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25841. 题目: Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove‐fringed coastal lagoon in Java, Indonesia
文章编号: N19121007
期刊: Global Change Biology
作者: K. Anggi Hapsari, Tim C. Jennerjahn, Martin C. Lukas, Volker Karius, Hermann Behling
更新时间: 2019-12-10
摘要: The identification and quantification of natural carbon (C) sinks is critical to global climate change mitigation efforts. Tropical coastal wetlands are considered important in this context, yet knowledge of their dynamics and quantitative data are still scarce. In order to quantify the C accumulation rate and understand how it is influenced by land use and climate change, a palaeoecological study was conducted in the mangrove‐fringed Segara Anakan Lagoon (SAL) in Java, Indonesia. A sediment core was age‐dated and analyzed for its pollen and spore, elemental and biogeochemical compositions. The results indicate that environmental dynamics in the SAL and its C accumulation over the past 400 years were controlled mainly by climate oscillations and anthropogenic activities. The interaction of these two factors changed the lagoon's sediment supply and salinity, which consequently altered the organic matter composition and deposition in the lagoon. Four phases with varying climates were identified. While autochthonous mangrove C was a significant contributor to carbon accumulation in SAL sediments throughout all four phases, varying admixtures of terrestrial C from the hinterland also contributed, with natural mixed forest C predominating in the early phases and agriculture soil C predominating in the later phases. In this context, climate‐related precipitation changes are an overarching control, as surface water transport through rivers serves as the “delivery agent” for the outcomes of the anthropogenic impact in the catchment area into the lagoon. Amongst mangrove‐dominated ecosystems globally, the SAL is one of the most effective C sinks due to high mangrove carbon input in combination with a high allochthonous carbon input from anthropogenically enhanced sediment from the hinterland and increased preservation. Given the substantial C sequestration capacity of the SAL and other mangrove‐fringed coastal lagoons, conservation and restoration of these ecosystems is vitally important for climate change mitigation.

25842. 题目: Effects of straw and manure management on soil and crop performance in North China Plain
文章编号: N19121006
期刊: CATENA
作者: Suying Chen, Xiying Zhang, Liwei Shao, Hongyong Sun, Junfang Niu, Xiuwei Liu
更新时间: 2019-12-10
摘要: The North China Plain (NCP) is one of the most intensively farmed agricultural regions in China, and the annual double-cropping system of winter wheat and summer maize produces a large quantity of straw. A field experiment was carried out from 2010 to 2016 to assess the effects of straw and manure management on crop performance, soil physical and chemical characteristics. Four management practices were tested: (1) all the straw from the annual double-cropping system was returned to the soil directly (as a control, WMs); (2) maize straw was removed as yellow silage and winter wheat straw was maintained (Ws); (3) manure produced from dairy farms was added to Ws (Ws + M); (4) extra manure was added to WMs (WMs + M). The results showed that the soil bulk density and soil aggregates were not significantly different among the four treatments. The soil nutrient contents and organic matter (OM) increased continuously under the four treatments. The results indicated that with at least one season of straw returning to the field would maintain an improved soil nutrient contents. The increase rate for organic matter, P and K for the treatments with manure addition was higher than that for the treatments without manure application. Both biomass and grain yield of summer maize were improved with the continuous addition of manure. Although the biomass of winter wheat was improved with manure addition, the grain yield of winter wheat was not affected due to the reduction in the harvest index, which might be related to the shortened grain-filling duration. No significant difference in water use efficiency was found among the four treatments for winter wheat or maize. The improved soil nutrient and organic matter contents affected the production of the two crops differently in this annual double-cropping system. The larger increase in organic matter contents using maize straw changed manure through animal feeding would benefit the grain production of summer maize as well as the soil carbon sequestration.

