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24181. 题目: Peroxide/Zero-valent iron (Fe0) pretreatment for promoting dewaterability of anaerobically digested sludge: A mechanistic study Peroxide/Zero-valent iron (Fe°) was reported to promote dewaterability of anaerobically digested sludge (ADS), but the mechanism of how Peroxide/Fe° facilitates ADS dewatering is unknown. This study therefore aims to uncover the details of how Peroxide/Fe° elevates ADS dewaterability. Experimental results showed that with 0.6 g Fe°/g TSS and 0.08 g peroxide/g TSS, capillary suction time, specific resistance to filtration, and time to filtration of ADS was 50.7%, 41.4%, and 54.4% of that in the control, respectively. In this condition, water content of sludge cake decreased from 91.2% ± 0.5% (the control) to 68.6% ± 1.3%. The mechanism explorations revealed that the elevated dewaterability was mainly caused by role of •OH and Fe(II)/Fe(III) species during Peroxide/Fe° pretreatment. •OH decreased the polysaccharides and proteins in extracellular polymeric substance (EPS), then injured the cytoderm & cytomembrane through the releases of lactate dehydrogenase and N-acetylglucosamine, and further facilitated the decrease of intracellular substances, which disengaged the water trapped in ADS. In addition, the cell lysis caused by •OH facilitated forming macro-pores. Moreover, •OH converted the conformational structure of extracellular proteins, which may strengthen the ADS hydrophobicity, promoting the discharge of unbound water and ADS flocculation. Meanwhile, Fe(II)/Fe(III) benefited aggregating the denatured ADS particulates. | |||||
24182. 题目: Eco-Corona vs Protein Corona: Effects of Humic Substances on Corona Formation and Nanoplastic Particle Toxicity in Daphnia magna | |||||
24183. 题目: The soil organic carbon stabilization potential of old and new wheat cultivars: a <sup>13</sup>CO<sub>2</sub>-labeling study | |||||
24184. 题目: Radiocarbon evidence of the impact of forest-to-plantation conversion on soil organic carbon dynamics on a tropical island Tropical soils are critical terrestrial carbon reservoirs with abundant biodiversity that respond rapidly to environmental change. Globally, the expanding conversion of natural tropical forest to plantations in recent decades, to meet economic demands, has markedly influenced the cycling of soil organic carbon (SOC) pools; however, the mechanisms underlying the changes in SOC dynamics are poorly understood. In this study, we examined the SOC dynamics and soil microbial communities at five adjacent tropical forest sites characterized by different logging and plantation practices over the past few decades on Hainan Island, China, by applying natural abundance radiocarbon (14C) and phospholipid fatty acid (PLFA) analysis. At a >35-year rubber plantation site and a >50-year eucalyptus plantation site, an abnormal up-profile decrease in radiocarbon abundance was observed in the upper 30 cm soil layer. This could be indicative of continued soil organic matter decomposition long after forest–plantation conversion, and was consistent with the SOC inventories in the upper 30 cm soil layer at the two sites being significantly lower than those of NF. Both the SOC apparent radiocarbon ages and SOC inventory at a eucalyptus plantation site in which tillage was stopped 20 years ago were similar to those of NF, indicating that a recovery process had occurred. The soil microbial biomass was generally lower at the plantation sites than at the NF site. Both the radiocarbon abundance and SOC inventories in the upper 30 cm soil layer showed positive correlations with the soil microbial biomass, suggesting that microbes may have played a key role in the fate of SOC. This study provided evidence that forest–plantation conversion may facilitate the dissimilation of SOC, and also demonstrated that radiocarbon can serve as a powerful tool for assessing the potential changes of soil carbon dynamics resulting from forest-to-plantation conversion. | |||||
