17381. 题目: Role of surface functionalities of nanoplastics on their transport in seawater-saturated sea sand
期刊: Environmental Pollution
作者: Zhiqiang Dong, Ling Zhu, Wen Zhang, Rui Huang, XiangWei Lv, Xinyu Jing, Zhenglong Yang, Junliang Wang, Yuping Qiu
摘要: The transport and retention of nanoplastics (NP, 200 nm nanopolystyrene) functionalized with surface carboxyl (NPC), sulfonic (NPS), low-density amino (negatively charged, NPA−), and high-density amino (positively charged, NPA+) groups in seawater-saturated sand with/without humic acid were examined to explore the role of NP surface functionalities. The mass percentages of NP recovered from the effluent (Meff) with a salinity of 35 practical salinity units (PSU) were ranked as follows: NPC (19.69%) > NPS (16.37%) > NPA+ (13.33%) > NPA− (9.78%). The homoaggregation of NPS and NPA− was observed in seawater. The transport of NPA− exhibited a ripening phenomenon (i.e., a decrease in the transport rate with time) due to the high attraction of NP with previously deposited NP, whereas monodispersed NPA+ presented a low Meff value because of the electrostatic attraction between NPA+ and negatively charged sand. Retention experiments showed that the majority of NPC, NPS and NPA+ accumulated in a monolayer on the sand surface, whereas NPA− accumulated in multiple layers. Suwannee River humic acid (SRHA) could remarkably improve the transportability of NPC, NPS, and NPA− by increasing steric repulsion. The strong attraction between NPA+ and the deposited NPA+ in the presence of SRHA triggered the weak ripening phenomenon. As seawater salinity decreased from 35 PSU to 3.5 PSU, the increase in electrostatic repulsion of NP-NP and NP-sand enhanced the transport of NPC, NPS, and NPA−, and the ripening of NPA− breakthrough curves disappeared. In deionized water, NPC, NPS, and NPA− achieved complete column breakthrough because the electrostatic repulsion between NP and sand intensified. However, the Meff values of NPA+ in 3.5 PSU seawater and deionized water presented limited increments of 15.49% and 23.67%, respectively. These results indicated that the fate of NP in sandy marine environments were strongly affected by NP surface functionalities, seawater salinity, and coexisting SRHA.
17382. 题目: High-dispersion zero-valent iron particles stabilized by artificial humic acid for lead ion removal
期刊: Journal of Hazardous Materials
作者: Qing Du, Guixiang Li, Shuaishuai Zhang, Jingpeng Song, Ying zhao, Fan Yang
摘要: Nano zero-valent iron (nZVI), as a high-efficiency adsorbent for heavy metals, often suffers being oxidized and assembling together due to small size and super reactivity, further decreasing its adsorption performance and limiting application ranges. Herein, we have designed a novel adsorbent with high-dispersion nZVI stabilized by as-prepared artificial humic acid (AHA-nZVI) derived from hydrothermal humification (HTH) technology. Introduction of artificial humic acid (A-HA) can effectively reduce the oxidation and agglomeration of nZVI, leading to superior kinetic removal efficiency of Pb2+ (> 99.2%) and huge Langmuir removal capacity of 649.0 mg/g. The combination of nZVI and A-HA (contained abundant functional groups, i.e. −OH and −COOH) via C–O-Fe bonding makes nZVI have good dispersion and oxidation resistance. Multiple interaction mechanisms including reduction reaction, complexation and co-precipitation between heavy metals and AHA-nZVI samples are realized. Overall, AHA-nZVI is a promising material for high-performance heavy metal contaminated water treatment.
