261. 题目: Soil organic carbon sequestration in temperate agroforestry systems – A meta-analysis
期刊: Agriculture, Ecosystems & Environment
作者: Stefanie Mayer, Martin Wiesmeier, Eva Sakamoto, Rico Hübner, Rémi Cardinael, Anna Kühnel, Ingrid Kögel-Knabner
摘要: Soil organic carbon (SOC) sequestration by improved agricultural practices is an acclaimed strategy to combat climate change. Nevertheless, the aim of increasing of SOC encounters limitations, e.g. with regards to permanence of carbon storage or leakage effects in food production. Agroforestry systems (AFS) are a promising land use option that is able to sequester substantial amounts of SOC while addressing these challenges. With a focus on temperate climate zones worldwide, available information on SOC in AFS was reviewed to determine their SOC sequestration potential and respective controlling factors. From a total of 61 observations, SOC sequestration rates in soils of AFS were derived for alley cropping systems (n = 25), hedgerows (n = 26) and silvopastoral systems (n = 10). The results showed that AFS have a potential for substantial SOC sequestration in temperate climates. SOC stocks were higher in the topsoil (0–20 cm) than in the control in more than 70% of the observations, and higher within the subsoil (20–40 cm) for 81% of all observations, albeit large variation in the data. The mean SOC sequestration rates were slightly higher at 0–20 cm (0.21 ± 0.79 t ha-1 yr-1) compared to 20–40 cm soil depth (0.15 ± 0.26 t ha-1 yr-1). Hedgerows revealed highest SOC sequestration rates in topsoils and subsoils (0.32 ± 0.26 and 0.28 ± 0.15 t ha-1 yr-1, respectively), followed by alley cropping systems (0.26 ± 1.15 and 0.23 ± 0.25 t ha-1 yr-1) and silvopastoral systems showing a slight mean SOC loss (−0.17 ± 0.50 and −0.03 ± 0.26 t ha-1 yr-1). Moreover, SOC sequestration rates tended to be higher for AFS with broadleaf tree species compared to coniferous species. We conclude that temperate AFS sequester significant amounts of SOC in topsoils and subsoils and represent one of the most promising agricultural measures for climate change mitigation and adaption.
262. 题目: Biochar and slow-releasing nitrogen fertilizers improved growth, nitrogen use, yield, and fiber quality of cotton under arid climatic conditions
期刊: Environmental Science and Pollution Research
作者: Sobia Manzoor, Muhammad Habib-ur-Rahman, Ghulam Haider, Iqra Ghafoor, Saeed Ahmad, Muhammad Afzal, Fahim Nawaz, Rashid Iqbal, Mubashra Yasin, , Subhan Danish, Abdul Ghaffar
摘要: The efficiency of nitrogenous fertilizers in South Asia is on a declining trajectory due to increased losses. Biochar (BC) and slow-releasing nitrogen fertilizers (SRNF) have been found to improve nitrogen use efficiency (NUE) in certain cases. However, field-scale studies to explore the potential of BC and SRNF in south Asian arid climate are lacking. Here we conducted a field experiment in the arid environment to demonstrate the response of BC and SRNF on cotton growth and yield quality. The treatments were comprised of two factors, (A) nitrogen sources, (i) simple urea, (ii)neem-coated urea, (iii)sulfur-coated urea, (iv) bacterial coated urea, and cotton stalks biochar impregnated with simple urea, and (B) nitrogen application rates, N 1 =160 kg ha -1 , N 2 = 120 kg ha -1 , and N 3 = 80 kg ha -1 . Different SRNF differentially affected cotton growth, morphological and physiological attributes, and seed cotton yield (SCY). The bacterial coated urea at the highest rate of N application (160 kg ha -1 ) resulted in a higher net leaf photosynthetic rate (32.8 μmol m -2 s -1 ), leaf transpiration rate (8.10 mmol s -1 ), and stomatal conductance (0.502 mol m -2 s -1 ), while leaf area index (LAI), crop growth rate (CGR), and seed cotton yield (4513 kg ha -1 ) were increased by bacterial coated urea at 120 kg ha -1 than simple urea. However, low rate N application (80 kg ha -1 ) of bacterial coated urea showed higher nitrogen use efficiency (39.6 kg SCY kg -1 N). The fiber quality (fiber length, fiber strength, ginning outturn, fiber index, and seed index) was also increased with the high N application rates than N2 and N3 application. To summarize, the bacterial coated urea with recommended N (160 kg ha -1 ) and 75% of recommended N application (120 kg ha -1 ) may be recommended for farmers in the arid climatic conditions of Punjab to enhance the seed cotton yield, thereby reducing nitrogen losses.
