181. 题目: High nitrogen enrichment increases the allocation of new organic carbon to deep soil layers
作者: Hanxia Yu, Xiaoshu Wei, Wenbing Tan
摘要: The response of soil organic carbon (SOC) dynamics to nitrogen enrichment in the scale of whole-soil profiles, especially in deeper soil layers containing approximately half of SOC, remains unclear. Here, the incorporation of new vegetation-derived carbon into whole-soil profiles is estimated by combining natural stable isotopes (13C and 15N) with radiocarbon analyses under elevated nitrogen inputs with field experiments. The new mechanism responsible for nitrogen-induced carbon sinking in soils is the increased allocation of new carbon to deep soil layers at high nitrogen enrichment resulting from enhanced vertical transport of SOC. Our work provides an unprecedented representation of deep carbon dynamics under elevated nitrogen input and thus supports the development of policies on soil carbon management.
182. 题目: Soil salinity and nutrients availability drive patterns in bacterial community and diversity along succession gradient in the Yellow River Delta
期刊: Estuarine, Coastal and Shelf Science
作者: Yong Li, Enze Kang, Bing Song, Jinsong Wang, Xiaodong Zhang, Jinzhi Wang, Meng Li, Liang Yan, Zhongqing Yan, Kerou Zhang, Haidong Wu, Xiaoming Kang
摘要: Exploring the main driving factors of microbial community in different succession stages of coastal wetland could provide insights into ecological restoration activities. The present study examined the soil microbial assemblage in a succession gradient of the coastal wetland in the Yellow River Delta (YRD) and elucidated the contributions of spatial structure, vegetation, and soil properties to microbial communities. Plant and soil samples in four succession stages from (S1, S2, S3, and S4) were selected in the coastal wetland of YRD. Soil bacterial community was analyzed using the 16S rRNA high-throughput sequencing technique. Partial mantel test and redundancy analysis were conducted to elucidate the relationship between bacterial community structure and environmental parameters. Soil pH and salinity decreased and soil nutrients increased with succession from mud flat to the late stage. Higher bacterial richness and diversity were also observed with coastal wetland succession. Although most of the soil properties, vegetation, and spatial distribution have an impact on the bacterial community, soil salinity and nutrient availability (e.g., total nitrogen content, nitrate content and dissolved organic carbon) have the greatest influence on the shift in the bacterial community along the succession gradient. Taken together, soil salinity and nutrients availability could be major drivers of variations in bacterial assemblage with coastal wetland succession. These findings improve our understanding of soil microbes as affected by environmental factors and microbial diversity could be considered as a helpful tool to evaluate the efficiency of ecological restoration in coastal wetlands.
183. 题目: Electrosorption of cadmium and arsenic from wastewaters using nitrogen-doped biochar: Mechanism and application
期刊: Journal of Environmental Management
作者: Shiwei Lin, Xiong Yang, Lihu Liu, Anyu Li, Guohong Qiu
摘要: Biochar has been widely applied as an adsorbent, whose electrochemical capacity and heavy metal adsorption performance can be improved by nitrogen doping. In this work, nitrogen-doped biochar (NBC) was synthesized by calcinating sodium humate with sodium bicarbonate (NaHCO3) and urea as the activation agent and nitrogen source, respectively. The NBC was then used to electrochemically adsorb Cd(II) and As(III,V) from simulated and actual wastewaters, respectively. The results indicated that NaHCO3 activation and nitrogen doping could increase the surface area and nitrogen content of the biochar, contributing to the enhancement of adsorption performance for Cd(II) and As(III,V). The electrosorption capacities for Cd(II) and total arsenic (As(T)) increased first and then reached equilibrium with increasing nitrogen content, increased first and then decreased with increasing calcination temperature, and consistently increased with increasing voltage. The Cd(II) electrosorption capacity (79.0 mg g−1) and As(T) removal ratio (94.0%) at 1.2 V in actual As-contaminated wastewater (1.16 mg L−1) were about 4 and 2.6 folds of their inorganic adsorption capacities, respectively. After five cycles of reuse, the Cd(II) and As(T) removal ratio could be maintained at 65.8% and 51.7% of the initial electrosorption capacity. This work expands the application of NBC for heavy metal removal.
