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61. 题目: Magnetic biochar supported α-MnO2 nanorod for adsorption enhanced degradation of 4-chlorophenol via activation of peroxydisulfate
文章编号: N20040402
期刊: Science of the Total Environment
作者: Hao Zhou, Xiaoying Zhu, Baoliang Chen
更新时间: 2020-04-04
摘要:

A novel magnetic catalytic composite (MBM) was developed by compositing α-MnO2 with a magnetic biochar containing Fe3O4. XRD and EDS confirmed the crystalline structure and the chemical composition of MBM, while the one-dimensional α-MnO2 nanorods were observed on MBM by SEM. 4-chlorophenol as a typical toxic chlorinated organic compound was selected as the model pollutant. Even the MBM composite (MnO2 content: 0.2 g/L) needed the same time (120 min) as the pure α-MnO2 nanorods (0.2 g/L) to completely remove the 4-chlorophenol (10 mg/L) with overdosed peroxydisulfate (PDS), MBM indicated faster pollutant removal rate than the pure α-MnO2 nanorods in the first 100 min. It is possible that the adsorption of 4-chlorophenol by biochar might shorten the migration pathway of the generated active species to the pollutants, resulting the boosted removal rate. MBM was stable in the neutral environment which was desirable for the efficient pollutant removal. Both the radical quenching tests and the EPR spectra identified the main active specie generated by activation of PDS through MBM was singlet oxygen possibly generated by recombination of superoxide ions from the metastable manganese intermediates at neutral pH. TOC data of the effluent ensured 63.5% of the pollutant molecules were completely mineralized after the degradation. The applied magnetic field could recover MBM easily for reuse. This work shed lights on the preparation of highly efficient and environmentally friendly catalytic composites for PDS activation in persistent pollutant removal.

62. 题目: Struvite-supported biochar composite effectively lowers Cu bio-availability and the abundance of antibiotic-resistance genes in soil
文章编号: N20040401
期刊: Science of the Total Environment
作者: Yuan Li, Xuejiang Wang, Yuan Wang, Fei Wang, Siqing Xia, Jianfu Zhao
更新时间: 2020-04-04
摘要:

The accumulation of heavy metals and the accelerated dissemination of antibiotic-resistance genes (ARGs) in soil receiving long-term manure application are causing worldwide concern. In this study, struvite-supported biochar composite (MAP/BC) obtained by N and P recovery from pig slurry with Mg(OH)2-modified biochar (Mg(OH)2/BC) was used as a novel amendment for the remediation of Cu- and ARG-contaminated agricultural soil. The effects of MAP/BC on Cu immobilization, ARG distribution, and the bacterial community in the soil were investigated simultaneously. The results showed that the mechanisms involved in the immobilization of Cu by MAP/BC included the formation of copper-phosphate precipitation and a surface complex. With a 10% MAP/BC modification, the acid-soluble Cu content in soil decreased by 0.47-fold at day 56 while the residual Cu content increased 1.41-fold. Meanwhile, the abundances of most of the target ARGs (tetX, tetT, tetW, tetG, ermB, sulI, sulII, and intlI) were reduced by 11.35–99.95%, and the abundance of total ARGs was reduced by 30.69%. The redundancy analysis indicated that the bio-available Cu content played a crucial role in the variations of both ARGs and bacterial communities. The network analysis further suggested that potential hosts of soil ARGs were mainly Firmicutes and Actinobacteria. The above results suggested that the application of MAP/BC can mitigate Cu and ARG pollution in manured soil.

63. 题目: Removal of nitrogen and phosphorus pollutants from water by FeCl3- impregnated biochar
文章编号: N20040318
期刊: Ecological Engineering
作者: Li Min, Zhang Zhongsheng, Li Zhe, Wu Haitao
更新时间: 2020-04-03
摘要: Chemical fertilizers and pesticides used are currently increasing alongside the human population grew and agriculture spread, resulting in high nitrogen (TN) and phosphorus (TP) contents in farmland soil and the surrounding water-bodies. Fabricating economic but effective metal impregnated biochar, as a sorbent to remove inorganic pollutants from water, is important to prevent eutrophication. In the present work, iron-loaded biochar was prepared by impregnating by FeCl3 and following pyrolyzing at 550 °C. The chemical functional groups, surface morphologies, and internal crystal structures of the Fe-loaded biochar (FeB) were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction, respectively. Results indicated that the preparing process induced a layer of Fe oxide at the surface of biochar, and changed the surface morphology and internal crystal structure. The FeCl3 content in soaking solution had remarkable effects on pore structure formation, surface morphology features and removal efficiencies of TN and TP from wastewater by biochar. The Langmuir model indicated that 1%-Fe impregnated biochar (B1) and the 10%-Fe impregnated biochar (B10) exhibited maximum adsorption capacity of TN and TP, which reached to more than 14 mg/g for TN and 90 mg/g for TP, respectively. B10 could remove over 85% of TP from artificial wastewater and less than 0.5% of TP was released in desorption experiments. Similarly, B1 could remove 60% of TN while only 1% was released in desorption experiments. B1 and B10 could remove 50% of TN and 80% of TP from the actual agricultural wastewater, respectively. This confirmed that Fe-impregnated biochar could effectively remove inorganic nutrients from wastewater and seal them in the prevention of secondary pollution. The FeB was characterized by FT-IR and SEM before and after its application as an adsorbent in agricultural wastewater, and results revealed that the removal of TN and TP was primarily attributed to the well-developed pore structure and the Fe oxides fixed on the surface of biochar. Inorganic nitrogen and phosphorus in wastewater are removed by surface complexation, coprecipitation, electrostatic interaction and ion exchange. In conclusion, the present work demonstrated that the FeB is an effective adsorbent for removing TN and TP pollutants from nutrient-rich wastewaters.

