41. 题目: Impacts of the components of conservation agriculture on soil organic carbon and total nitrogen storage: A global meta-analysis
期刊: Science of The Total Environment
作者: Yves N'Dri Bohoussou, Yi-Hong Kou, Wei-Bao Yu, Bai-jian Lin, Ahmad Latif Virk, Xin Zhao, Yash Pal Dang, Hai-Lin Zhang
摘要: Conservation agriculture (CA) can be an important strategy for improving soil organic carbon (SOC) and total nitrogen (TN). Numerous studies have examined SOC and TN dynamics in different cropping systems. However, there is some uncertainty regarding the relative impacts of some CA practices, and it is not always clear how other agricultural management, particularly nitrogen addition, interacts with these practices to influence SOC and TN sequestration. Thus, we conducted a global meta-analysis of 752 comparisons from 97 papers to analyze the impacts of nitrogen fertilizers and CA practices (namely crop diversification, minimal soil disturbance (no-tillage) and permanent soil cover), on SOC and TN content worldwide. Overall, our study showed the most significant increase of SOC [21.39 % (CI = 15.16 to 28.64)] and TN [54.34 % (CI = 26.19 to 96.69)] stock with CA practices compared to conventional practices in the 0–15 cm soil depth. It also showed a significant increase in SOC and TN stock with all the individual components of CA compared to conventional practices in the 0–15 cm soil depth. However, the impact of CA on SOC and TN is reduced in 0–60 cm depths compared to surface soil depths due to the limited input of crop residue deeper in the soil profile. Manure and manure mixed with mineral-N led to greater SOC sequestration [20.67 % (CI = 15.23 to 27.10) and 41.67 % (CI = 31.03 to 52.79), respectively] than mineral-N alone [9.08 % (CI = 6.44 to 11.83)]. Cropping systems that included legume residue decreased the C/N ratio. This highlights that adequate mineral-N fertilizer addition may also be required in conjunction with residue retention practices to improve SOC and TN content. Overall, these results show that CA systems that include legume residue and manure mixed with mineral-N have great potential to increase SOC and TN, particularly at 0–15 cm and 0–30 cm soil depth.
42. 题目: Insight into dead space effects in granular anammox process with organic stress
期刊: Bioresource Technology
作者: Dong Li, Ziqing Wei, Shuai Li, Huiping Zeng, Jie Zhang
摘要: In this study, the dead space was demonstrated to enhance the robustness of anammox nitrogen (N)-removal under organic stress. Different from the “yellow aggregates” that inhabit in mixing space were assembled by anammox and heterotrophic micro-colonies, the “red granules” that inhabit in dead space were formed by initial anammox aggregates that growing outward with higher anammox-activity, settleability and sludge stability, which endowed the dead space the role of “anammox-stabilizer” with prominent anammox N-removal contribution (63.8%) especially under high organic stress. The extracellular polymeric substances (EPS) dynamic balance test revealed that the high and stable EPS contents in dead space were attributed to the low EPS degradation rate and low proportion of heterotrophic bacteria (HB)-produced EPS, respectively. The weak hydrodynamic forces were the key to less HB-colonization and high granular stability in dead space. Retaining a certain dead space is necessary to prevent anammox bacteria (AnAOB) loss under organic stress.
43. 题目: Subarctic soil carbon losses after deforestation for agriculture depend on permafrost abundance
期刊: Global Change Biology
作者: Tino Peplau, Julia Schroeder, Edward Gregorich, Christopher Poeplau
摘要: The northern circumpolar permafrost region is experiencing considerable warming due to climate change, which is allowing agricultural production to expand into regions of discontinuous and continuous permafrost. The conversion of forests to arable land might further enhance permafrost thaw and affect soil organic carbon (SOC) that had previously been protected by frozen ground. The interactive effect of permafrost abundance and deforestation on SOC stocks has hardly been studied. In this study, soils were sampled on 18 farms across the Yukon on permafrost and non-permafrost soils to quantify the impact of land-use change from forest to cropland and grassland on SOC stocks. Furthermore, the soils were physically and chemically fractionated to assess the impact of land-use change on different functional pools of SOC. On average, permafrost-affected forest soils lost 15.6 ± 21.3% of SOC when converted to cropland and 23.0 ± 13.0% when converted to grassland. No permafrost was detected in the deforested soils, indicating that land-use change strongly enhanced warming and subsequent thawing. In contrast, the change in SOC at sites without permafrost was not significant but had a slight tendency to be positive. SOC stocks were generally lower at sites without permafrost under forest. Furthermore, land-use change increased mineral-associated SOC, while the fate of particulate organic matter (POM) after land-use change depended on permafrost occurrence. Permafrost soils showed significant POM losses after land-use change, while grassland sites without permafrost gained POM in the topsoil. The results showed that the fate of SOC after land-use change greatly depended on the abundance of permafrost in the pristine forest, which was driven by climatic conditions more than by soil properties. It can be concluded that in regions of discontinuous permafrost in particular, initial conditions in forest soils should be considered before deforestation to minimise its climate impact.