184. 题目: Biochars intended for water filtration: A comparative study with activated carbons of their physicochemical properties and removal efficiency towards neutral and anionic organic pollutants
作者: Michele Castiglioni, Luca Rivoira, Irene Ingrando, Lorenza Meucci, Rita Binetti, Martino Fungi, Ayoub El-Ghadraoui, Zaineb Bakari, Massimo Del Bubba, Maria Concetta Bruzzoniti
摘要: Seven biochars (BCs) obtained from pyrolysis or gasification of different vegetal feedstocks were thoroughly characterized in comparison with three commercial activated carbons (ACs) routinely used in drinking water treatment plants. BCs and ACs characterization included the determinations of ash, iodine and methylene blue adsorption indexes, and the release of metals and polycyclic aromatic hydrocarbons, which were performed according to international standards applied for adsorption media to be used in drinking waters. Total specific surface area, micropore and mesopore specific surface area, pH of the point of zero charge, and the release of polychlorinated biphenyls were also determined in all chars. Principal component analysis and cluster analysis were performed in order to summarize the complex set of information deriving from the aforementioned characterizations, highlighting the BC most similar (BC6 from high temperature gasification of woody biomass) and most different (BC7 from low-temperature pyrolysis of corn cob) from ACs. These BCs were studied for their adsorption in ultrapure water towards diiodoacetic acid (an emergent disinfection by-product), benzene, and 1.2-dichlorobenzene, in comparison with ACs, and results obtained were fitted by linearized Freundlich equation. Overall, BC6 showed higher sorption performances compared to BC7, even though both BCs were less performing sorbents than ACs. However, the sorption properties of BCs were maintained also in real water samples collected from drinking water treatment plants.
185. 题目: Seasonal trace metal distribution, partition and fluxes in the temperate macrotidal Loire Estuary (France)
期刊: Estuarine, Coastal and Shelf Science
作者: Nicolas Briant, Jean-François Chiffoleau, Joël Knoery, Daniel F. Araújo, Emmanuel Ponzevera, Sylvette Crochet, Bastien Thomas, Christophe Brach-Papa
摘要: Estuaries can be considered as biogeochemical reactors, acting both as sinks or sources for trace metals depending on environmental factors. Distribution of dissolved and particulate Cd, Co, Cu, Mn, Ni, and Zn were determined in samples collected from the Loire river estuary (France) during seasonal contrasting flow conditions (summer, spring and winter). Mean concentrations of dissolved Cd (0.13 ± 0.07 nM) were below concentrations previously observed in the estuary, while Cu (23.00 ± 8.07 nM) concentrations were similar to those found ten years ago. The results also demonstrated a wide fluctuation of the TMZ (Turbidity Maximum Zone) following the water discharge conditions and various reactivity behaviours depending on the type of metal even if all metals presented stable log KD values along the estuary. Rapid adsorption of suspended matter occurs at the salinity front, and only Ni and Cu are conservative through the salinity gradient. Organic matter appeared to be a major factor in metals fractioning and its role though the estuary is discussed. Riverine particulate and dissolved metal inputs, and estuary dissolved efflux have been estimated, and show a large export of Cu and Zn to the sea. However, the Loire river outputs only play a minor contribution to the ocean at the global scale. These results provide unique information concerning the contemporary distribution of dissolved and particulate trace metals in the Loire estuary, and provide a geochemical baseline dataset to assess the evolution of historical contaminants in the estuary. Ongoing studies on emerging metallic elements must be carried out to understand the impact of urban development in this part of the river.
186. 题目: Performance study of fouling resistant novel ultrafiltration membranes based on the blends of poly (ether ether sulfone)/poly (vinyl pyrrolidone)/nano-titania for separation of humic acid, dyes and biological macromolecular proteins from aqueous solutions
期刊: Journal of Hazardous Materials
作者: Jenet George, Maheswari Purushothaman, Isita Singh, Ishani Singh, Vinoth Kumar Vaidyanathan
摘要: This study explains the use of a ultrafiltration membrane made of polyvinyl pyrrolidone (PVP) and poly(ether ether sulfone) (PEES)/Nano-titania (n-TiO2) for the organic compounds separation. The results of the porosity, water content, surface chemistry, membrane morphology, and contact angle demonstrate that the developed membranes have more hydrophilicity than PEES membranes due to the redundant hydrophilic nature of PVP and n-TiO2. The membrane's pure water flux, which contains 5 wt% PVP and 1.5 wt% n-TiO2, was 312.76 Lm–2h–1, about three-fold that of pristine membrane (95.71 Lm–2h–1). Employing bovine serum albumin as a model foulant, the fouling resistance of the PEES/PVP/n-TiO2 membrane was examined. According to the analysis of flux recovery ratio and irreversible resistance, modified membranes are less likely to foul, and the PEES/n-TiO2 membrane with 5% PVP addition was recommended as optimal. The fabricated membranes effectively removed more than 95% of various organic compounds such as humic acid, safranin O, egg albumin, pepsin, and trypsin from aqueous solution. Permeability of safranin O and humic acid of PEES/PVP/n-TiO2 membranes was about 118 Lm–2h–1 and 138 Lm–2h–1, respectively.