64. 题目: Probing the intermolecular interaction mechanisms between humic acid and different substrates with implications for its adsorption and removal in water treatment
文章编号: N20040317
期刊: Water Research
作者: Lei Xie, Qiuyi Lu, Xiaohui Mao, Jingyi Wang, Linbo Han, Junqing Hu, Qingye Lu, Yixiang Wang, Hongbo Zeng
更新时间: 2020-04-03
摘要: Humic substance is a ubiquitous class of natural organic matter (NOM) in soil and aquatic ecosystems, which severely affects the terrestrial and aquatic environments as well as water-based engineering systems by adsorption on solids (e.g., soil minerals, nanoparticles, membranes) via different interaction mechanisms. Herein, the chemical force microscopy (CFM) technique was employed to quantitatively probe the intermolecular forces of humic acid (HA, a representative humic substance) interacting with self-assembled monolayers (SAMs, i.e., OH-SAMs, CH3-SAMs, NH2-SAMs and COOH-SAMs) in various aqueous environments at the nanoscale. The interaction forces measured during approach could be well fitted by the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory by incorporating the hydrophobic interaction. The average adhesion energy followed the trend as: NH2-SAMs (∼3.11 mJ/m2) > CH3-SAMs (∼2.03 mJ/m2) > OH-SAMs (∼1.38 mJ/m2) > COOH-SAMs (∼0.52 mJ/m2) in 100 mM NaCl at pH 5.8, indicating the significant role of electrostatic attraction in contributing to the HA adhesion, followed by hydrophobic interaction and hydrogen bonding. The adhesion energy was found to be dependent on NaCl concentration, Ca2+ addition and pH. For the interaction between NH2-SAMs and HA, their electrostatic attraction at pH 5.8 turned to repulsion under alkaline condition which led to the sudden drop of adhesion energy. Such results promised the adsorption and release of HA using the recyclable magnetic Fe3O4 nanoparticles coated with (3-aminopropyl)tiethoxysilane (APTES). This work provides quantitative information on the molecular interaction mechanism underlying the adsorption of HA on the solids of varying surface chemistry at the nanoscale, with useful implications for developing effective chemical additives to remove HA in water treatment and many other engineering processes.

65. 题目: Photogeneration and steady-state concentration of hydroxyl radical in river and lake waters along middle-lower Yangtze region, China
文章编号: N20040316
期刊: Water Research
作者: Huacheng Xu, Yani Li, Jin Liu, Haiyan Du, Yingxun Du, Yaling Su, Helong Jiang
更新时间: 2020-04-03
摘要: Hydroxyl radical (HO∙) in natural waters plays a critical role in contaminant transformation and ecosystem health. In this study, the photogeneration and steady-state concentration of HO∙ in different aquatic environments (e.g., river and lake) along the middle-lower Yangtze region, China, were evaluated. The results showed that, compared to lake samples, the river waters were characterized by lower HO∙ photoformation rate (RHO∙) (5.10–11.69 × 10−11 vs. 1.10–1.82 × 10−10 M s−1) and steady-state HO∙ concentration ([HO∙]) (1.76–3.11 × 10−17 vs. 2.50–10.33 × 10−17 M). The contribution of nitrate and nitrite to the total RHO∙ in river waters was generally higher than that in lake waters, and photolysis of nitrite exhibited contributions 1–2 times higher than those of nitrate (0–25% vs. 0–9%) irrespective of sample types. As a result, the photosensitization by chromophoric dissolved organic matter (CDOM) contributed more than 70% of the total RHO∙ for all samples except for River Ganjiang. [HO∙] among all samples was positively correlated with dissolved organic carbon (DOC) concentration, and the DOC-normalized [HO∙] was further related to the physicochemical properties of CDOM samples (e.g., aromaticity, humification, and molecular weight). The humic-like aromatic substances with low molecular weight were the controlling factors influencing [HO∙] in the studied surface waters. The results contributed to a deeper understanding of behaviors and fate of aquatic DOMs in terms of HO∙ formation and contaminant attenuation.