25843. 题目: Sodium azide inhibition of microbial activities and impact on sludge floc destabilization
文章编号: N19121005
期刊: Chemosphere
作者: Akshaykumar Suresh, Chaozhi Pan, Wun Jern Ng
更新时间: 2019-12-10
摘要: Absence of sludge deflocculation under prolonged (24 h or longer) conditions with dissolved oxygen (DO) less than 0.5 mg L⁻¹ was recently reported. The reduced aerobic microbial activity, was speculated, had been compensated by the activity of other bacterial (i.e. facultative) communities. To assess such a compensation mechanism and to better evaluate impact of overall microbial activity on the flocculation process, SBR sludge samples were inhibited by using sodium azide under various DO conditions. Sludge deflocculated only in the presence of sodium azide, regardless of DO conditions. This was linked to sodium azide’s inhibitory effects on the microbes as indicated by the reduced ammonium and DOC removals. Extracellular potassium level in the mixed liquor of azide spiked samples also indicated simultaneous cell lysis. Fluorescence excitation emission matrix (FEEM) analysis of the extracted bound EPS and fluorescence quenching based interaction studies indicated sodium azide had interacted with the EPS components, and especially with the bound EPS proteins. The impact of such interactions on reduced floc stability needs consideration. This study confirmed the importance of overall microbial activity in the biological flocculation process and the role of bacterial communities, other than the aerobes, in mitigating deflocculation under low DO conditions.
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25844. 题目: Biochar mitigates the effect of nitrogen deposition on soil bacterial community composition and enzyme activities in a Torreya grandis orchard
文章编号: N19121004
期刊: Forest Ecology and Management
作者: Quan Li, Xinzhang Song, Kim Yrjälä, Jianhua Lv, Yongfu Li, Jiasheng Wu, Hua Qin
更新时间: 2019-12-10
摘要: Increased reactive N deposition has widespread effects on terrestrial ecosystems, such as biodiversity loss, soil acidification, as well as stimulated plant growth. Empirical studies show that biochar often affects soil quality, crop productivity, soil microbial community composition and enzyme activities. However, the effect of biochar addition on forest soil bacterial community along with enzyme activities under nitrogen (N) deposition and its related mechanisms have not been well studied yet. Therefore, a 2-year field study was conducted to investigate the effects of biochar amendment (0, 20, 40 kg biochar ha⁻¹ yr⁻¹) on soil nutrients, enzyme activities, and bacterial community in a Torreya grandis orchard under different levels of N deposition (0, 30, 60 kg N ha⁻¹ yr⁻¹). N deposition significantly increased soil nutrients availability, such as N, phosphorus (P) and potassium (K), while biochar amendment led to significant increase in soil pH, organic carbon (SOC), total N (TN), total P (TP), available P (AP) and available K (AK). Both N deposition and biochar amendment significantly decreased the soil microbial biomass carbon (MBC), altered soil microbial community and enzyme activities significantly. Biochar addition increased the relative abundance of phylum Proteobacteria under different levels of N deposition, but had variable effect on Acidobacteria groups. Non-metric multidimensional scaling (NMDS) indicated that biochar amendment can mitigate the effect of N deposition on soil bacterial community composition and enzyme activities. Soil pH and SOC played an important role in shaping soil bacterial community composition, while available AP and AK contents significantly related to the variation of soil enzyme activities. Structure equation modeling (SEM) revealed that N deposition had negative effect on soil enzyme activities while biochar amendment can mitigate this negative effect through increasing AP content. Our result suggests that biochar amendment can mitigate the alteration of soil bacterial community and enzyme activities induced by N deposition, and this mitigation effect was linked to the alteration of soil physicochemical properties, especially the increased AP content. Thus, biochar amendment could be a promising way to develop sustainable forest management under increasing N deposition.

25845. 题目: Characteristics of sewer biofilms in aerobic rural small diameter gravity sewers
文章编号: N19121003
期刊: Journal of Environmental Sciences
作者: Wenkai Li, Tianlong Zheng, Yingqun Ma, Junxin Liu
更新时间: 2019-12-10
摘要: Small diameter gravity sewers (SDGS) are extensively used to collect rural sewage as they are low in cost and quick to construct. However, the characteristics of biofilms in rural SDGS are still not clear. In this study, biofilms characteristics of aerobic rural SDGS were investigated using simulations in a lab under different flow conditions and slopes. Results indicated that the average thickness of aerobic rural SDGS biofilms was in the range of 350–650 μm, decreasing at locations with variable flow and high slopes. Protein was the most abundant substance in extracellular polymeric substance of SDGS biofilms. The most abundant bacteria, Proteobacteria, Actinobacteria, and Bacteroidetes, and functional bacteria showed different distributions when analyzed through Illumina HiSeq sequencing of 16S rRNA. The relative abundances of denitrifying bacteria, nitrite-oxidizing bacteria, and sulfate-reducing bacteria (SRB) were lower during variable flow than during stable flow. High slopes (15‰) decreased SRB presence, which could be used to mitigate H₂S accumulation in aerobic SDGS. Overall, this study describes the characteristics of aerobic rural SDGS biofilms and provides valuable suggestions for the optimal design of SDGS based on these characteristics.