187. 题目: Performance of field‐scale lab vs in situ visible/near‐ and mid‐infrared spectroscopy for estimation of soil properties
期刊: European Journal of Soil Science
作者: Isabel Greenberg, Michael Seidel, Michael Vohland, Bernard Ludwig
摘要: Comparison of laboratory vs in situ visible/near- (visNIR) and mid-infrared (MIR) spectroscopy for prediction of various soil properties is required to demonstrate trade-offs between accuracy and efficiency. Field visNIR (ASD FieldSpec 3 Hi-Res) and MIR (Agilent Technologies 4,300 Handheld FTIR) measurements were made on an arable field in Germany (silt loam Haplic Luvisol) and material was collected for lab visNIR (Foss XDS Rapid Content Analyzer) and MIR (Bruker-TENSOR 27) measurements on dried and ground soil and determination of total, labile (>63 μm light), stabilized (>63 μm heavy + <63 μm oxidizable), and resistant organic carbon (OC) content, total nitrogen (Nt), pH and texture. Partial least squares regression models were calculated for five repeated partitions of the dataset (n = 238) into training (75%) and test (25%) sets. Lab spectral models outperformed in situ models for total OC (root mean squared error (RMSE) = 0.24–1.0 g kg−1), Nt (RMSE = 0.026–0.088 g kg−1), pH (RMSE = 0.12–0.28) and texture (RMSE = 0.53–1.5%). For both lab and field spectra, the accuracy of visNIR models was comparable or slightly better than MIR for sand, silt and clay. Spectral estimations for labile (RMSE = 0.34–0.47 g kg−1) and stabilized OC (RMSE = 0.41–0.85 g kg−1) were slightly (lab spectra) to substantially (field spectra) inferior to estimations from multiple linear regressions using total OC, Nt, clay and pH as predictors. Variable importance in the projection scores elucidated differences in spectral prediction mechanisms by spectrometer and OC fraction, and found mineral spectral signatures were highly important. For this field-scale study with 14% median soil gravimetric water content (GWC), the loss of accuracy from lab to field measurement was lower for visNIR than MIR. Analysis of the driest soils (<9% GWC) found field MIR outperformed field visNIR for OC and Nt estimation and vice versa for the wettest soils (>18%), demonstrating the moisture dependence of performance rankings.
188. 题目: Disentangling the abiotic versus biotic controls on C3 plant leaf carbon isotopes: Inferences from a global review
期刊: Earth-Science Reviews
作者: Sayak Basu, Sambit Ghosh, Debarati Chattopadhyay
摘要: The carbon isotopic composition of C3 plant leaf tissue (δ13CC3) provides insights into carbon cycling, climate, and vegetation at various spatiotemporal scales. By disentangling the competing influences of climatic and biological factors, modern δ13CC3 calibrations can offer quantitative constraints on their applications. In this work, we examined the response of δ13CC3 values to rainfall, temperature, and atmospheric CO2 concentration (pCO2) across wide range of ecosystem gradients. Towards this, we prepared a global database of bulk (δ13CC3-Bulk, n = 737) and n-alkane (δ13CC3-C29, n = 831) δ13C values from species-level C3 plants for various plant functional types (PFTs). The δ13CC3-Bulk and δ13CC3-C29 values refer to carbon isotopic composition of total organic carbon and the C29 homologue of C3 plant leaves, respectively. The PFTs were classified according to their leaf senescence (deciduous versus evergreen), seed cover (angiosperm versus gymnosperm), and growth forms (tree, shrub, herb, grass, forb, etc.). Though rainfall is commonly believed to be the major driver of δ13CC3 variability, our work demonstrated that, at the species level, it only influences δ13CC3-Bulk values of evergreen shrubs (R2 = 0.47, p < 0.05) and grasses (R2 = 0.26, p < 0.05). Across a gradient from 251 to 398 ppm, pCO2-effect is apparent only on the δ13CC3-Bulk values of deciduous shrubs (R2 = 0.32, p < 0.05), while δ13CC3 values of other plant types are insensitive to low pCO2 conditions. For the first time, we showed that both species-level δ13CC3-Bulk and δ13CC3-C29 values of many PFTs are affected by annual temperature. Our meta-analysis provided evidences for a weak yet significant temperature effect on the δ13CC3 values of deciduous herbs (δ13CC3-Bulk: R2 = 0.18, p < 0.05; δ13CC3-C29: R2 = 0.11, p < 0.05) and evergreen angiosperm trees (δ13CC3-Bulk: R2 = 0.17, p < 0.05; δ13CC3-C29: R2 = 