66. 题目: Natural purification capacity of tidal flats for organic matters and nutrients: A mesocosm study
文章编号: N20040315
期刊: Marine Pollution Bulletin
作者: Taewoo Kim, Junsung Noh, Bong-Oh Kwon, Changkeun Lee, Beomgi Kim, Inha Kwon, Seongjin Hong, Gap Soo Chang, Won Keun Chang, Jungho Nam, Jong Seong Khim
更新时间: 2020-04-03
摘要: The regulating services by natural tidal flats to purify organic pollutants are increasingly recognized, but a quantitative assessment is very limited. We developed a mesocosm system to determine removal efficiency of organic matters and nutrients by simulating a natural tidal condition. The tidal flat sediments significantly removed waterborne organic pollutants to background levels in ~2 and 6–7 days for COD and TP, respectively. This rapid removal of organic matters by natural sediments could be attributed to the microbe community degrading the corresponding pollutants. Temporal trend and degree of removal rates for COD and TP were similar between the bare tidal flat and the salt marsh. Meantime, the salt marsh environment removed waterborne DIP much quickly and also efficiently, implying a high affinity of halophytes on dissolved organic matters. Of note, sedimentary organic sink prevailed in defaunated condition under the smaller bioturbation effect. A mini-review on the purification capacity of natural and/or constructed coastal wetlands generally supported a high efficiency of vegetation to remove various sources of organic matters.

67. 题目: Responses of soil quality indicators to innovative and traditional thinning in a beech (Fagus sylvatica L.) forest
文章编号: N20040314
期刊: Forest Ecology and Management
作者: Federico Romeo, Giovanna Settineri, Maria Sidari, Carmelo Mallamaci, Adele Muscolo
更新时间: 2020-04-03
摘要: Soil has a pivotal role in keeping high the productivity of forest ecosystem but its physical and chemical properties are highly influenced by changes in forest species composition and forest management practices. Thinning is the most effective silvicultural practice used in Europe to increase the ecological and economic value of forest stands. The aim of this study was to identify the most appropriate forestry practice to preserve soil fertility and biodiversity in a beech (Fagus sylvatica L.) forest in Calabria, southern Italy. The effects of innovative (T3) and traditional (T2) thinning on soil properties with respect to unmanaged forest (T1) were assessed by using biological indicators. Results showed that T2 had the highest dissolved organic carbon (DOC) and the lowest water content (WC), organic carbon (OC) and nitrogen (N) amount. The humification index was the highest in T2 as well as fungi, ergosterol, fluorescein diacetate hydrolase (FDA) and catalase (CAT). The highest values of NO3−, SO4−, Na+, Mg2+ and Ca2+ were found in the T2. QBS-ar was significantly higher in T2 and T3 than in the T1. In short, our results evidenced that organic matter, total nitrogen, C/N ratio and water content cannot be considered alone or in combination indices of quality to evaluate the effect of thinning on soils. Rather, is the data crossing of microbiota and ions with organic matter pools (stable and labile) that can give important and accurate information on how thinning can affects soil biological properties that are strictly correlated to soil fertility and quality.

68. 题目: Depth-dependent soil C-N-P stoichiometry in a mature subtropical broadleaf forest
文章编号: N20040313
期刊: Geoderma
作者: Yang Qiao, Jing Wang, Heming Liu, Kun Huang, Qingsong Yang, Ruiling Lu, Liming Yan, Xihua Wang, Jianyang Xia
更新时间: 2020-04-03
摘要: As the balance of multiple chemical substances in ecological interactions, stoichiometry of soil carbon (C), nitrogen (N) and phosphorus (P) is critical for forest sustainability. Soil depth is critical in regulating soil C-N-P stoichiometry; however, the vertical pattern of soil C-N-P stoichiometry remains unclear at the local scale in mature subtropical forests. Here, we sampled 555 soil columns from 185 grids at three soil depths (i.e., 0–20, 20–40, and 40–60 cm) in a mature subtropical evergreen forest of eastern China. We found the C:N, N:P, and C:P ratios decreased with increasing soil depth. However, the strength of bivariate correlations among C, N, and P converged from the top to the deepest soil layer. Such vertical convergence was jointly driven by decreasing C-N (R2 as 0.84, 0.80, and 0.76) and increasing C-P (R2 as 0.11, 0.26, and 0.31) correlations from 0–20 to 40–60 cm depths. Further analyses with a structural equation model showed that the spatial variations in C, N, and P were influenced by different environmental factors. For example, the spatial variations in soil organic C and total N in the top soil layer were largely influenced by soil pH, whereas the spatial variation in total P was jointly influenced by topographical, biotic, and soil factors. Our results validate the important impact of soil depth on soil C-N-P stoichiometry at the landscape scale. The converging bivariate correlations between C, N and P along the increasing soil depth indicate the depth-dependent roles of different nutrient elements in soil C cycling.