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25846. 题目: Linking the electron donation capacity to the molecular composition of soil dissolved organic matter from the Three Gorges Reservoir areas, China
文章编号: N19121002
期刊: Journal of Environmental Sciences
作者: Tao Jiang, Joeri Kaal, Jiang Liu, Jian Liang, Yaoling Zhang, Dingyong Wang
更新时间: 2019-12-10
摘要: Soil dissolved organic matter (DOM) plays an essential role in areas of the Three Gorges Reservoir (TGR) as a linkage between terrestrial and aquatic systems. In particular, the reducing capacities of soil DOM influence the geochemistry of contaminants such as mercury (Hg). However, few studies have investigated the molecular information of soil DOM and its relationship with relevant geochemical reactivities, including redox properties. We collected samples from eight typical sites in TGR areas and established a linkage between the molecular characteristics of DOM and their electron donation capacities (EDCs) toward Hg(II). The average kinetic rate and EDC of soil DOM in TGR areas were (0.004 ± 0.001) hr⁻¹ and (2.88 ± 1.39) nmol e⁻/mg DOM_bulk, respectively. Results suggest that higher EDCs and more rapid kinetics were related to the greater electron donation components of lignin-derived and perhaps pyrogenic DOM, which are the aromatic constituents that predominantly influence the reducing capacities of DOM. Molecular details revealed that even the typical autochthonous markers are important for the EDCs of DOM, in contrast to what is generally assumed. More studies identifying specific DOM molecular components involved in the abiotic reduction of Hg(II) are required to further understand the relations between DOM sources and their redox roles in the environmental fate of contaminants.
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25847. 题目: Climatic and human impact on the environment: insight from the tetraether lipid temperature reconstruction in the Beibu Gulf, China
文章编号: N19121001
期刊: Quaternary International
作者: Weisen Liao, Jianfang Hu, Haoda Zhou, Ping’an Peng
更新时间: 2019-12-10
摘要: Organic proxies have been widely used to reconstruct temperature and terrestrial input variation at the interface between land and sea. However, the impact of human activities on these proxies has been little constrained, which might cause the misinterpretation of the sediment profile. In order to study the climatic and human impact on the environment, proxies in coastal regions, glycerol dialkyl glycerol tetraethers (GDGTs) in a sediment core spanning 115 years was analyzed from Beibu Gulf, China. The results indicate that isoprenoid GDGTs in the Beibu Gulf were derived mainly from Thaumarchaeota and the branched GDGTs originated mainly from terrestrial soil bacteria. The TEX₈₆ index was applied to reconstruct the temporal SST variation. The results show that variation of TEX₈₆-derived SST is controlled mainly by East Asian Monsoon system and partly by ENSO events. The methylation index of branched tetraethers or the cyclization index of branched tetraethers (MBT/CBT) derived mean annual air temperature (MAAT) agreed with MAAT record at the Qinzhou Station before 1982 AD. However, the population growth and economic development after 1982 AD caused the reduction of terrestrial organic matter input and increase of nutrient, leading to the thriving of Thaumarchaeota and increasing of in situ branched GDGTs proportion, which created the scatter of the MBT/CBT-reconstructed MAAT after 1982 AD. Therefore, human influence on GDGT proxies can be constrained in this way to avoid misinterpretation of paleoclimate and paleoenvironment records.

25848. 题目: Predicting Cr(VI) adsorption on soils: the role of the competition of soil organic matter
文章编号: N19120901
期刊: Environmental Science: Processes Impacts
作者: Zhenqing Shi, Shimeng Peng, Xiaofeng Lin, Yuzhen Liang, Suen-Zone Lee, Herb Allen
更新时间: 2019-12-09
摘要: Cr(VI) has posed a serious risk for environment and human beings because of its pollution and toxicity. It is essential to understand the equilibrium behavior of Cr(VI) in soils. In this study, the adsorption of Cr(VI) on fourteen soils were studied with batch experiments and quantitative modeling. The batch experiments included the adsorption edge and adsorption isotherm experiments, investigating the adsorption of Cr(VI) under varying soil properties, solution pH, and the initial Cr(VI) concentrations. The experimental data were then modeled using the surface complexation models in Visual MINTEQ of CD-MUSIC by considering the adsorption of Cr(VI) and ions onto Fe (hydr)oxides and Al(hydr)oxides, and the Stockholm Humic Model and the fixed charge site model by accounting the adsorption of the cations to soil organic matter and clay, respectively. Particularly, the modeling method of this study introduced an important parameter RO- to account for the amount of soil organic matter irreversibly adsorbed on soil minerals. Overall, the model predicted reasonably well for the equilibrium partition of Cr(VI) at various conditions with a root-mean-square-error of 0.35 for the adsorption edge data and 0.19 for the adsorption isotherm data. According to the model calculations, ferrihydrite dominated the binding of Cr(VI) at pH of 3.0 – 7.0. The content of ferrihydrite and reactive soil organic matter were found to be the main factors influencing RO-. The modeling results help to understand and predict Cr(VI) adsorption on different soils and are beneficial to the environmental risk assessment and pollution remediation.