44. 题目: Rhizobium leguminosarum bv. trifolii exopolysaccharide and sunflower husk biochar as factors affecting immobilization of both tetracycline and Cd2+ ions on soil solid phase
期刊: Journal of Soils and Sediments
作者: Katarzyna Szewczuk-Karpisz, Agnieszka Tomczyk, Katarzyna Grygorczuk-Płaneta, Sadiq Naveed
摘要: Purpose Industrialization and application of large amount of fertilizers together with animal wastes increased pollution of environment with antibiotics and heavy metals. Due to their negative impact on organisms and biodiversity, it is necessary to limit their mobility. Carbonaceous materials and bacterial exopolysaccharides can be a solution. Therefore, we examined the impact of sunflower husk biochar and Rhizobium leguminosarum bv. trifolii exopolysaccharide (EPS) on kaolinite adsorption capacity towards tetracycline (TC) and cadmium (Cd). Materials and methods The experiments were performed on kaolinite—natural element of soil sorption complex, biochar—product of sunflower husks pyrolysis (650 °C), and their simple composite prepared by wet mixing. The solids were characterized by various methods—nitrogen adsorption/desorption, Fourier-transform infrared spectroscopy, potentiometric titration, and scanning electron microscopy. The adsorbed concentrations of TC and Cd on selected solids were examined as a function of pH and EPS presence. TC concentration was analyzed using high-performance liquid chromatography, whilst that of Cd by ion selective electrodes. Results and discussion Among all tested solids, biochar was characterized by the highest heterogeneity and highest adsorption capacity relative to Cd and TC. It adsorbed 63.4% of Cd ions (at pH 8) and 30.4% of TC (at pH 5). The biochar addition to kaolinite improved its adsorption capacity, but maximally by 5.5%. This was dictated by poor textural parameters of the selected biochar. The pH value was not a factor strongly affecting the efficiency of biochar addition to kaolinite—the difference between pH 5 and pH 8 was only 1%. EPS enhanced accumulation of Cd and TC, but this trend was clear only for the selected adsorbents. For Cd adsorption, the highest increase was noted for B (by 13.8%), whereas for TC adsorption for K (by 7.5%). The simultaneous addition of biochar and exopolysaccharide contributed to increase in Cd adsorption on kaolinite by 7%, whilst TC adsorption by 10.5%. Conclusions Simultaneous application of Rhizobium leguminosarum bv. trifolii exopolysaccharide and sunflower husk biochar increased adsorption capacity of kaolinite. Together with these substances, additional functional groups were introduced into the system. However, it must be emphasized that, due to low porosity and specific surface area of the selected biochar, the final improvement of kaolinite adsorptive ability was not satisfying. In the future, biochars of better textural parameters should be applied in such procedures. Their application together with EPS should reduce the bioavailability of hazardous substances more effectively.
45. 题目: Novel Insights into the Impact of Nano-Biochar on Composition and Structural Transformation of Mineral/Nano-Biochar Heteroaggregates in the Presence of Root Exudates
期刊: Environmental Science & Technology
作者: Fei Lian, Shiguo Gu, Yaru Han, Zhenyu Wang, Baoshan Xing
摘要: Multiple lines of existing evidence indicate that natural organic matter (NOM) could protect poorly crystalline Fe(III) (oxyhydr)oxides from Fe(II)-catalyzed mineral transformation. Conversely, we find that nano-sized biochar (nano-BC), a pyrogenic form of NOM, promotes the phase transformation of ferrihydrite (Fh) in nano-BC/Fh heteroaggregates in the presence of aqueous Fe(II) and rice root exudates. The nano-BC/Fh heteroaggregates are composed of a core–shell like structure where the inner-layered nano-BC is more compacted and plays the dominant role in accelerating the phase transformation of Fh relative to that in the outer sphere. The extent of phase transformation is more regulated by the reversible redox reactions between quinone and hydroquinone in nano-BC than the electron transfer via its condensed aromatic structures. Furthermore, the reductive organic acids in root exudates contribute to the mineral transformation of nano-BC/Fh associations by donating electrons to Fe(III) through nano-BC. Our results suggest that heteroaggregates between nano-BC and Fe minerals are subjected to partial dissociation during their co-transport, and the stably attached nano-BC is favorable to the phase transformation of poorly crystalline Fe minerals (e.g., Fh), which might have profound implications on biogeochemical cycles of carbon and Fe in the prevailing redox environments.
