121. 题目: Evolution of physicochemical properties and bacterial community in aerobic composting of swine manure based on a patent compost tray
期刊: Bioresource Technology
作者: Yihui Wei, Zhengwu Liang, Yan Zhang
摘要: The objective of this study was to explore the changes in physicochemical properties and bacterial community during swine manure composting with a new compost tray (CT). The results showed that the organic matter (OM), moisture content (MC), and C/N decreased. The total Kjeldahl nitrogen (TKN), P2O5, K2O and humic acids (HAs) contents of the compost increased. The properties of the final compost product comply with the requirements of regulation except for the moisture according to NY/T 525-2012. Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes were the major phyla during the composting. Genus Terrisporobacter played a key role in degrading organic (OM). The content of K2O was main factors driving the succession of bacterial communities. These findings shed some novel lights into the dynamic changes of physicochemical propertied and their impact on bacterial community in a composting process.
122. 题目: Quantification of DOM effects on tetracyclines transport during struvite recovery from swine wastewater
期刊: Water Research
作者: Xuewei Huang, Zhi-Long Ye, Jiasheng Cai, Lifeng Lin
摘要: Struvite (MgNH4PO4•6H2O) recovered from livestock wastewater may impose a pharmacological threat to the environment, due to the extensive existence of antibiotics in the wastewater. In this study, tetracyclines (TCs) were selected as the typical antibiotics, and the individual processes of dissolved organic matters (DOM) evolution and their effects on TCs migration in struvite recovery from swine wastewater were discriminated and quantified. Results revealed that TCs transport was contributed by the adsorption of pure struvite crystals, struvite adsorbing DOM-TCs complex and DOM aggregation, which occupied 2.29%-6.53%, 23.53%-34.66%, and 59.09%-74.19% of the total TCs migration amounts, respectively. A tangential flow filtration system was employed to divide DOM into five fractional parts on the basis of molecular weight cut-offs. Experimental results indicated that under alkaline conditions of struvite crystallization, DOMs with larger molecular weights, hydrolyzed to DOMs with smaller molecular weights, which consequently promoted TCs re-distribution in DOMs from higher molecular weights to those with lower molecular weights. Furthermore, a distribution model was developed to characterize TCs transport in struvite recovery by describing TCs distribution among various phases, including struvite adsorption, DOM-TCs complexing, DOM aggregation, and free state in the solution, respectively. These outcomes provided new understanding on DOM evolution and effects on antibiotics transport in phosphate recovery from wastewater.
123. 题目: Insight into removals of PARAFAC components from dissolved and particulate organic matter in wastewater treatment process by two-dimensional correlation and structure equation modeling
期刊: Environmental Sciences Europe
作者: Benxin Yu, Dongping Liu, Jian Wang, Yingxue Sun
摘要: Background Most particulate organic matter (POM) cannot be directly degraded in the conventional wastewater treatment, which should be transformed into dissolved organic matter (DOM) through a hydrolysis process. However, non-hydrolyzed POM in the biological treatment can limit treated efficiencies for the wastewater treatment plants (WWTPs) facilities. Hence an operational tool is indispensable for insight into removals of DOM and POM factions in the WWTP. In this study, excitation-emission matrix fluorescence spectroscopy (EEM) combined parallel factor analysis (PARAFAC), two-dimensional correlation (2D-COS) and structural equation modeling (SEM) was employed to evaluate removals of DOM and POM in a wastewater treatment plant. Results Four fluorescence components were identified in DOM and POM substances from the WWTP by EEM combined with PARAFAC, i.e., tyrosine-like (TYLF), tryptophan-like (TRLF), microbial byproduct-like (MBLF), and fulvic acid-like (FALF). In A2/O process, the TYLF and TRLF of DOM were removed to a larger extent than those of MBLF and FALF in anaerobic tank, while TYLF and MBLF of POM were removed to a great extent than those of TRLF and FALF in primary sedimentation and aerobic tanks. By the 2D-COS, a decreasing variation order of DOM fractions in the wastewater treatment process was UV-FALF → MBLF2 → Vis-FALF → TRLF → TYLF, while the decreasing order of POM fractions was Vis-FALF → UV-FALF → MBLF2 → TYLF → MBLF1 → TRLF. SEM revealed that TRLF and TYLF of DOM were degraded by anaerobic microorganism, and TRLF could be transformed partially into FALF. However, TRFL and TYLF of POM were discomposed by aerobic microorganism. Conclusions The 2D-COS and SEM can be practicable tools as EEM-PARAFAC for monitoring DOM and POM in the WWTP. The study could present a theoretical support to improving the retrofit of WWTP and formulating emission standards for organic pollutants.