69. 题目: Effect of biochar and redmud amendment combinations on Salix triandra growth, metal(loid) accumulation and oxidative stress response
文章编号: N20040312
期刊: Ecotoxicology and Environmental Safety
作者: Manhattan Lebrun, Florie Miard, Gabriella S. Scippa, Christophe Hano, Domenico Morabito, Sylvain Bourgerie
更新时间: 2020-04-03
摘要: Remediation of metal(loid) polluted soils is an important area of research nowadays. In particular, one remediation technique is much studied, phytomanagement. Phytomanagement combines amendment application and plant growth in order to reduce the risk posed by contaminants. Salicaceae plants showed tolerance towards metal(loid)s and the ability to accumulate high amounts of metal(loid)s in their tissue. Amendments are often applied to counterbalance the reduced soil fertility and high metal(loid) concentrations. Two amendments gathered attention over the last decades, biochar (product of biomass pyrolysis), which can be activated for better effects, and redmud (by-product of alumina production). Those two amendments showed ability to improve soil conditions and thus plant growth, although few studied their combined application. Moreover, since metal(loid)s are known to induce the overproduction of reactive oxygen species, it is important to measure the level of oxidative stress in the plant, to which plants respond using enzymatic and non-enzymatic systems. But no studies evaluate the response of Salicaceae plants to metal(loid) stress and amendment application at the biochemical level in a real soil condition. Therefore, a mesocosm study was set up to evaluate the effect of amending a mine soil with redmud combined to diverse biochars on the soil properties and Salix triandra growth, metal(loid) accumulation and stress marker levels. Results showed that all amendment combinations improved the soil fertility, reduced metal(loid) mobility and thus ameliorated Salix triandra growth, which accumulated metal(loid)s mainly in its roots. Moreover, among the different amendment combinations, Salix triandra plants still suffered from oxidative stress when grown on PG soil amended with redmud and chemical activated carbon, showing elevated levels of phenolic compounds and salicinoids and important antioxidant and enzymatic activities. Finally, one treatment showed levels of these stress markers similar or lower than the control, the combination of redmud with steam activated carbon. In conclusion, this treatment seemed a good solution in a phytomanagement strategy using Salix triandra, improving soil conditions and plant growth and reducing oxidative stress level in the plant roots.

70. 题目: Iron/zinc and phosphoric acid modified sludge biochar as an efficient adsorbent for fluoroquinolones antibiotics removal
文章编号: N20040311
期刊: Ecotoxicology and Environmental Safety
作者: Yongfei Ma, Ping Li, Lie Yang, Li Wu, Liuyang He, Feng Gao, Xuebin Qi, Zulin Zhang
更新时间: 2020-04-03
摘要: Iron/zinc (Fe/Zn), phosphoric acid (H3PO4) or in combination (Fe/Zn + H3PO4) modified sludge biochar (SBC) were prepared and tested in this study to adsorb fluoroquinolones antibiotics including ciprofloxacin (CIP), norfloxacin (NOR) and ofloxacin (OFL) from water. Fe/Zn + H3PO4-SBC had an increased surface area (SBET), total pore volume (Vtot), mesoporous volume (Vmes), pore diameter (Dp) and oxygen-containing functional groups. It exhibited superior adsorption performance for CIP, NOR and OFL with the maximum adsorption amount of 83.7, 39.3, 25.4 mg g−1, respectively. Pseudo-second kinetic and Freundlich isotherm model presented the better fitting. The results of models and characterization analysis in combination indicated that physisorption and chemisorption, including pore filling, hydrogen bonding, π-π interaction, electrostatic interaction and functional groups complexation on a heterogeneous surface were the dominant process and mechanism. Liquid film diffusion was the main rate-limiting step. The adsorption process of CIP, NOR and OFL onto Fe/Zn + H3PO4-SBC were a spontaneous endothermic process. This study demonstrated that Fe/Zn + H3PO4 modified SBC exhibited high adsorption capacity, which was a promising adsorbent for fluoroquinolones as well as for other antibiotics effective removal from waters.