17383. 题目: Mechanism of Cr(VI) removal by magnetic greigite/biochar composites
期刊: Science of The Total Environment
作者: Xuedong Wang, Jin Xu, Jia Liu, Jun Liu, Fang Xia, Cuicui Wang, Randy A. Dahlgren, Wei Liu
摘要: This study synthesized magnetic greigite/biochar composites (MGBs) by a solvothermal method and tested their ability to remove Cr(VI) from heavy metal-polluted wastewater. X-ray diffraction (XRD), Fourier transformed infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) revealed that magnetic greigite (Fe3S4) flakes were aggregated and anchored to the biochar surface, resulting in more active sites than pristine biochar. Maximum Cr removal efficiency and capacity of MGB-30 (greigite/biochar = 30%) at an initial Cr(VI) concentration of 20 mg/L were 93% and 23.25 mg/g, respectively. A pseudo-first-order kinetic model was determined for the Cr(VI) removal process and the Cr(VI) removal rate constants were highly dependent on the mass ratios of Fe3S4 loaded on biochar, initial MGB and Cr(VI) concentrations and solution pH. X-ray photoelectron spectroscopy (XPS) and flame atomic absorption spectrometric (FAAS) analysis demonstrated that Cr(VI) was preferentially adsorbed on MGBs and subsequently reduced to Cr(III) by MGBs. Electron paramagnetic resonance (EPR) spectroscopy and iron redox transformations revealed that the Cr(VI) removal enhancement was attributed to efficient surface Fe(III)/Fe(II) cycling via electron transfer with the persistent free radicals (PFRs) of biochar. These novel findings provide new insights into the Fe(III)/Fe(II) cycle induced by biochar and the prospects of using magnetic greigite/biochar composites for remediation of Cr(VI)-rich wastewaters.
17384. 题目: Biochar bound urea boosts plant growth and reduces nitrogen leaching
期刊: Science of The Total Environment
作者: Wei Shi, Yanyan Ju, Rongjun Bian, Lianqing Li, Stephen Joseph, David R.G. Mitchell, Paul Munroe, Sarasadat Taherymoosavi, Genxing Pan
摘要: Over use of N fertilizers, most commonly as urea, had been seriously concerned as a major source of radiative N (Nr) for severe environment impacts through leaching, volatilization, and N2O emission from fertilized croplands. It had been well known that biochar could enhance N retention and use efficiency by crops in amended croplands. In this study, a granular biochar-mineral urea composite (Bio-MUC) was obtained by blending urea with green waste biochar supplemented with clay minerals of bentonite and sepiolite. This Bio-MUC material was firstly characterized by microscopic analyses with FTIR, SEM-EDS and STEM, subsequently tested for N leaching in water in column experiment and for N supply for maize in pot culture, compared to conventional urea fertilizer (UF). Microscopic analyses indicated binding of urea N to particle surfaces of biochar and clay minerals in the Bio-MUC composite. In the leaching experiment over 30 days, cumulative N release as NH4+-N and of dissolved organic carbon (DOC) was significantly smaller by >70% and by 8% from the Bio-MUC than from UF. In pot culture with maize growing for 50 days, total fresh shoot was enhanced by 14% but fresh root by 25% under Bio-MUC compared to UF. This study suggested that N in the Bio-MUC was shown slow releasing in water but maize growth promoting in soil, relative to conventional urea. Such effect could be related mainly to N retention by binding to biochar/mineral surfaces and partly by carbon bonds of urea to biochar in the Bio-MUC. Therefore, biochar from agro-wastes could be used for blending urea as combined organo/mineral urea to replace mineral urea so as to reduce N use and impacts on global Nr. Of course, how such biochar combined urea would impact N process in soil-plant systems deserve further field studies.
17385. 题目: Effect of three artificial aging techniques on physicochemical properties and Pb adsorption capacities of different biochars
期刊: Science of The Total Environment
作者: Lianshuai Tan, Zhanghuai Ma, Kaiqi Yang, Qingliang Cui, Ke Wang, Tongtong Wang, Gao-Lin Wu, Jiyong Zheng
摘要: Biochar is beneficial for soil amendment, but further research is still required on changes in its physicochemical properties during aging, especially in oxygen-containing functional groups and associated adsorption behaviors. Here, we used two different biochars, apple tree branch biochar and maize stalk biochar, and simulated the aging process by using freeze-thaw cycles, dry-wet cycles, and chemical oxidation methods. We investigated the changes in the physicochemical properties and Pb adsorption behavior of the biochars before and after aging treatments. The characterization results showed that the biochar surface structure changed after aging treatments. In general, the specific surface areas (SSAs) of the two biochars increased after chemical oxidation treatment but decreased after the other two treatments. The elemental content analyses indicated a decrease in the C content and increase in O content after artificial aging. In addition, the content of oxygen-containing functional groups in most biochars is increasing after treatment. The increase or decrease in SSA resulted in an increase or decrease in adsorption sites, respectively, thereby enhancing or reducing the adsorption capacity of the biochar. Furthermore, oxygen-containing functional groups enhanced the Pb adsorption capacity of biochar by complexation of free carboxyl and hydroxyl functional groups with Pb. Our research indicated that aging can lead to changes in the Pb adsorption capacity of biochar and that these changes vary depending on the type of aging and biochar. Our results will help to provide a better understanding of the changes in physicochemical properties and Pb adsorption capacity of biochar during the aging process in soil toward making full use of biochar for soil amendment.