124. 题目: The impacts of intensive scallop farming on dissolved organic matter in the coastal waters adjacent to the Yangma Island, North Yellow Sea
期刊: Science of The Total Environment
作者: Bo Yang, Xuelu Gao, Jianmin Zhao, Lei Xie, Yongliang Liu, Xiaoqing Lv, Qianguo Xing
摘要: In-situ field investigations coupled with incubation experiments were conducted in the coastal waters adjacent to the Yangma Island to explore the impacts of intensive bay scallop farming on the quantity and composition of dissolved organic matter (DOM). During the scallop farming period, the values of dissolved organic carbon (DOC), chromophoric dissolved organic matter (CDOM) and fluorescence dissolved organic matter (FDOM) in the mariculture area (MA) were generally higher than those in the non-mariculture area (NMA). Bay scallops released a large amount of DOM with the characteristics of high molecular weight and low degree of humification into the water column through excretion, which altered the DOM biogeochemical cycle. The DOM excretion fluxes by scallop were calculated based on incubation experiments. The results showed that, without considering the DOM transformation in the water, the excretion process of bay scallops in a growth cycle can increase the concentration of DOC, CDOM and fluorescent components C1–C4 in the seawater in MA by 19.7 μmol l−1, 0.048 m−1, 0.065 QSU, 0.164 QSU, 0.017 QSU and 0.015 QSU, respectively. Assuming that the labile part of DOM excreted by scallops was completely aerobic decomposed, it could reduce DO and pH in the seawater by ~13.4 μmol l−1 and ~ 0.018 in MA. This study highlights the impact of human activities (scallop farming activities) on DOM cycle in coastal waters, which can help guide future policy formulating of mariculture and ecological protection.
125. 题目: Biochar aging: Impact of pyrolysis temperature on sediment carbon pools and the availability of arsenic and lead
期刊: Science of The Total Environment
作者: Matheus Bortolanza Soares, Carlos Eduardo Pellegrino Cerri, José A.M. Demattê, Luís Reynaldo Ferracciú Alleoni
摘要: Arsenic (As) and lead (Pb) are potentially toxic elements capable of developing several diseases in human beings such as cancer. Several adsorbent materials, including biochars, have been adopted as alternative measures designed to reduce the availability of As and Pb in water. The retention capacity of potentially toxic elements in biochars varies according to time, feedstock, and the pyrolysis temperature to produce the biochar. Our objectives in this study were to evaluate i) the aging effect of sugarcane straw pyrolyzed biochars at 350 (BC350), 550 (BC550), and 750 °C (BC750) and their ability to immobilize As and Pb; and ii) how the pyrolysis temperature and biochar aging alter the carbon content and quality of the solution and sediment. Biochars were applied at 5% (w/w), and their aging together with As and Pb immobilization effects were evaluated every 45 days over a total period of 180 days. The results were obtained using visible ultraviolet spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy combined with physical fractionation of organic matter and multivariate statistics. The groups formed in the Principal Component Analysis indicated that the change in the availability of As and Pb was related to the aging of the biochar and the temporal changes in the content and quality of organic carbon in the sediment and solution. The pyrolysis temperature was a key factor in the (im)mobilization capacity of As and Pb during the aging of the biochar. The increase in polysaccharides and organic matter associated with the particulate fraction can enhance the release of As in solution (24%). Increasing the fraction of organic matter associated with minerals reduced the availability of Pb by 58%. These findings may provide new insights into understanding the dynamics of organic matter and its role in the immobilization of As and Pb during biochar aging.