0.17, p < 0.05). We also observed that combined increase in annual rainfall and temperature can negatively drive the δ13CC3 values of evergreen shrubs (δ13CC3-Bulk: adjusted R2 = 0.61, p < 0.05; δ13CC3-C29: adjusted R2 = 0.25, p < 0.05) and deciduous angiosperm trees (δ13CC3-Bulk: adjusted R2 = 0.32, p < 0.05; δ13CC3-C29: adjusted R2 = 0.38, p < 0.05), and δ13CC3-Bulk values of grasses (adjusted R2 = 0.61, p < 0.05). Overall, our results suggest the abiotic stressors (included in this work) can explain 12–61% and 0–38% of the total variations in the δ13CC3-Bulk and δ13CC3-C29 values, respectively. We propose that using PFT-specific δ13CC3 values-abiotic stressor relationship, instead of a generalized relationship for all types of C3 plants, will add more certainty in paleoenvironment reconstructions and isotope-based PFT model preparation.
189. 题目: Remediation of metal-contaminated mine tailings by the application of organic and mineral amendments
期刊: Journal of Soils and Sediments
作者: Leila Benidire, Sofia Pereira, Wafae Aboudrar, Mohamed Hafidi, Paula Castro, Ali Boularbah
摘要: Purpose Tailings are generally characterized by severe physicochemical conditions that limit the establishment of vegetation. The present study aimed to select suitable combinations of organo-mineral amendments to improve the physicochemical, biochemical, and biological properties of spolic technosols, highly contaminated with metals. Materials and methods Several substrates were prepared by mixing mine tailings (MT) of an abandoned mining area with non-contaminated agricultural soil (anthrosol), green waste compost, lime, and rock phosphate at different rates: S1 — 50% of MT + 50% of agricultural soil; S2 — S1 + 3% of lime (CaCO3); S3 — S1 + 6% of rock phosphate; S4 — S1 + 10% of compost; S5 — S1 + 10% of compost + 3% of lime; S6 — S1 + 10% of compost + 6% of rock phosphate. Untreated MT and agricultural soil were analyzed immediately, and 8 months after incorporating the amendments. Results and discussion Heterotrophic microorganisms were not recovered from untreated MT due to the highly acidic pH and available metal concentrations. However, the addition of organo-mineral amendments ameliorated the tailings’ characteristics by increasing pH, conductivity, total organic carbon, and available P levels. Moreover, after 8 months, heterotrophic microorganisms were recovered from those substrates and dehydrogenase activity was enhanced. The incorporation of agricultural soil and green waste compost mixed either with lime (S5) or rock phosphate (S6) was the most effective treatment. Conclusions Both S5 and S6 mixtures successfully reduced the environmental risk posed by tailings, suggesting the potential use of these amendments for the remediation of pyrite mines.
190. 题目: Comparison on soil organic carbon and nitrogen dynamics between urban impervious surfaces and vegetation
期刊: Land Degradation & Development
作者: Xiaolin Dou, Meng Lu, Liding Chen
摘要: Impervious surface (IS) is widespread globally due to increasing urbanization, and relatively static carbon (C) and nitrogen (N) processes are usually expected in these soils. However, an understanding of how soil organic carbon (SOC) and soil organic nitrogen (SON) dynamics under impervious surface in comparison with urban vegetations is still lacking. Here we used soil fractionation and stable isotopic analysis to examine C&N dynamics in IS soils and soils that were vegetated for 20 to 30 years in Guangzhou and Shenzhen, China. Soil samples from bare land (CK) and other land uses (grass, forest and IS) were split into different chemical fractions. The C&N content, C/N ratio, δ13C, δ15N, C&N recalcitrant indices (RIC, RIN), and mean residence time (MRT) were analyzed. The results showed that soil C&N stocks increased in the first (20 years) as reflected in the enhanced labile (LP) and recalcitrant C pools (RP), but then stabilized or decreased after 30 years with the IS ages in both cities. IS had a lower SOC decomposition rate and thus resulted in five to ten times longer MRT (259–465 years) than that in vegetated soils (39–55 years). The study showed that IS caused remarkable changes in soil C&N pools and turnover rates compared with vegetated lands. Our results are potentially useful for better understanding, predicting and managing of soil C dynamics under urbanization.
