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17341. 题目: Arsenate phytotoxicity regulation by humic acid and related metabolic mechanisms The use of irrigation water containing arsenic (As) had led to large areas of As-contaminated farmland, and as a result, plants and food have become severely poisoned. Humic acid (HA) can be complexed with metals, which in turn affects the metals' behavior. Herein, we explored the accumulation of arsenate in lettuce treated with different concentrations of arsenate and studied the effects of HA on the accumulation and toxicity of arsenate. The addition of HA did not cause significant changes in the arsenate content in lettuce but had a significant effect on the activity of antioxidant enzymes, which improved the antioxidant capability of the lettuce plants. Furthermore, HA promoted the accumulation of nutrients, such as magnesium (Mg), calcium (Ca), molybdenum (Mo) and manganese (Mn), in the leaves. Arsenate disrupted metabolic pathways, such as amino acid metabolism, carbohydrate metabolism, and aminoacyl-tRNA biosynthesis. The addition of HA increased the contents of amino acids and sugars, thereby improving lettuce growth. The present study explored the effects of HA on As accumulation and related physiological changes (antioxidant enzyme activities, absorption of nutrients and metabolic mechanisms) and provided insights into the regulation of As contamination by HA, which is relatively inexpensive. | |||||
17342. 题目: Assessing the potential of Chlorella vulgaris for valorization of liquid digestates from agro-industrial and municipal organic wastes in a biorefinery approach Effluents from anaerobic digesters, digestates, represent promising substrates for cultivation of microalgae, resulting in efficient digestate treatment and production of a valuable feedstock for bio-based products. However, further research is needed until a large-scale application is established. Under this scope, the purpose of the present study was to investigate cultivation of the microalga Chlorella vulgaris in different types of digestates, derived from agro-industrial and municipal organic waste respectively, as well as under various culture conditions, and to explore the potential uses of the produced biomass. Cultivation in agro-waste digestate initiated from 10% (v/v) loading, while enrichment with 15% cheese whey (CW) increased both maximum specific growth rate, μmax and biomass production, reaching 0.84 d−1 and 1.63 g L−1, respectively. Increasing digestate concentration up to 50% decreased μmax, while 80% loading totally inhibited microalgal growth. In contrast, digested municipal organic wastes could be effectively used up to 100% resulting in biomass production of 1.24 g L−1. In terms of digestate remediation, removal of organic carbon, total nitrogen and phosphorus reached up to 92%, 77% and 94%, respectively depending on the applied conditions. Furthermore, culture conditions and digestate type determined composition of C. vulgaris' biomass, which was mostly rich in proteins and carbohydrates. Photosynthetic pigments increased with increasing digestate concentration, while lipids, mostly rich in polyunsaturated fatty acids (PUFAs) decreased. Lastly, biomass extracts inhibited growth of Bacillus subtilis, with minimum inhibitory concentrations (MIC) between 0.3 and 2.85 mg mL−1, revealing the potential of digestate-grown microalgae for pharmaceuticals production. | |||||
17343. 题目: Treatment of high strength wastewater by thermophilic aerobic membrane reactor and possible valorisation of nutrients and organic carbon in its residues The depletion of nitrogen and phosphorus represents a significant problem. Two real high strength wastewaters were treated by Thermophilic Aerobic Membrane Reactor (TAMR), an advanced biological process, obtaining significant removal of pollutants. Unlike the previous works, this paper does not focus on the optimization of the performance of the TAMR, but it studied the possible reuses of liquid (permeate) and solid (biological excess sludge) matrices to recover organic carbon, nitrogen and phosphorus and promote a circular economy model. The high nitrogen content of permeate can be exploited stripping ammonia with performances higher than 80% in best conditions to produce ammonium sulphate (useful as fertilizer). Moreover, the respiromeric tests demonstrated that permeate can be used in conventional active sludge systems as external source of organic carbon granting similar denitrification rate as methanol. In the sludge residue extracted from TAMR a significant presence of organic carbon and phosphorus (as hydroxyapatite) were revealed demonstrating the feasibility of recover this residue in land application. A preliminary management costs estimation showed that TAMR, coupled with a stripping and adsorption system to recover nutrients, is economically sustainable. | |||||