126. 题目: Plant mixture effects on carbon-degrading enzymes promote soil organic carbon accumulation
期刊: Soil Biology and Biochemistry
作者: Baogang Zhang, Yanjiang Cai, Shuijin Hu, Scott X. Chang
摘要: Microbial decomposition of soil organic carbon (SOC) is a major determinant of the global climate and terrestrial ecosystem services. Despite the rapid loss of plant species worldwide, it remains unclear how plant species richness impacts SOC decomposition, especially the decomposition of labile vs. recalcitrant SOC. This is partly because of the variable responses of soil C-degrading enzyme activities to plant species richness. Through a global meta-analysis of 490 paired observations of plant mixtures versus monocultures, we show that plant mixtures significantly enhanced soil C-hydrolase (degrades labile C) and C-oxidase (degrades recalcitrant C) activities by 29.4 and 14.9%, respectively. However, in mixtures, C-hydrolase activity marginally (P = 0.051) increased, while C-oxidase activity significantly decreased with plant species richness. In addition, in mixtures, C-hydrolase but not C-oxidase activity significantly increased with plant functional type richness and experimental duration. These plant species richness and functional type effects on C-hydrolase and C-oxidase activities were consistent among diverse terrestrial ecosystems, plant life forms, the presence/absence of legumes, and climate types. Moreover, increases in C-hydrolase but not C-oxidase activity were positively related with increasing microbial biomass C and SOC under plant mixtures, suggesting that faster microbial decomposition and transformation of labile C pools mediate SOC accumulation at higher plant species richness. These results highlight that plant species richness differentially affects labile and recalcitrant C-degrading enzymes, thereby influencing SOC decomposition, dynamics, and accumulation.
127. 题目: Evolution of the transport properties of soil aggregates and their relationship with soil organic carbon following land use changes
期刊: Soil and Tillage Research
作者: Feng Wang, Xiaoxian Zhang, Andrew L. Neal, John W. Crawford, Sacha J. Mooney, Aurélie Bacq-Labreuil
摘要: Aggregates are functional units to describe the impact of soil structural changes on physical and biogeochemical processes in soil. Both incubation and field experiments have shown that changing agricultural practices could reshape the intra-aggregate structure in a matter of days, but most such data were obtained from a single time-point and it is hence impossible to interpret that such a change was just a temporal transition or the new equilibria towards which the aggregates had evolved following the management changes. Understanding this is indispensable as intra-aggregate structure and its ability to transport substrates modulate all biogeochemical processes involved in soil carbon and nutrient cycle. This paper investigates this using soil samples archived from a reversion experiment initiated in 2008 at Rothamsted Research (UK), where parts of a plot that had been fallow since the 1950 s were converted to wheat or grass in 2008. We used X-ray Computed Tomography images, acquired at voxel size 1.5 µm, of aggregates in the archived soils to investigate the evolution of transport property of the aggregates over time, as well as its relationship with soil organic carbon (SOC). We also evaluated the development of pore connectedness following the conversion. The results show that the transport ability of the aggregates explains the SOC change much better than the porosity, and that noticeable changes in porosity of the connected pores and their ability to transport substrates did not emerge until the sixth year after the conversion. Ten years after the conversion, there was still no sign of the porosity of the connected pores and the bulk diffusion coefficient to plateau. In addition, we found the conversion to grass changed the intra-aggregate pore geometry significantly in that the bulk diffusion coefficients of their aggregates trends with their porosities in a way differing significantly from those for the bare fallow and arable treatments. All these suggest that the intra-aggregate reconfiguration following the conversion is a slow process, and that the ability of pore space to transport substrates is more important than the habitat they provide in SOC stabilisation.