71. 题目: Rhizosphere priming effects differ between Norway spruce (Picea abies) and Scots pine seedlings cultivated under two levels of light intensity
文章编号: N20040310
期刊: Soil Biology and Biochemistry
作者: Jian Li, Moyan Zhou, Saeed Alaei, Per Bengtson
更新时间: 2020-04-03
摘要: Accelerated or reduced turnover of organic matter in the presence of roots is a phenomenon known as the rhizosphere priming effect (RPE). The RPE is an important regulator of soil organic matter (SOM) decomposition and carbon and nitrogen cycling in forest soils, but little is known about how the RPE varies among different tree species under different environmental conditions. Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) are two commercially important tree species in the boreal region that differs in their photosynthetic intensity under different light conditions. Since the photosynthetic intensity is of importance for determining below-ground plant C allocation and the root exudation rate, we hypothesized that the RPE would also differ between the two species. The hypothesis was tested in a greenhouse experiment using a combined 13CO2 pulse-chase and 15N pool-dilution approach designed to quantify the root exudation rate, SOM decomposition, gross N mineralization, and the RPE. The results demonstrated that spruce induced a positive RPE while pine induced a negative RPE. The results also showed that the light intensity is an important regulator of the RPE, depending on the plant species present. Spruce induced higher priming of SOM decomposition and gross nitrogen mineralization when kept under low light intensity, while there was no connection between the RPE and light intensity in the Pine treatment. Variations in root exudation rates among treatments could not explain the findings. It instead appears as if variation in soil nitrogen availability was the reason for differences in the RPE between the different species and light intensities, with severe nitrogen limitation leading to plant-microbial competition for nitrogen and reduced SOM decomposition and gross nitrogen mineralization rates. The findings suggest that plant and microbial responses to environmental factors that influence nitrogen availability need to be considered in order to accurately predict how the RPE influences SOM decomposition and gross nitrogen mineralization rates.

72. 题目: Transfer and transformation mechanisms of Fe bound-organic carbon in the aquitard of a lake-wetland system during reclamation
文章编号: N20040309
期刊: Environmental Pollution
作者: Rui Liu, Teng Ma, Chaohong Lin, Juan Chen, Kun Lei, Xin Liu, Wenkai Qiu
更新时间: 2020-04-03
摘要: Organic carbon (OC) can help control greenhouse gas emissions by participating in biogeochemical reactions and preventing the migration of contaminants in groundwater systems. The association of OC with Fe (Iron) oxide minerals plays a significant role in stabilizing OC and regulating the biogeochemical cycles of OC on the earth's surface. Reclaiming farmland from lakes changes an original lake into a wetland, but the destiny of Fe bound-OC in the underlying aquitard during this process has been poorly understood. The mechanisms of migration and transformation of Fe bound-OC were investigated in subsurface aquitard sediments of three typical boreholes in the Chen Lake wetland, central China. The Fe bound-OC content in the natural sedimentary conditions (borehole A), transition area (borehole B), and intensive reclamation area (borehole C) were 0.17–3.87, 0.28–3.98 and 0.13–7.08 mg g−1, respectively. The reclamation changed the redox, water, and infiltration conditions of the surface environment, resulting in a transformation of Fe oxides phases, and then cause the change of content and structure of Fe bound-OC. The fresh organic matter provided by undecomposed crops causes oxygen- and nitrogen-rich compounds to combine with Fe oxides extensively through adsorption, resulting in higher δ13C values of Fe bound-OC than non-Fe bound-OC. Fe bound-OC has strong resistance to biodegradation. The Fe bound-OC: total OC ratios generated by adsorption and coprecipitation on the surface layer (0 to −3.5 m) of borehole C was 10.37% and 18.86%, 6.92% and 12.46% higher than those of boreholes A and B, respectively. Coprecipitation has a stronger OC-binding ability and enriches more carboxylates and aromatics, while adsorption gradually assumed a dominant position in OC-Fe interaction in deep aquitard. The reduction dissolution of Fe oxide causes Fe bound-OC to transfer into pore water, leading to an increase of Fe ion and dissolved OC in deep strata.