25849. 题目: Dark carbon fixation in the Arabian Sea oxygen minimum zone contributes to sedimentary organic carbon (SOM)
文章编号: N19120805
期刊: Global Biogeochemical Cycles
作者: Sabine K. Lengger, Darci Rush, Jan Peter Mayser, Jerome Blewett, Rachel Schwartz‐Narbonne, Helen M. Talbot, Jack J. Middelburg, Mike S.M. Jetten, Stefan Schouten, Jaap S. Sinninghe Damsté, Richard D. Pancost
更新时间: 2019-12-08
摘要: In response to rising CO₂ concentrations and increasing global sea surface temperatures, oxygen minimum zones (OMZ), or “dead zones”, are expected to expand. OMZs are fueled by high primary productivity, resulting in enhanced biological oxygen demand at depth, subsequent oxygen depletion, and attenuation of remineralization. This results in the deposition of organic carbon‐rich sediments. Carbon drawdown is estimated by biogeochemical models; however, a major process is ignored: carbon fixation in the mid‐ and lower water column. Here, we show that chemoautotrophic carbon fixation is important in the Arabian Sea OMZ; and manifests in a ¹³C‐depleted signature of sedimentary organic carbon. We determined the δ¹³C values of SOM deposited in close spatial proximity but over a steep bottom‐water oxygen gradient, and the δ¹³C composition of biomarkers of chemoautotrophic bacteria capable of anaerobic ammonia oxidation (anammox). Isotope mixing models show that detritus from anammox bacteria or other chemoautotrophs likely forms a substantial part of the organic matter deposited within the Arabian Sea OMZ (~17%), implying that the contribution of chemoautotrophs to settling organic matter is exported to the sediment. This has implications for the evaluation of past, and future, OMZs: biogeochemical models that operate on the assumption that all sinking organic matter is photosynthetically derived, without new addition of carbon, could significantly underestimate the extent of remineralization. Oxygen demand in oxygen minimum zones could thus be higher than projections suggest, leading to a more intense expansion of OMZs than expected.

25850. 题目: Adsorption Kinetics of 2,2′,4,4′-Tetrabromodiphenyl Ether (BDE-47) on Maize Straw-Derived Biochars
文章编号: N19120804
期刊: Pedosphere
作者: Guangxia LIU, Yang SONG, Hongjie SHENG, Mao YE, Robert D. STEDTFELD, Yongrong BIAN, Chenggang GU, Xin JIANG, Fang WANG
更新时间: 2019-12-08
摘要: The chars in the natural environment can affect the migration of polybrominated diphenyl ethers (PBDEs). However, there is insufficient research relating to the adsorption behavior and mechanisms of PBDEs on biochars. This study examined the adsorption kinetics of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) on maize straw-derived biochars (MSBCs) pyrolyzed at four different temperatures via batch experiments. The biochar samples were characterized using Fourier transform infrared (FTIR) spectroscopy, Raman spectra, and elemental analysis. A two-compartment first-order model and pseudo-second-order model exhibited a better fit compared to a pseudo-first-order model in describing the BDE-47 adsorption on biochars, which was dominated by a slow adsorption compartment and chemisorption. The MSBC pyrolyzed at 600 °C had the highest BDE-47 adsorption capacity owing to its relatively large specific surface area and relatively high aromaticity compared with the other three MSBCs pyrolyzed at 300, 400, and 500 °C. However, there was no significant difference in adsorption capacity among the other three biochars. The organic functional groups coupled with the graphene structures of biochars and the hydrophobic effect of the functional groups promoted the adsorption of BDE-47. Pore diffusion was not the sole rate-limiting step; film diffusion was also involved in the adsorption process of BDE-47 on biochars. The overall results demonstrate the transport and potential treatment of PBDEs using biochars.