24185. 题目: N addition increased microbial residual carbon by altering soil P availability and microbial composition in a subtropical Castanopsis forest Microbial residual carbon (C) plays a crucial role in soil organic C (SOC) stabilization, and exogenous nutrients have frequently been observed to increase the proportion of microbial residual C in soils with limited nitrogen (N). However, how microbial residual C responds to N deposition and their mechanisms in subtropical forest soil with low phosphorus (P) availability remains poorly understood. To fill this knowledge gap, an experiment with 5.5 consecutive years of N addition (control, 40 and 80 kg N ha−1y−1) to a Castanopsis carlesii forest in Fujian, China was performed. Soil properties (e.g., soil C, N, P, and pH), amino sugars (biomarkers of microbial residual C), phospholipid fatty acids (PLFAs), and enzyme activities were investigated. We found that N application and soil depths had significant interactive effects on amino sugars, the PLFAs, and soil enzyme activities. N addition significantly increased the contents of amino sugars and their proportions to soil C in the 0–10 cm soil layer but not the 10–20 cm soil layer (P > 0.05). In addition, glucosamine (GluN), which was mostly derived from fungal cell walls, accounted for 64.9–73.9% of the total amino sugars across three treatments, and the proportion of GluN to total C also increased after N addition in the 0–10 cm layer. These results indicate that N addition elevated the contribution of amino sugars, especially GluN, to soil C sequestration of the 0–10 cm soil layer but not 10–20 cm soil layer. Moreover, N addition significantly enhanced the biomass of fungi and ectomycorrhizal fungi (EMF) and the activities of phosphatase (ACP), phosphodiesterase (PD), N-acetyl glucosaminidase (NAG), acid phenol oxidase (PhOx), and peroxidase (Perox), while it significantly decreased soil organic P (OP) in the 0–10 cm soil layer. These results implied that changes in N:P ratio caused by N addition contributed to the increases of EMF and fungi, which have high P acquisition ability, this in turn enhanced soil P availability. The increased microbial biomass of EMF and fungi likely attributed to the increased contribution of amino sugars to SOC accumulation in the studied forest soil. Our study revealed a novel mechanism of soil C sequestration in subtropical forest ecosystems with low soil P under ongoing N deposition. | |||||
24186. 题目: Occurrence, fate and environmental risk assessment of pharmaceutical compounds in soils amended with organic wastes One of the most common ways of getting rid of sewage sludge is land spreading on agricultural fields as a source of nutrients and organic matter. However, sewage sludge may be contaminated with pharmaceuticals and can represent a cause of environmental contamination. The objectives of this study was (i) to determine the occurrence and the fate of pharmaceuticals such as antibiotics belonging to different classes: antibiotics (sulfadiazine, sulfamethoxazole, sulfamethoxypyridazine, ciprofloxacin, norfloxacin, tylosin, trimethoprim), anti-inflammatories (diclofenac) and anticonvulsants (carbamazepine) in the soil after spreading stabilized sludge (composted, limed and digested) and solid digestat, (ii) to evaluate agronomic benefits and (iii) to determine the potential ecotoxicological consequences of pharmaceutical compounds on the environment using a risk quotient approach. For this purpose, four different types of sludge samples, coming from the same treatment plant but submitted to different stabilization processes, were incorporated into three soils with different physicochemical characteristics and pedogenetic factors. The obtained results highlighted that the sludge treatments have a great influence on sludge contamination. Once applied onto the soil, the agronomic benefits will depend on the soil's properties as well as the sludge's characteristics. The risks concerning the ecotoxicity of pharmaceuticals, found in the sludge, are low but not insignificant. | |||||
24187. 题目: CDOM in the source regions of the Yangtze and Yellow Rivers, China: optical properties, possible sources, and their relationships with environmental variables | |||||
24188. 题目: Pathways to persistence: plant root traits alter carbon accumulation in different soil carbon pools | |||||