191. 题目: Water Residence Time and Temperature Drive the Dynamics of Dissolved Organic Matter in Alpine lakes in the Tibetan Plateau
期刊: Global Biogeochemical Cycles
作者: YingXun Du, FeiZhou Chen, Kang Xiao, ChunQiao Song, Hu He, QiaoYing Zhang, YongQiang Zhou, Kyoung‐Soon Jang, YiBo Zhang, Peng Xing, ZhengWen Liu, YunLin Zhang, YueHan Lu
摘要: Lakes are hotspots of dissolved organic matter (DOM) degradation and play an active role in carbon cycles. Alpine lakes are under the most immediate impacts of climate change and act as sentinels of alpine ecosystem's response to global warming, yet the primary environmental drivers of DOM variability in alpine lakes remain unidentified. Here, we sampled and analyzed DOM from 25 alpine lakes (>4000 m above mean sea level) across the Tibetan Plateau. We found that the water residence time (WRT) of lakes and mean annual temperature (MAT) accounted for 30–59% of the variance in the abundance of chromophoric DOM (CDOM) and fluorescent DOM (FDOM), which decreased with increasing WRT and MAT. Molecular-level analysis of selected DOM samples showed that a higher WRT corresponded to DOM with lower molecular intensities, lower proportions of aromatic, oxidized compounds, and higher proportions of reduced and N-containing compounds. These results show that in-lake DOM processing dominated the regional variability of CDOM and FDOM. Under the scenario of climate warming and lake enlargement due to increasing precipitation and glacier melting, more DOM could be processed and removed from the Tibetan lakes. Our findings are the first that identified WRT as a significant predictor of the amount of various DOM pools in Tibetan lakes and this observation may be broadly applicable to alpine lakes since they share similar DOM source-sink characteristics. The simple empirical models (DOM vs. WRT+MAT) can be integrated into more sophisticated numerical models in predicting changes in the carbon cycle of alpine lakes.
192. 题目: Assessment of the Effect of Organic Matter on the Retention of Pb+2 in Artificial Soils
期刊: Water, Air, & Soil Pollution
作者: Rubén Albeiro Sánchez-Andica, Andrés Felipe Chamorro-Rengifo, Martha Isabel Páez-Melo
摘要: Four artificial soils (AS) were prepared based on a mixture of humus, bentonite, kaolinite, and polyvinyl chloride (PVC), as inert matter, in the following proportion: 0%, 12.44%, 37.50%, 78.55% of humus, 10.5% of bentonite, 10.5% of kaolinite, and 78.92%, 66.26%, and 41.46% of PVC. The AS were prepared with variable content of organic matter (OM) in order to evaluate the retention of lead (II) due solely to the content of OM. The results indicated that retention capacity of Pb+2 increases (19.74 mg/g, 20.89 mg/g, 61.61 mg/g, and 79.48 mg/g) as OM increases (0%, 1%, 5%, and 10%); however, this retention is not proportional to the OM increment. An increase of background solution concentration of 0.01 M to 0.1 M resulted in a 50% decrease in the lead retention capacity. The fitting of lead adsorption was performed by the regression coefficient (R2). All R2 of the Langmuir model fit successfully to all types of AS (0.973 for 10-OM, 0.9845 for 5-OM, 0.999 for 1-OM, 0.994 for 0-OM). The adsorption kinetics also fits well to the pseudo-second-order model (R210-OM = 0.989, R25-OM = 0.999, R21-OM = 0.999, and R20-OM = 0.999). The thermodynamic values of the Gibbs free energy (ΔG010-OM = − 10.62, ΔG05-OM = − 11.50, ΔG01-OM = − 14.23, and ΔG00-OM = − 17.06) indicated that it was a spontaneous process, and the energy of the process suggests a retention mechanism by ion exchange. A soil with high content of OM does not guarantee high retention of lead, even more so when the adsorption mechanism is given by ion exchange.