25851. 题目: Soil microbial community structure affected by biochar and fertilizer sources
文章编号: N19120803
期刊: Applied Soil Ecology
作者: Sadikshya Dangi, Suduan Gao, Yinghua Duan, Dong Wang
更新时间: 2019-12-08
摘要: Use of organic fertilizer or organic amendments can potentially mitigate the deleterious environmental impacts of inorganic fertilizers in agroecosystems, but they can also affect soil microorganisms which have not been well defined. The aim of this research was to evaluate an incorporation of poultry-waste based organic fertilizer in various combinations of inorganic fertilizer and amendment with biochar on soil microbial properties after two growing seasons of serrano chili peppers. Treatments included combinations of inorganic N with different rates (0%, 50%, 75% and 100% of total N supply) of organic N (org-N) and inorganic N with amendment of three rates (10, 30 and 50 t ha⁻¹) of a coconut shell biochar. After two years of application, the amounts of total, arbuscular mycorrhizal fungal (AMF), and Gram positive and Gram negative bacterial phospholipid fatty acid (PLFA) increased significantly at the higher rates of biochar compared to those at lower rates, unfertilized, and non-amended soil. However, significant differences were not observed for fungal PLFA between inorganic N with biochar and those without addition of biochar. Organic N application also increased (with the highest from 75% rate) the amounts of total, Gram positive and Gram negative bacterial and AMF PLFAs compared to unfertilized and inorganic N treatments, but the amounts of fungal PLFA significantly decreased as organic N application rate increased. All the rates of biochar and org-N amendments increased the pepper yield compared to unfertilized and inorganic N treatments in the second year. Results indicate that soil amendment with biochar or incorporation of organic fertilizer for about two years affected microbial community biomass, composition and crop yield. Thus, in conventional farming, the combined use of inorganic fertilizers with org-N source or organic amendment with biochar can improve soil health and crop productivity.

25852. 题目: Dynamics of soil water extractable organic carbon and inorganic nitrogen and their environmental controls in mountain forest and meadow ecosystems in China
文章编号: N19120802
期刊: CATENA
作者: Junjun Zhang, Changhui Peng, Wei Xue, Bin Yang, Zhenan Yang, Shuli Niu, Qiuan Zhu, Meng Wang
更新时间: 2019-12-08
摘要: We investigated the differences among two types of forest (pine and oak forests) and a meadow in soil water extractable organic carbon (WEOC), ammonium (NH₄⁺) and nitrate (NO₃⁻) concentrations in the Qinling Mountains, China. Our results showed that soil WEOC, NH₄⁺ and NO₃⁻ concentrations were higher in the meadow than in the forests, and they were higher in the pine forest than in the oak forest. The soil surface temperature and soil water content were positively correlated with WEOC and inorganic nitrogen concentrations (P < 0.01). In addition, there was a significantly negative correlation between soil WEOC concentration and pH (P < 0.01). Moreover, soil WEOC concentration was positively correlated with the inorganic nitrogen concentration (P < 0.01). Generally, soil WEOC concentration decreased in the forests, and increased in the meadow under warming condition. The effects of warming on soil WEOC and dissolved inorganic nitrogen (DIN) concentrations varied with time. We elucidated that warming had a significant influence on soil WEOC concentration in the pine forest, whereas soil DIN concentration was affected significantly by warming only in the meadow. Our findings indicate that soil WEOC and DIN show different responses to warming in the mountain forest and meadow ecosystems. This study could provide useful insights for the prediction of soil carbon and nitrogen cycling and their responses to climate change in the complex mountain ecosystem.

25853. 题目: Opposite patterns of soil organic and inorganic carbon along a climate gradient in the alpine steppe of northern Tibetan Plateau
文章编号: N19120801
期刊: CATENA
作者: Chenjun Du, Yongheng Gao
更新时间: 2019-12-08
摘要: Both soil organic carbon (SOC) and inorganic carbon (SIC) are important components of soil carbon storage. However, few studies have attempted to estimate the magnitude and patterns of SIC in arid areas. We measured the concentrations of SOC and SIC in alpine steppe grasslands along a climate gradient in the Tibetan Plateau. At all sites, an opposing trend was found in the distribution of SOC compared with SIC. SOC increased with increasing precipitation, while SIC decreased. Within sites, SOC decreased with soil depth, while SIC increased. Among the variables considered, soil total nitrogen (TN) and soil water content explained the most variability in SOC (r² = 0.95 for TN, r² = 0.93 for soil water content), and soil pH had the highest correlation with SIC (r² = 0.90). This finding indicates that SOC is closely related to biological processes, such as biomass input and litter accumulation, while SIC is determined by abiotic factors such as chemical and physical processes of soil formation. SOC and SIC densities showed that the SOC pool comprised 91% of total carbon (TC) storage in these alpine steppe soils. A decrease in SOC density occurred with depth, but this pattern was the opposite for SIC density in all soil profiles. These findings help to characterize the C cycle in the alpine steppe of the Tibetan Plateau.