128. 题目: Spatial Variability of Soil Organic Carbon and Total Nitrogen in Desert Steppes of China’s Hexi Corridor
期刊: Frontiers in Environmental Science
作者: Xuyang Wang, Yuqiang Li, Yulong Duan, Lilong Wang, Yayi Niu, Xiaohui Li, Meng Yan
摘要: Stock estimates are critical to quantifying carbon and nitrogen sequestration, quantifying greenhouse gas emissions, and understanding key biogeochemical processes (i.e., soil carbon and nutrient cycling). Many studies have assessed soil organic matter and nutrients in different ecosystems. However, the spatial distribution of carbon and nitrogen and the key influencing factors in arid desert steppe remain unclear. Here, we investigated the soil organic carbon ( SOC ) and soil total nitrogen ( STN ) to a depth of 100 cm at 126 sites in a desert steppe in northwestern China. SOC and STN contents decreased with increasing depth; the highest average SOC and STN contents were 12.70 and 0.65 g kg −1 in the surface 5 cm, and the lowest were from 80 to 100 cm (4.49 and 0.16 g kg −1 , respectively). SOC density ( SOCD ) and STN density ( STND ) to a depth of 100 cm averaged 8.94 and 0.45 kg m −2 , respectively. The top 1 m of the soils stored approximately 1,041 Tg SOC and 52 Tg STN in the study area. Geostatistical analysis showed strong and moderate spatial autocorrelation for SOCD in different soil layers, but the autocorrelation for STND gradually weakened with increasing depth. SOCD and STND decreased from southwest to northeast in the study area, along an elevation gradient. Both were significantly positively correlated with topographic variables, precipitation, and the normalized-difference vegetation index, but negatively correlated with temperature and aridity. More than 40% of the SOCD and STND spatial variation was explained by elevation, which was the dominant factor. The data and high-resolution maps from this study will support future soil carbon and nitrogen analyses.
129. 题目: Natural versus urban global soil organic carbon stocks: A meta-analysis
期刊: Science of The Total Environment
作者: Shih-Chieh Chien, Jennifer Adams Krumins
摘要: Increasingly, the human existence in urban environments is growing. In addition, anthropogenic activity has altered the global carbon (C) cycle and triggered climate change. Soil is the largest pool of organic C in terrestrial ecosystems, but its ability to retain and store C varies. As humans move forward to mitigate climate change, there is a growing need to understand the C storing capacity of soils and their interactions with factors like climate, vegetation or a footprint of human activity. Here, we constructed a meta-analysis which focused on 30 cm soil depth by collecting data from over 191 studies measuring soil organic carbon (SOC) stocks across natural, urban green space, and urban intensive habitats. We then compared the SOC data between different climatic zones, vegetation types, and anthropogenic influences with the human footprint index. The results indicate that SOC stocks in natural habitats (98.22 ± 49.10 Mg ha−1) are significantly higher than those of urban green spaces (54.61 ± 22.02 Mg ha−1) and urban intensive habitats (65.88 ± 35.27 Mg ha−1). We find a significant and negative relationship between the human footprint and SOC stocks of natural habitats but not between the human footprint and either of the urban habitats. Urban intensive and urban green space habitat soils store less C than natural ones. However, when compared across climatic zones or vegetation types, the capacity of natural soils to store C is variable and vulnerable to human activity. Carbon storage in urban soils is likely limited by persistent and stable anthropogenic influences keeping variability low. This is most pronounced in urban green spaces where human management is high (i.e. a golf course) and SOC is low. A comprehensive understanding of C storage in soils is essential to land management and climate mitigation measures.
130. 题目: Ozone Consumption by Soils: A Critical Factor in In Situ Ozonation Processes
期刊: ACS ES&T Water
作者: Zhian Ying, Yinon Yecheskel, Mingxin Huo, Uwe Hübner, Ines Zucker
摘要: In situ chemical ozonation (ISCO3), in which gaseous ozone is being injected into the subsurface, is a common method for remediating contaminated groundwater that is largely affected by the inevitable consumption of ozone by soil itself (rather than the target contaminants). In this study, ozone consumption by two main soil types of Israeli coastline aquifer was examined. Iron-rich soil showed considerably higher reactivity than did calcareous soil. We further investigated the effect of both physical and chemical soil characteristics on finite and catalytic ozone decay, hydroxyl-radical formation, and ozone transport behavior. Ozone consumption increased by >90% in the presence of fine soil particles (<100 μm), resulting from the large number of reactive sites and the higher content of ozone consumers compared to coarse soil particles. Soil organic matter consumed ozone twice as fast as iron components, promoted radical formation at higher rates, and mainly acted as a finite ozone consumer. In continuously fed column experiments, the reactions with iron components dominate catalytic ozone consumption during transport in porous media. Overall, this study demonstrates that the characterization of ozone reactions in soil can be helpful in evaluating the feasibility and efficiency of ISCO3 and inform the design of ISCO3 treatment, e.g., the need to inject additional radical promoters.