17386. 题目: Reservoir CO2 evasion flux and controlling factors of carbon species traced by δ13CDIC at different regulating phases of a hydro-power dam
期刊: Science of The Total Environment
作者: Imali Kaushalya Herath, Shengjun Wu, Maohua Ma, Ping Huang
摘要: As the world largest hydropower reservoir, the Three Gorges Reservoir (TGR) significantly impacted on the carbon cycle since reservoirs are sources of carbon sink. This study was carried out to investigate the effects of damming on the carbon cycle. δ13CDIC and δ13CDOC were used to trace the origin of dissolved organic (DOC) and inorganic carbon (DIC). The estimated CO2 evasion flux in two regulating phases (discharge and recharge) with averages of 111 mg/m2 h and 264 mg/m2 h, respectively. At the basin scale, average CO2 flux was about 188 mg/m2 h and varies from −158 mg/m2 h to 1092 mg/m2 h. The highest average pCO2 (1294 ppmv) was observed during the discharge period, which was oversaturated than atmospheric equilibrium value; hence, the TGR act as a considerable sink of atmospheric carbon. The δ13CDIC varies from −8.95‰ to 0.00‰ with mean −1.87‰; these enrich isotope values indicated that metabolic process (photosynthesis and respiration) and the rapid kinetics of carbonate weathering by soil CO2 control the pCO2. The low pCO2 of reservoir water caused the rapid dissolution of CO2 from the atmosphere during the recharge period. The δ13CDOC varies between −30.64‰ to −23.05‰, which is similar to the values of C3 vegetation; thus, the source of DOC would be the degradation of soil organic matter. Overall, this study revealed the δ13CDIC signature coupled with soil CO2 dissolution and admixture of atmospherically equilibrated waters resulting in the sink of atmospheric CO2 of the reservoir and impoundment of the dam alters the carbon cycle and aquatic carbon budget in TGR. The findings of this study provide a global image on the contribution of reservoirs to the carbon cycle and aquatic carbon budget. Coupling with isotope signatures and elemental concentrations, investigation of the biogeochemical cycle of the carbon can be effectively traced.
17387. 题目: Precursors for brominated haloacetic acids during chlorination and a new useful indicator for bromine substitution factor
期刊: Science of The Total Environment
作者: Lili Zheng, Hongjie Sun, Chouye Wu, Yibo Wang, Yuanyuan Zhang, Guangcai Ma, Hongjun Lin, Jianrong Chen, Huachang Hong
摘要: Brominated haloacetic acids (HAAs) are much more cytotoxic and genotoxic than chlorinated one, yet little information is available for their organic precursors. In the present study, 8 water samples were collected in East China: 2 from lakes, 2 from rivers, 2 from reservoirs, a well and a mountain spring. Dissolved organic carbon (DOC), UV absorbance at 254 (UVA), specific UVA (SUVA) and chlorophyll a (Chl-a) were determined in raw water samples; formation of 9 HAA species as well as bromine substitution factor (BSF) were measured in chlorinated water samples. Results showed that water samples located in city generally contained higher levels of DOC (6.4–12.2 mg/L) and UVA (0.124–0.194/cm), while those in the country side, low DOC (2.4–5.9 mg/L) and UVA (0.061–0.109/cm) levels were observed. Negative relationship (p < 0.01) was found between SUVA values and Chl-a levels. Among 9 HAA species, 4 brominated HAA were detected. As for BAA and DBAA (i.e. Br-HAAs), their yields (μg/L) were significant related (p < 0.05) with DOC; In terms of BCAA and BDCAA (i.e. ClBr-HAAs), they were not only related with DOC, but also with UVA. These two results were quite different from DCAA and TCAA (Cl-HAAs), whose yields (μg/mg C) were only correlated with SUVA values, suggesting that precursors of Cl-HAA, Br-HAA and ClBr-HAA were different from each other, and their aromaticity/hydrophobicity may be in the order of Br-HAA < ClBr-HAA < Cl-HAA. Interrelationship between Br/DOC, SUVA and BSF revealed that BSF can be influenced by SUVA and Br/DOC, but in comparison, Br/UVA was the best indicator to describe BSF. This pattern is not only true in di-HAAs and tri-HAAs in this study, but also valid in other water samples and other species of disinfection by-product (e.g. trihalomethanes, dihaloacetonitriles, trihalonitromethanes).