25854. 题目: Short-term impacts of biochar, tillage practices, and irrigation systems on nitrate and phosphorus concentrations in subsurface drainage water
文章编号: N19120709
期刊: Environmental Science and Pollution Research
作者: Saeid Shahvarooghi Farahani, Mohammad Amin Asoodar, Bijan Khalili Moghadam
更新时间: 2019-12-07
摘要: Leaching of nitrogen (N) and phosphorus (P) from agricultural lands can cause serious environmental problems such as eutrophication. The objective of this study was to investigate the impacts of biochar application, tillage practices, and irrigation systems on nitrate and dissolved phosphorus (DP) concentrations in subsurface drainage water and grain yield of winter wheat using a strip-split plot design with 3 replications. Irrigation at three different levels (flood (I_fl), furrow (I_fu), and sprinkler (I_s) systems) considered as main factor, tillage at two levels (reduced tillage (T_r) and conventional systems (T_c)) as subplot factor, and bagasse biochar at two levels (without biochar (B₀) and 20 ton ha⁻¹ biochar (B₁)) as sub-subplot factor. Polyvinyl chloride (PVC) standpipes were used in each sub-subplot to collect leachate water at 100-cm depth. The results indicated that irrigation had significant effects on yield, collected water volume (CWV), nitrate, and DP concentrations (P < 0.01). Interaction of tillage and irrigation was significant for grain yield (P < 0.05). Biochar application only caused a significant decrease in nitrate concentration under sprinkler irrigation (P < 0.05), while no significant impact was observed under flood and furrow irrigation systems. Under sprinkler irrigation, the total nitrate collected in the PVC standpipes decreased by 37.51 and 34.29% compared with flood and furrow irrigations, respectively. Biochar application reduced the total nitrate collected by 16.84%, while difference among tillage treatments was negligible (4.51%). The total DP collected under sprinkler irrigation was lower in comparison with flood and furrow irrigations by 42.24 and 38.76%, respectively. Biochar application reduced the total DP collected by 10.84%, while reduced tillage increased the total DP collected by 8.90% compared with the conventional tillage.

25855. 题目: 13 C- 14 C relations reveal that soil 13 C-depth gradient is linked to historical changes in vegetation 13 C
文章编号: N19120708
期刊: Plant and Soil
作者: Alexia Paul, Jérôme Balesdent, Christine Hatté
更新时间: 2019-12-07
摘要: Aims: The understanding of the dynamics of subsoil (>30 cm) soil organic matter (SOM) is critical to predict the future evolution of the carbon cycle. Stable carbon isotopes ratios (¹³C/¹²C) are helpful to study the dynamics of SOM, but their variations with depth are still speculative. Methods: Several studies indicated that the ¹³C/¹²C ratio of C₃ vegetation decreased over time more than that of atmospheric CO₂ did. From these studies, we modelled the average variation of δ¹³C values of vegetation from 20,000 years Before Present (BP) to today. Then, we conducted a meta-analysis of the δ¹³C vs ∆¹⁴C values relations in forty-five soil profiles sampled all around the world. Results: We first found evidence of the change in SOM δ¹³C values with the sampling year of the profile. Then, by converting ∆¹⁴C values into mean calendar age of SOM, we showed that 40% of the change in SOM δ¹³C values was explained by the historical change in plant δ¹³C values. Conclusion: We conclude that the average increase of SOM δ¹³C values with depth was mostly linked to the change in vegetation δ¹³C values over the last 20,000 years. The variance around the trend was attributed to the contribution of root derived carbon and to soil processes such as interaction of SOM with minerals or to microbial processes.