131. 题目: Adsorption of norfloxacin from aqueous solution on biochar derived from spent coffee ground: Master variables and response surface method optimized adsorption process
作者: Van-Truc Nguyen, Thi-Dieu-Hien Vo, Thanh-Binh Nguyen, Nguyen Duy Dat, Bui Trung Huu, Xuan-Cuong Nguyen, Thanh Tran, Thi-Ngoc-Chau Le, Thi-Giang-Huong Duong, Manh-Ha Bui, Cheng-Di Dong, Xuan-Thanh Bui
摘要: In this study, biochar derived from spent coffee grounds (SCGB) was used to adsorb norfloxacin (NOR) in water. The biochar properties were interpreted by analysis of the specific surface area, morphology, structure, thermal stability, and functional groups. The impacts of pH, NOR, and ion's present on SCGB performance were examined. The NOR adsorption mode of SCGB is best suited to the Langmuir model (R2 = 0.974) with maximum absorption capacity (69.8 mg g−1). By using a Response Surface Method (RSM), optimal adsorption was also found at pH of 6.26, NOR of 24.69 mg L−1, and SCGB of 1.32 g L−1. Compared with biochars derived from agriculture such as corn stalks, willow branches, potato stem, reed stalks, cauliflower roots, wheat straw, the NOR adsorption capacity of SCGB was 2–30 times higher, but less than 3–4 times for biochars made from Salix mongolica, luffa sponge and polydopamine microspheres. These findings reveal that spent coffee grounds biochar could effectively remove NOR from aqueous solutions. Approaching biochar derived from coffee grounds would be a promising eco-friendly solution because it utilizes solid waste, saves costs, and creates adsorbents to deal with emerging pollutants like antibiotics.
132. 题目: Sustainable production of value-added sulfonated biochar by sulphuric acid carbonization reduction of rice husks
期刊: Environmental Technology & Innovation
作者: Zhimao Zhou, Daqing Yao, Shifei Li, Fei Xu, Ying Liu, Ruixia Liu, Zhaohui Chen
摘要: Biochar is an effective vehicle for sequestering carbon and mitigating the greenhouse gas effect as a way to combat climate change. Currently pyrolysis is the main treatment method to prepare biochar, and generally only half of the carbon (C) can be retained in the pyrolytic biochar. In this paper, we introduce a new low-cost method for the preparation of biochar from biomass by one-step carbonized reduced sulfuric acid. The results show that the carbonization reaction of rice husk with alkylated waste sulfuric acid can yield more than 80% of biochar, which is much higher than the pyrolysis biochar. Besides, the prepared biomass sulfonated char has abundant functional groups including ￼SO3H, ￼OH and exhibits excellent adsorption performance for Cd2+ with the maximum adsorption capacity of 93.98 mg/g. In conclusion, the method used in this paper to prepare sulfonated biochar has fewer steps, a lower processing cost and higher value-added products, thus making it more sustainable and economical, and supporting a wider range of sulfuric acid carbonization methods. It has the potential to inspire and lead the way for the safe, economical and sustainable preparation of value-added sulphonated carbon materials for commercial applications.
133. 题目: Effect of biochar combined with a biotrickling filter on deodorization, nitrogen retention, and microbial community succession during chicken manure composting
期刊: Bioresource Technology
作者: Yinchao Li, Jun Ma, Xiaoyu Yong, Liwen Luo, Jonathan W.C. Wong, Yabing Zhang, Hao Wu, Jun Zhou
摘要: The high-nitrogen content and dense structure of poultry manure compost cause volatilization of N to ammonia (NH3). This study evaluated the combined application of biochar and biotrickling filtration (BTF) to remove of odor in chicken manure mixed straw compost (w/w, 2.5:1). Adding of 10% biochar reduced NH3, hydrogen sulfide (H2S), and total volatile organic compounds (TVOCs) contents by 20.04%, 16.18%, and 17.55% respectively, and decreased the N loss rate by 8.27%, compared with those observed in control. The organic matter content decreased by 28.11% and germination index reached 97.36% in the experimental group. Meanwhile, the N-cycling microorganisms such as Pusillimonas and Pseudomonas became more active, and the relative abundance of sulfur-cycling microorganisms Hydrogenispora decreased in the experimental group. Following BTF application, the NH3, H2S, and TVOCs removal rates reached 95%, 97%, and 53%, respectively.