17344. 题目: Impacts of sulfadiazine on the performance and membrane fouling of a hybrid moving bed biofilm reactor-membrane bioreactor system at different C/N ratios The performance and membrane fouling of a hybrid moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) system was evaluated when exposed to 0.5 mg/L of antibiotic sulfadiazine (SDZ). Results indicated that although SDZ reduced the removal efficiency of NH4+-N and TN (up to 12%) and TOC (up to 6%) at low C/N (2.5 and 4), it had no significant effect at high C/N (6 and 9). It was found that SDZ was removed 75% and 58% at high C/N of 9 and low C/N of 2.5, respectively. SDZ decreased the ratio of volatile biomass/total biomass and sludge particle size and increased the concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) in MBR. Consequently, this accelerated the membrane fouling rates, with an average increase of 6.85 kPa/d at low C/N (2.5) and 0.513–0.701 kPa/d at medium and high C/N (4, 6 and 9). | |||||
17345. 题目: Impact of biochar addition on three-dimensional structural changes in aggregates associated with humus during swine manure composting Aerobic composting is widely used to recycle agricultural organic waste. From a micro perspective, the dynamic changes in the internal structure of compost aggregates during composting can reflect aeration conditions, which is worthy of further study to improve composting efficiency. This study set three composting treatments (swine manure: rice straw = 4:1 and 8:1, swine manure: rice straw: biochar = 8:1:1, wet mass ratio), to detect 3-D microstructures of compost aggregate with the involvement of humus and biochar during composting. The results showed that biochar addition to compost enhanced humic acid formation and humification degree, and it greatly decreased bulk density by 45.89% and increased free air space by 31.25% compared with the initial stage of the compost. Compost materials tended to become looser during composting, and biochar aided an increase in total porosity of compost aggregates by approximately 90% compared with other treatments, mainly attributed to decomposition effects. It is assumed that large aggregates break up with the assistance of biochar, and these small parts of the materials gradually stick together with the formation of humus colloids to develop final dense particles. Therefore, it can be concluded that when biochar is used as an additive, it can improve the physical structure with the involvement of humus during composting. | |||||
17346. 题目: Biochar Simultaneously Reduces Nutrient Leaching and Greenhouse Gas Emissions in Restored Wetland Soils | |||||
17347. 题目: Effects of Dissolved Organic Carbon, Ultraviolet Light and their Co‐Exposure on Deepwater Horizon crude oil acute toxicity to larval red drum (Sciaenops ocellatus) In the aquatic environment, ubiquitous natural factors such as ultraviolet light (UV) and dissolved organic carbon (DOC) are likely to influence crude oil toxicity. This study examined the interactive effects of DOC, UV and DOC‐UV co‐exposure on the acute toxicity of Deepwater Horizon crude oil on larval red drum (Sciaenops ocellatus). While DOC alone did not influence crude oil toxicity, it mildly reduced UV photo‐enhanced toxicity. This article is protected by copyright. All rights reserved. | |||||
17348. 题目: Adsorption Mechanism and Structure-Performance Relationship of Chromium Ions by Biochar | |||||
17349. 题目: Using catchment characteristics to model seasonality of dissolved organic carbon fluxes in semi-arid mountainous headwaters | |||||
17350. 题目: Efficacy of Woodchip Biochar and Brown Coal Waste as Stable Sorbents for Abatement of Bioavailable Cadmium, Lead and Zinc in Soil | |||||
17351. 题目: Soil mass and grind size used for sample homogenization strongly affect permanganate-oxidizable carbon (POXC) values, with implications for its use as a national soil health indicator Permanganate oxidizable carbon (POXC) is increasingly used in soil health assessments as an indicator of labile or active soil organic carbon (SOC). The POXC method owes its popularity to its rapidity and low cost and its responsiveness to soil management. However, the method's sensitivity to variation in methodological parameters may compromise the comparability of POXC values across soils. Here, we measured the effects of soil mass and the method of sample homogenization (grind size) on POXC values for a set of 42 soil samples, representing diverse geographic areas and