24189. 题目: Microbial community composition turnover and function in the mesophilic phase predetermine chicken manure composting efficiency The aim of this work was to study the influence of inoculation with microbial inoculants (MI) or mature compost (MC) by comparing the resultant composting efficiency with that in a noninoculated (CK) treatment. MI and MC application both accelerated the composting process according to fluorescence excitation-emission matrix (EEM) detection and germination index testing. Bacterial and fungal community composition both differed significantly over the composting period. However, the turnover of the initial bacterial community played a significant role in the composting process, and the key operational taxonomic units (OTUs) of MI (OTU_26, Thermicanus) and MC (OTU_48, Tepidimicrobium) showed significant explanatory power for the formation of humic acid-like and fulvic acid-like substances, respectively, during the stage of composting. Thus, our results indicate that microbial inoculation accelerates the composting process by stimulating key resident microbes in the initial stage. | |||||
24190. 题目: Microbial extracellular polymeric substances (EPS) acted as a potential reservoir in responding to high concentrations of sulfonamides shocks during biological wastewater treatment Extracellular polymeric substances (EPS), one of the main components of activated sludge, could complex with pollutants and thus influence their fate in wastewater treatment system. In this work, the roles of EPS in resisting sulfamethazine (SMZ) shocks were investigated in a continuous flow membrane bioreactor. Results show that SMZ could be intercepted in the EPS of activated sludge during the lag phase of biodegradation. EPS acted as a potential reservoir against SMZ shocks, guaranteeing undetectable SMZ in the effluent. The increased production of EPS in responding to SMZ shocks improved the binding capability of EPS to SMZ. The critical roles of microbial EPS in removing bio-refractory contaminants such as sulfonamides are probably underestimated previously. | |||||
24191. 题目: Adsorption of toluene on various natural soils: Influences of soil properties, mechanisms, and model This study investigated toluene adsorption on natural soils. The linear partition model was found to represent the adsorption isotherm well (R2 = 0.958–0.994), compared with the Freundlich model (R2 = 0.901–0.991). Therefore, the coefficient, Kd, of the linear model indicated the adsorption capacity of soils A to F. Traditionally, Kd and the total organic carbon (TOC) content have a good linear relationship. However, this relationship was weak (correlation coefficient (r) = 0.689) when TOC values (8.43–12.9 mg/g) were low and close. To correct this deviation, this study investigated the influences of physicochemical properties, such as special surface area, mineral composition, functional groups, pH, and potentials. As soils B and C consisted of a large amount of active clayey minerals (69.4% kaolinite and 79.3% nacrite, respectively) and rich functional groups, they demonstrated the strongest adsorption capacity. Additionally, the r for pH-Kd, zeta potential-Kd, and redox potential-Kd were high, at 0.806, 0.914, and 0.932, respectively. To explore adsorption mechanisms, the adsorption thermodynamic parameter (enthalpy) was used initially to determine the forces. Combined with the analysis of soil properties, the mechanisms identified were hydrophobic interaction and hydrogen-pi bonding, involving co-adsorption with water molecules. Based on all studies, the properties were quantified and simplified by the plastic limit (PL), and TOC was simplified by soil organic matter (SOM). Then, PL and SOM were weighted by the entropy-weight method to obtain the determination factor, DF, a logarithmic parameter to replace TOC. Finally, a new model describing toluene adsorption on natural soils was established and expressed as Kd = 4.80 + 3.53DF. This new model had significantly improved the correlation between Kd and TOC (r = 0.933) and expanded the engineering adaptability. | |||||
24192. 题目: Biochar mitigates the negative effect of chloropicrin fumigation on beneficial soil microorganisms Chloropicrin (CP) is the most commonly used soil fumigant worldwide. Although CP effectively controls soilborne pathogens, it is also detrimental to beneficial soil microorganisms unless measures can be put in place to protect them from the effects of fumigation. In this study, we evaluated the ability of biochar made from the invasive weed Eupatorium adenophorum to mitigate the effects of CP fumigation on beneficial species. Our results showed that the addition of biochar to the soil effectively reduced the detrimental effects of CP on beneficial species and their ecological functions. Biochar added to CP-fumigated soil shortened the time to 28–84 