134. 题目: Dynamics and composition of soil organic carbon in response to 15 years of straw return in a Mollisol
期刊: Soil and Tillage Research
作者: Xiangxiang Hao, Xiaozeng Han, Shouyu Wang, Lu-Jun Li
摘要: Crop straw return is being widely applied as a sustainable soil management practice to improve soil organic carbon (SOC) storage in intensive agricultural ecosystems. However, the dynamics and chemical composition of SOC under long-term straw return are not fully understood. Based on a 15-year field experiment with soybean (Glycine max (L.) Merrill.)–maize (Zea mays L.) cropping system, we studied SOC temporal dynamics under no fertilization (NF), mineral fertilizers (NPK) and mineral fertilizers with straw return (NPKS). Meanwhile, we determined five labile carbon (C) pools, i.e., microbial biomass C (MBC), water-soluble organic C (WSOC), light fraction C (LFC), readily oxidizable organic C (ROC), and particulate organic C (POC), as well as δ13C values and organic functional groups of soil organic matter (SOM). After 15-year application of continuous straw return with mineral fertilizer application, SOC content increased by 14.2%. The δ13C values of SOC increased with time under all treatments, and its positive relationship with cumulative maize C input indicated a larger C contribution to SOC from maize than soybean residues. The NPKS treatment significantly increased the contents of MBC, WSOC, LFC, ROC, and POC and their proportion in SOC, compared with the NF treatment. The aliphatic and aromatic relative peak areas were significantly affected by straw return, with an increasing relative peak area at 2930 cm−1 and decreasing at 1620 cm−1, respectively. Our results demonstrate that straw return could continuously increase SOC in an inter-annual rotation of soybean and maize cropping system in Mollisol. Meanwhile, long-term fertilization can alter SOM chemical composition, with lower humification degree under the combined application of straw and mineral NPK fertilizers.
135. 题目: Soil nitrification and nitrogen mineralization responded non-linearly to the addition of wood biochar produced under different pyrolysis temperatures
期刊: Journal of Soils and Sediments
作者: Ashrafun Nessa, Shahla Hosseini Bai, Dianjie Wang, Zakaria Karim, Negar Omidvar, Juan Zhan, Zhihong Xu
摘要: Purpose Nitrogen (N) cycle is one of the key biogeochemical cycles in terrestrial ecosystems. Global climate change and soil management practices have disrupted the soil N cycling processes due to increased water and N limitations. Biochar is a soil amendment and improves soil–plant water and N retentions. However, it is uncertain to what extent biochar pyrolysis temperature would affect soil N transformations under two soil moisture regimes. This study aimed to explore how pyrolysis temperature would affect biochar properties and subsequently soil N transformations through a short-term laboratory incubation study at two moisture levels. Materials and methods An incubation study was carried out for 5 days. Biochar added to the soil at a rate of 5% (w/w) was produced under six different pyrolysis temperatures (e.g., 500, 600, 650, 700, 750, and 850 °C). We used 15N natural abundance (δ15N) of inorganic N (NH4+-N and NO3−-N) to assess the potential of biochar materials in facilitating forest soil N transformations at two different soil moisture levels of 50% and 65% water holding capacity (WHC). Results and discussion Pyrolysis temperature significantly increased cumulative nitrification and N mineralization initially, peaked between 600 and 700 °C and decreased thereafter. However, both cumulative nitrification and N mineralization were significantly lower in the biochar-amended soils than those of the control soil, with significantly lower δ15N of NH4+-N and δ15N of NO3−-N. The 65% WHC had higher cumulative nitrification and N mineralization compared with those in 50% WHC. This study highlights that application of biochar would reduce N losses and improve soil N retention particularly for forest soil. Conclusions The present study highlights the importance of biochar pyrolysis temperatures for their use as soil conditioner to increase soil N retention. An optimum pyrolysis temperature range of 600–700 °C was identified for improving soil nitrification and N mineralization under the laboratory incubation conditions.