soil types of the USA. Total SOC contents ranged from 3.0 to 288.4 g kg−1. Ten treatments, combinations of five sample masses (0.25–5.0 g) and two grind sizes (<2 mm, <0.18 mm), were evaluated for POXC based on Weil et al. (2003). Results showed that POXC values decreased exponentially with increasing soil mass used, while analytical variability decreased as well. Decreasing grind size from <2 mm to <0.18 mm increased POXC values by 49% and decreased analytical variability. Strong correlations between POXC values obtained at two different soil masses (r = 0.91–0.97) or grind sizes (r = 0.96) indicate that general trends in POXC values across soils are maintained irrespective of soil mass or grind size, but the results are not interchangeable since POXC values differ considerably. Therefore methodological parameters, including soil mass and intensity of soil homogenization, should be strictly controlled to ensure comparability. However, standardizing soil mass presents a challenge for its use in national monitoring schemes as none of the soil masses yielded results within the method's quantitation limits for all soils included in our sample set. A more fundamental problem challenging the comparison and interpretation of POXC values relates to the use of a fixed soil mass for POXC analysis across soils with different SOC contents. Whereas the initial amount of MnO4− is fixed, the amount of SOC that takes part in the oxidation reaction is soil specific and not controlled for when using a fixed soil mass. This leads to variation in the [MnO4−] : SOC mass ratio during the reaction, which affects the size and the biochemical composition of the fraction of total SOC being oxidized. We conclude that the POXC method falls short as an analytical method for measuring a well-defined C pool. Performing POXC analyses based on a fixed SOC mass may improve comparability of POXC values across soils with contrasting SOM contents, but would compromise the main advantages of the POXC method in terms of simplicity, speed and low-cost. | |||||
17352. 题目: El Niño‐Driven Dry Season Flushing Enhances Dissolved Organic Matter Export from a Subtropical Watershed The 2015/16 super El Niño event resulted in a positive precipitation anomaly during dry seasons in the Jiulong River watershed, southeast China. Four years (2014‐17) of high frequency, in situ humic‐like fluorescent DOM (FDOMH) data in the Jiulong Estuary was coupled with extrapolation to a freshwater endmember FDOMH concentration and river discharge data to estimate riverine FDOMH export. The wetter El Niño dry season was followed by lower FDOMH export during the subsequent wet season. Furthermore, in the dry season after El Niño reached its strongest phase, a 90‐187% increase in FDOMH export occurred. If widespread, this pattern suggests El Niño events may enhance export of FDOMH from south China rivers in dry seasons resulting in seasonal and annual shunting of the terrestrial DOM export, modulating coastal carbon cycling. This study highlights the need to incorporate climate‐driven regulation patterns on DOM transport across the land‐ocean interface. | |||||
17353. 题目: Fifteen-year no tillage of a Mollisol with residue retention indirectly affects topsoil bacterial community by altering soil properties Soil microbes play an important role in nutrient cycling in agricultural soils and can be influenced by tillage. Conservation tillage aims to reduce energy inputs and conserve soil and water by decreasing disturbance of soil and returning a portion of crop residue. The response of the soil microbial community to conservation tillage is complex and quantitative analysis is largely absent regarding how tillage and depth, combined with soil properties, affect soil microbial diversity and community composition. Here, the diversity and composition of the soil bacterial community and its relationship with soil properties were explored by high-throughput sequencing technology and Structural Equation Modeling (SEM) at two soil depths (0–5 cm and 15–20 cm) under conventional tillage and no tillage with residue retention. No tillage significantly increased alpha diversity (Chao 1 and Shannon) at 0-5 cm and altered the composition of the bacterial community, coinciding with changes in physical-chemical properties. Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, and Gemmatimonadetes were the most abundant phyla across all samples. Alpha diversity was significantly correlated with soil bulk density (BD) and pH. The SEM showed that tillage and depth explained 86% of the bacterial diversity and 84% of the composition. In addition, tillage and depth had indirect effects on bacterial diversity and composition by affecting soil BD, pH and soil organic carbon. Results indicate that the soil bacterial community is altered by conservation tillage, especially in the topsoil, and highlight the importance of soil physical-chemical properties in shaping the diversity and composition of the soil bacterial community. Our findings contribute to a broad understanding of tillage disturbance and differentiated effects in the soil profile for the bacterial community. | |||||