17388. 题目: Impact of bloom events on dissolved organic matter fluorophore signatures in Ohio waters
期刊: Science of The Total Environment
作者: Carissa Hipsher, Joel Barker, Allison MacKay
摘要: Due to the increase in severe cyanobacterial blooms in drinking water sources and recreational waters across the globe, inexpensive and reliable methods of detecting oncoming blooms are needed. Cyanobacterial blooms can contribute substantially to the bulk chromophoric dissolved organic matter pool. Thus, the fluorescence signature of organic matter derived from these blooms may be an indicator of upcoming blooms. Water samples from five sites around Ohio were collected regularly between February and October 2017. A PARAFAC model was developed to determine if these protein-like fluorophores could be linked to bloom biomass and whether they were absent in dissolved organic matter from oligotrophic waters. One reference site at an oligotrophic reservoir was included to confirm the lack of protein-like fluorophores in the absence of a bloom event. We found that an increase in tryptophan-like and tyrosine-like fluorophores occurs before the increase in chlorophyll a levels, associated with bloom biomass, in some Ohio waters affected by cyanobacterial blooms; however, protein-like fluorophores are not correlated with levels of the cyanotoxin, microcystin. The excitation and emission wavelengths of these fluorophores (tryptophan-like: 239/341 nm, tyrosine-like: 248/306 nm) may be used to monitor impending blooms in waters heavily impacted by cyanobacteria but may not be applicable to waters receiving treated wastewater discharges.
17389. 题目: Degradation of diclofenac in aqueous solution by ionizing radiation in the presence of humic acid
期刊: Separation and Purification Technology
作者: Run Zhuan, Jianlong Wang
摘要: Diclofenac (DFC) is becoming a ubiquitous pollutant and pose a risk to ecosystem and human beings, which is usually used as a nonsteroidal anti-inflammatory drug for treating painful diseases. In this study, the degradation of DFC in aqueous solution by ionizing radiation was investigated in the presence of various concentrations of humic acid, due to its wide existence in water matrix as natural organic matter (NOM). The experimental results showed that the removal efficiency of DFC was 80.8% at 0.8 kGy absorbed dose and initial concentration of 30 mg/L. The DFC degradation by ionizing radiation could be described by pseudo first-order kinetics model. Humic acid had negative influence on the degradation efficiency of DFC, which decreased from 80.8% to 62.9% when humic acid concentration was 30 mg/L, mainly due to the competition between humic acid and DFC for OH radicals. Several intermediate products were identified by LC-MS analysis during DFC degradation process, and a possible degradation pathway of DFC by ionizing radiation was proposed.
17390. 题目: Soil organic matter is stabilized by organo-mineral associations through two key processes: The role of the carbon to nitrogen ratio
作者: Peter M. Kopittke, Ram C. Dalal, Carmen Hoeschen, Cui Li, Neal W. Menzies, Carsten W. Mueller
摘要: The loss of organic matter (OM) from soil during long-term agricultural cropping results in a decrease in the inherent fertility of the soil as well as releasing greenhouse gases. Despite the importance of organo-mineral associations in the stabilization of OM within soils, much remains unknown about these organo-mineral associations. We used nano-scale secondary ion mass spectrometry (NanoSIMS) to investigate the incorporation and stabilization of 13C and 15N labelled residues of lucerne (Medicago sativa) and buffel grass (Cenchrus ciliaris) when incubated in a Vertisol from temperate Australia for up to 365 d. We show that newly-added OM forms organo-mineral associations through two mechanisms. Firstly, it was observed that the newly-added OM forms associations with the existing mineral-bound OM. However, this apparent stabilization of newly-added OM by associating with existing mineral-bound OM was not influenced by the C:N ratio of the plant residues, with the lucerne residues (C:N ratio of 11) being incorporated to a similar extent as the buffel grass (C:N ratio of 35). Secondly, we observed that N-rich microbial metabolites attached directly to mineral particle surfaces that did not contain existing OM patches, thereby creating new organo-mineral associations through which additional stabilization of OM would be possible. The information obtained in this study is valuable in understanding the stabilization of OM through organo-mineral associations, and raises the possibility of using cover crops or catch crops with narrow C:N ratios to allow for formation of new organo-mineral associations for increased stabilization of OM in soil.