263. 题目: Plant community change mediated heterotrophic respiration increase explains soil organic carbon loss before moderate degradation of alpine meadow
期刊: Land Degradation & Development
作者: Chimin Lai, Chengyang Li, Fei Peng, Xian Xue, Quangang You, Wenjuan Zhang, Shaoxiu Ma
摘要: Alpine meadows on the Qinghai-Tibet Plateau (QTP) store a huge amount of plant and soil carbon (C). The degradation of the alpine meadow has led to a significant loss of soil organic C (SOC), which endangers its weak C sink. The change in heterotrophic respiration (Rh) was hypothesized as one of the primary biological processes associated with the SOC loss alongside the degradation of alpine meadow. However, little is known about how land degradation impacts Rh due to changes in plant communities and consequent labile organic C inputs. Rh, vegetation productivity, plant community composition, plant lignin concentration, leaf C/N, SOC, and soil labile C (SLC) were measured for alpine meadow grasslands with five degradation levels in two years. Our results showed that the SOC of the surface layer (0–10 cm) gradually decreased with land degradation. The plant lignin concentration and C/N ratio gradually increased with land degradation due to the proportion of sedges decreased while that of forbs increased, which consequent led to the soil C quality (SLC) increased before the moderate degradation level (MD) while significantly reduced in severe and very severe degradation levels (SD and VSD). The structural equation modeling result (SEM) revealed that the degradation-induced change in soil C quality (SLC) due to an alteration in plant community composition relates to the Rh change with grassland degradation, and the Rh (C output) and aboveground biomass (AGB: C input) further mediated the loss of SOC alongside alpine meadow degradation. On average, Rh increased by 49% and 59% from the Intact to slight degradation level (SLD) and MD and reduced by 56% and 69% from MD to SD and VSD. The temperature sensitivity of Rh (Q10) was higher in the SLD (Q10 = 2.84) and MD (Q10 = 2.62) comparing with the Intact (Q10 = 2.58) respectively, but it was lower in SD (Q10 = 2.19) and VSD (Q10 = 1.65). AGB and belowground net primary productivity (BNPP) had no significant change until the MD, while reduced by 60–90% in SD and VSD. Our results suggest that Rh and its Q10 change moderated by soil C quality alteration due to the plant community shifting could be one mechanism for the soil C loss before MD, but could not be the main pathway for the SOC loss at SD and VSD.
264. 题目: Mosses are Important for Soil Carbon Sequestration in Forested Peatlands
期刊: Frontiers in Environmental Science
作者: Å Kasimir, H He, P.-E. Jansson, A Lohila, K Minkkinen
摘要: Nutrient-rich peat soils have previously been demonstrated to lose carbon despite higher photosynthesis and litter production compared to nutrient-poor soils, where instead carbon accumulates. To understand this phenomenon, we used a process-oriented model (CoupModel) calibrated on data from two closely located drained peat soil sites in boreal forests in Finland, Kalevansuo and Lettosuo, with different soil C/N ratios. Uncertainty-based calibrations were made using eddy-covariance data (hourly values of net ecosystem exchange) and tree growth data. The model design used two forest scenarios on drained peat soil, one nutrient-poor with dense moss cover and another with lower soil C/N ratio with sparse moss cover. Three vegetation layers were assumed: conifer trees, other vascular plants, and a bottom layer with mosses. Adding a moss layer was a new approach, because moss has a modified physiology compared to vascular plants. The soil was described by three separate soil organic carbon (SOC) pools consisting of vascular plants and moss litter origin and decomposed organic matter. Over 10 years, the model demonstrated a similar photosynthesis rate for the two scenarios, 903 and 1,034 g C m −2 yr −1 , for the poor and rich site respectively, despite the different vegetation distribution. For the nutrient-rich scenario more of the photosynthesis produce accumulated as plant biomass due to more trees, while the poor site had abundant moss biomass which did not increase living aboveground biomass to the same degree. Instead, the poor site showed higher litter inputs, which compared with litter from vascular plants had low turnover rates. The model calibration showed that decomposition rate coefficients for the three SOC pools were similar for the two scenarios, but the high quantity of moss litter input with low decomposability for the nutrient poor scenario explained the major difference in the soil carbon balance. Vascular plant litter declined with time, while SOC pools originating from mosses accumulated with time. Large differences between the scenarios were obtained during dry spells where soil heterotrophic respiration doubled for the nutrient-rich scenario, where vascular plants dominated, owing to a larger water depletion by roots. Where moss vegetation dominated, the heterotrophic respiration increased by only 50% during this dry period. We suggest moss vegetation is key for carbon accumulation in the poor soil, adding large litter quantities with a resistant quality and less water depletion than vascular plants during dry conditions.