193. 题目: Loss on ignition vs. thermogravimetric analysis: a comparative study to determine organic matter and carbonate content in sediments
期刊: Journal of Paleolimnology
作者: Mohammed Bensharada, Richard Telford, Ben Stern, Vince Gaffney
摘要: Mass loss at specified temperatures has been used widely to determine amounts of organic matter and carbonate in sediment samples. The loss on ignition (LOI) method is cheap and simple, but is time-consuming and provides information only for specific, pre-determined temperatures. It also requires relatively large sample sizes and is destructive. Thermogravimetric analysis (TGA) is an alternative method for determination of organic and carbonate content in sediment samples, and provides accurate and precise data in a time-efficient manner. We compared results from these two thermal analysis techniques, which were applied to sediment samples from a submerged landscape (Doggerland). An organic-rich peat sample and a silty fine-sand sample were used. An unpaired t-test was used to test agreement and repeatability of the two analytical techniques. One advantage of being able to monitor mass loss throughout the analytical operation is that free and bound moisture losses can be distinguished. TGA is less time-consuming, involves automated sample handling (minimising operator error), and can yield reliable data from sample masses (typically 30–50 mg), which are much smaller than those needed for LOI (typically 3–5 g). The unpaired t-test, along with precision and repeatability analyses led us to conclude that TGA can be used instead of LOI to provide reliable measures of organic matter and carbonate content in sediments, and has several advantages over LOI.
194. 题目: Selective sequestration of perfluorinated compounds using polyaniline decorated activated biochar
期刊: Chemical Engineering Journal
作者: Yeonji Yea, Gyuri Kim, Dengjun Wang, Sewoon Kim, Yeomin Yoon, S.SD. Elanchezhiyan, Chang Min Park
摘要: Poly- and perfluorinated compounds (PFCs) in wastewater could induce the poisonous effects to the living beings throughout the world. In this present investigation, polyaniline (PANI) decorated activated biochar (AB) hybrid composite (AB@x%PANI, x= 0%, 25%, 50%, 75%, and 100% of PANI) was fabricated for PFCs adsorption via in situ chemical oxidation and co-precipitation with calcination. The physical and chemical properties of AB@x%PANI before and after adsorption were characterized by FTIR, PXRD, XPS, FE-SEM with EDX, HR-TEM, 13C-NMR, and TGA analysis. Batch experiments for the effect of contact time, initial PFCs concentration, solution pH, and co-existing cations were conducted for the maximum adsorption capacity of as-synthesized adsorbents. The AB@75%PANI hybrid composite exhibited higher adsorption capacity for the removal of perfluorooctanoic, perfluorooctanesulfonic, and perfluorohexanesulfonic acids than powdered activated carbon, AB, PANI, AB@25%PANI, and AB@50%PANI. The adsorption isotherm and kinetic results demonstrated that the adsorption system using AB@75%PANI hybrid composite followed pseudo-second-order and Langmuir isotherm models. The PFCs adsorption by AB@75%PANI was mainly governed by various interaction forces such as hydrogen bonding, electrostatic attraction, hydrophobic interaction, and surface complexation in the presence of co-existing cations. These findings shed light on how to selectively eliminate PFCs from wastewater.
195. 题目: Enhanced adsorption of rhodamine B from water by Fe-N co-modified biochar: Preparation, performance, mechanism and reusability
期刊: Bioresource Technology
作者: Xiumin Li, Jingxin Shi, Xianxin Luo
摘要: To adsorb rhodamine B (RhB) in wastewater by pristine biochar was limited, while the modified biochar has shown great potential adsorption performance. Here, coconut shell mixed with FeSO4·7H2O and urea was prepared to synthesize Fe-N co-modified biochar by once pyrolysis method at 500℃. The results showed Fe-N-BC had larger surface area (972.8714 m2·g-1), higher developed porous structure (0.65016 cm3·g-1), and more oxygen-containing groups, which collectively contributed to significantly improve the adsorption performance of the Fe-N-BC towards RhB. The maximum adsorption capacity of RhB reached 12.41 mg·g-1 by Fe-N-BC which was 1.58, 1.43 and 1.26 folds than that of BC, N-BC and Fe-BC, respectively. The mechanism of adsorption for Fe-N-BC towards RhB including ion exchange, pore filling, surface complexation, H-bond and π–π interaction. This study indicates that Fe-N-BC is an excellent adsorbent for RhB removal from wastewater.
