161. 题目: Converting rice paddy to upland fields decreased plant lignin but increased the contribution of microbial residue to SOC
作者: Quan-Cheng Wang, Weiqi Wang, Yong Zheng, Tony Vancov, Yunying Fang, Yun Xia, Xuyang Liu, Yuexin Fan, Zhihua Wei, Liuming Yang
摘要: Most land-use changes profoundly alter the composition of soil organic carbon (SOC) via changes in plant- and microbial-derived C in soils. Whether this equally holds true for soils converted from paddy fields to upland fields is hitherto unknown. Herein, we investigate and report on plant-derived C (lignin phenols as biomarkers), microbial-derived C (amino sugars as biomarkers), Phospholipid fatty acids (PLFAs), and soil properties following the conversion of rice paddy to upland (vegetable and jasmine) fields in a subtropical farmland ecosystem. Lower moisture, pH, and available nitrogen (AN) but higher temperatures were observed in upland soils compared to paddy soils. Moreover, fungal- and bacterial-PLFAs were 41–63% and 58–69% lower, respectively, in upland soils than in paddy soils. Compared to paddy soils, concentrations of SOC, total lignin phenols (VSC) and amino sugars (TAS) declined in upland soils by 18–46%, 32–70% and 6–31%, respectively. Converting rice paddy fields to vegetable/jasmine cropping fields also altered the composition of SOC; i.e., the contribution of total lignin phenols to SOC declined by 25–48% in the upland soils, while total amino sugars input towards SOC increased by 22–28%. Our findings highlight the ecological risk of carbon loss caused by land-use changes, namely, the conversion of paddy fields to upland field systems.
162. 题目: Mercury Removal from Contaminated Water by Wood-Based Biochar Depends on Natural Organic Matter and Ionic Composition
期刊: Environmental Science & Technology
作者: Sampriti Chaudhuri, Gabriel Sigmund, Sharon E Bone, Naresh Kumar, Thilo Hofmann
摘要: Biochars can remove potentially toxic elements, such as inorganic mercury [Hg(II)] from contaminated waters. However, their performance in complex water matrices is rarely investigated, and the combined roles of natural organic matter (NOM) and ionic composition in the removal of Hg(II) by biochar remain unclear. Here, we investigate the influence of NOM and major ions such as chloride (Cl–), nitrate (NO3–), calcium (Ca2+), and sodium (Na+) on Hg(II) removal by a wood-based biochar (SWP700). Multiple sorption sites containing sulfur (S) were located within the porous SWP700. In the absence of NOM, Hg(II) removal was driven by these sites. Ca2+ bridging was important in enhancing removal of negatively charged Hg(II)-chloro complexes. In the presence of NOM, formation of soluble Hg-NOM complexes (as seen from speciation calculations), which have limited access to biochar pores, suppressed Hg(II) removal, but Cl– and Ca2+ could still facilitate it. The ability of Ca2+ to aggregate NOM, including Hg-NOM complexes, promoted Hg(II) removal from the dissolved fraction (<0.45 μm). Hg(II) removal in the presence of Cl– followed a stepwise mechanism. Weakly bound oxygen functional groups in NOM were outcompeted by Cl–, forming smaller-sized Hg(II)-chloro complexes, which could access additional intraparticle sorption sites. Therein, Cl– was outcompeted by S, which finally immobilized Hg(II) in SWP700 as confirmed by extended X-ray absorption fine structure spectroscopy. We conclude that in NOM containing oxic waters, with relatively high molar ratios of Cl–: NOM and Ca2+: NOM, Hg(II) removal can still be effective with SWP700.