265. 题目: Simulating the effects of erosion on organic carbon dynamics in agricultural soils
作者: Honghong Lin, Xingwu Duan, Yawen Li, Lanlan Zhang, Li Rong, Ruimin Li
摘要: Soil erosion in croplands has a strong impact on global carbon (C) cycle. Assessment of erosional effects on soil organic carbon (SOC) dynamics in agricultural soils suffers from the difficulty of distinguishing the erosional effects and complex interaction processes between erosion and C cycling. To simulate the effects of soil erosion, a plots experiment including six erosion levels (0, 5, 10, 20, 30, and 40 cm eroded) was conducted for seven years (2012–2018). The erosion levels were simulated using artificial soil profiles created by mixing soils from different layers in the original soil profile (never eroded) in a certain proportion. Subsequently, based on the field observations during 2012–2018, the SOC dynamics of each experimental plot were simulated by using a process-oriented C cycle model (denitrification-decomposition (DNDC)) to quantify the effects of erosion on SOC dynamics. The measurements at the beginning of the plots experiment showed that simulated erosion resulted in the depletion of SOC with an average reduction rate of 9.7% per 10 cm of soil loss; SOC in eroded soils recovered after seven years of cropping, the declining slope of the SOC measured in 2018 was 3.0% per 10 cm of soil loss, suggesting that dynamic replacement had occurred. Model simulation results indicated that soil erosion could reduce the C inputs from crop residue by lowering soil productivity; soil heterotrophic respiration in eroded soils was restricted due to the lower initial SOC content. As a result, the simulated overall SOC stock in eroded soils was restored after erosion stopped because of the lower C output. These results indicated that SOC loss at eroding sites was caused mainly by lateral transport rather than enhanced decomposition. The fate of the displaced SOC within catchments is key to assess the net impacts of soil erosion on SOC dynamics at a large scale.
266. 题目: Biochar nanoparticles with different pyrolysis temperatures mediate cadmium transport in water-saturated soils: Effects of ionic strength and humic acid
期刊: Science of the Total Environment
作者: Ming Chen, Dengjun Wang, Xiaoyun Xu, Yue Zhang, Xiangyang Gui, Bingqing Song, Nan Xu
Biochar is advocated as an environment-friendly and cost-effective material for removing both heavy metals and organic contaminants in soil remediation. However, our understandings on the cotransport potential of contaminants with the nanoscale biochar downward along soil profiles (e.g., potential environmental risks towards groundwater) remain largely unknown. This study investigated the effects of wheat straw-derived biochar nanoparticles pyrolyzed at 350 °C and 500 °C (BNP350 and BNP500) on the transport of cadmium (Cd(II)) in water-saturated soil packed columns. Different ionic strengths (ISs) without/with humic acid (HA) were tested to mimic the scenarios during soil remediation. BNPs could act as a vehicle mediating Cd(II) transport in soils. At a low IS (1.0 mM KCl), compared to the limited transport of individual Cd(II), BNP500 enhanced (69 times) Cd(II) transport (Cd(II) mass recovery (M) = 7.59%) in soils, which was greater than that by BNP350 (54 times, M = 5.92%), likely due to the higher adsorption of Cd(II) onto BNP500. HA further increased the Cd(II) transport by BNPs (M = 8.40% for BNP350 and M = 11.95% for BNP500), which was mainly due to the increased mobility of BNPs carrying more absorbed Cd(II). In contrast, at a high IS (10 mM KCl), BNP500 dramatically inhibited the transport of Cd(II) (M = 12.9%), decreasing by about 61.6%, compared to the BNPs absence (M = 33.6%). This is because a large amount of BNP500-Cd(II) was retained in soils at a high IS. This inhibition effect of Cd(II) transport by BNPs was reinforced with the presence of HA. Our findings suggest that the pyrolysis temperature of biochar should be carefully considered when applying biochar for in-situ remediation of soils contaminated by heavy metals such as Cd(II) under various organic matter and IS conditions.
267. 题目: Soft computing-based models and decolorization of Reactive Yellow 81 using Ulva Prolifera biochar
作者: Ravindiran Gokulan, Saravanan Praveen, Alagumalai Avinash, Subbarayan Saravanan
摘要: The present research explores the application of optimization tools namely Response Surface Methodology (RSM), Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) in the decolorization of Reactive Yellow 81 (RY81) from an aqueous solution. The characterization of the biochar was carried out using FTIR, elemental analysis, proximate analysis, BET analysis and Thermogravimetric analysis. Five independent variables namely solution pH, biochar dose, contact time, initial dye concentration and temperature were analyzed using RSM, ANN and ANFIS models. The maximum removal efficiency of 86.4% was obtained and the statistical error analysis was calculated. The correlation coefficient of 0.9665, 0.9998 and 0.9999 was obtained for RSM, ANN and ANFIS models, respectively. Adsorption Isotherm models and kinetic models were used to understand the adsorption mechanism. Maximum monolayer adsorption of 225 mg g−1 was predicted by Hill isotherm model. A partition coefficient of 4.09 L g−1 was obtained at an initial dye concentration of 250 mg L−1. It was revealed from the thermodynamic studies that reactions are endothermic and spontaneous. Further, to check the potential of the biochar, regeneration cycle was studied. The desorption efficiency of 99.5% was achieved at an S/L ratio of 3, regeneration cycles of 2, and sodium hydroxide was found as the best elutant for the desorption.
