and landscape organization index) and LFA functional attributes varied significantly between the sites with various management histories (P < 0.05), these attributes along with total patch area and number of patches per 10 m did not have significant differences between the protected and grazing-free area. Most soil quality indicators were also significantly different between the national park and grazing-free area, but MWD, SOC, and POM were not significantly different between the protected and grazing-free areas (P < 0.05). High protection level (i.e. lower grazing impact) led to more soil stability and higher proportion of macro-aggregates in the national park area compared to other areas. The methods used in this study are applicable for exploring the role of national parks in maintaining the structure and function of ecosystems in similar ecoregions.

7607. 题目: Three years of management with cover crops protecting sloping olive groves soils, carbon and water effects on gypsiferous soil
文章编号: N18072102
期刊: CATENA
作者: Blanca Sastre, Maria Jose Marques, Andrés García-Díaz, Ramón Bienes
更新时间: 2018-07-21
摘要: Soils of olive grove are usually managed by tillage, leading to organic matter depletion and soil structure degradation. Cover crops to protect soils have been revealed as a sustainable land management practice for erosion control and remediation of degraded soils, but in some cases, water competition can be a problem, all these effects (particularly soil water) are site and climate specific. A trial in a rainfed olive grove in gypsiferous soils under semiarid Mediterranean climatic conditions has been set up in Central Spain. Several parameters (plant cover, root density, organic carbon, organic nitrogen, aggregate stability, porosity, infiltration, water storage and soil penetration resistance) have been studied under different management practices: three types of cover crops, two annuals (legume and barley) and one permanent (Brachypodium distachyon); and minimum tillage. After three years of treatments, slight improvements in particulate organic carbon, aggregate stability, microporosity at 0–5 cm depth and soil water storage at 30 cm were found in cover crops; B. distachyon also increased organic carbon, and improved C/N ratio and available water. >3 years of a sustainable land management are needed to recover olive groves soil quality in gypsiferous soils under semiarid climate. In this study, cover crops facilitated carbon stratification, higher SOC content in deeper layers are important in the context of carbon sequestration.
图文摘要:

7608. 题目: Sorption of tetracycline on H3PO4 modified biochar derived from rice straw and swine manure
文章编号: N18072101
期刊: Bioresource Technology
作者: Tingwei Chen, Ling Luo, Shihuai Deng, Guozhong Shi, Shirong Zhang, Yanzong Zhang, Ouping Deng, Lilin Wang, Jing Zhang, Luoyu Wei
更新时间: 2018-07-21
摘要: Currently, the information about the sorption of tetracycline (TC) on animal manure derived biochar was rare although plant residue derived biochar showed high sorption of TC). Therefore, this study explored the sorption of TC on swine manure derived biochar, and compared with rice straw derived biochar simultaneously. Also, H3PO4 was adopted to modify both types of biochar. The sorption kinetic and isotherm data showed H3PO4 modification enhanced the sorption of TC on both types of biochar (especially swine-manure-biochar), and indicated the chemisorptions including H-bonding and π-π electron donor acceptor interaction might be the primary mechanism. Moreover, the strengthened electrostatic attraction between TC and biochars might largely explain the enhanced sorption capacity of TC along with pH increasing from 5.0 to 9.0. At the same conditions, swine manure derived biochar demonstrated lower sorption capacity of TC than rice straw biochar, but still could be good material for the sorption of TC.

7609. 题目: Assessing the metabolism of sedimentary microbial communities using the hydrogen isotopic composition of fatty acids
文章编号: N18072008
期刊: Organic Geochemistry
作者: Sandra M. Heinzelmann, Laura Villanueva, Yvonne A. Lipsewers, Danielle Sinke-Schoen, Jaap S. Sinninghe Damsté, Stefan Schouten, Marcel T.J. van der Meer
更新时间: 2018-07-20
摘要: The hydrogen isotopic composition of fatty acids (FAs) has previously been shown to reflect the metabolism of microorganisms in pure culture, but has rarely been tested in the environment. Here, we report the abundance and hydrogen isotopic composition of polar lipid derived FAs extracted from surface sediments of the saline Lake Grevelingen (The Netherlands), at two different stations and during two seasons with oxic bottom water conditions during spring and hypoxic to anoxic conditions during late summer. These data are compared with the bacterial diversity revealed by 16S rRNA gene amplicon sequencing. All measured FAs were depleted in deuterium relative to the bottom water by 103‰ to 267‰. FAs associated with heterotrophic bacteria (i-15:0 and ai-15:0) showed the smallest fractionation (–103‰ to –185‰) while those derived from pelagic photoautotrophic phytoplankton (20:5) showed the largest fractionation (–230‰ to –267‰). Overall, the hydrogen isotope fractionation reflected in the majority of the more commonly occurring FAs (14:0, 16:0, 16:1ω7) is relatively large (–172‰ to –217‰). Together with the high relative abundance of the 20:5 FA, this suggests a substantial contribution from dead pelagic biomass settling from the water column to the sedimentary polar lipid derived FA pool and not from the in situ microbial communities. Therefore, the majority of the isotope signal in the fatty acids from surface sediments might not represent the general metabolism of the active sedimentary communities. Therefore, the input of pelagic biomass into sedimentary environments may bias the information contained in the hydrogen isotopic composition of FAs.