73. 题目: Popular wood and sugarcane bagasse biochars reduced uptake of chromium and lead by lettuce from mine-contaminated soil
文章编号: N20040308
期刊: Environmental Pollution
作者: Amir Zeb Khan, Sardar Khan, Tehreem Ayaz, Mark L. Brusseau, Muhammad Amjad Khan, Javed Nawab, Said Muhammad
更新时间: 2020-04-03
摘要: As a result of metal mining activities in Pakistan, toxic heavy metals (HMs) such as chromium (Cr) and lead (Pb) often enter the soil ecosystem, accumulate in food crops and cause serious human health and environmental issues. Therefore, this study examined the efficacy of biochar for contaminated soil remediation. Poplar wood biochar (PWB) and sugarcane bagasse biochar (SCBB) were amended to mine-contaminated agricultural soil at 3% and 7% (wt/wt) application rates. Lactuca sativa (Lettuce) was cultivated in these soils in a greenhouse, and uptake of HMs (Cr and Pb) as well as biomass produced were measured. Subsequently, health risks were estimated from uptake data. When amended at 7%, both biochars significantly (P<0.01) reduced plant uptake of Cr and Pb in amended soil with significant (P<0.01) increase in biomass of lettuce as compared to the control. Risk assessment results showed that both biochars decreased the daily intake of metals (DIM) and associated health risk due to consumption of lettuce as compared to the control. The Pb human health risk index (HRI) for adults and children significantly (P<0.01) decreased with sugarcane bagasse biochar applied at 7% rate relative to other treatments (including the control). Relative to controls, the SCBB and PWB reduced Cr and Pb uptake in lettuce by 69%, 73.7%, respectively, and Pb by 57% and 47.4%, respectively. For both amendments, HRI values for Cr were within safe limits for adults and children. HRI values for Pb were not within safe limits except for the sugarcane bagasse biochar applied at 7%. Results of the study indicated that application of SCBB at 7% rate to mine impacted agricultural soil effectively increased plant biomass and reduced bioaccumulation, DIM and associated HRI of Cr and Pb as compared to other treatments and the control.

74. 题目: A subcellular level study of copper speciation reveals the synergistic mechanism of microbial cells and EPS involved in copper binding in bacterial biofilms
文章编号: N20040307
期刊: Environmental Pollution
作者: Huirong Lin, Chengyun Wang, Hongmei Zhao, Guancun Chen, Xincai Chen
更新时间: 2020-04-03
摘要: The synergistic cooperation of microbial cells and their EPS in biofilms is critical for the biofilm's resistance to heavy metals and the migration and transformation of heavy metals in biofilms. However, the effects of different components of biofilms have not been fully understood. In this study, the spatial distribution and speciation of copper in the colloidal EPS, capsular EPS, cell walls and membranes, and intracellular fraction of unsaturated Pseudomonas putida (P. putida) CZ1 biofilms were fully determined at the subcellular level. It was found that 60–67% of copper was located in the extracellular fraction of biofilms, with 44.7–42.3% in the capsular EPS. In addition, there was 15.5–20.1% and 17.2–21.2% of copper found in the cell walls and membranes or the intracellular fraction, respectively. Moreover, an X-ray absorption fine structure spectra analysis revealed that copper was primarily bound by carboxyl-, phosphate-, and hydrosulfide-like ligands within the extracellular polymeric matrix, cell walls and membranes, and intracellular fraction, respectively. In addition, macromolecule quantification, fourier-transform infrared spectroscopy spectra and sulfur K-edge x-ray absorption near edge structure analysis further showed the carboxyl-rich acidic polysaccharides in EPS, phospholipids in cell walls and cell membranes, and thiol-rich intracellular proteins were involved in binding of copper in the different components of biofilm. The full understanding of the distribution and chemical species of heavy metals in biofilms not only promotes a deep understanding of the interaction mechanisms between biofilms and heavy metals, but also contributes to the development of effective biofilm-based heavy metal pollution remediation technologies.

75. 题目: Water Table Fluctuations Regulate Hydrogen Peroxide Production and Distribution in Unconfined Aquifers
文章编号: N20040306
期刊: Environmental Science & Technology
作者: Na Zhang, Xiaochuang Bu, Yiming Li, Yanting Zhang, Songhu Yuan, Zhang Wen, Man Tong, Li Lin
更新时间: 2020-04-03
摘要: Significance of reactive oxygen species (ROS) in subsurface has been increasingly documented in recent years, whereas the mechanisms controlling ROS production and distribution in subsurface remain poorly understood. Here we show that water table fluctuations regulate the dynamics of hydrogen peroxide (H2O2) production and distribution in unconfined aquifers. In one hydrological year, we measured the dynamics of H2O2 distribution in an unconfined aquifer impacted by a 14 m water level fluctuation in the adjacent Yangtze River. H2O2 concentrations in groundwater attained up to 123 nM at rising water table stage in summer, but were low or even below the detection limit at the other stages of stable and falling water table. Lab experiments and kinetic models revealed that abiotic reactions between dissolved O2 and reduced species (i.e., Fe(II) and organic matter) were responsible for H2O2 production in the aquifers. Both field observations and reactive transport models unveiled that a rising water table developed a thermodynamically unstable banded zone in the unconfined aquifer in which elevated coexisting dissolved O2 and reduced species favored abiotic H2O2 production. Our findings provide fundamentals for understanding and predicting ROS distribution in unconfined aquifers, and constrain the significance of ROS in aquifers to specific temporal and spatial domains.