268. 题目: Fungi population metabolomics and molecular network study reveal novel biomarkers for early detection of aflatoxigenic Aspergillus species
期刊: Journal of Hazardous Materials
作者: Huali Xie, Xiupin Wang, Justin JJ van der Hooft, Marnix H Medema, Zhi-Yuan Chen, Xiaofeng Yue, Qi Zhang, Peiwu Li
摘要: Mycotoxins threaten global food safety, public health and cause huge socioeconomic losses. Early detection is an effective preventive strategy, yet efficient biomarkers for early detection of aflatoxigenic Aspergillus species are lacking. Here, we proposed to use untargeted metabolomics and machine learning to mine biomarkers of aflatoxigenic Aspergillus species. We systematically delineated metabolic differences across 568 extensive field sampling A. flavus and performed biomarker analysis. Versicolorin B, 11-hydroxy-O-methylsterigmatocystin et.al metabolites shown a high correlation (from 0.71 to 0.95) with strains aflatoxin-producing capacity. Molecular networking analysis deciphered the connection of aflatoxins and biomarkers as well as potential emerging mycotoxins. We then developed a model using the biomarkers as variables to discern aflatoxigenic Aspergillus species with 97.8% accuracy. A validation dataset and metabolome from other 16 fungal isolates confirmed the robustness and specificity of these biomarkers. We further demonstrated the solution feasibility in agricultural products by early detection of biomarkers, which predicted aflatoxin contamination risk 35–47 days in advance. A developed operable decision rule by the XGBoost algorithm help regulators to intuitively assess the risk prioritization with 87.2% accuracy. Our research provides novel insights into global food safety risk assessment which will be crucial for early prevention and control of mycotoxins.
269. 题目: A robust initialization method for accurate soil organic carbon simulations
作者: Eva Kanari, Lauric Cécillon, François Baudin, Hugues Clivot, Fabien Ferchaud, Sabine Houot, Florent Levavasseur, Bruno Mary, Laure Soucémarianadin, Claire Chenu, Pierre Barré
摘要: . Changes in soil organic carbon (SOC) stocks are a major source of uncertainty for the evolution of atmospheric CO2 concentration during the 21st century. They are usually simulated by models dividing SOC into conceptual pools with contrasted turnover times. The lack of reliable methods to initialize these models, by correctly distributing soil carbon amongst their kinetic pools, strongly limits the accuracy of their simulations. Here, we demonstrate that PARTYsoc, a machine-learning model based on Rock-Eval® thermal analysis optimally partitions the active and stable SOC pools of AMG, a simple and well validated SOC dynamics model, accounting for effects of soil management history. Furthermore, we found that initializing the SOC pool sizes of AMG using machine-learning strongly improves its accuracy when reproducing the observed SOC dynamics in nine independent French long-term agricultural experiments. Our results indicate that multi-compartmental models of SOC dynamics combined with a robust initialization can simulate observed SOC stock changes with excellent precision. We recommend exploring their potential before a new generation of models of greater complexity becomes operational. The approach proposed here can be easily implemented on soil monitoring networks, paving the way towards precise predictions of SOC stock changes over the next decades.
270. 题目: Effect of long-term low concentrations of TiO2 nanoparticles on dewaterability of activated sludge and the relevant mechanism: the role of nanoparticle aging
期刊: Environmental Science and Pollution Research
作者: Chengyu Jiang, Qingjin Chen
摘要: Nanoparticles can undergo aging phenomena in sewage treatment systems, which alter their physical and chemical properties. However, the effect of aged nanoparticles on the dewatering performance of activated sludge under long-term low concentrations is yet to be reported in sewage treatment systems. Here, we compared the chronic effects of pristine and aged TiO2 nanoparticles on the sludge dewatering index, which includes specific resistance to filtration (SRF) and bound water (BW) in a sequencing batch reactor (SBR) at μg/L concentration levels, and analyzed the relevant mechanisms. The results indicated that aging in the sludge supernatant altered the photosensitivity and water stability of nanoparticles, which was mainly due to the changes in the zeta potential and energy band of the particle and was ultimately attributed to the combined effect of particle surface inclusions such as organic matter and inorganic salt. At 10 μg/L, nanoparticles reduced the sludge dewaterability, which observed an improvement at 100 μg/L. This is because 10 μg/L promoted the secretion of extracellular polymeric substances (EPS), which regulated the structure of sludge flora and increased the abundance of secreted quorum sensing-acyl-homoserine lactones (QS-AHL) and EPS genera, while the corresponding exposure results for 100 μg/L were the opposite, owing to the damage and necrosis effects caused by exposure under long-term light, which reduced EPS production and increased sludge density. Interestingly, aging could alleviate the effects of two exposure concentrations on sludge dewatering, mainly because of the decrease in the photoactivity of the nanoparticles. The results of this study show that environmental aging could delay, but not reverse the results of exposure to specific concentrations of nanoparticles. However, the significantly different ecological effects of photosensitive nanoparticles with two environmentally relevant concentration should be refined and confirmed again in freshwater environments to provide a basis for subsequent scientific management and control of photosensitive nanoparticles.