136. 题目: Sieving soil before incubation experiments overestimates carbon mineralization but underestimates temperature sensitivity
期刊: Science of The Total Environment
作者: Zheng-Rong Kan, Wen-Xuan Liu, Wen-Sheng Liu, Cong He, N'dri Yves Bohoussou, Yash Pal Dang, Xin Zhao, Hai-Lin Zhang
摘要: The sensitivity of soil organic carbon (SOC) mineralization to temperature could affect the future atmospheric CO2 levels under global warming. Sieved soils are widely used to assess SOC mineralization and its temperature sensitivity (Q10) via laboratory incubation. However, sieved soils cause a temporary increase in mineralization due to the destruction of soil structure, which can affect estimates of SOC mineralization, especially in soils managed with no-till (NT). To identify the effects of soil sieving on SOC mineralization and Q10, soil was collected from an 11-year field experiment under a wheat-maize cropping system managed with a combination of tillage [NT and plow tillage (PT)] and residue [residue returning (RR) and residue removal (R0)]. Soil was either sieved or left in an undisturbed state and incubated at 15 °C and 25 °C. SOC mineralization in sieved soils at 25 °C was 47.28 g C kg−1 SOC, 160.1% higher than SOC mineralization in undisturbed soils (P < 0.05). Interestingly, Q10 values in sieved soils were 1.29, 77.6% lower than Q10 in undisturbed soils (P < 0.05). Highly significant correlations (P < 0.01) were observed between sieved and undisturbed soils for SOC mineralization (r = 0.85–0.98) and Q10 (r = 0.78–0.87). Soil macro-aggregates had lower SOC mineralization by 6.1–21.9%, but higher Q10 values by 4.7–6.5% compared with micro-aggregates, contributing to lower mineralization and higher Q10 under NT and RR. Furthermore, structure equation and random forest modelling showed that increased SOC contents in NT and RR could not only reduce SOC mineralization, but also constrained the improvement of Q10 in NT and RR. Overall, these results indicated that although sieved soils overestimated SOC mineralization and underestimated Q10 due to the destruction of macro-aggregates, the patterns between treatments were similar and sieving soil for incubation is considered as a suitable approach to evaluate the relative impacts of NT and RR on SOC mineralization and Q10.
137. 题目: Arbuscular mycorrhizal symbiosis enhances water stable aggregate formation and organic matter stabilization in Fe ore tailings
作者: Zhen Li, Songlin Wu, Yunjia Liu, Qing Yi, Fang You, Yuanying Ma, Lars Thomsen, Ting-Shan Chan, Ying-Rui Lu, Merinda Hall, Narottam Saha, Yuanfang Huang, Longbin Huang
摘要: Organo-mineral association and water-stable aggregation in finely textured tailings are critically important to the eco-engineered soil formation from alkaline Fe ore tailings for sustainable mine site rehabilitation. Arbuscular mycorrhizal (AM) symbiosis plays important roles in soil aggregate formation and organic matter (OM) stabilization. However, it is unknown if AM symbiosis could enhance aggregate formation and OM stabilization in alkaline Fe ore tailings. The present study aimed to investigate the establishment of AM symbiosis and their role in tailing aggregate formation coupled with OM stabilization, as well as the underlying mechanisms. After initial eco-engineering (OM amendment and pioneer plant cultivation) to improve physicochemical conditions for plant survival, Sorghum spp. Hybrid cv. Silk inoculated with/without AM fungi (Glomus spp.) were cultivated in the tailings under glasshouse conditions for 14 weeks. The results indicated that AM fungi formed symbiotic association with Sorghum spp. plants, improved mineral nutrient (e.g., P) acquisition and root growth in the eco-engineered tailings. The AM symbiosis significantly improved aggregate formation. The association of organic carbon and nitrogen with tailing minerals of the aggregates was enhanced by the AM symbiosis. As revealed by synchrotron-based C 1 s near edge X-ray absorption fine structure (C 1 s NEXAFS) and Fe K edge X-ray absorption fine structure (Fe K edge XAFS) spectroscopy, the AM symbiosis favoured carboxyl and aromatic C association with secondary Fe-Si minerals, which may have been formed from AM driven mineral weathering. Overall, the study revealed that the AM symbiosis could not only improve the growth of pioneer plant species in the early eco-engineered tailings, but also advance soil formation through enhancing organic C and N sequestration and physical structure development via water-stable aggregation. These findings help to advance our understanding of the importance of AM symbiosis in the eco-engineering of tailings into functional soil (or technosols) for sustainable rehabilitation of Fe-ore tailings.