17354. 题目: Fresh biochar application provokes a reduction of nitrate which is unexplained by conventional mechanisms Soil-applied biochar has been reported to possess the potential to mitigate nitrate leaching and thus, exert beneficial effects beyond carbon sequestration. The main objective of the present study is to confirm if a pine gasification biochar that has proven able to decrease soil-soluble nitrate in previous research can indeed exert such an effect and to determine by which mechanism. For this purpose, lysimeters containing soil-biochar mixtures at 0, 12 and 50 t biochar ha−1 were investigated in two different scenarios: a fresh biochar scenario consisting of fresh biochar and a fallow-managed soil, and an aged biochar scenario with a 6-yr naturally aged biochar in a crop-managed soil. Soil columns were assessed under a mimicked Mediterranean ambient within a greenhouse setting during an 8-mo period which included a barley crop cycle. A set of parameters related to nitrogen cycling, and particularly to mechanisms that could directly or indirectly explain nitrate content reduction (i.e., sorption, leaching, microbially-mediated processes, volatilisation, plant uptake, and ecotoxicological effects), were assessed. Specific measurements included soil solution and leachate ionic composition, microbial biomass and activity, greenhouse gas (GHG) emissions, N and O isotopic composition of nitrate, crop yield and quality, and ecotoxicological endpoints, among others. Nitrate content reduction in soil solution was verified for the fresh biochar scenario in both 12 and 50 t ha−1 treatments and was coupled to a significant reduction of chloride, sodium, calcium and magnesium. This effect was noticed only after eight months of biochar application thus suggesting a time-dependent process. All other mechanisms tested being discarded, the formation of an organo-mineral coating emerges as a plausible explanation for the ionic content decrease. | |||||
17355. 题目: Climatic, land cover, and anthropogenic controls on dissolved organic matter quantity and quality from major alpine rivers across the Himalayan-Tibetan Plateau Alpine rivers in mountainous regions are crucial not only for land-ocean transfer of chemical species and sediments, but also for water, food, and energy security. Here, we examined dissolved organic matter (DOM) from the major alpine waters on the Tibetan Plateau. Our results revealed a decreasing trend of DOM quantity juxtaposed to an increasing trend of aromaticity from the northern to southern plateau. This is potentially caused by a general decreasing gradient of dust load combined with an increasing gradient of precipitation and vegetation from the NW to SE plateau. Furthermore, most proglacial streams and smaller tributaries were found to be relatively dominated by tyrosine-like fluorescent DOM from glaciers. In contrast, most main stems of rivers and tributaries within larger catchment basins were more controlled by humic-like fluorescent DOM from terrestrial origins. Condensed aromatics accounts for 14–21% of molecular formulas for riverine DOM, much higher than the world's average of ~11%, which indicated anthropogenic black soot pollution. In addition, there is a higher level of DOM amount in the monsoon season than in winter, and DOM characteristics varied more widely (dissolved organic carbon concentration: 0.2-37 mg-C L−1, Fluorescence Index: 1.2-1.8) on the Tibetan Plateau in comparison to other global alpine watersheds. This suggests heterogeneous land cover, anthropogenic, and climatic factors at play, which is reflected in DOM quantity and quality, over the highest plateau on Earth. | |||||