271. 题目: Impact of algal extracellular polymeric substances on the environmental fate and risk of molybdenum disulfide in aqueous media
期刊: Water Research
作者: Wei Zou, Zepeng Wan, Chenxu Zhao, Guoqing Zhang, Xingli Zhang, Qixing Zhou
摘要: Molybdenum disulfide (MoS2) poses great potential in water treatment as a popular transition metal dichalcogenide, arousing considerable concern regarding its fates and risk in aquatic environments. This study revealed that the interplay with extracellular polymeric substances (EPS) of freshwater algae significantly changed the properties and toxicity of MoS2 to aquatic fish. The predominant binding of aromatic compounds, polysaccharides, and carboxyl-rich proteins in EPS on the 1T polymorph of MoS2 via hydrophilic effects and the preferential adsorption of carboxylic groups contributed to morphological alterations, structural disorders (band gap and phase alterations), and the attenuated aggregation of MoS2 in aqueous solutions. Electron charge transfer and n-π* interactions with EPS decreased the catalytic activity of MoS2 by inhibiting its capability of generating reactive intermediates. The dissolution of MoS2 slowed down after interacting with EPS (from 0.089 to 0.045 mg/L per day) owing to rapid initial oxidation (i.e., forming Mo-O bond) and carbon grafting. Notably, the morphological and structural alterations after EPS binding alleviated the toxicity (e.g., malformation and oxidative stress) of MoS2 to infantile zebrafish. Our findings provide insights into the environmental fate and risk of MoS2 by ubiquitous EPS in natural waters, serving as valuable information while developing water treatment processes accordingly.
272. 题目: Effects of long-term nitrogen addition on dissolved organic matter characteristics in a temperate wetland of Northeast China
期刊: Ecotoxicology and Environmental Safety
作者: Yi-Dong Ding, Chang-Chun Song, Guang-Jiao Chen, Xin-Hou Zhang, Rong Mao
摘要: Dissolved organic matter (DOM) plays an indispensable role in ecosystem services and functions in wetlands. While most wetlands have undergone increased nitrogen (N) loading due to intensive human activities, the response of DOM characteristics to long-term N addition remains unexplored. In this study, we assessed the changes in dissolved organic carbon (DOC), NH4+, NO3-, dissolved organic N (DON), dissolved total N (DTN), and dissolved total phosphorus (DTP) in surface water and soil pore water at 15 cm depth after 10 years of N addition at four levels (0, 60, 120, and 240 kg N hm−2 year−1) in a freshwater marsh of Northeast China. We also examined the effect of N addition on DOM aromaticity and humification by measuring the specific UV absorbance at 254 nm (SUVA254), the color per C unit (C/C ratio), and the fulvic acid/humic acid ratio (E4/E6 ratio). Our results showed that N addition significantly altered DOM properties, but the direction and magnitude of these changes generally did not vary with the N addition level. During the growing season, DOC, NH4+, NO3-, DON, and DTN concentrations in both surface water and soil pore water were increased by N addition. Accordingly, N addition increased the DOC/DTP and DTN/DTP ratios but decreased the DOC/DTN ratio in surface water and soil pore water. In addition, the SUVA254 value and C/C ratio increased, while the E4/E6 ratio reduced after N addition in surface water and soil pore water, indicating increases in DOM aromaticity and humification. These observations suggest that long-term N addition changes DOM characteristics by causing stoichiometric imbalances and increasing recalcitrant compounds in temperate freshwater wetlands, which may then deteriorate water quality, alter microbial-mediated ecological processes, and impact downstream aquatic ecosystem structures.