7610. 题目: Thermodynamics of Hg(II) Bonding to Thiol Groups in Suwannee River Natural Organic Matter Resolved by Competitive Ligand Exchange, Hg LIII-Edge EXAFS and 1H NMR Spectroscopy
文章编号: N18072007
期刊: Environmental Science & Technology
作者: Yu Song, Tao Jiang, Van Liem-Nguyen, Tobias Sparrman, Erik Bj?rn, Ulf Skyllberg
更新时间: 2018-07-20
摘要: A molecular level understanding of the thermodynamics and kinetics of the chemical bonding between mercury, Hg(II), and natural organic matter (NOM) associated thiol functional groups (NOM-RSH) is required if bioavailability and transformation processes of Hg in the environment are to be fully understood. This study provides the thermodynamic stability of the Hg(NOM-RS)2 structure using a robust method in which cysteine (Cys) served as a competing ligand to NOM (Suwannee River 2R101N sample) associated RSH groups. The concentration of the latter was quantified to be 7.5 ± 0.4 μmol g–1 NOM by Hg LIII-edge EXAFS spectroscopy. The Hg(Cys)2 molecule concentration in chemical equilibrium with the Hg(II)-NOM complexes was directly determined by HPLC-ICPMS and losses of free Cys due to secondary reactions with NOM was accounted for in experiments using 1H NMR spectroscopy and 13C isotope labeled Cys. The log K ± SD for the formation of the Hg(NOM-RS)2 molecular structure, Hg2+ + 2NOM-RS– = Hg(NOM-RS)2, and for the Hg(Cys)(NOM-RS) mixed complex, Hg2+ + Cys– + NOM-RS– = Hg(Cys)(NOM-RS), were determined to be 40.0 ± 0.2 and 38.5 ± 0.2, respectively, at pH 3.0. The magnitude of these constants was further confirmed by 1H NMR spectroscopy and the Hg(NOM-RS)2 structure was verified by Hg LIII-edge EXAFS spectroscopy. An important finding is that the thermodynamic stabilities of the complexes Hg(NOM-RS)2, Hg(Cys)(NOM-RS) and Hg(Cys)2 are very similar in magnitude at pH values <7, when all thiol groups are protonated. Together with data on 15 low molecular mass (LMM) thiols, as determined by the same method (Liem-Ngyuen et al. Thermodynamic stability of mercury(II) complexes formed with environmentally relevant low-molecular-mass thiols studied by competing ligand exchange and density functional theory. Environ. Chem. 2017, 14, (4), 243 253.), the constants for Hg(NOM-RS)2 and Hg(Cys)(NOM-RS) represent an internally consistent thermodynamic data set that we recommend is used in studies where the chemical speciation of Hg(II) is determined in the presence of NOM and LMM thiols.
图文摘要:

7611. 题目: Optimization of integrated ultrasonic-Fenton system for metal removal and dewatering of anaerobically digested sludge by Box-Behnken design
文章编号: N18072006
期刊: Science of The Total Environment
作者: Jannatul Rumky, Mohamed Chaker Ncibi, Rutely C. Burgos-Castillo, Anjan Deb, Mika Sillanp??
更新时间: 2018-07-20
摘要: This study reveals the optimization of ultrasonic-Fenton process for the treatment of sludge taken from a local municipal wastewater treatment plant after anaerobic digestion. Box-Behnken design (BBD), a common approach of response surface methodology (RSM), was applied to evaluate and optimize the individual and interactive effects of three process variables, namely Fe2+ dose, H2O2 amount and sonication time for Fenton-ultrasonication method. Five dependent parameters including total organic carbon (TOC), extracellular polymeric substances (EPS), as LB-EPS and TB-EPS, and metals such as Zn and Cu were considered as the responses to investigate. According to the results of analysis of variances (ANOVA), five modelling equations are proposed that can be used to operate the design space with high regression coefficient R2. Modelling results suggest that Fenton parameters, such as: H2O2 and Fe2+ dosage had the significant effects on the overall removal of TOC; whereas, sonication improved the metal removal from the sludge sample. Based on response surface methodology, best performance is achievable under the following conditions: 36 mM of Fe2+, 320 mM H2O2 with 30 min of sonication respectively for all of the responses.
图文摘要:

7612. 题目: 20th century increase in body size of a hypoxia-tolerant bivalve documented by sediment cores from the northern Adriatic Sea (Gulf of Trieste)
文章编号: N18072005
期刊: Marine Pollution Bulletin
作者: Tomá? Fuksi, Adam Toma?ov?ch, Ivo Gallmetzer, Alexandra Haselmair, Martin Zuschin
更新时间: 2018-07-20
摘要: An increase in the frequency of hypoxia, mucilages, and sediment pollution occurred in the 20th century in the Adriatic Sea. To assess the effects of these impacts on bivalves, we evaluate temporal changes in size structure of the opportunistic bivalve Corbula gibba in four sediment cores that cover the past ~500 years in the northern, eutrophic part and ~10,000 years in the southern, mesotrophic part of the Gulf of Trieste. Assemblages exhibit a stable size structure during the highstand phase but shift to bimodal distributions and show a significant increase in the 95th percentile size during the 20th century. This increase in size by 2–3 mm is larger than the northward size increase associated with the transition from mesotrophic to eutrophic habitats. It coincides with increasing concentrations of total organic carbon and nitrogen, and can be related to enhanced food supply and by the tolerance of C. gibba to hypoxia.

7613. 题目: Interactions between aged biochar, fresh low molecular weight carbon and soil organic carbon after 3.5-years soil-biochar incubations
文章编号: N18072004
期刊: Geoderma
作者: Xinyu Jiang, Xiangping Tan, Jiong Cheng, Michelle L. Haddix, M. Francesca Cotrufo
更新时间: 2018-07-20
摘要: Biochar has been considered a stable additive for long-term soil carbon (C) storage and climate change mitigation. However, our understanding of the long-term interactions between aged biochar, soil organic C (SOC), and fresh low molecular weight C compounds (LMW-C) is still limited. In addition to the changes in the chemical properties of biochar and the SOC after aging, biochar stability and C sequestration potentials might be affected by the LMW-C availability. After 3.5 years of incubation, aged soils and aged soil-biochar mixtures (4 atom‰ 13C enriched grass-derived biochar, 10% addition rate) of two different soil types were used in this study, with or without the addition of LMW-C. The 13C natural abundance of the LMW-C was manipulated by mixing cane sucrose (C4) and beet sugar (C3) to make it different from or equal to the native SOC isotopic signature of the two soil types, which allowed the partitioning of the LMW-C and biochar C from the SOC in non-biochar and biochar addition treatments, respectively. We traced the 13C in the cumulative CO2, microbial biomass C (MBC), and dissolved organic C (DOC) at the beginning and the end of the 28 days of incubation. Results indicated that this aged biochar was not as effective for SOC protection as it was when fresh. Aged biochar caused significant increases in the native SOC-derived CO2 compared to non-biochar treatment during the 3.5 years of aging. Within the 28 days of incubation, aged biochar not only promoted the total CO2 emission but also did not limit the priming effect of LMW-C on native SOC mineralization. SOC-derived DOC in the aged soil-biochar mixture was significantly higher than that in the aged soil, which further increased the SOC loss. A decline in the SOC stability with aged biochar might be associated with the attenuated sorption of SOC on aged biochar, the decline in bulk density with the high biochar addition rate, and a modified microbial community. The priming of aged SOC mineralization with the addition of LMW-C might be associated with the enhanced microbial N demand in aged soils and soil-biochar mixtures. The effect of aged biochar on the soil DOC and the effect of LMW-C on the aged biochar and SOC stabilities should be further investigated in field conditions, under continuous fresh C inputs, to better evaluate the effects of biochar on long-term SOC storage.