163. 题目: Contribution of Water-Insoluble Organic Nitrogen to Nitrogen Deposition on a Forest: a Case Study in a Red Pine Forest on the Northern Foot of Mt. Fuji, Japan
期刊: Water, Air, & Soil Pollution
作者: Kiyoshi Matsumoto, Akino Nishiyama, Tomohiro Kuwabara, Takashi Nakano
摘要: The observations of rainfall, throughfall, stemflow, and aerosols were conducted at a forested site on the northern foot of Mt. Fuji in Japan. The aims of this study were to understand the deposition fluxes and processes of the water-insoluble organic nitrogen (WION) from the atmosphere to the forest canopy and floor. The deposition flux of the total nitrogen (TN) that includes all nitrogen species to the forest floor was 1.944 mgN m−2 day−1 on average. The contribution of the WION to the TN deposition flux was about 29%, which suggests the importance of the WION for discussing the nitrogen deposition from the atmosphere to forests and the nitrogen cycle in the forest ecosystem. The estimation by a canopy budget model indicated that the dry deposition of aerosols on the canopy was the most important process for the WION deposition.
164. 题目: Alder encroachment alters subsoil organic carbon pool and chemical structure in a boreal peatland of Northeast China
期刊: Science of The Total Environment
作者: Fu-Xi Shi, Hui-Min Chen, Xian-Wei Wang, Rong Mao
摘要: Boreal peatlands have been experiencing increased abundances of symbiotic dinitrogen-fixing woody plants (mainly alder species). However, how alder encroachment alters soil organic carbon (C) pool and stability is unclear. To examine the effects of alder encroachment on soil organic C, we measured soil organic C pool, phenol oxidase (POX) activity, organic C mineralization rate, and organic C chemical structure (alkyl C, O-alkyl C, aromatic C, and carbonyl C) using solid-state 13C nuclear magnetic resonance spectroscopy in the 0–10 cm, 10–20 cm, and 20–40 cm depths in the Alnus sibirica islands and adjacent open peatlands in the north of Da'xingan Mountain, Northeast China. A. sibirica islands had 28 %, 25 %, and 30 % greater POX activity and 36 %, 31 %, and 100 % higher organic C mineralization than open peatlands in the 0–10 cm, 10–20 cm, and 20–40 cm soil depths, respectively. Despite no significant changes in the 0–10 cm and 10–20 cm depths, alder encroachment reduced soil organic C pool in the 20–40 cm depth. Soil organic C pool in the 0–40 cm depth was higher in A. sibirica islands (315 Mg ha−1) than in the open peatlands (298 Mg ha−1). Moreover, alder encroachment increased alkyl (7 %) and carbonyl (57 %) C fractions but reduced O-alkyl C fraction (16 %) in the 20–40 cm depth, resulting in increased aliphaticity and recalcitrance indices. These findings suggest that alder encroachment will reduce soil organic C accumulation by accelerating microbial decomposition, and highlight that increased biochemical stabilization would attenuate soil organic C loss after alder expansion in boreal peatlands. Our results will help assess and project future C budgets in boreal peatlands.
165. 题目: The isotopic composition of organic carbon, nitrogen and provenance of organic matter in surface sediment from the Jiangsu tidal flat, southwestern Yellow Sea
期刊: Marine Pollution Bulletin
作者: Tianning Li, Gucheng Zhang, Shuai Wang, Changping Mao, Zhen Tang, Wenbo Rao
摘要: The Jiangsu tidal flat is a significant organic matter reservoir, but quantitative studies of organic matter sources are scarce. In this study, total organic carbon (TOC) and total nitrogen (TN) concentrations and δ13Corg and δ15Ntotal values of surface sediment from Jiangsu tidal flat were investigated for their distributions, influencing factors, and sources of organic matter. TOC and TN were high in the center of study area and correlated well with grain size, indicating hydrodynamic influence on organic matter. High TOC/TN and low δ13Corg and δ15Ntotal in estuaries were characteristic of C3 plants, soil, and fertilizer sources, suggesting source effect on the distribution of organic matter. The MixSIAR model revealed that marine sources were dominant with a contribution reaching 56.9 %, followed by uniform of C3 plants, soil and fertilizer, while domestic sewage was least prominent. This study enriched theories of the biogeochemical cycle and ecological protection in the southwestern Yellow Sea.