46. 题目: Palaeo-environmental evolution and organic matter enrichment of Eopalaeozoic shales, northwestern Tarim Basin, China: Integrated organic and inorganic geochemistry approach
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Feng Li, Xiuxiang Lü, Jianfa Chen, Rui Wang, Yangyang Wang, Zeya Chen
摘要: The Eopalaeozoic was a pivotal transitional period following the Neoproterozoic glaciation that witnessed dramatic changes in global ocean environments. The black rock series were extensively sedimented, preserving the original seawater signature. However, due to the scarcity of geological records, the palaeo-environment and organic matter (OM) enrichment in the Tarim Basin, China, are poorly constrained. Herein, Eopalaeozoic shales from typical outcrops in the Kalpin block, northwestern Tarim Basin, have been subjected to integrated organic and inorganic geochemistry research. In the study area, Eopalaeozoic black rock series can be found in the Yuertusi Formation (YUF), Saergan Formation (SAF) and Yingan Formation (YIF) from bottom to top. Although the maturity is moderate (~1.2%), the OM abundance varies greatly vertically. Microscopic observations and biomarkers revealed that the OM source was dominated by diverse planktonic algae. The chemical alteration index indicates a transition from cold and dry climates with low chemical weathering to warm and humid climates with moderate chemical weathering, and subsequently back to cold and dry climates. The stratified water column and euxinic–suboxic conditions are revealed by redox proxies (Mo, enrichment factors, Th/U, Mo￼U covariation pattern, pristane/phytane and gammacerane index). The YUF was deposited in a euxinic environment. Productivity proxies (biogenic Ba, Cu/Al, Ni/Al and carbon isotopes) show that primary productivity was superelevated in the lower YUF and moderate in the other formations. Primary productivity and preservation conditions were heavily influenced by complementary hydrothermal activities and upwelling currents. The hydrothermal activities and upwelling currents provide abundant nutrients and highly reductive environments, creating enormous possibilities for the formation of excellent source rocks with considerable hydrocarbon geological significance.
47. 题目: Oxygen Limitation Accelerates Regeneration of Active Sites on a MnO 2 Surface: Promoting Transformation of Organic Matter and Carbon Preservation
期刊: Environmental Science & Technology
作者: Zhiqiang Wang, Hanzhong Jia, Haoran Zhao, Ru Zhang, Chi Zhang, Kecheng Zhu, Xuetao Guo, Tiecheng Wang, Lingyan Zhu
摘要: Birnessite (δ-MnO2) is a layered manganese oxide widely present in the environment and actively participates in the transformation of natural organic matter (NOM) in biogeochemical processes. However, the effect of oxygen on the dynamic interface processes of NOM and δ-MnO2 remains unclear. This study systematically investigated the interactions between δ-MnO2 and fulvic acid (FA) under both aerobic and anaerobic conditions. FA was transformed by δ-MnO2 via direct electron transfer and the generated reactive oxygen species (ROS). During the 32-day reaction, 79.8% of total organic carbon (TOC) in solution was removed under anaerobic conditions, unexpectedly higher than that under aerobic conditions (69.8%), suggesting that oxygen limitation was more conducive to the oxidative transformation of FA by δ-MnO2. The oxygen vacancies (OV) on the surface of δ-MnO2 were more exposed under anaerobic conditions, thus promoting the adsorption and transformation of FA as well as regeneration of the active sites. Additionally, the reaction of FA with δ-MnO2 weakened the strongly bonded lattice oxygen (Olatt), and the released Olatt was an important source of ROS. Interestingly, a part of organic carbon (OC) was preserved by forming MnCO3, which might be a novel mechanism for carbon preservation. These findings contribute to an improved understanding of the dynamic interface processes between MnO2 and NOM and provide new insights into the effects of oxygen limitation on the cycling and preservation of OC.