7614. 题目: Evaluation of coastal wetland soil properties in a degrading marsh
文章编号: N18072003
期刊: Estuarine, Coastal and Shelf Science
作者: Jacob F. Berkowitz, Christine M. VanZomeren, Candice D. Piercy, John R. White
更新时间: 2018-07-20
摘要: Coastal salt marshes consist of a mosaic of vegetated and open water features, which naturally evolve and change over time. However, the rapid expansion of open water areas has been associated with marsh degradation and there is a growing need for detailed studies as coastal wetlands continue to degrade under increasing rates of sea level rise and related stressors. Yet, few studies investigate soil physicochemical and biogeochemical properties within different marsh landscape features, which could provide insight into mechanisms of the formation and expansion of open water areas. The current study compared wetland soil physical and microbial properties observed in vegetated areas with shallow open water areas called pannes, identifying a number of significant differences. Panne soils possessed lower bulk density, total C, N, P, SOC, DOC, and SRP compared with vegetated marsh areas, suggesting a shift in nutrient pools as vegetated areas transition into shallow open water features. Panne features also displayed significantly lower microbial pool sizes and processing rates than vegetated marsh soils, suggesting reduced capacity for nutrient processing in open water areas. Further, extractable NH4-N was highest in the panne soils suggesting that the absence of macrophytes decreased N uptake in open water areas. Also related to the lack of vascular plants, extractable DOC in pannes averaged less than half the concentration found in vegetated marsh areas, despite a smaller difference in soil total C. Results underscore the importance of incorporating heterogeneous landscape soil conditions when evaluating marsh degradation and considering potential restoration activities.

7615. 题目: High oxygen reduction reaction performance nitrogen-doped biochar cathode: A strategy for comprehensive utilizing nitrogen and carbon in water hyacinth
文章编号: N18072002
期刊: Bioresource Technology
作者: Jiaxiang Liang, Diyong Tang, Li Huang, Yifei Chen, Wei Ren, Jie Sun
更新时间: 2018-07-20
摘要: In this study, a novel nitrogen-doped biochar oxygen reduction reaction cathode-water hyacinth carbon, was prepared by ZnCl2 molten salt carbonization without additional nitrogen source, which displayed a high performance in electro-Fenton (E-Fenton) process. The BET result shows that water hyacinth carbon achieved a much larger specific surface area (829 m2·g-1) than non-melt salt carbonized one (323 m2·g-1) and graphite powder (28 m2·g-1). Furthermore, characterization by XPS and EIS shows that both pyridinic-N (43.24%) and graphitic-N (56.75%) existed in water hyacinth carbon and Warburg constant was only 0.051. Because of a high H2O2 producing yield 1.7 mmol·L 1 and corresponding current efficiency 81.2 ± 2.5% in molten salt carbonized water hyacinth biochar, a high kinetic constant 0.318 min-1 in DMP degradation was achieved, which was 4 times higher than graphite powder (0.076 min-1). The TOC removal achieved 86.8% in 30 min and the corresponding energy consumption reached a low level 60.15 kW·h·kgTOC-1.
图文摘要:

7616. 题目: Influence of soil temperature and moisture on the dissolved carbon, nitrogen, and phosphorus in organic matter entering lake ecosystems
文章编号: N18072001
期刊: Biogeochemistry
作者: Brittni L. Bertolet, Jessica R. Corman, Nora J. Casson, Stephen D. Sebestyen, Randy K. Kolka, Emily H. Stanley
更新时间: 2018-07-20
摘要: Concentrations of terrestrially derived dissolved organic matter (DOM) have been increasing in many north temperate and boreal lakes for over two decades. The concentration of DOM in lakes is influenced by a number of environmental factors, but there is still considerable debate about how the availability of terrestrial DOM, and associated dissolved nitrogen and phosphorus, may be affected by drivers of climatic change. Using experimental and observational methods, we considered how changes in soil temperature and moisture affected the composition of carbon, nitrogen, and phosphorus entering freshwater lakes. In our experiment, organic soil cores were collected from the wetland shoreline of a darkly-stained seepage lake in northern Wisconsin, USA and manipulated in laboratory with temperature and moisture treatments. During the 28-day study, soil leachate was sampled and analyzed for optical properties of DOM via UV/Vis absorbance, as well as concentrations of dissolved organic carbon (DOC), total dissolved nitrogen, and total dissolved phosphorus (TDP). DOM optical properties were particularly sensitive to moisture, with drier scenarios resulting in DOM of lower molecular weight and aromaticity. Warmer temperatures led to lower DOC and TDP concentrations. To consider long-term relationships between climate and lake chemical properties, we analyzed long-term water chemistry data from two additional Wisconsin lakes from the long term ecological research (LTER) project in a cross correlation analysis with Palmer drought severity index data. Analysis of the LTER data supported our experimental results that soil moisture has a significant effect on the quality of DOM entering lakes and that climate may significantly affect lake chemical properties. Although unexpected in terms of DOM loading for climate change scenarios, these results are consistent with patterns of decomposition in organic soils and may be attributed to an increase in soil DOM processing.