25856. 题目: Feasibility of using biochar as buffer and mineral nutrients replacement for acetone-butanol-ethanol production from non-detoxified switchgrass hydrolysate
文章编号: N19120707
期刊: Bioresource Technology
作者: Xiao Sun, Hasan K. Atiyeh, Yinka Adesanya, Christopher Okonkwo, Hailin Zhang, Raymond L. Huhnke, Thaddeus Ezeji
更新时间: 2019-12-07
摘要: Biochar can be an inexpensive pH buffer and source of mineral and trace metal nutrients in acetone-butanol-ethanol (ABE) fermentation. This study evaluated the feasibility of replacing expensive 4-morpholineethanesulfonic acid (MES) P2 buffer and mineral nutrients with biochar made from switchgrass (SGBC), forage sorghum (FSBC), redcedar (RCBC) and poultry litter (PLBC) for ABE fermentation. Fermentations using Clostridium beijerinckii ATCC 51743 in glucose and non-detoxified switchgrass hydrolysate media were performed at 35 °C in 250 mL bottles for 72 h. Medium containing buffer and minerals without biochar was the control. Similar ABE production (about 18.0 g/L) in glucose media with SGBC, FSBC and RCBC and control was measured. However in non-detoxified switchgrass hydrolysate medium, SGBC, RCBC and PLBC produced more ABE (about 18.5 g/L) than the control (10.1 g/L). This demonstrates that biochar is an effective buffer and mineral supplement for ABE production from lignocellulosic biomass without costly detoxification process.
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25857. 题目: Flame retardant property of flax fabrics coated by extracellular polymeric substances recovered from both activated sludge and aerobic granular sludge
文章编号: N19120706
期刊: Water Research
作者: Nam Kyeun Kim, Ningtao Mao, Richard Lin, Debes Bhattacharyya, Mark C.M. van Loosdrecht, Yuemei Lin
更新时间: 2019-12-07
摘要: In this research, extracellular polymeric substances (EPS), such as EPS_flocs and EPS_granules, were successfully extracted from activated and aerobic granular sludge, respectively, and tested as bio-based flame retardant materials. Flax fabric was coated by the biopolymeric substances and its flammability was evaluated based on a vertical burning test defined in US Federal Aviation Regulation. Both EPS_flocs and EPS_granules coated flax fabrics achieved the self-extinguishment due to effective char formation. In particular, the result of the EPS_granules coated sample met the aviation requirements for the aircraft interior. Moreover, the presence of carbonated hydroxyapatite was identified in EPS_granules char residue by using FTIR and XRD analysis. It can contribute to the self-extinguishing property of the fabric by enhancing char formation. Thermogravimetric analysis also demonstrated that EPS_granules coated flax was able to produce greater amount of char residue and its decomposition rate was significantly reduced. This research indicates that there is a great potential to use this biopolymer as a resource for developing high performance bio-inspired flame retardant materials and contribute to a circular economy.
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25858. 题目: Estimation of soil organic carbon losses and counter approaches from organic materials in black soils of northeastern China
文章编号: N19120705
期刊: Journal of Soils and Sediments
作者: Shichao Wang, Yawen Zhao, Jinzhou Wang, Jiajia Gao, Ping Zhu, Xi’an Cui, Minggang Xu, Baoku Zhou, Changai Lu
更新时间: 2019-12-07
摘要: Purpose: The northeast plain of China is one of three extensive regions with black soil rich in organic matter in the northern hemisphere. The replacement of natural grassland with cropland has resulted in massive loss of soil organic carbon (SOC), causing serious degradation in this region. Therefore, long-term field experiments combined with modelling approaches were used to examine and project effects of different soil management practices on SOC sequestration. Materials and methods: The RothC model was used to simulate SOC stocks, and the straw retention factor was adjusted in our study. Strategies for improving carbon sequestration were evaluated over 30 years under four carbon input scenarios: straw return at the current rate (with a straw retention factor of 40%), complete straw retention (with a straw retention factor of 100%), manuring at the current rate (0.43 Mg C ha⁻¹ yr⁻¹), and manuring at double the current rate (0.86 Mg C ha⁻¹ yr⁻¹). Results and discussion: Simulations with the RothC model indicated that the SOC stock in the 0–20-cm soil profile at the experimental sites has decreased by 64.1% since the 1980s. Moreover, SOC levels appear to have declined rapidly during the first 10 years after site reclamation, with losses ranging from 3.51 to 5.89 Mg ha⁻¹ yr⁻¹. Straw return at the current rate was predicted to reduce the SOC sequestration rate by 0.07 Mg ha⁻¹ yr⁻¹ in the northern black soils over the 30-year simulation period but cause SOC levels to slowly increase toward equilibrium in the southern black soil region. In simulations with the higher rate of straw retention, SOC stocks rapidly increased (by 0.36–0.53 Mg ha⁻¹ yr⁻¹) across the black soil region over the 30-year period. SOC stocks also increased under the higher rate of manuring, by 0.01–0.19 Mg ha⁻¹ per year. Conclusions: The results suggest that increasing inputs of carbon sources such as straw and manure, together with appropriate tillage, could substantially improve SOC sequestration in the black soil region of northeastern China.