166. 题目: Biochar and lime amendments promote soil nitrification and nitrogen use efficiency by differentially mediating ammonia-oxidizer community in an acidic soil
期刊: Applied Soil Ecology
作者: Jie Zheng, Lu Luan, Yu Luo, Jianbo Fan, Qinsong Xu, Bo Sun, Yuji Jiang
摘要: Lime and biochar have been proposed as effective ameliorants for increasing soil fertility and nitrogen (N) cycling by regulating the ammonia-oxidizer community. However, the biological mechanisms of lime- and biochar-induced changes in the ammonia-oxidizer community, soil nitrification, crop productivity, and N use efficiency (NUE) remain largely unknown. Here, we established a 9-year field experiment to explore the ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities and measure potential nitrification activity (PNA), crop productivity, and NUE in response to biochar and lime amendments. We found that soil pH was significantly increased under lime amendment more than under biochar amendment, while soil organic carbon, total nitrogen, and ammonia nitrogen followed the opposite trend. Lime and biochar amendments significantly increased the abundance and diversity of AOA and AOB, and substantially shaped the AOA and AOB community compositions. The co-occurrence networks analysis indicated that potential keystone taxa had negative relationships with connected members in the network, which exhibited significant correlations with the abundance and diversity of AOA and AOB communities, PNA, crop productivity, and NUE. Structural equation modelling indicated that biochar amendment may mediate potential keystone taxa to increase the abundance and diversity of AOB community, and exhibit a stronger impact on PNA, crop productivity, and NUE than lime amendment. Collectively, our results highlight the ecological importance of lime- and biochar-induced effects on the ammonia-oxidizer community and soil N cycling dynamics.
167. 题目: The influence of alkali-modified biochar on the removal and release of Zn in bioretention systems: Adsorption and immobilization mechanism
期刊: Environmental Pollution
作者: Zenghui Su, Ping Sun, Youyuan Chen, Jiaxin Liu, Jie Li, Tianyuan Zheng, Shiying Yang
摘要: Generally, Zn in stormwater runoff is considered as low toxicity, but in the senarios of roads and zinc-based materials roof runoff, the concentration of Zn becomes extremely high and cannot be ignored. Bioretention systems are used to remove heavy metals from stormwater runoff, while Zn adsorption is insufficient by conventional filler and is prone to secondary release when exposed to acid rain or high salinity runoff. This study integrated batch experiments and density functional theory calculation to investigate the mechanisms of how KOH-modified biochar (KBC) influences the removal and release of Zn in bioretention systems. The results revealed that KBC adsorbed 89.0–97.5% Zn in the influent, the main adsorption mechanism were complexation and precipitation, and precipitation is more important. In addition, 67% of Zn was immoblized as the residual form by KBC. In acidic and saline runoff, KBC reduced Zn secondary release by 43.6% and 37.08% compared to the results in the absence of KBC, which was attributed to the convertion of most dissolved Zn in acidic and saline runoff into residual Zn. Therefore, KBC has a considerable application potential not only to decontaminate the runoff of roads and Zn-containing roofs, but also to deal with secondary Zn release in acid rain or under the treatment of snow-melting agents.