48. 题目: Electron shuttle potential of biochar promotes dissimilatory nitrate reduction to ammonium in paddy soil
期刊: Soil Biology and Biochemistry
作者: Dan Yuan, Gaoqi Wang, Chunsheng Hu, Shungui Zhou, Tim J Clough, Nicole Wrage-Mönnig, Jiafa Luo, Shuping Qin
摘要: Enhancing dissimilatory nitrate reduction to ammonium (DNRA) is environmentally and agronomically beneficial due to DNRA improving nitrogen (N) retention in soil. However, the rate of DNRA is generally considerably lower than that of denitrification because DNRA requires more electron donors than denitrification. Biochar has been increasingly reported to act as an “electron shuttle” to facilitate electron transfer and to promote redox reactions in soil. Thus, this study aimed to investigate whether and how biochar could enhance the DNRA process in a paddy soil. The results showed that, compared with the no-biochar control, the application of rice straw biochar increased the DNRA rate from 0.2 to 0.7 mg NH4+-N kg−1 dry soil d−1. As well, biochar simultaneously, increased the relative abundance of DNRA functional microbes (nrfA-type microbes) and functional gene (nrfA) expression levels. Biochar's enhancement of DNRA was positively correlated with the biochar properties relevant to electron shuttling (e.g., specific capacitance). In contrast, the application of electron shuttle-weakened biochar (oxidized by H2O2) did not increase, or even decreased, the DNRA rate in the paddy soil. These results demonstrate that biochar can act as an electron shuttle to enhance electron availability for DNRA functional microorganisms and consequently promote the DNRA process in paddy soil. Our results indicate that amendment of paddy soil with biochar containing a high-capacity electron shuttle function is beneficial for preserving N by transforming the mobile nitrate anion into the less mobile ammonium cation in paddy soils.
49. 题目: Probing the outfall-related anomalous Hg levels in the Danshuei Estuarine Coastal, Taiwan
期刊: Marine Pollution Bulletin
作者: Chun-Mao Tseng, Yi-Sheng Chen, Shin-Jing Ang, Kuo-Chen Li, Hao-Cheng Peng, Gwo-Ching Gong
摘要: Seasonal and spatial distributions of total mercury (THg) in the Danshuei Estuary and adjacent coastal areas near the ocean outfall of Taipei, Taiwan, have been successfully investigated from May 2003 to January 2005. We found spatio-temporal variation in THg levels in the Danshuei coastal area was the result of sources and supplies of Hg. High THg concentrations in sediments and seawater were particularly found near the effluent outfall. Average THg levels (avg.: 9–22 ng L−1) were much higher than those in surrounding coastal seawaters (avg.:1–2 ng L−1). Organic carbon contents then played vital roles in controlling water and sedimentary Hg concentrations and occurrences. Hg enrichment factor (EF) as an index of contamination status in surface sediments of the Danshuei coastal area averaged 2.0 ± 0.8 (EFs > 1), indicating an extra non-crustal source from anthropogenic loadings. It implies the Dansheui coastal environment nearby the sewer outfall is facing Hg pollution.