25859. 题目: Effects of dissolved organic matter derived from freshwater and seawater on photodegradation of three antiviral drugs
文章编号: N19120704
期刊: Environmental Pollution
作者: Chengzhi Zhou, Qing Xie, Jieqiong Wang, Xi Chen, Junfeng Niu, Jingwen Chen
更新时间: 2019-12-07
摘要: Dissolved organic matter (DOM) is the most important light absorber that may induce indirect photolytic transformation of organic pollutants in natural waters. In this study, effects of DOM derived from freshwater and seawater on the photodegradation of three antiviral drugs acyclovir, lamivudine and zidovudine were investigated. Results show that the photodegradation of acyclovir is promoted mainly by excited triplet states DOM (³DOM*), and the photodegradation of lamivudine is accelerated by ³DOM*, •OH and ¹O₂ together; however, the photodegradation of zidovudine is inhibited by DOM mainly via light screening. Compared with DOM from freshwater, promotion effect of DOM extracted from seawater (SDOM) on the photodegradation of acyclovir and lamivudine is weaker, which is attributed to lower productivity of reactive intermediates. On the other hand, inhibitory effect of SDOM on the photodegradation of zidovudine is also weaker, which is due to weaker light screening caused by lower light absorption. Photodegradation half-lives of the three antiviral drugs are predicted to be all more than 20 days in freshwater and seawater bodies of the Yellow River estuarine region. These findings are significant for understanding the phototransformation processes of antiviral drugs and other organic pollutants in estuarine and coastal regions.
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25860. 题目: Bacterial diversity and microbial functional responses to organic matter composition and persistent organic pollutants in deltaic lagoon sediments
文章编号: N19120703
期刊: Estuarine, Coastal and Shelf Science
作者: Annamaria Zoppini, Lucia Bongiorni, Nicoletta Ademollo, Luisa Patrolecco, Tamara Cibic, Annalisa Franzo, Marco Melita, Matteo Bazzaro, Stefano Amalfitano
更新时间: 2019-12-07
摘要: Lagoons in river deltas are highly productive systems that receive high loads of organic matter and nutrients. Among the major environmental stress factors and human health-related issues, the anthropogenic contamination is of particular concern, since coastal lagoons are intensively exploited for aquaculture activities. Although microbial communities constitute the most abundant fraction of the benthic biomass, also providing valuable ecosystem services, the links between sediment quality and microbial processes were largely disregarded. In this study, we aimed to elucidate whether different levels of riverine influence could provide favourable or adverse environmental conditions to sustain microbial diversity and processes. Sediments collected from four lagoons of the Po River delta were analysed to assess biochemical composition (biopolymeric carbon, Bio-PC), target organic pollutants (polycyclic aromatic hydrocarbons, PAHs; nonylphenols; bisphenol A), and microbial community properties (bacterial community composition, prokaryotic biomass, prokaryotic carbon production rate, PCP, community respiration rates, CR, extracellular enzyme activities, EEAs). The major physical and chemical sediment properties allowed identifying two statistically distinct groups of sediments with relatively low (LI) and high (HI) riverine influence. HI sediments were characterised by higher Bio-PC and PAHs concentrations, along with relatively high PAHs potential toxicity estimated by the Toxic Equivalent concentration approach. Contrasting results were obtained by linking the occurrence of dominant bacterial taxa (i.e., Desulfobulbaceae and Desulfobacteraceae) to sediment contamination patterns. Notably, the increasing pollution levels were likely to positively affect the occurrence of the family SVA1033, whereas detrimental effects were found against the family Ectothiorhodospiraceae. In addition, the concurrent increase of PCP/CR ratio along with key EEAs, highlighted that the benthic microbial community could consistently contribute to accelerate the degradation of persistent organic pollutants, with potential implication on the sediment self-purification processes.