7617. 题目: Effect of modified coconut shell biochar on availability of heavy metals and biochemical characteristics of soil in multiple heavy metals contaminated soil
文章编号: N18071925
期刊: Science of The Total Environment
作者: Huakang Liu, Fei Xu, Yanluo Xie, Can Wang, Akang Zhang, Lingling Li, Heng Xu
更新时间: 2018-07-19
摘要: On account of the potential in immobilizing metals and improving soil environment, various biochar materials have been extensively applied in environmental remediation. The purpose of this experiment was to evaluate the effect of modified coconut shell biochar (MCSB) on the availability of metals and soil biological activity in multi-metals (cadmium (Cd), nickel (Ni) and zinc (Zn)) contaminated soil. MCSB was obtained from coconut shell biochar (CSB) by hydrochloric acid pickling and ultrasonication, which has significantly improved its surface functional groups and microcosmic pore structure. Sandy soil samples were incubated at 25 °C amended with MCSB or CSB by 0%, 2.5% and 5% addition for 63 days, respectively. The results showed that the acid soluble Cd, Ni and Zn decreased by 30.1%, 57.2% and 12.7%, respectively, in groups with 5% MCSB addition, which indicated MCSB had a better effect on immobilizing metals compared with CSB. In addition, higher soil biological activities were detected in different treatments compared with control (CK). Especially, the maximum bacterial number was found in 5% MCSB treatment, which increased by 149.43% compared with CK. Accordingly, our results suggested that MCSB could be used as an ameliorant to immobilize heavy metals in contaminated soils and improve soil physicochemical and biological properties.

7618. 题目: Factors influencing the ecological and human health risks of DDTs in soils and air at the isomeric and enantiomeric levels
文章编号: N18071924
期刊: Journal of Hazardous Materials
作者: Lili Niu, Chao Xu, Siyu Zhu, Hangjun Zhang, Weiping Liu
更新时间: 2018-07-19
摘要: Even though the application of dichlorodiphenyltrichloroethanes (DDTs) has been restricted for over 30 years, their ubiquitous existence still poses profound adverse impacts on ecosystem and human health. In this study, simultaneous soil and air sampling campaigns at different functional areas were conducted in warm and cold seasons. Based on the residue levels and enantiomeric signatures of DDT and its metabolites in soils and air, the parameters influencing ecological and human health risks were explored. ΣDDT concentrations in soils correlated positively with organic matter (OM) and negatively with pH, whereas atmospheric DDT levels were primarily facilitated by increased temperature. High temperature and low soil pH were also favorable for the transformation of DDT into its metabolites. The inhabitants living in agricultural regions or in areas with higher soil OM or pH < 7 were exposed to higher existing and potential health risks of soil DDTs. In addition, at lower temperatures, the existing and potential carcinogenic risks of DDTs from soil exposure were higher, whereas risks from air inhalation were lower. Health risks would be increased when considering the enantioselective toxicity of o,p’-DDT and o,p’-DDD. The results from this study could provide baseline support for risk control and avoidance of DDTs.