50. 题目: Role of natural organic matter and hardness on lead release from galvanic corrosion
期刊: Environmental Science: Water Research & Technology
作者: Patrick W King, Sigrid Peldszus, Anushka Mishrra, Benjamin F Trueman, Kimia Aghasadeghi, Graham A Gagnon, Daniel E Giammar, Peter M Huck
摘要: Lead release into drinking water from lead service lines, lead containing solder and plumbing fixtures continues to challenge many utilities. Corrosion inhibitors such as orthophosphate are often added to water to mitigate lead release, but their use may not be feasible for many utilities and may not be sufficient to meet regulatory limits. Thus, there is a need to identify other treatment strategies to minimize lead release. Two possible means that have not been thoroughly studied include natural organic matter (NOM) removal and hardness adjustment (e.g., water softening). Accordingly, this study employed a two-level fractional factorial design to investigate the role of NOM and hardness in conjunction with dissolved inorganic carbon (DIC), and pH, on the galvanic corrosion of lead. This study followed a “dump and fill” protocol and employed test pieces consisting of new lead and copper pipes with an external galvanic connection. Suwannee River NOM (SRNOM) increased the release of dissolved lead by an order of magnitude in collected water samples. To be precise, average dissolved lead release in the synthetic waters with and without SRNOM was 140 and 2460 μg L−1 respectively (potentially significant [i.e., 0.05 < p < 0.1]; p = 0.060). Using fluorescence excitation emission matrices, it was found that the release of dissolved lead was correlated to decreases in the NOM humic-like peaks A (R2 = 0.85; p = 4.4 × 10−8) and C (R2 = 0.87; p = 1.3 × 10−8). It is plausible that the decrease in fluorescence was due to the quenching effect of lead–NOM complexation, providing evidence that complexation mobilized dissolved lead. Hardness and DIC did not have a significant effect on lead release, however the galvanic current between the lead and copper pipes was 28.5 μA higher when the DIC concentration was 80 mg L−1 compared to 10 mg L−1 (potentially significant; p = 0.051). Finally, average total lead release at a pH of 7 was 7190 μg L−1 compared to only 2800 μg L−1 at a pH of 8.5 (potentially significant; p = 0.089), and there was some indication that the impact of SRNOM was lower at a higher pH.
51. 题目: Acetamiprid fate in a sandy loam with contrasting soil organic matter contents: A comparison of the degradation, sorption and leaching of commercial neonicotinoid formulations
期刊: Science of The Total Environment
作者: Jessica Potts, Davey L Jones, Andrew Macdonald, Qingxu Ma, Paul Cross
摘要: The impacts of neonicotinoids have generally focussed on the responses of the pure active ingredient. Using a selection of two commercial formulations and the active ingredient, we ran three laboratory studies using 14C-labelled acetamiprid to study the leaching, sorption and mineralisation behaviours of the commercially available neonicotinoid formulations compared to the pure active ingredient. We added 14C-spiked acetamiprid to a sandy loam soil that had received long-term additions of farmyard manure at two rates (10 t/ha/yr and 25 t/ha/yr) and mineral fertilisers, as a control. We found significant differences in acetamiprid mineralisation across both the SOM and chemical treatments. Sorption was primarily impacted by changes in SOM and any differences in leachate recovery were much less significant across both treatment types. The mineralisation of all pesticide formulations was comparatively slow, with <23 % of any given chemical/soil organic matter combination being mineralised over the experimental period. The highest mineralisation rates occurred in samples with the highest soil organic matter levels. The results also showed that 82.9 % ± 1.6 % of the acetamiprid applied was leached from the soil during repeated simulated rainfall events. This combined with the low sorption values, and the low rates of mineralisation, implies that acetamiprid is highly persistent and mobile within sandy soils. As a highly persistent neurotoxin with high invertebrate selectivity, the presence of neonicotinoids in soil presents a high toxicology risk to various beneficial soil organisms, including earthworms, as well as being at high risk of transfer to surrounding watercourses.
52. 题目: Enrichment of 13C with depth in soil organic horizons is not explained by CO2 or DOC losses during decomposition
作者: Michael Philben, Keri Bowering, Frances A Podrebarac, Jérôme Laganière, Kate Edwards, Susan E Ziegler
摘要: Stable isotope ratios of soil organic carbon (SOC) are a potentially powerful, integrative tool for analyzing the soil C cycle. However, limited understanding of the mechanisms for C isotope fractionation in soil prevents their widespread application. Soil organic carbon (SOC) is progressively enriched in 13C with age and depth in the soil profile even though CO2 produced during soil respiration is typically enriched in 13C compared to SOC. This results in an apparent mass balance paradox. To resolve this paradox, we hypothesized that the loss of 13C-depleted DOC during soil diagenesis, the combination of microbial decomposition and abiotic processes such as leaching, can account for the increase in SOC δ13C with depth. We combined three independent approaches (field measurements, a laboratory incubation experiment, and seasonal sampling of DOC across a climate transect) to systematically evaluate the relationship between the δ13C of soil respiration, DOC, and the SOC it is derived from. However, DOC was not significantly depleted in 13C compared to SOC in any of the three approaches, and mass balance calculations indicated that the DOC flux cannot account for the full extent of 13C enrichment of SOC with depth in the soil profile. We suggest that vertical C transport by plant roots or fungi, rather than diagenesis, may be largely responsible for the observed C isotope profile. Future studies aimed at understanding these vertical transport processes should enable increased application of soil δ13C, enhancing soil biogeochemical studies.