273. 题目: The applicability of commonly-used tracers in identifying eroded organic matter sources
期刊: Journal of Hydrology
作者: Yize Sun, Xiaodong Nie, Zhongwu Li, Shilan Wang, Jia Chen, Fengwei Ran
摘要: Tracing decomposition of organic carbon sources can balance carbon budget and reduce soil erosion targetedly. However, tracers may provide inaccurate source information, possibly due to the instability of organic matter under different land use types. Little is known about which stable tracer to choose based on different erosion scenarios. We, therefore, evaluated the availability of three commonly-used tracers techniques (i.e., bulk stable isotopes, fluorescence proxies and stoichiometric ratios) under different mixed end-members (i.e., Woodland, arable land and grassland) via a laboratory-scale controlled experiment. Combining fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC), Bayesian isotope mixing model and three evaluation criteria. Bulk stable isotopes (δ13C, δ15N) were considered to be the most suitable tracers for terrestrial organic matter sources tracing (Most of the R2 > 0.85, % difference < 10%), especially under Arable land-Woodland (A-W) mixed end-member, followed by traditional tracers (C/N, DOC). Unfortunately, the fluorescent indices were not suitable for terrestrial organic matter sources tracing, due to the similarities between different terrestrial organic matter sources, especially under Grassland-Woodland (G-W) mixed end-member (Most of the P-value > 0.05, % difference > 10%). Our results recommend that when selecting a tracer, not only the stability of the tracer should be considered, but also the difference among eroded organic matter sources. This study provides new insights into the validation of commonly-used tracers in identifying eroded organic matter sources accurately.
274. 题目: Effects of Organic Carbon Origin on Hydrophobic Organic Contaminant Fate in the Baltic Sea
期刊: Environmental Science & Technology
作者: Inna Nybom, Gisela Horlitz, Dorothea Gilbert, Naiara Berrojalbiz, Jannik Martens, Hans Peter H Arp, Anna Sobek
摘要: The transport and fate of hydrophobic organic contaminants (HOCs) in the marine environment are closely linked to organic carbon (OC) cycling processes. We investigated the influence of marine versus terrestrial OC origin on HOC fluxes at two Baltic Sea coastal sites with different relative contributions of terrestrial and marine OC. Stronger sorption of the more than four-ring polycyclic aromatic hydrocarbons and penta-heptachlorinated polychlorinated biphenyls (PCBs) was observed at the marine OC-dominated site. The site-specific partition coefficients between sediment OC and water were 0.2–1.0 log units higher at the marine OC site, with the freely dissolved concentrations in the sediment pore-water 2–10 times lower, when compared with the terrestrial OC site. The stronger sorption at the site characterized with marine OC was most evident for the most hydrophobic PCBs, leading to reduced fluxes of these compounds from sediment to water. According to these results, future changes in OC cycling because of climate change, leading to increased input of terrestrial OC to the marine system, can have consequences for the availability and mobility of HOCs in aquatic systems and thereby also for the capacity of sediments to store HOCs.
275. 题目: Investigation of ICP‐MS/MS for total sulfur quantification in freshwater dissolved organic matter
期刊: Journal of Environmental Quality
作者: Marissa L Kneer, James Lazarcik, Matthew Ginder‐Vogel
摘要: Sulfur-containing functional groups in dissolved organic matter (DOM) interact with trace metals, which in turn affects trace metal mobility and bioavailability in aquatic environments. Typical methods for identification and quantification of sulfur in DOM are costly, complex, and time intensive. Triple quadrupole inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) is capable of part per billion level sulfur quantification in environmental samples and is a more accessible analytical technique compared to other available methods. To date, this study is the first published investigation of ICP-MS/MS for the direct quantification of sulfur in freshwater dissolved organic matter. Sulfur (32S) detection occurs at a mass-to-charge ratio of 48 as 32S16O+ after removal of interferences and reaction with oxygen gas. We compare three commonly used dissolved organic matter preparation methods to assess variability among replicate samples. Preparation of freshwater DOM samples by solid phase extraction followed by evaporation overnight and dissolution in 2% nitric acid results in the most accurate quantification of sulfur. Analysis of sulfur in Suwannee River Fulvic Acid standard serves as method validation, measuring a carbon normalized sulfur concentration that is approximately 20% higher than previously reported methods. We apply the ICP-MS/MS analysis method to determine sulfur concentrations in DOM from nine lakes in the Northern Midwest. Carbon normalized sulfur concentrations in the selected lakes are in general agreement with previously reported percentages of sulfur-containing formulas in DOM found by Fourier transform-ion cyclotron resonance-mass spectroscopy.