days for microbial diversity and nitrogen cycle functions to be restored to unfumigated levels. At the same time, the inorganic nitrogen (NH4+-N, NO3−-N) content and N2O production potential level in CP-fumigated soil returned to unfumigated levels relatively quickly, which showed that nitrogen metabolism improved with the addition of biochar. The mitigation effect of biochar in CP-fumigated soil was more evident at higher biochar amendment rates. Our results suggest that the addition of biochar to CP-fumigated soil significantly reduced the impact of CP on beneficial species and their ecological functions, and significantly shortened the time for beneficial species to recover to pre-fumigation levels. Field research is required to determine biochar's ability to mitigate the impact of CP and other fumigants on beneficial species and to quantify its benefits on crop quality and yield. | |||||
24193. 题目: Bioavailability of organic phosphorus in the water level fluctuation zone soil and the effects of ultraviolet irradiation on it in the Three Gorges Reservoir, China Ultraviolet (UV) irradiation is an abiotic pathway for the transformation of complex phosphorus (P) components into inorganic P in ecosystems. To explore the effect of UV irradiation on organic P (OP) bioavailability in the water level fluctuation zone (WLFZ) soil, we collected representative soil samples from WLFZ of the Pengxi River, a tributary of the TGR, China. We determined the contents of different forms of OP in the WLFZ soil through sequential extraction. The bioavailability of different forms of OP and the effect of UV light were characterised using a combination of enzymatic hydrolysis and UV irradiation. The OP contents of the different extracts (Po) were ranked as NaOH-Po > NaHCO3-Po > H2O-Po, whereas those of enzymatically hydrolysable organic P (EHP) were ranked as NaOH-EHP > NaHCO3-EHP > H2O-EHP. UV irradiation was found to improve OP bioavailability, as demonstrated by increased levels of UV-sensitive P (UV-P) and EHP in the extracts after irradiation. The total contents of bioavailable Po in extracts were 5.6–35.3% higher after UV irradiation than before irradiation. Thus, the effect of UV irradiation on the OP bioavailability and release activity cannot be neglected in TGR WLFZ soil. | |||||
24194. 题目: Distribution of chemical forms of mercury in sediments from abandoned ponds created during former gold mining operations in Colombia Total mercury (THg) and methylmercury (MeHg) were studied in sediments from 27 abandoned gold mining ponds (AGMPs) through small-scale artisanal gold mining in the district of San Juan in Chocó region of Colombia. The AGMPs were abandoned in the last century (1997) and were grouped into three distinct groups (2–6; 7–12; 13–20 years). Overall concentration (in ng g−1) pattern of THg in sediments varied from 39.06 to 1271.32 (avg. 209.57) with 174.81 (13–20 years), 205.56 (7–12 years) and 248.33 (2–6 yrs) respectively. MeHg concentrations accounted for 3.3–10.9% (avg. 6.5%) of THg and were significantly correlated with THg during all periods. Correlations between organic matter (OM) vs MeHg and THg were negative in the oldest pools, signifying a dilution effect or natural burial of THg and MeHg. Results for sequential extraction indicate that the fraction of elemental Hg (Hg-e) and organo chelated Hg (Hg-o) represent the main chemical forms of Hg in the sediments, regardless of the abandonment period, whereas the bioavailable fraction was only 0.12–1.65% of THg. The significant statistical relationship between MeHg, THg and OM suggests that these parameters control the distribution, mobility, toxicity and bioavailability of Hg in the sediments of these abandoned ponds. Evaluation of THg with sediment quality guidelines indicates that the values are on the higher side for Threshold effect concentration and Upper continental crust. Comparing of MeHg with many other regions outside Colombia is a worrying factor and needs immediate attention to protect the human health. | |||||