76. 题目: Molecular Mechanisms of Chromium(III) Immobilization by Organo–Ferrihydrite Co-precipitates: The Significant Roles of Ferrihydrite and Carboxyl
文章编号: N20040305
期刊: Environmental Science & Technology
作者: Jianjun Yang, Xing Xia, Jin Liu, Jian Wang, Yongfeng Hu
更新时间: 2020-04-03
摘要: The interaction mechanisms of heavy metals with organo–Fe hydroxides co-precipitates (OFC) remain unclear due to the structural complexity of the OFC. In this study, batch experiments were conducted to investigate the immobilization mechanisms of Cr(III) by the OFC, which was prepared by co-precipitating Fe3+ with rice/rape straw-derived dissolved organic carbon, through sorption and co-precipitation using synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy and scanning transmission X-ray microscopy (STXM). At an Fe/C molar ratio ≥ 0.3, both the sorption and co-precipitation immobilized the majority of Cr(III), but the co-precipitation desorbed less Cr(III) than the sorption regardless of DOC loadings and sources. In contrast, Cr(III) immobilization was significantly reduced at an Fe/C molar ratio of 0.1 for both reactions. Linear combination fitting of Cr K-edge XANES spectra revealed the predominance of ferrihydrite-bound Cr(III), but enhanced organic Cr(III) occurred with increased organic carbon (OC) loading for both the sorption and co-precipitation. STXM coupled with multi-edge XANES analysis confirmed the primary association of Cr(III) with ferrihydrite and directly probed carboxyl as the binding site for Cr(III) retention on the OC constituents of the OFC. These results provided new molecular-level insights into the Cr(III) retention mechanisms on the OFC, particularly for the interactions of Cr(III) and OC constituents of the OFC, which could benefit the management of Cr-contaminated soils with straw returning.

77. 题目: Comprehensive chemical analysis and characterization of heavy oil electric desalting wastewaters in petroleum refineries
文章编号: N20040304
期刊: Science of the Total Environment
作者: Huangfan Ye, Baodong Liu, Qinghong Wang, Zuo Tong How, Yali Zhan, Pamela Chelme-Ayala, Shaohui Guo, Mohamed Gamal El-Din, Chunmao Chen
更新时间: 2020-04-03
摘要: Large quantities of highly polluted point-source wastewaters (EDWs) are generated from electric desalting process of heavy oils (HOs), resulting in severe impacts on the efficiency of wastewater treatment plants in petroleum refineries. In the present study, a comprehensive chemical analysis and characterization of EDWs of two typical Chinese heavy oils, Liaohe heavy oil (LHO) and Karamy heavy oil (KHO), were investigated using Daqing light oil (DLO) as a control. The HO-EDWs (LHO-EDW and KHO-EDW) show high pollutants contents with complicated compositions, more polar dissolved organic pollutants (DOPs), strong emulsion stability and high acute biotoxicity towards Vibrio fischeri, compared to DLO-EDW. LHO-EDW and KHO-EDW have nearly equal pollutants contents but different compositions and distributions, where more types of DOPs exist in KHO-EDW. Large amounts of biologically recalcitrant aromatic compounds, as well as heteroatomic compounds such as CHO, CHOS and CHON species, extensively distribute in HO-EDWs. The organic nitrogen compounds (e.g., anilines and N2–3Ox, N1OxS1) in KHO-EDW most probably contribute to and thus leading to elevated levels of acute biotoxicity. Additionally, highly dispersed colloidal, micron-sized particles and polar compounds promote the emulsification and stabilization of HO-EDWs. These results can guide the development of pretreatment technologies for HO-EDWs, thus improving the treatment and management of heavy oil refineries' wastewater streams.