276. 题目: Insight into the activation mechanisms of biochar by boric acid and its application for the removal of sulfamethoxazole
期刊: Journal of Hazardous Materials
作者: Xu Zhang, Daniel Dianchen Gang, Jingjing Zhang, Xiaobo Lei, Qiyu Lian, William E Holmes, Mark E Zappi, Hong Yao
摘要: Sulfamethoxazole (SMX) is frequently detected in the environment and causes a huge threaten to human health. Biochar (BC) is a metal-free adsorbent and generally exhibits a good adsorption capacity for SMX. However, the current activated methods usually result in the high energy consumption and low yield of the biochar. In this study, biochar was activated by boric acid under limited oxygen condition. The yield of biochar was increased by 103% after the activated by boric acid. The specific surface area of BC was significantly increased from 766.6 m2·g-1 to 1190.6 m2·g-1. The intensity of the (111) diamond peak of B-BC was higher than that of BC, suggesting that boric acid affected the surface pyrolysis temperature of biochar. The proposed roles of boric acid in the activation process were to: 1) enhance the generation of micropores during the pyrolysis process; 2) improve the yield of biochar via the transformation pathways of C-corresponding bonds and physical blocking. The boric acid activated biochar (B-BC) had a higher adsorption capacity for SMX than BC under the various aqueous conditions. Hence, boric acid activated biochar is a promising porous adsorbent to enhance the removal of SMX and achieve the practical application.
277. 题目: Investigation of the variations in dissolved organic matter properties and complexations with two typical heavy metals under the influence of biodegradation: A survey of an entire lake
期刊: Science of The Total Environment
作者: Haoyu Ren, Tuantuan Fan, Xin Yao, Feiyang Ma, Li Liu, Junde Ming, Shitong Wang, Yinghao Zhang, Huanguang Deng
摘要: Biodegradation is a key factor determining the properties and metal binding behaviour of dissolved organic matter (DOM). In this study, the contributions of biodegradation to DOM properties and metal binding behaviour in Dongping Lake were explored by using synchronous fluorescence (SF) spectroscopy, two-dimensional correlation spectroscopy (2D-COS) excitation-emission matrix and parallel factor analysis (EEM-PARAFAC). According to the ratio of the fluorescence intensity of different materials to the entire fluorescence intensity (%Fmax), protein-like substances were the main substances of DOM in this lake. The reduction of protein-like substances and the enhancement of humification could be found in the whole lake under the influence of biodegradation. 3 areas (Area A, Area B and Area C) were obtained by principal component analysis (PCA), however, PCA results suggested that DOM properties and sources had some differences in the 3 areas, and DOM bioavailability in Area C was stronger than that in the other 2 areas. With copper (Cu2+) and lead (Pb2+) addition, different substances exhibited various affinities to different metal types. The locations of crosspeaks in asynchronous maps illustrated that protein-like substances were more affiliative with Cu2+, while humic-like substances were bound to Pb2+ earlier. Biodegradation had a conspicuous impact the metal binding ability of DOM in Dongping Lake. The effective quenching constants (LogK) of protein-like substances (protein-like component 2: LogKCu = 3.85 ± 0.23, LogKPb = 3.32 ± 0.23) were higher than those of humic-like substances (humic-like component 3: LogKCu = 3.15 ± 0.02, LogKPb = 2.93 ± 0.17) for both Cu2+ and Pb2+ before biodegradation. When biodegradation was finished, binding ability of humic-like substances was enhanced from 3.15 ± 0.02 to 3.41 ± 0.10 for DOM-Cu and 2.93 ± 0.17 to 3.79 ± 0.15 for DOM-Pb. On a spatial scale, metal binding ability of DOM in Dongping Lake also changed due to the influence of biodegradation. For both DOM-Cu and DOM-Pb, binding ability in south of Dongping Lake was stronger than that in other areas with the end of biodegradation.
278. 题目: Root functional traits mediate rhizosphere soil carbon stability in a subtropical forest
期刊: Soil Biology and Biochemistry
作者: Haidong Xu, Biao Zhu, Xiaomeng Wei, Mukui Yu, Xiangrong Cheng
摘要: Plants can be classified as either resource-acquisitive or resource-conservative strategies based on a suite of root functional traits. Compared with conservative trees, resource-acquisitive trees can produce larger amounts of readily decomposable carbon, owing to their high specific root length (SRL) and low root C:N ratio, which would reduce the content and stability of soil organic carbon (SOC). In this study, we assessed the content of labile particulate organic carbon (POC) and stable mineral-associated organic carbon (MAOC) in the rhizosphere and bulk soils of acquisitive and conservative trees in a subtropical forest. Contrary to our expectations, we found that SOC content in the rhizosphere soil of acquisitive trees (26 g kg-1) was 53% higher than that in the rhizosphere soil of conservative trees (17 g kg-1), which was mainly attributed to an approximately 1-fold higher MAOC content. Correlation and structural equation modeling analyses indicated that this rhizosphere MAOC was primarily derived from root and mainly stimulated by high SRL, rhizosphere soil microbial biomass C, and enzyme C:N ratio, whereas the POC was mainly derived from aboveground litter. We further found that the contrasting plant strategies had no significant influence on the POC content of bulk or rhizosphere soil, which could be ascribed to the similar properties of aboveground litter of acquisitive and conservative trees. These findings indicate that acquisitive trees enhance rhizosphere soil C stability primarily via the mediation of root traits and highlight the necessity of considering plant ecological strategies when assessing the effects of tree species on soil C content and stability.