17356. 题目: Evaluation of a hybrid process of magnetic ion-exchange resin treatment followed by ozonation in secondary effluent organic matter removal The presence of effluent organic matter (EfOM) and organic micro-pollutants (OMPs) in secondary effluent is receiving increasing concern due to their potential impacts on the aquatic environment and human health. In this study, the removal characteristics of EfOM by magnetic ion-exchange resin (MIEX), ozonation, and the hybrid process of MIEX followed by ozonation (M + O) were compared by measuring the bulk organic indicators (BOIs), OMPs, bio-toxicity, and fluorescence. Furthermore, the desorption characteristics of MIEX were comprehensively studied. Ozonation could reduce the OMPs, total fluorescence (TF), genotoxicity, and oestrogenic activity more effectively than MIEX, with reductions of 80.3%, 97.8%, 98.9%, and 94.6%, respectively. The M + O process was capable of removing more EfOM than the individual MIEX or ozonation processes and could reduce the genotoxicity and oestrogenic activity to the detection limit. By implementing MIEX as a pre-treatment, the generation of ammonia–nitrogen and nitrate–nitrogen was effectively reduced in the subsequent ozonation process as MIEX adsorbed organic nitrogen and nitrite-nitrogen. The different regenerants influenced the OMP desorption performance of MIEX by changing the desorption mechanisms, and NaCl + NaOH was the best regenerant due to its high total OMP desorption efficiency. Parallel factor analysis coupled with self-organising maps further explained the differences in fluorescence desorption due to the addition of NaOH to the regenerated solution. Pearson correlation analysis indicated the potential of using spectroscopic indicators, such as ultraviolet absorbance and TF, to assess the evolution of OMPs and bio-toxicity during the M + O and MIEX desorption processes. | |||||
17357. 题目: Soil organic carbon stocks in an investigated watershed transect linked to ecological restoration practices on the Loess Plateau Lager scale ecological restoration practices are increasing soil organic carbon (SOC) stocks. Meta‐analysis is by far the most widely applied technique for describing SOC at large spatial scales, but there is a lack of field‐based investigations on a series of individual watersheds. In this study, a watershed transect of 6 watersheds distributed along the hilly and gully area of the Loess Plateau was investigated in order to achieve sustainable practices. The results indicate that ecological restoration practices significantly increased SOC stocks to varying degrees (p < 0.05). Grasslands were associated with the largest SOC stocks (39.42 ± 22.21 t hm−2), which were larger than the SOC stocks of artificial immature forest (<20 years) (26.58 ± 14.32 t hm−2) in the 50 cm soil profile. However, in the long term, afforestation seems to increase SOC stocks to the level of secondary forest, 81.15 ± 4.69 t hm−2, in a suitable environment. Appropriate land use management is also an effective approach to improving soil C sequestration capacity. SOC stocks were measured as 34.11 ± 7.66 t hm−2 in abandoned terraced farmland, which was similar to the grassland SOC stocks. Soil and plant factors contributed approximately 60% to the variation in the spatial distribution of SOC stocks at 0–50 cm; their contributions increased and diminished with increasing soil depth, respectively. This study indicates naturally restored grassland and engineering practices are suitable on the Loess Plateau by investigating a watershed transect and enhances our understanding of the comprehensive contributions of environmental factors to the spatial distribution of SOC stocks on a large spatial scale. | |||||
17358. 题目: Simultaneous photometric determination of oxidation kinetics and average manganese valence in manganese products in situ formed in the reactions of aqueous permanganate with model organic compounds and natural organic matters In this study, a colorimetric method using 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) was adopted to investigate oxidation kinetics by permanganate (Mn(VII)) in trace levels (lower than 1 mg/L or 6 µM) and measure average manganese valence in manganese product bulks in (i) synthetic waters containing selected model compounds with electron-rich moieties, (ii) natural organic matters (NOM) isolate solution, and (iii) real water samples including river water, reservoir water and secondary wastewater effluent. The second-order rate constant for Mn(VII) oxidation of phenol determined using ABTS method was demonstrated to be comparable to that measured by traditional high-performance liquid chromatography (HPLC) method at pH 5–9. This method was applied to measure the rate constants of the reactions between Mn(VII) and model compounds with electron-rich moieties. Average manganese valence in manganese product bulks from Mn(VII) oxidation of selected model compounds was lower than 4 at acidic pH, suggesting that Mn(III) was likely to be generated during Mn(VII) oxidation. Possible mechanisms for Mn(III) formation via one/two-electron process were also proposed. Mn(VII) reaction with NOM isolate sample followed two-phase kinetics with rate constants of 3.47 × 10-5 s−1 (mg C/L)-1 and 6.94 × 10-6 s−1 (mg C/L)-1 in the initial and secondary phases at pH 8. Similarly, two-phase kinetics were also found in the consumption of Mn(VII) in real waters. Mn(VII) consumption rates in different real waters followed the order of their dissolved organic carbon levels. In contrast, chlorine decay rates were mainly based on the order of their dissolved organic nitrogen levels. Moreover, average valence in manganese products in real water samples was determined as around 4, which was mainly ascribed to the one-electron-transfer processes of Mn(VII) with NOM constituents in real water samples such as phenols and amines at ambient weak alkaline pH. | |||||