17391. 题目: Hybrid ash/biochar biocomposites as soil amendments for the alleviation of cadmium accumulation by Oryza sativa L. in a contaminated paddy field
作者: Sicong Lei, Yan Shi, Cong Xue, Junliang Wang, Lei Che, Yuping Qiu
摘要: A novel ash/biochar (A/B) biocomposite composed of 90% biomass bottom ash from agroforestry biomass direct-fired power plants, 5% animal-derived biochar from carcass pyrolysis, and 5% bentonite as an adhesive was amended in cadmium (Cd)-polluted paddy soil to alleviate cadmium accumulation by Oryza sativa L. Ash increased the soil pH and contributed exogenous available silicon. Biochar with high Ca/P components played an important role in soil cadmium immobilization. A 1-year field experiment with consecutive rice growing seasons (early and late rice) was conducted in Xiangtan, China, to examine the effects of A/B amendment in Cd-contaminated paddy soil. The A/B biocomposite was amended into soil through one-time addition at three application rates (1, 5, and 10 kg/m2). When A/B amendment was ≥5 kg/m2, the soil pH increased from 4.11 to more than 6. The available silicon content in the soil even increased by 22.9 times. For early rice soil, the CaCl2-extractable Cd(II) and toxicity characteristic leaching procedure (TCLP)-extractable Cd(II) decreased by 77.9%–96.1% and 52.4%–70.7%, respectively. A/B remarkably reduced Cd accumulation in rice organs, and this observation was related to A/B treatment rates. Ash and biochar contributed to the inhibition of Cd accumulation in rice organs and Cd translocation from roots to stems. The Cd concentrations in brown rice decreased to 0.11 and 0.12 mg/kg in early and late rice, respectively, and these values were lower than the national food safety standard limit value of China (0.2 mg/kg).
17392. 题目: Nitrogen addition promotes the transformation of heavy metal speciation from bioavailable to organic bound by increasing the turnover time of organic matter: An analysis on soil aggregate level
期刊: Environmental Pollution
作者: Renfei Li, Wenbing Tan, Guoan Wang, Xinyu Zhao, Qiuling Dang, Hanxia Yu, Beidou Xi
摘要: Nitrogen (N) addition can change physicochemical properties and biogeochemical processes in soil, but whether or not these changes further affect the transport and transformation of heavy metal speciation is unknown. Here, a long-term (2004–2016) field experiment was conducted to assess the responses of different heavy metal speciation in three soil aggregate fractions to N additions in a temperate agroecosystem of North China. The organic matter turnover time was quantified based on changes in δ13C following the conversion from C3 (wheat) to C4 crop (corn). Averagely, N addition decreases and increases the heavy metal contents in bioavailable and organic bound fractions by 27.5% and 16.6%, respectively, suggesting N addition promotes the transformation of heavy metal speciation from bioavailable to organic bound, and such a promotion in a small aggregate fraction is more remarkable than that in a large aggregate fraction. The transformations of heavy metal speciation from bioavailable to organic bound in all soil aggregate fractions are largely dependent on the increments in the turnover time of organic matter. The increase in organic matter turnover time induced by N addition may inhibit the desorption of heavy metals from organic matter by prolonging the interaction time between heavy metals and organic matter and enhance the capacity of organic matter to adsorb heavy metals by increasing the humification degree and functional group. Our work can provide insights into the accumulation, migration, and transformation of heavy metals in soils in the context of increasing global soil N input from a microenvironmental perspective.