279. 题目: A spatio-temporal analysis of rice production in Tonle Sap floodplains in response to changing hydrology and climate
期刊: Agricultural Water Management
作者: Manuel Marcaida, Yasmine Farhat, E-Nieng Muth, Chou Cheythyrith, Lyda Hok, Gordon Holtgrieve, Faisal Hossain, Rebecca Neumann, Soo-Hyung Kim
摘要: Rice is one of the most important agricultural commodities throughout the Mekong River Basin including the Tonle Sap Lake floodplains in Cambodia. Recent increases in hydropower dams along the Mekong River have likely altered the surface water hydrology impacting the arable areas and soil qualities for rice production in the Tonle Sap lowland. Along with the hydrological impacts, the region’s rice farming is facing a rapidly changing climate. It is critical to understand how the hydrological changes associated with dam development impact the region’s rice production in a changing climate. The aims of this study were to assess the impacts of recent increases in hydropower dams on the timing and areas of rice cropping in the Tonle Sap floodplains and to evaluate the effects of changing hydrology, rising temperature, and adaptive farming practices on rice productivity using a process-based rice crop model: ORYZA (v3). The effect of dams on arable areas for rice was identified by a remote-sensing method based on the PhenoRice algorithm for the period of 2001–2019 in two rice-growing provinces: Kampong Thom and Battambang. The PhenoRice method identified an increase in rice growing areas as well as shifts in both timing and location of rice cropping towards the sources of irrigation during the dry season since 2010. The ORYZA model simulated a substantial yield reduction with an increase of 2 °C in air temperature in the region. The model predicted that the rice productivity in the region is sensitive to soil organic carbon content which is expected to change with surface water hydrology. The model also predicted that region’s rice yield can increase by optimizing the timing and amount of N fertilization. The findings from this study highlight how hydrology, climate, and agronomic practices can interact to impact rice production in the Lower Mekong Region and provide insights for effective water management and agronomic practices to attain food security in the region in a changing climate.
280. 题目: Seawater chemistry of a modern subtropical ‘epeirić sea: spatial variability and effects of organic decomposition
期刊: Geochimica et Cosmochimica Acta
作者: Chelsea L Pederson, Yuzhu Ge, Stephen W Lokier, Peter K Swart, Hubert Vonhof, Harald Strauss, Simon Schurr, Flavia Fiorini, Sylvia Riechelmann, Tobias Licha, Adrian Immenhauser
摘要: Direct studies of recent epeiric seawater chemistry and their geological significance are relatively few compared to the far more abundant studies from ancient epeiric marine carbonates. Acknowledging the limitations of analogue studies in the modern glaciated world, we propose that the recent Abu Dhabi offshore and lagoonal areas share important attributes with the shallow-marine coastal zones of a subtropical epeiric carbonate sea. The study area in Abu Dhabi is dwarfed by the vast epeiric seas of the geological past, but its seawater properties and related geochemistry have relevance for paleoenvironmental interpretations for similar ancient systems. This study documents the geochemical properties of seawater along the Abu Dhabi coast, and discusses their trends within a spatial context. Results show a positive correlation between salinity, temperature, elemental concentrations, and oxygen isotopic composition of seawater, indicating a significant influence of evaporation on seawater chemistry. A distal-to-proximal negative correlation between seawater Mg/Ca and Sr/Ca ratios may be related to a landward increase in abundance of high-Mg calcite foraminifera. After normalization to chloride, seawater elemental (Ca2+, Mg2+, Sr2+) concentrations and alkalinity show decreasing trends in a landward direction, consistent with seawater aging from the open marine to restricted lagoonal settings. Lower ΔAlk (alkalinity change) : ΔCa2+ (Ca2+ change) ratios in seawater compared with the theoretical value, and more negative δ13CDIC values relative to typical (sub)tropical oceans in the study area indicate an influence of factors apart from CaCO3 precipitation on properties of aged seawater. An input of alkalinity and 12C-enriched carbon by organic carbon decomposition (via sulfate reduction) during early diagenesis is proposed to account for these deviations from typical values. The input of alkalinity and 12C-enriched carbon by organic carbon decomposition may be further related to reduced seawater pCO2 and early-marine cementation. Findings discussed here suggest that organic carbon decomposition during early-marine diagenesis may influence the geochemical properties of the coastal areas of shallow epeiric seas, and thus assumedly produce significant differences in proxy data compared with those from carbonates deposited in open oceans.