196. 题目: Active Iron Phases Regulate the Abiotic Transformation of Organic Carbon during Redox Fluctuation Cycles of Paddy Soil
期刊: Environmental Science & Technology
作者: Ning Chen, Qinglong Fu, Tongliang Wu, Peixin Cui, Guodong Fang, Cun Liu, Chunmei Chen, Guangxia Liu, Wenchao Wang, Dixiang Wang, Peng Wang, Dongmei Zhou
摘要: Iron (Fe) phases are tightly linked to the preservation rather than the loss of organic carbon (OC) in soil; however, during redox fluctuations, OC may be lost due to Fe phase-mediated abiotic processes. This study examined the role of Fe phases in driving hydroxyl radical (•OH) formation and OC transformation during redox cycles in paddy soils. Chemical probes, sequential extraction, and Mössbauer analyses showed that the active Fe species, such as exchangeable and surface-bound Fe and Fe in low-crystalline minerals (e.g., green rust-like Fe phases), predominantly regulated •OH formation during redox cycles. The •OH oxidation strongly induced the oxidative transformation of OC, which accounted for 15.1–30.8% of CO2 production during oxygenation. Microbial processes contributed 7.3–12.1% of CO2 production, as estimated by chemical quenching and γ-irradiation experiments. After five redox cycles, 30.1–71.9% of the OC associated with active Fe species was released, whereas 5.2–7.1% was stabilized by high-crystalline Fe phases due to the irreversible transformation of these active Fe species during redox cycles. Collectively, our findings might unveil the under-appreciated role of active Fe phases in driving more loss than conservation of OC in soil redox fluctuation events.
197. 题目: Influence mechanisms of iron, aluminum and manganese oxides on the mineralization of organic matter in paddy soil
期刊: Journal of Environmental Management
作者: Yi Zhuang, Jun Zhu, Lei Shi, Qingling Fu, Hongqing Hu, Qiaoyun Huang
摘要: The mineralization of soil organic matter (SOM) is closely related to the emission of greenhouse gas into atmosphere and the stability of organic carbon in soil. The influence of minerals on SOM mineralization in the specific soil received very few attentions. The influence characteristics and potential mechanisms of oxides on the mineralization of SOM in the paddy soil were observed in this study by incubating soil with the addition (dosage: 10 g kg−1) of prepared gibbsite, goethite, ferrihydrite or birnessite for 60 days. A sequence control treatment (753 mg CO2–C kg−1) > goethite treatment (656 mg CO2–C kg−1) ≈ gibbsite treatment (649 mg CO2–C kg−1) > birnessite treatment (529 mg CO2–C kg−1) > ferrihydrite treatment (441 mg CO2–C kg −1) was found in the cumulative amount of released CO2 in 60 days of incubation. Oxides especially ferrihydrite significantly decreased the content of dissolved organic matter (DOM) but tended to increase the content of microbial biomass carbon (MBC). The molecular structure of DOM in the paddy soil was simplified by gibbsite, ferrihydrite and birnessite after the incubation. Oxides especially birnessite and ferrihydrite reduced soil pH and the content of soil available N but increased soil redox potential (Eh). All examined oxides especially Fe oxides enhanced soil bacterial abundance but only birnessite significantly affected bacterial composition at phyla level. The stimulation on the immobilization and/or microbial assimilation of labile organic carbon, the modulation on soil basic properties (available N, pH, Eh), and the decrease of the relative abundance of some decomposing bacteria phyla such as Actinobacteria were the potential pathways of oxides in decreasing SOM mineralization.
198. 题目: Revealing the link between evolution of electron transfer capacity of humic acid and key enzyme activities during anaerobic digestion
期刊: Journal of Environmental Management
作者: Xiqing Wang, Tao Lyu, Renjie Dong, Shubiao Wu
摘要: Humic acid (HA) is an important active compound formed during anaerobic digestion process, with a complex structure and dynamic electron transfer capacity (ETC). However, the mechanisms by which these macromolecular organic compounds dynamically interact with the microbial anaerobic digestion process at different operating temperatures are still unclear. In this study, the link between the evolution of the ETC of HAs and the microbial community under mesophilic and thermophilic conditions was investigated. The results showed an increasing trend in the ETC of HAs in both mesophilic (671–1479 μmol gHA−1) and thermophilic (774–1506 μmol gHA−1) anaerobic digestion (AD) until day 25. The ETC was positively correlated with the bacterial community of hydrolytic and acidogenic phases, but negatively correlated with the archaeal community of the methanogenic phase. Furthermore, the relationship between ETC and key enzyme activity was explored using a co-occurrence network analysis. HAs revealed a high potential to promote key enzyme activities during hydrolysis (amylase and protease) and acidification (acetate kinase, butyrate kinase, and phosphotransacetylase) while inhibiting the key enzyme activity in the methanogenic phase during the anaerobic digestion process. Moreover, HAs formed under thermophilic conditions had a greater influence on key enzyme activities than those formed under mesophilic conditions. This study advances our understanding of the mechanisms underlying the influence of HAs on anaerobic digestion performance.