78. 题目: Biodegradation of bisphenol compounds in the surface water of Taihu Lake and the effect of humic acids
文章编号: N20040303
期刊: Science of the Total Environment
作者: Nan Zhou, Yanhua Liu, Siqi Cao, Ruixin Guo, Yini Ma, Jianqiu Chen
更新时间: 2020-04-03
摘要: Bisphenol analogues (BPs) pollution in the aquatic environment is increasingly a worldwide concern. There is an urgent need to understand the fate of BPs in the aquatic environment. In this study, we studied the biodegradation of eight BPs in Taihu Lake and discussed the effect of humic acid (HA), which was extracted from Taihu Lake sediment, on the disappearance of BPs. Under aerobic conditions, bisphenol AF (BPAF) and bisphenol S (BPS) were recalcitrant to biodegradation in the lake water. The half-lives for bisphenol F (BPF), bisphenol A (BPA), bisphenol B (BPB), bisphenol E (BPE), bisphenol Z (BPZ), and bisphenol M (BPM) ranged from 34 to 75 days in the Taihu Lake water collected in October 2018 and 12–72 days in that collected in May 2019. The biodegradation of BPs in summer was significantly higher than that in autumn. The presence of HA promoted the disappearance of BPs from Taihu Lake water by adsorbing and binding BPs. The disappearance rate of BPs accelerated with increasing concentrations of HA. However, the presence of HA decreased the biodegradation of BPs. When the concentration of HA was 10 mg/L, the single-adsorption capacities for BPS, BPA, BPB, BPM and BPAF were 3.18–10.33 mg/g in the Taihu Lake water with little desorption. BP adsorption and desorption in the BP mixtures were different from that in the single BPs. Competitive desorption occurred among the mixtures. The results of this study are the first to indicate the biodegradation of eight BPs in natural lake water and the possible effect of HA on the fate of BPs in the environment.

79. 题目: Regional measurements and spatial/temporal analysis of CDOM in 10,000+ optically variable Minnesota lakes using Landsat 8 imagery
文章编号: N20040302
期刊: Science of the Total Environment
作者: Leif G. Olmanson, Benjamin P. Page, Jacques C. Finlay, Patrick L. Brezonik, Marvin E. Bauer, Claire G. Griffin, Raymond M. Hozalski
更新时间: 2020-04-03
摘要: Information on colored dissolved organic matter (CDOM) is essential for understanding and managing lakes but is often not available, especially in lake-rich regions where concentrations are often highly variable in time and space. We developed remote sensing methods that can use both Landsat and Sentinel satellite imagery to provide census-level CDOM measurements across the state of Minnesota, USA, a lake-rich landscape with highly varied lake, watershed, and climatic conditions. We evaluated the error of satellite derived CDOM resulting from two atmospheric correction methods with in situ data, and found that both provided substantial improvements over previous methods. We applied CDOM models to 2015 and 2016 Landsat 8 OLI imagery to create 2015 and 2016 Minnesota statewide CDOM maps (reported as absorption coefficients at 440 nm, a440) and used those maps to conduct a geospatial analysis at the ecoregion level. Large differences in a440 among ecoregions were related to predominant land cover/use; lakes in ecoregions with large areas of wetland and forest had significantly higher CDOM levels than lakes in agricultural ecoregions. We compared regional lake CDOM levels between two years with strongly contrasting precipitation (close-to-normal precipitation year in 2015 and much wetter conditions with large storm events in 2016). CDOM levels of lakes in agricultural ecoregions tended to decrease between 2015 and 2016, probably because of dilution by rainfall, and 7% of lakes in these areas decreased in a440 by ≥3 m-1. In two ecoregions with high forest and wetlands cover, a440 increased by >3 m-1 in 28 and 31% of the lakes, probably due to enhanced transport of CDOM from forested wetlands. With appropriate model tuning and validation, the approach we describe could be extended to other regions, providing a method for frequent and comprehensive measurements of CDOM, a dynamic and important variable in surface waters.

80. 题目: Effects of heavy metals on organic matter decomposition in inundated soils: Microcosm experiment and field examination
文章编号: N20040301
期刊: Science of the Total Environment
作者: Osim Enya, Natalie Heaney, Grace Iniama, Chuxia Lin
更新时间: 2020-04-03
摘要: Microcosm and field investigation were conducted to examine the effects of heavy metals on the decomposition and accumulation of organic carbon in contaminated Mersey estuarine floodplain, northwest England. The results show that inhibition of microbially mediated decomposition of organic matter occurred in the water-inundated soils. However, individual heavy metals had differential effects on the inhibition of soil organic matter decomposition with arsenic and copper being much stronger, as compared to other investigated heavy metals. The weak inhibitory effects of chromium on organic matter decomposition was due to the conversion of highly toxic Cr(VI) to less toxic Cr(III) under reducing conditions. Lead also had a weaker capacity to inhibit organic matter decomposition due to its low solubility. It was surprising that the same phenomenon was not clearly observed during the field examination. The inhibitory effects of heavy metals on soil organic matter decomposition could be curtained under field conditions. pH, Eh and EC played more important roles, as compared to soil-borne heavy metals, in affecting the soil carbon dynamics in the contaminated Mersey estuarine floodplain.

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