53. 题目: Hydrothermal carbonization improves the quality of biochar derived from livestock manure by removing inorganic matter
作者: Eun-Suk Jang, Do-Yoon Ryu, Daegi Kim
摘要: The application of hydrothermal carbonization to improve biomass-derived energy sources is crucial because of insufficient supplies of fossil fuels and concerns associated with the impact of fossil fuels on the environment. Hydrothermal carbonization technology has been developed to circumvent the energy-intensive drying step required for the thermal conversion of high-moisture organic feedstocks into fuel. In this study, the quality of livestock manure was upgraded, and its energy density was increased through hydrothermal carbonization at various temperatures. The evolution of waste biomass under hydrothermal carbonization was chemically analyzed. The increased carbon content of the resulting biochar upgraded its fuel properties, leading to energy savings in the treatment process. After hydrothermal carbonization, the H/C and O/C ratios were lower owing to chemical conversion. The optimal temperature for hydrothermal carbonization was approximately 220 °C. The inorganic content resulted in a lowered degree of agglomeration and reduced the likelihood of fouling during combustion. The thermogravimatric analysis also provided the changing combustion characteristics due to the increased fixed carbon content. Fourier transform infrared spectra revealed that hydrothermal carbonization reaction reduced the numbers of C–O and C–H functional groups and increased the number of aromatic C–H functional groups. The equilibrium moisture content decreased rapidly when hydrothermal carbonization was conducted at temperatures higher than 200 °C, and the initial moisture content was reduced by 75% after hydrothermal carbonization at 300 °C.
54. 题目: MgO-modified activated biochar for biojet fuels from pyrolysis of sawdust on a simple tandem micro-pyrolyzer
期刊: Bioresource Technology
作者: Hari Prasad Reddy Kannapu, Sumin Pyo, Su Shiung Lam, Jungho Jae, Gwang Hoon Rhee, Moonis Ali Khan, Byong-Hun Jeon, Young-Kwong Park
摘要: The aim of this work was to study on MgO-modified KOH activated biochar (AC) catalysts, in the pyrolysis of sawdust for the direct production of bio-jet fuels using a tandem micro-pyrolyzer. AC catalysts with various MgO contents (5 to 20 wt. %) were synthesized using an impregnation method. The mesopores generated (4 to 18 nm) in the carbon has a great potential in the conversion of oxygenated to jet fuel. The importance of basic nature in the catalysts is demonstrated with the maximum bio-jet fuel yield of 29 % at 10 % MgO. Further, the temperature of 600 °C and a catalyst/sawdust ratio of 10 are identified as the optimal conditions. The nanosize of MgO and the synergism of acid and base sites seemed to enhance deoxygenation, via decarboxylation and decarbonylation, and oligomerization, which are required for jet fuel formation in high amounts from sawdust pyrolysis.
55. 题目: Natural versus anthropogenic controls on the dissolved organic matter chemistry in lakes across China: insights from optical and molecular level analyses
期刊: Water Research
作者: Yingxin Shang, Zhidan Wen, Kaishan Song, Ge Liu, Fengfa Lai, Lili Lyu, Sijia Li, Hui Tao, Junbin Hou, Chong Fang, Chen He, Quan Shi, Ding He
摘要: Dissolved organic matter (DOM) plays an essential role in the global carbon biogeochemical cycle for aquatic ecosystems. The complexity of DOM compounds contributes to the accurate monitoring of its sources and compositions from large-scale patterns to microscopic molecular groups. Here, this study demonstrates the diverse sources and compositions for humic-rich lakes and protein-rich lakes for large-scale regions across China with the linkage to optical components and molecular high-resolution mass spectrometry properties. The total fluorescence intensity of colored DOM (CDOM) for humic-rich lake regions (0.176 Raman unit; R.U.) is significantly (p<0.05) higher than that of the protein-rich lake region (0.084 R.U.). The combined percentages of CDOM absorption variance explained by the anthropogenic and climatic variables across the five lake regions of Northeastern lake region (NLR), Yungui Plateau lake region (YGR), Inner Mongolia-Xinjiang lake region (MXR), Eastern lake region (ELR), and Tibetan-Qinghai Plateau lake region (TQR) were 86.25%, 82.57%, 80.23%, 88.55%, and 87.72% respectively. The averaged relative intensity percentages of CHOS and CHONS formulas from humic-rich lakes (90.831‰, 10.561‰) were significantly higher than that from the protein-like lakes (47.484‰, 5.638‰), respectively. The more complex molecular composition with higher aromaticity occurred in the humic-rich lakes than in the protein-rich lakes. The increasing anthropogenic effects would significantly enhance the sources, transformation, and biodegradation of terrestrial DOM and link to the greenhouse gas emission and the carbon cycle in inland waters.