17359. 题目: Three-dimensional fractal characteristics of soil pore structure and their relationships with hydraulic parameters in biochar-amended saline soil Due to poor soil quality, coastal saline soil limits soil productivity. Therefore, it is of great importance to find appropriate and efficient methods to improve the quality of coastal saline soil. Biochar has been widely used as a soil amendment to improve soil properties, but the effects of biochar amendment on soil pore structure and soil hydraulic properties are unclear. In recent years, with the development of fractal theory and computer technology, fractal geometry based on image analysis has been employed for quantitatively characterizing the structure and heterogeneity of soil pores. In this study, field experiments were established with three proportions of straw biochar (0, 2 and 5 %, w/w) to study the biochar amendment effects on soil structure and soil hydraulic properties. Three replicates were set for each treatment. The results showed that the addition of biochar to saline soil improved soil pore structures and soil hydraulic characteristics. The biochar amendment led to the strong pore spatial variation, complex pore structure and irregular pore shape. The biochar-amended saline soil had a high considerable water retention capacity (, AWC). Biochar had a long-term effect on saline soil improvement. For multifractal analysis, it is better to use the and values to analyze the multifractal characteristics of soil. The heterogeneity of the soil pore distribution became stronger after biochar amendment. Multifractal parameters had significant changes with the time of biochar amendment. The changes of soil pore structure resulted in the improvement of soil hydraulic characteristics. The value improved as the pore connectivity increased. The strong pore spatial variation, complex pore structure and irregular pore shape aided in increasing the value. The available water content value was improved as the number of soil pores, especially the micropores, increased. In response, this study proposes a new approach to analyzing soil pore structure to explain the association between the soil pore structure and soil hydraulic characteristics in biochar-amended saline soil. | |||||
17360. 题目: Regional and Sectoral Sources for Black Carbon over South China in Spring and Their Sensitivity to East Asian Summer Monsoon Onset Besides local emissions, biomass burning (BB) emissions in peninsula Southeast Asia (PSEA) and domestic anthropogenic emissions in North China (NC) are also significant black carbon (BC) sources over South China (SC) in spring. Meanwhile, the East Asian summer monsoon (EASM) is established with the wind field reversal, influencing the region‐based contributions to BC over SC. Herein, BC sources for SC were tracked by region and by sector using the Community Earth System Model with a BC‐tagging technique. During the spring of 2000‐2014, 27% of BC surface concentration (BCS) and 64% of BC column burden (BCC) over SC stems from nonlocal sources. BC from NC is mainly transported below 850 hPa. It is the dominant nonlocal contribution to BCS (17%) and largely composed of residential and industrial sectors. Nonlocal emissions inside and outside China contribute 28% and 36% to BCC, respectively. Generally transported above 850 hPa, BC from PSEA is the largest nonlocal contributor (20%) to BCC and contributes 80% of BCC in BB sector. Additionally, the interannual variation in EASM onset times bring a maximum of ‐5% to +7%/‐2% to +7% variation in BCC/BCS. The BC outflow/inflow contributed from NC dominates the BC decrease/increase over SC with southerly/northerly wind anomaly induced by early/late EASM onset, yet regional transport from PSEA contributes minor BC changes. The simulated BC is significantly positively correlated with the varying EASM onset times, but not with emissions, indicating the decisive role of meteorology in the interannual variation of BC over SC during springtime. | |||||