24195. 题目: Processes of chromium (VI) migration and transformation in chromate production site: A case study from the middle of China The migration and redox transformation processes of toxic Cr(VI) in the upper and deep soil of chromate-polluted site are of great importance for the environmental risk control and soil remediation. In this study, soils from surface to deep (around 30–60 m) and the groundwater in a typical abandoned chromate production plant site which has experienced decades of contamination were both sampled and analyzed. The results show that the soil in the leaching workshop of Cr(VI), dichromate transformation workshop and chromium slag dumping ground exhibits severe contamination of chromium and the pollution has extended to the groundwater, causing serious pollution in groundwater too. The vertical migration and transformation of Cr(VI) in the soil layer are mainly affected by the soil permeability, organic matter content and the amount of water passing through the soil layer. During the downward migration, Cr(VI) tends to be retained by the clay layer and further accumulates around the depth of 5–10 m where the concentrations of both hexavalent and total Cr reach maximum values, and then continues to diffuse from the accumulation layer towards the deeper soil. Accompanying with the reduction of Cr(VI) by organic matter in the soil, the Cr(III) exists at various depths. When the depth is below the groundwater level of saturated aquifer, the distribution of chromium in the soil and groundwater reaches leaching and redox equilibrium due to the long-term interaction between the soil and groundwater. | |||||
24196. 题目: Organic composition in feed solution of forward osmosis membrane systems has no impact on the boron and water flux but reduces scaling This study aimed to characterize the impact of organic and inorganic compounds in the feed solution on the membrane fouling and the boron flux in a forward osmosis (FO) membrane system. Lab-scale FO membrane systems were operated in batch mode, with a solution containing organic compounds (humic acid (HA), bovine serum albumin (BSA), sodium alginate (SA)), scaling constituents (calcium chloride, sodium sulfate), and boric acid as feed solution, and with concentrated sodium chloride as draw solution. Preparations of membrane sample for scanning electron microscopy and energy dispersed spectroscopy (SEM-EDX) by freeze- and by oven-drying showed different results and can therefore not be considered as suitable for the evaluation of the samples. Results showed that the organic fouling layer did not have an impact on water and boron fluxes, but reverse salt flux was reduced in the presence of BSA and HA. The molar flux ratio between water and boron was roughly 105, regardless of the presence of the fouling. The hydrophobicity and surface charge of the fouling layer were not related to the boron transport rate. A thicker and more uniform organic fouling layer, as observed, caused a reduced RSF. The organic compounds in the feed solution impeded the crystallisation of gypsum, which can lead to reduce scaling. | |||||
24197. 题目: Point bars retained particulate organic carbon within a meandering river corridor in Zoige Basin of the Tibetan Plateau Carbon retention within river corridors influences ecosystem processes of catchments and regulates regional to global carbon budgets. Previous studies lack focus of carbon retention associated with meandering river migration. To fill the gap, this study concentrated on particulate organic carbon (POC) retention by point bars that built via hydrogeomorphic processes within meandering river corridors. We selected a typical meandering river (White River) in Zoige Basin of the Tibetan Plateau to conduct field works in the growing seasons of 2016, 2018, and 2019. We found (i) concentration of POC retained within point bars was 0.17%-2.52%, three to five times significantly lower than on general areas of floodplain, and did not show downstream trends; (ii) POC was homogeneously distributed within individual point bars, whereas the positions pioneer plants invaded had significantly higher concentrations; (iii) the order for POC concentration within the river corridor was: positions of bars without plants (1.08%) < positions of bars with pioneer plants (2.96%) < general area of floodplain (5.65%); (iv) the frequency of pioneer plants invasion increased downstream by advantage of the widened channel. Hydrogeomorphic processes through building point bars exerted an intense influence in modifying the POC concentration within the meandering river corridor. | |||||