56. 题目: Covering extracellular polymeric substances to enhance the reactivity of sulfidated nanoscale zerovalent iron toward Cr(VI) removal
期刊: Chemical Engineering Journal
作者: Yanni Xi, Yangtao Wu, Yanfen Liu, Tanghuan Xie, Huinian Liu, Zhu Su, Yicai Huang, Xingzhong Yuan, Chang Zhang, Xin Li
摘要: For effective removal and recovery of carcinogenic hexavalent chromium (Cr(VI)), we synthesized sulfidated nanoscale zerovalent iron@extracellular polymeric substances (SnZVI@EPS) with the aim of combining the respective advantages of EPS and SnZVI. EPS was introduced during the synthesis of SnZVI and successfully covered SnZVI, resulting in a larger specific surface area and better environmental friendliness of SnZVI@EPS over that of SnZVI (108.6362 vs. 10.9331 m2/g, 4.04-log vs. 6.42-log Escherichia coli reduction). SnZVI@EPS was more effective than SnZVI in removing Cr(VI) (64.90 mg/g vs. 43.76 mg/g), also under anaerobic, aerobic, wide pH, and high concentration of coexisting ions. The total Cr removal by SnZVI@EPS was higher than that of SnZVI (64.64 mg/g vs. 41.83 mg/g). The pseudo-second order model described well the adsorption process of SnZVI and SnZVI@EPS with equilibrium removal capacity of 44.21 and 66.18 mg/g for 20 mg/L Cr(VI) removal. Chemisorption and monolayer-based adsorption were dominated during Cr(VI) adsorption by SnZVI@EPS. The covered EPS provided better Cr(VI) removal and Cr(III) precipitation of SnZVI@EPS than SnZVI through the faster electron transfer, stronger solid-liquid reactions between SnZVI@EPS and Cr(VI), and additional binding sites for Cr(III)-Fe(III) coprecipitation. This work proved that environmental friendliness and efficient Cr(VI) removal and recovery of SnZVI can be improved by EPS modification.
57. 题目: Effect of biochar derived from biogas residue on methane production during dry anaerobic fermentation of kitchen waste
期刊: Waste Management
作者: Dongyang Li, Mengyang Sun, Jianfeng Xu, Tiancheng Gong, Meiying Ye, Yi Xiao, Tianxue Yang
摘要: Kitchen wastes (KW) dramatically increasing with population and economy enhancing, and dry anaerobic fermentation was used to treat it. However, the large amount of biogas residue severely restricted the application of dry anaerobic fermentation, because the high total solid might lead to the system failure. Therefore, it is urgent to find appropriate way to improve the efficiency of dry anaerobic fermentation and reduce the great amount of biogas residue. In this study, a tentative experiment was conducted to investigate the effect of biochar prepared from biogas residue on the performance of dry anaerobic fermentation system. The results showed that almost half of the biogas residue was reduced and converted into biochar. At the presence of biochar, methane yield was 308.6 mL/gVS, which was 10.5% higher than that of control. Compared to the system without biochar, the highest volatile fatty acid (VFA) concentration was 19.3% higher and the percentage of acetate and valerate was 25.3％ and 12.8％, while it was 16.3% and 22.0% in the control, suggesting that biochar accelerated the degradation of VFA. Bacteria community diversity increased, Fastidiosipila and Proteiniphilum enriched at the presence of biochar, which might accelerate the hydrolysis and acidification of KW. Hydrogenotrophic methanogens was dominated and syntrophic acetate oxidation was the primary pathway to produce methane. This study developed a new recycle route for improving the efficiency of dry anaerobic fermentation while reducing the large amount of biogas residue generated from dry anaerobic fermentation.