138. 题目: Elevated temperature altered the binding sequence of Cd with DOM in arable soils
作者: Xiping Hu, Chenchen Qu, Yafeng Han, Wenli Chen, Qiaoyun Huang
摘要: Dissolved organic matter (DOM) is one of the most active soil components, which plays pivotal roles in the migration and fate of heavy metals in soils. The interactions of heavy metals with DOM are controlled by the structure and properties of DOM. The changes of temperature have a significant effect on the content and composition of DOM and thus may affect the binding nature of heavy metals with DOM. In the current study, we conducted a 180-d incubation experiment with an arable soil at temperatures of 15, 30 and 45 °C. Fluorescence spectroscopy was used to examine the composition of DOM and two-dimensional correlation spectroscopy was applied to determine the binding intensity and sequence between cadmium (Cd) with DOM. Two humic-like substances (C1, C3) and a protein-like substance (C2) were identified from soil DOM. Elevated temperature changed the characteristic and structure of DOM. The humification degree and aromaticity of DOM increased from 15 °C to 30 °C but decreased at high temperature (45 °C). The alterations in temperature exert no impact on the type of organic functional groups in DOM binding with Cd. However, elevated temperature changed the binding sequence of Cd with DOM fractions. Polysaccharide, phenolic, and aromatic groups exhibited the fastest response to Cd at 15, 30, and 45 °C, respectively. These observations would provide a better understanding on the environmental behavior of Cd in arable soils under the context of global warming.
139. 题目: Persulfate adsorption and activation by carbon structure defects provided new insights into ofloxacin degradation by biochar
期刊: Science of The Total Environment
作者: Hao Li, Yi Liu, Feng Jiang, Xing Bai, Huijie Li, Di Lang, Lin Wang, Bo Pan
摘要: Cellulose and lignin derived biochars with significant differences in persistent free radicals (PFRs), oxygen-containing functional groups, and defective structure were prepared to explore the mechanism of biochar mediated persulfate (PS) activation. EPR spin trapping and quenching technique coupled with degradation experiments confirmed that the defective structures could activate PS to generate superoxide anions (O2•−), which was converted to singlet oxygen (1O2), especially in the acidic condition. 1O2 dominated the degradation of ofloxacin (OFL, a fluoroquinolone antibiotic). An improved iodometric measurement was applied for direct quantification of adsorbed PS on biochar. The amounts of adsorbed PS were consistent with the degradation of OFL and the measured electric current during the reaction indicated that PS adsorption was a prerequisite for PS activation, which may be neglected in previous studies. The results of this study highlighted the key roles of defective structure and adsorption of PS on biochar for the activation of PS.
140. 题目: Weak electrical stimulation on biological denitrification: Insights from the denitrifying enzymes
期刊: Science of The Total Environment
作者: Xinyi Dong, Hongbo Liu, Shiping Long, Suyun Xu, Eric Lichtfouse
摘要: In order to improve the denitrification efficiency of low carbon to nitrogen ratio (C/N) wastewater, we conducted continuous flow experiments of weakly electrically stimulated denitrification using a direct current output voltage. The results showed that the best denitrification was achieved at a voltage of 0.2 V. The removal of nitrate and total nitrogen was increased by 20% and the production of intermediate greenhouse gas (N2O) was reduced by 62.6%. We explored the specific pathways involved in the weak electrical stimulated denitrification using enzyme activity as a cut-off point. The enzyme activity analysis and 3D fluorescence spectroscopy revealed that nitrate reductase (NAR) and nitrite reductase (NIR) activities were significantly enhanced by weak electrical stimulation, and the aromatic protein content in extracellular polymers substances (EPS) increased, accelerating electron transfer and promoting the conversion of loosely bound EPS (LB) to tightly bound EPS (TB). The accelerated electron transfer further increased enzyme activity and the metabolic rate of microorganisms. This study indicates that weak electrical stimulation could improve activities of biological enzymes to enhance denitrification efficiency.