168. 题目: Inferring Ecosystem Function from Dissolved Organic Matter Optical Properties: A Critical Review
期刊: Environmental Science & Technology
作者: Juliana D’Andrilli, Victoria Silverman, Shelby Buckley, Fernando L Rosario-Ortiz
摘要: Over the last 30 years, the optical property community has shifted from conducting dissolved organic matter (DOM) measurements on new complex mixtures in natural and engineered systems to furthering ecosystem understanding in the context of past, present, and future carbon (C) cycling regimes. However, the appropriate use of optical properties to understand DOM behavior in complex biogeochemical systems is of recent debate. This critical review provides an extensive survey of DOM optical property literature across atmospheric, marine, and terrestrial biospheres using a categorical approach that probes each biosphere and its subdivisions. Using this approach, a rubric of ecosystem variables, such as productive nature, C cycling rate, C inputs, and water quality, sets the foundation for interpreting commonly used optical property DOM metrics such as fluorescence index (FI), humification index (HIX), and specific ultraviolet absorbance at 254 nm (SUVA254). Case studies and a meta-analysis of each biosphere and subdivision found substantial overlap and characteristic distributions corresponding to ecosystem context for FI, HIX, and SUVA254, signifying chromophores and fluorophores from different ecosystems may be more similar than originally thought. This review challenges researchers to consider ecosystem connectivity when applying optical property results rather than making traditional “if this, then that” results-style conclusions.
169. 题目: The mechanism of C–N–S interconnection degradation in organic-rich sediments by Ca(NO3)2 – CaO2 synergistic remediation
期刊: Environmental Research
作者: Chao Zhang, Meng Li, Jingmei Sun, Shiwei Zhang, Jianjun Huang
摘要: The rebound of black-odorous occurred in organic-rich sediments has become a critical issue due to its great harm to the ecological environment. Elements such as S, C, and N play a crucial role in the biogeochemical cycle of black-odorous rivers. As electronic acceptors, Ca(NO3)2 and CaO2 can effectively remove acidified volatile sulfide (AVS) and organic matter to control the black-odorous rebound. However, the remediation mechanisms in organic-rich sediments by Ca(NO3)2 and CaO2 are unclear. The present study explored the mechanism of C–N–S interconnection degradation in organic-rich urban river sediments by adding different ratios and sequences of Ca(NO3)2 and CaO2. The results showed that Ca(NO3)2 remediation followed by CaO2 and the accepted electron ratio 1:1 of Ca(NO3)2 to CaO2 is an effective method for controlling the rebound of black-odorous and reducing the accumulation NO2−-N. Mainly attributed to that, CaO2 enhanced the degradation of organic matter by stimulating enzymatic activities in the sediments, which is also the main reason for controlling the rebound of black-odorous. Since CaO2 releases O2 and •OH, which inhibit nosZgenes, NO2−-N accumulates when remedied simultaneously with Ca(NO3)2 and CaO2. Co-occurrence network analysis illustrated that sulfur-driven autotrophic denitrification bacteria, heterotrophic denitrifying bacteria, and sulfate-reducing bacteria interact strongly inside one module, clarifying a solid interaction of C–N–S substances among these bacteria. Our results reveal the C–N–S interconnection degradation mechanism and provide a new perspective on applying biochemical remediation in organic-rich urban river sediments.
170. 题目: Soil macroaggregates determine soil organic carbon in the natural grasslands of the Loess Plateau
作者: Xi Yang, Ming'an Shao, Tongchuan Li, Miao Gan, Mingyu Chen, Zhiyong Li
摘要: Soil aggregates are generally thought to be the nucleus of all carbon sequestration mechanisms. However, the Loess Plateau, a typical region where a fragile ecosystem has gradually recovered, has high variability in soil aggregates due to differences in climate and soil properties; thus, the driving mechanism of soil aggregates to changes in soil organic carbon (SOC) content remain unclear. To determine the dominant mechanisms affecting SOC content, we performed a large-scale investigation of the aggregate size fractions, aggregate-associated OC, OC in bulk soil, and environmental factors of the natural grasslands across a climatic gradient (semi-arid to semi-humid) on the Loess Plateau. The results showed that the proportion of macroaggregates (MA) decreased but that of microaggregates (MI) increased in the soil from south to north on the Loess Plateau. MA content decreased with soil depth, whereas MI and the silt + clay fraction (SC) contents increased with soil depth. In addition, aggregate-associated OC decreased with soil depth. The contribution rate of macroaggregate-associated OCwf (MAFC) to OC in bulk soil from south to north in the Loess Plateau showed a trend of decreasing first and then increasing, and the contribution rates were 73.77 % (Fufeng), 62.29 % (Huangling), 32.78 % (Suide), 28.31 % (Shenmu), and 47.62 % (Dalad Banner), respectively. For the entire Loess Plateau, MAFC contributed the most to SOC in different soil layers and the contribution rates were 64.68 % (0–5 cm), 49.54 % (5–10 cm), 44.43 % (10–20 cm), and 37.23 % (20–30 cm), respectively. Across the considered depths and sites, the MA, MAFC, and OC content of MA had significantly (p < 0.05) positive direct effects on the OC in bulk soil. Furthermore, MAFC was mainly dependent on the OC content and proportion of MA. Therefore, these results indicated that the proportion of MA and OC content within MA dominated the OC dynamics in bulk soil in the Loess Plateau.