7619. 题目: Distribution of soil organic carbon in Wadi Al-Thulaima, Saudi Arabia: A hyper-arid habitat altered by wastewater reuse
文章编号: N18071923
期刊: CATENA
作者: Mohamed A. El-Sheikh, Salman A. Al-Oteiby, Ahmed H. Alfarhan, Damia Barcelo, Yolanda Picó, Abdulrahman A. Alatar, Saad B. Javed, Ebrahem M. Eid
更新时间: 2018-07-19
摘要: The carbon cycle is being altered as a result of human-induced changes in the Earth's system. Therefore, ecosystems such as wetlands, authentic CO2 sinks, are becoming especially important. Little information exits on the soil organic carbon (SOC) stock for the middle east-countries man-made wetlands making wadis permanent with the outflow of wastewater treatment plants. This paper presents the vertical distribution of SOC content, soil bulk density (SBD) and SOC density in soil of vegetated and bare sites in Wadi Al-Thulaima, one of the artificial wetlands in central Saudi Arabia. The mean distribution of SBD in the vegetated and bare sites increased significantly with depth. Inversely, the SOC content declined significantly with depth, from 17.1 g C kg-1 at 0–3 cm depth to 3.3 g C kg-1 at 15–18 cm depth in vegetated sites and from 4.7 g C kg-1 at 0–3 cm depth to 0.7 g C kg-1 at the 15–18 cm depth in bared sites. Vegetation significantly affected the SOC pool, the total mean SOC pool of the vegetated sites (2.0 kg C m-2) was higher than that of the bare sites (0.5 kg C m-2). Therefore, arid regions could contribute to carbon sequestration with appropriate management, which would result in the enhancement of soil quality.

7620. 题目: Pedogenic and microbial interrelations to regional climate and local topography: New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile
文章编号: N18071922
期刊: CATENA
作者: Nadine Bernhard, Lisa-Marie Moskwa, Karsten Schmidt, Ralf A. Oeser, Felipe Aburto, Maaike Y. Bader, Karen Baumann, Friedhelm von Blanckenburg, Jens Boy, Liesbeth van den Brink, Emanuel Brucker, Burkhard Büdel, Rafaella Canessa, Michaela A. Dippold, Todd A. Ehlers, Juan P. Fuentes, Roberto Godoy, Patrick Jung, Ulf Karsten, Moritz K?ster
更新时间: 2018-07-19
摘要: The effects of climate and topography on soil physico-chemical and microbial parameters were studied along an extensive latitudinal climate gradient in the Coastal Cordillera of Chile (26°–38°S). The study sites encompass arid (Pan de Azúcar), semiarid (Santa Gracia), mediterranean (La Campana) and humid (Nahuelbuta) climates and vegetation, ranging from arid desert, dominated by biological soil crusts (biocrusts), semiarid shrubland and mediterranean sclerophyllous forest, where biocrusts are present but do have a seasonal pattern to temperate-mixed forest, where biocrusts only occur as an early pioneering development stage after disturbance. All soils originate from granitic parent materials and show very strong differences in pedogenesis intensity and soil depth. Most of the investigated physical, chemical and microbiological soil properties showed distinct trends along the climate gradient. Further, abrupt changes between the arid northernmost study site and the other semi-arid to humid sites can be shown, which indicate non-linearity and thresholds along the climate gradient. Clay and total organic carbon contents (TOC) as well as Ah horizons and solum depths increased from arid to humid climates, whereas bulk density (BD), pH values and base saturation (BS) decreased. These properties demonstrate the accumulation of organic matter, clay formation and element leaching as key-pedogenic processes with increasing humidity. However, the soils in the northern arid climate do not follow this overall latitudinal trend, because texture and BD are largely controlled by aeolian input of dust and sea salts spray followed by the formation of secondary evaporate minerals. Total soil DNA concentrations and TOC increased from arid to humid sites, while areal coverage by biocrusts exhibited an opposite trend. Relative bacterial and archaeal abundances were lower in the arid site, but for the other sites the local variability exceeds the variability along the climate gradient. Differences in soil properties between topographic positions were most pronounced at the study sites with the mediterranean and humid climate, whereas microbial abundances were independent on topography across all study sites. In general, the regional climate is the strongest controlling factor for pedogenesis and microbial parameters in soils developed from the same parent material. Topographic position along individual slopes of limited length augmented this effect only under humid conditions, where water erosion likely relocated particles and elements downward. The change from alkaline to neutral soil pH between the arid and the semi-arid site coincided with qualitative differences in soil formation as well as microbial habitats. This also reflects non-linear relationships of pedogenic and microbial processes in soils depending on climate with a sharp threshold between arid and semi-arid conditions. Therefore, the soils on the transition between arid and semi-arid conditions are especially sensitive and may be well used as indicators of long and medium-term climate changes. Concluding, the unique latitudinal precipitation gradient in the Coastal Cordillera of Chile is predestined to investigate the effects of the main soil forming factor – climate – on pedogenic processes.

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