17393. 题目: Anthropogenic influences on mercury in Chinese soil and sediment revealed by relationships with total organic carbon
期刊: Environmental Pollution
作者: Wen Xue, Sae Yun Kwon, Stephan E. Grasby, Elsie M. Sunderland, Xin Pan, Ruiyang Sun, Ting Zhou, Haiyu Yan, Runsheng Yin
摘要: Rapid industrialization has led to high levels of mercury (Hg) releases from anthropogenic sources in China. When deposited to terrestrial ecosystems, Hg has a high affinity for natural organic carbon. This means that Hg concentrations will vary naturally as a function of the total organic carbon (TOC) content of different soils and sediment. Thus, Hg to TOC ratios in topsoil and surface sediment provides a useful normalized tracer of the anthropogenic impact on Hg contamination. We compiled literature-documented Hg and total organic carbon (TOC) data for topsoil (n = 957) and surface sediment (n = 1142) in China. Topsoil samples (n = 100) were also collected in this study to broaden the spatial coverage. We found large differences in Hg:TOC ratios among topsoil from background sites, agricultural and urban areas, and mining sites and surface sediment from fluvial, coastal, and marine environments. Specifically, a significant increase in Hg:TOC ratios occurred between soils from background sites (median: Hg:TOC = 21.1; Inter-Quartile Range (IQR): 9.67 to 40.7) and agricultural areas (median: 34.1; IQR: 22.1 to 58.7), urban areas (median: 62.1 ng g−1; IQR: 34.2 to 154) and mining sites (median: 2780; range: 181 to 43500). Urban and mining sites show the largest increase in Hg:TOC ratios, reflecting elevated anthropogenic Hg inputs in these areas. Fluvial sediment showed higher Hg:TOC ratios (median: 197; IQR: 109 to 389) than coastal (median: 88.3; IQR: 46.8 to 168) and marine sediment (median: 89.7; IQR: 53 to 138), indicating decreased anthropogenic Hg input from rivers to coastal and marine regions. Results of our study suggest Hg:TOC ratios are a useful normalized indicator of the influence of anthropogenic Hg releases on Hg enrichment in topsoil and surface sediment.
17394. 题目: Oxygen-rich biochar from torrefaction: A versatile adsorbent for water pollution control
期刊: Bioresource Technology
作者: Liang Li, Mei Yang, Qian Lu, Wenkun Zhu, Hanqing Ma, Lichun Dai
摘要: Compared to pyrochar (PC), little is known about the capability of torrefaction char (TC) in water pollution control. In this study, the physicochemical properties of TC and PC, and their adsorption performances for uranium (U(VI)) and methylene blue (MB) were investigated. Results showed that TC was higher in oxygen content, and richer in oxygen-containing functional groups. The maximum U(VI) and MB adsorption capacities were increased from 56.21 and 192.67 mg/g for PC, respectively, to > 100 and > 350 mg/g for TC, respectively, indicating that TC was much more efficient than PC. Furthermore, torrefaction atmosphere affected the adsorption performance of resulting TC. For example, TC from N2 was more efficient in MB adsorption, while TC from air was more efficient in U(VI) adsorption. Thus, attributed to the lower processing temperature, simpler preparation route, and higher adsorption capacity, TC could be a competent candidate for water pollution control.
17395. 题目: Influence of mineral water constituents, organic matter and water matrices on the performance of the H2O2/IO4−-advanced oxidation process
期刊: Environmental Science: Water Research & Technology
Nor Elhouda Chadi,
摘要: We have recently reported that the reaction of H2O2/IO4− could be a new advanced oxidation process (AOP) for water treatment [N. E. Chadi, S. Merouani, O. Hamdaoui, M. Bouhelassa and M. Ashokkumar, H2O2/periodate (IO4−): a novel advanced oxidation technology for the degradation of refractory organic pollutants, Environ. Sci.: Water Res. Technol., 2019, 5, 1113–1123]. Experiments were conducted in deionized water using toluidine blue (TB) as a model pollutant, in which the impact of all operating conditions was clarified. Herein, we report, for the first time, the impact of mineral water constituents (salts), different kinds of organic additives (surfactants, sucrose, glucose and carboxylic acids) and water matrices (natural mineral water, seawater and treated wastewater effluent) on the performance of this emerging AOP. It was observed that the presence of salts decreased the degradation efficiency of the process. The one exception is that of bicarbonate which notably accelerated the TB degradation rate but only at low HCO3− concentration. Similarly, the presence of organic competitors diminished the efficiency of TB degradation through consuming radicals and oxidizing species generated by the reaction of H2O2 with periodate. The quenching impact of organic competitors and salts increased with their concentrations in the solution. Degradation trials conducted in real environmental matrices showed that more than 50% of the process efficacy was lost when the pH of the matrices was adjusted to 5.4, but a lower loss was observed when the process was operated at natural pH (∼7.6). All these findings were discussed and interpreted with regard to the reactivity of radicals formed with additives present in the system.