199. 题目: Substrate quality effects on stabilized soil carbon reverse with depth
作者: Mengmeng Li, Travis Meador, Leopold Sauheitl, Georg Guggenberger, Gerrit Angst
摘要: High-quality plant inputs to the soil with low lignin to nitrogen ratios have been conceptualized to foster the formation of soil organic matter (SOM) and carbon (C) in stabilized soil compartments, such as aggregates and organo-mineral associations (MAOM), in dependence of the soil’s capacity to store additional C (i.e., C saturation deficit). Yet, evidence for these conceptualizations from field experiments is scarce and it is unclear whether factors commonly not included in laboratory experiments (such as soil depth) may modulate the influence of substrate quality on SOM formation. We, thus, tested the effect of substrates with different qualities (from European alder and Scots pine) on C stocks in bulk soil, free particulate and aggregate-occluded organic matter, and MAOM in soils at various ages after reclamation and at different soil depths in a common-garden field experiment. Our results revealed that substrate quality generally acted in the predicted way in the upper investigated soil layer (0–5 cm depth), i.e., high-quality substrates increased C stocks in MAOM. Surprisingly, the effect of substrate quality reversed with depth (5–15 cm; i.e., low-quality litters were associated with higher C stocks in MAOM), potentially due to a higher sensitivity (or “priming”) of native SOM in response to high-quality substrates at depth or a lower probability of such substrates reaching deeper soil layers. These patterns appeared to be largely independent of the soils’ theoretical capacity to stabilize additional C, which was exceeded in all investigated soils. Based on the results of our field experiment, we highlight the need to refine recent conceptualizations by focusing on environmental factors that are commonly not accounted for in laboratory-scale experiments and that may alter the direction in which substrate quality acts to influence the formation of SOM.
200. 题目: Hydrological seasonality and nutrient stoichiometry control dissolved organic matter characterization in a headwater stream
期刊: Science of The Total Environment
作者: Siyue Li, Jiachen Luo, Y. Jun Xu, Liuqing Zhang, Chen Ye
摘要: Dissolved organic matter (DOM) is a diverse and highly complex mixture of organic macromolecules, and thus plays a central role in aquatic ecosystems. However, responses of components and sources of DOM to hydrological process and trophic levels (nutrient stoichiometric ratios) are poorly understood particularly in monsoonal headwater streams of Asia that are vulnerable to catchment physical characteristics. In this study, the excitation - emission matrix florescence spectroscopy coupled with parallel factor analysis (EEM-PARAFAC) was used to explore the DOM characters in a headwater stream, where seasonal rainfalls and nutrient levels vary largely. The EEM-PARAFAC modelling identified one autochthonous protein-like fluorescence substance (C1) and two allochthonous fulvic- and humic-like fluorescence compounds (C2 and C3). The allochthonous compounds dominated the overall DOM signal in the headwaters. The hydrological seasonality coupled with nutrients was key in modulating headwater DOM sources and components. Seasonal rainfall events contributed more allochthonous terrestrial-derived DOM flushing into river waters, resulting in higher fulvic- and humic-like organic matter (C2 + C3) in the wet season. In the dry season, longer water residence time accompanying with higher C:P stoichiometric ratio was responsible for higher autochthonous microbial- and plant-derived DOM (tryptophan and tyrosine fractions), also reflected by higher C1, biological index (BIX) and freshness index (β:α). In-stream microbial metabolism of labile DOM fractions largely contributed to autochthonous DOM and partial pressure CO2 increase in the headwater stream. Our findings indicate that quality and quantity of DOM in headwater streams play a crucial role in downstream carbon cycle. Furthermore, the evidence combined from PARAFAC components, pCO2 and spectral slope clearly highlights the importance of microbial metabolism carbon dynamics in lotic systems, especially during a dry season with increased residence time.