58. 题目: Complexation, retention and release pattern of arsenic from humic/fulvic acid extracted from zinc and iron enriched vermicompost
期刊: Journal of Environmental Management
作者: Sudip Sengupta, Kallol Bhattacharyya, Jajati Mandal, Asoke Prasun Chattopadhyay
摘要: Arsenic (As) is a highly poisonous heavy metal with major environmental ramifications. Inorganic components such as zinc (Zn) and iron (Fe), as well as organic vermicompost, have been used as management solutions, with limited attempts of using them together. The current study involved preparing non-enriched vermicompost as well as six distinct Zn and Fe enriched vermicomposts and analyzing their chemical composition using the standard procedures. Organic fractions from these seven vermicompost and arsenic polluted soils of West Bengal, India were recovered and separated into humic (HA) and fulvic acid (FA) fractions. Potentiometric titrations, viscometric assays, and visible spectrophotometry were used to characterize the HA and FA samples. In aqueous phase the stability constant (log K) of the complexes formed with As indicates that stability of FA extracted from enriched vermicompost V4 (Zn and Fe sulphate @ 10% w/w dry weight basis of composting substrates before application of vermiworms) was maximum as 10.20 with a mole ratio (x) value of 1.36. Fourier-transform infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM) studies confirmed the complexation of As with HA/FA. The release isotherm of As from the HA/FA complexes in the presence of competitive oxy-anions was found to follow the order of sulphate > nitrate > phosphate.
59. 题目: Quantifying pH buffering capacity in acidic, organic-rich Arctic soils: Measurable proxies and implications for soil carbon degradation
作者: Jianqiu Zheng, Erin C Berns-Herrboldt, Baohua Gu, Stan D Wullschleger, David E Graham
摘要: Dynamic pH change promoted by biogeochemical reactions in Arctic tundra soils can be a major control on the production and release of CO2 and CH4, which contribute to rising global temperatures. Large quantities of soil organic matter (SOM) in these soils are susceptible to microbial decomposition, leading to pH changes during permafrost thaw. Soil pH buffering capacity (β) modulates the extent of pH change but has not been thoroughly studied and represented in predictive ecosystem scale biogeochemical models in Arctic tundra soils. In this study, we generated titration curves for 21 acidic tundra soils from three Arctic sites across northern Alaska, United States of America. Geochemical and hydrological soil properties were evaluated, and correlations with β were developed. Strong correlations between β and both gravimetric water content (Θg) (R2 = 0.847, p < 0.001) and soil water retention (SWR) (R2 = 0.849, p = 0.001) indicate that the ability of soil to retain water could be associated with its buffering properties. Correlations between β and soil organic carbon (SOC) and cation exchange capacity (CEC) were also explored, and relationships to SWR are discussed. These correlations were then used with existing soil databases reporting SOC, CEC, and SWR to estimate β across Alaska soils. We further demonstrated the quantitative relationships between β and the simulated rates of biogeochemical reactions and show that lower β leads to higher soil pH and more CH4 production. Our study provides simple proxies for β in Arctic soils and highlights the importance and implications of representing soil buffering in predictive models, thereby enabling quantitative coupling between pH dynamics associated with biogeochemical reactions. Integrating β into predictive models of Arctic biogeochemical cycling may reduce model uncertainty and further our understanding of permafrost SOM degradation accelerated by warming.
60. 题目: Activation effect of catechol on biotic and abiotic factors of humus formation during chicken manure composting
期刊: Waste Management
作者: Haishi Qi, Jialin Wang, Linyuan Zhang, Lihua Chen, Yue Zhao, Zimin Wei
摘要: In this present study, catechol was added to promote humus formation in chicken manure composting using 12.5-L working volume lab-scale reactors. Chicken manure composting were carried out on two treatments, control (CK) and 0.5% (w/w) catechol treated group. Results showed that catechol addition reduced organic matter loss and improved the content of recalcitrant components. Humus and humic acid (HA) contents were, respectively, 69.2% and 82.3% higher in catechol treated-compost than in the control. With the addition of catechol, the bacterial community composition and richness was changed, e.g., the relative percentage of Bacillus and Sinibacillus were increased, which might contribute to humus and HA formation. Additionally, the activities of polyphenol oxidase and laccase (related to humus formation) were increased by the addition of catechol. Importantly, the catechol addition reduced the polyphenol content by 39.6% compared to control. Overall, the addition of catechol enhanced the biotic and abiotic factors to promote the humification process during composting, which might be a promising approach for accelerating the humification process and reducing contamination of phenolic compounds.