24198. 题目: Arctic amplification of global warming strengthened by sunlight oxidation of permafrost carbon to CO2 Once thawed, up to 15% of the ∼1,000 Pg of organic carbon (C) in arctic permafrost soils may be oxidized to carbon dioxide (CO2) by 2100, amplifying climate change. However, predictions of this amplification strength ignore the oxidation of permafrost C to CO2 in surface waters (photomineralization). We characterized the wavelength dependence of permafrost dissolved organic carbon (DOC) photomineralization and demonstrate that iron catalyzes photomineralization of old DOC (4,000‐6,300 a BP) derived from soil lignin and tannin. Rates of CO2 production from photomineralization of permafrost DOC are two‐fold higher than for modern DOC. Given that model predictions of future net loss of ecosystem C from thawing permafrost do not include the loss of CO2 to the atmosphere from DOC photomineralization, current predictions of an average of 208 Pg C loss by 2299 may be too low by ~14%. | |||||
24199. 题目: Composition characterization and biotransformation of dissolved, particulate and algae organic phosphorus in eutrophic lakes Characteristics and transformation of organic phosphorus in water are vital to biogeochemical cycling of phosphorus and support of blooms of phytoplankton and cyanobacteria. Using solution 31P nuclear magnetic resonance (NMR), combined with field surveys and lab analyses, composition and structural characteristics of dissolved phosphorus (DP), particulate phosphorus (PP) and organic P in algae were studied in two eutrophic lakes in China, Tai Lake and Chao Lake. Factors influencing migration and transformation of these constituents in lake ecosystems were also investigated. A method was developed to extract, flocculate and concentrate DP and PP from lake water samples. Results showed that orthophosphate (Ortho-P) constituted 32.4%–81.3% of DP and 43.7%–54.9% of PP, respectively; while monoester phosphorus (Mono-P) was 13.2%–54.0% of DP and 32.9%–43.7% of PP, respectively. Phosphorus in algae was mostly organic P, especially Mono-P, which was ≥50% of TP. Environmental factors and water quality parameters such as temperature (T), electrical conductivity (EC), pH, secchi depth (SD), dissolved oxygen (DO), chemical oxygen demand (CODcr), chlorophyll-a (Chl-a), affected the absolute and relative concentrations of various P components in the two lakes. Increased temperature promoted bioavailable P (Ortho-P and Mono-P) release to the lake waters. The results can provide an important theoretical basis for the mutual conversion process of organic P components between various media in the lake water environment. | |||||
24200. 题目: Nitrogen induced DOC and heavy metals leaching: Effects of nitrogen forms, deposition loads and liming Atmospheric nitrogen (N) deposition is believed to accelerate dissolved organic carbon (DOC) production and could lead to increased heavy metal mobility into water resources. We sampled intact soil cores from the Isle of Skye with low background N deposition history and having Serpentine rock known for its higher heavy metal concentrations including zinc (Zn), copper (Cu), nickel (Ni) and lead (Pb). The effects of 16 (16kgN) and 32 kg N ha−1 year−1 (32kgN), and liming with 32kgN (32kgN + Lime) on soil solution chemistry and heavy metal mobilization were investigated over the 15-month study. Nitrogen in deposition load was added at five ammonium (NH4+) to nitrate (NO3−) ratios of 9:1, 5:1, 1:1, 1:5 and 1:9 along NO3−dominance. We found significant effects of load on Cu and NH4+/NO3− ratio on pH, DOC and Zn in soil solution. However, under lime and ratio experimental factors, liming significantly influenced pH, DOC, Cu and Pb, and NH4+/NO3− ratio pH, DOC, Ni and Zn whereas interactions between lime and ratio was significant for Ni and Cu. pH and DOC increased with N load, liming and NO3− dominance, and both correlated significantly positively. Liming under NH4+ dominance enhanced DOC production due to supply of base cations in lime. Mobilization of Cu, Ni and Pb was driven by DOC concentrations and, therefore, increased with load, liming and NO3− dominance in deposition. However, in contrast, low pH and high NH4+ dominance was associated with Zn mobilization in soil solution. On the contrary, despite of some patterns, heavy metals in soil HNO3 extracts were devoid of any load, lime and NH4+/NO3− ratio effects. Our study suggests that the effects of N load and forms in deposition on sites with high accumulated loads of metals need to be better quantified through soil solution partitioning models. | |||||