17396. 题目: Simultaneous in-situ remediation and fertilization of Cd-contaminated weak-alkaline farmland for wheat production
期刊: Journal of Environmental Management
作者: Juan Li, Panyue Zhang, Junpei Ye, Guangming Zhang, Yajing Cai
摘要: In-situ remediation of heavy metal-contaminated farmland mainly focuses on acidic soil, however, weak-alkaline farmland widely exists in north China. Meanwhile, fertilization is usually ignored, but it may influence remediation efficiency as well as grain production. In this paper, field experiments were carried out to investigate in-situ simultaneous remediation and fertilization of Cd-contaminated weak-alkaline soil by microbial agent mixed with fulvic acid (MFA), wheat straw biochar, sepiolite and their mixture. Results showed that addition of these conditioners decreased the soil available Cd by 39.86%–71.33% and the wheat Cd by 41.94%–87.10%. The decrease order of soil available Cd followed sepiolite > mixture > biochar > MFA, while the decrease order of wheat Cd was mixture > sepiolite > biochar > MFA. With addition of mixture, the wheat Cd reduced to 0.08 mg/kg, lower than the Cd limit of 0.1 mg/kg in Contaminant Limit in Food of National Food Safety Standards (GB2762-2017), and the highest wheat yield reached 7590 kg/hm2. The MFA had significant effects on improvement of soil organic matters, nutrients and rhizosphere microbes; the biochar was prominent in improving soil organic matters, inhibiting wheat Cd and soil available Cd; the sepiolite had obvious advantages in reducing wheat Cd and soil available Cd; and the mixture had a more balanced effect on soil remediation and fertilization. Correlation study showed that soil available Cd significantly affected the uptake of Cd by wheat, and wheat yield was significantly positively correlated with soil organic matters, available N. Therefore, reducing soil available Cd, increasing soil organic matters and nutrients are the keys to simultaneous remediation and fertilization of Cd-contaminated weak-alkaline soil for wheat production.
17397. 题目: Size‐resolved characterization of the chromophores in atmospheric particulate matter from a typical coal‐burning city in China
期刊: Journal of Geophysical Research: Atmospheres
作者: Qingcai Chen, Zhen Mu, Wenhuai Song, Yuqin Wang, Zhaohong Yang, Lixin Zhang, Yan‐Lin Zhang
摘要: This study reports the size‐resolved characterization of the chromophores in atmospheric particulate matter in Linfen, a typical coal‐burning city in China. The optical properties of both the water‐soluble and water‐insoluble chromophores in atmospheric particulates are studied using excitation‐emission matrix (EEM) spectroscopy and follow the parallel factor (PARAFAC) analysis of EEM data. The mass absorption efficiency (MAE) and normalized fluorescence volume (NFV) by mass concentration of the organic carbon in methanol‐soluble matter (MSM) in the particulate samples are stronger than that of the water‐soluble matter (WSM). We found that the total absorption (Abs), fluorescence volume (FV), MAE and NFV of particle extracts with sizes less than 10 μm increased with the decreasing particle size. The total concentration of the selected seven polycyclic aromatic hydrocarbons (PAHs) was positively correlated with the Abs365 and FV of both the WSM and MSM, but the average contribution of the selected PAHs to the total Abs and FV was very small (<3%). This study is the first to report a size‐resolved characterization of the chromophores in atmospheric particulate matter. Humic‐like substances tend to be present in small particles, and tryptophan‐like and tyrosine‐like components tend to increase with increasing particle size.
17398. 题目: Molecular-Scale Investigations Reveal Noncovalent Bonding Underlying the Adsorption of Environmental DNA on Mica
期刊: Environmental Science & Technology
作者: Hang Zhai, Lijun Wang, Christine V Putnis
摘要: Mineral–soil organic matter (SOM including DNA, proteins, and polysaccharides) associations formed through various interactions, play a key role in regulating long-term SOM preservation. The mechanisms underlying DNA–mineral and DNA–protein/polysaccharide interactions at nanometer and molecular scales in environmentally relevant solutions remain uncertain. Here, we present a model mineral–SOM system consisting of mineral (mica)–nucleic acid (environmental DNA, eDNA)/protein (bovine serum albumin)/polysaccharide (alginate), and combine atomic force microscopy (AFM)-based dynamic force spectroscopy and PeakForce quantitative nanomechanical mapping using DNA-decorated tips. Single-molecule binding and adhesion force of eDNA to mineral and to mineral adsorbed by protein/polysaccharide reveal the noncovalent bonds and that systematically changing ion compositions, ionic strength, and pH result in significant differences in organic–organic and organic–mineral binding energies. Consistent with the bond-strength measurements, protein, rather than polysaccharide, promotes mineral-bound DNA molecules by ex situ AFM deposition observations in relatively high concentrations of divalent cation-containing acidic solutions. These molecular-scale determinations and nanoscale observations should substantially improve our understanding of how environmental factors influence the organic–mineral interfacial interactions through the synergy of collective noncovalent and/or covalent bonds in mineral–organic associations.
17399. 题目: New insights into the variation of dissolved organic matter components in different latitudinal lakes of northeast China
期刊: Limnology and Oceanography
作者: Longji Zhu, Yue Zhao, Sicong Bai, Haixuan Zhou, Xiaomeng Chen, Zimin Wei
摘要: Dissolved organic matter (DOM) plays a key role in the carbon cycle of freshwater ecosystems. We explored DOM composition from six lakes encompassing a typical latitudinal gradient of lakes in northeast of China (41.9°N–48.6°N). Generally, the relative contents of protein‐like components decreased while humic‐like components increased with increasing latitude. Additionally, the results from modified two‐dimensional correlation spectroscopy indicated that humic‐like components with relatively simple structure were formed earlier than those with relatively complex structure. Furthermore, structural equation models suggested that at higher latitude, lake DOM tended to stabilize as protein‐like component was transformed into humic‐like component. We also found that nutrients (e.g., nitrogen and phosphorus) were key factors affecting DOM composition in low‐latitudinal lakes, whereas temperature was the key factor affecting DOM composition in high‐latitudinal lakes. In conclusion, this study identified the factors which explained the observed latitudinal pattern of DOM in northeast lakes of China. This study provided a theoretical basis for DOM management of lakes at different latitudes.
17400. 题目: Eukaryotic influence on the oceanic biological carbon pump in the Scotia Sea as revealed by 18S rRNA gene sequencing of suspended and sinking particles
期刊: Limnology and Oceanography
作者: Manon T. Duret, Richard S. Lampitt, Phyllis Lam
摘要: Suspended marine particles constitute most of the particulate organic matter pool in the oceans, thereby providing substantial substrates for heterotrophs, especially in the mesopelagic. Conversely, sinking particles are major contributors to carbon fluxes defining the strength of the biological carbon pump (BCP). This study is the first to investigate the differential influence of eukaryotic communities to suspended and sinking particles, using 18S rRNA gene sequencing on particles collected with a marine snow catcher in the mixed layer and upper mesopelagic of the Scotia Sea, Southern Ocean. In the upper mesopelagic, most eukaryotic phytoplankton sequences belonged to chain‐forming diatoms in sinking particles and to prymnesiophytes in suspended particles. This suggests that diatom‐enriched particles are more efficient in carbon transfer to the upper mesopelagic than those enriched in prymnesiophytes in the Scotia Sea, the latter more easily disintegrating into suspended particles. In the upper mesopelagic, copepods appeared most influential on sinking particles whereas soft‐tissue metazoan sequences contributed more to suspended particles. Heterotrophic protists and fungi communities were distinct between mixed layer and upper mesopelagic, implying that few protists ride along sinking particles. Furthermore, differences between predatory flagellates and radiolarians between suspended and sinking particles implied different ecological conditions between the two particles pools, and roles in the BCP. Molecular analyses of sinking and suspended particles constitute powerful diagnostic tools to study the eukaryotic influence on the BCP in a more holistic manner compared to classic carbon export studies focusing on sinking particles.