171. 题目: Diffuse reflectance mid infra-red spectroscopy combined with machine learning algorithms can differentiate spectral signatures in shallow and deeper soils for the prediction of pH and organic matter content
作者: Felipe Bachion de Santana, Eric C Grunsky, Mairéad M Fitzsimons, Vincent Gallagher, Karen Daly
摘要: Precision and sustainable agriculture requires information about soil pH and organic matter (OM) content at higher spatial and temporal scales than current agronomic sampling and analytical methods allow. This study examined the accuracy of spectral models using high throughput screening (HTS) in diffuse reflectance mode in mid Infra-red (MIR)/DRIFT combined with machine learning algorithms to predict soil pH(CaCl2) and %OM in shallow and deeper topsoils compared to laboratory methods. Models were developed from an archive of samples taken on a 4 km2 grid from the northern half of Ireland (Terra Soil project), which includes 18,859 samples (9,396 shallow + 9,463 deeper). The application of Cubist models showed that for different depths there are minor different spectral group associations with pH and %OM values. These differences resulted in a loss of accuracy in the extrapolation of the topsoil model to predict values from deeper topsoils or vice versa. Therefore we recommend the use of samples from both depths to build a calibration model. The proposed methodology was able to determine %OM and pH using a unique multivariate regression model for both depths, with RMSEP values of 1.12 and 0.89 %; RPIQ values of 42.34 and 38.48; R2val of 0.9989 and 0.9993 for %OM determinations in shallow and deeper topsoils, respectively. For pH determinations the RMSEP values obtained were 0.25 and 0.34; RPIQ values of 6.04 and 4.94; R2val 0.9385 and 0.8954. Both regression models are classified as excellent predictions models, yielding RPIQ values >4.05 for shallow and deeper topsoils. The results demonstrated the high potential of HTS-DRIFT combined with machine learning algorithms as a rapid, accurate, and cost-effective method to build large soil spectral libraries, displaying predicted results similar to two separate soil laboratory methods (pH and LOI).
172. 题目: Study on treatment of city tail water by constructed wetland with corn straw biochar substrate
期刊: Environmental Technology & Innovation
作者: Hanxi Wang, Jianling Xu, Lianxi Sheng, Haowen Teng
摘要: Constructed wetland (CW) has obvious advantages in city tail water treatment. The biochar preparation from corn straw is an effective measure for improving the straw utilization. In order to improve the pollutant removal rate of CW, the city tail water treatment based on straw biochar substrate was studied. The thermogravimetric experiment of straw, characteristics test (scanning electron microscope, pore structure, element, adsorption) of biochar and city tail water treatment experiment by CW was carried out. The results show that the carbon fixation rate of straw biochar prepared at 450 °C (10 °C⋅ min −1, 2 h, N2) was 67.72%, and the adsorption capacity of biochar exceeded 40% of the requirements of wood activated carbon adsorption standard. When the proportion of biochar in substrate was 2.95%, the mean removal rates of ammonia nitrogen, total nitrogen and nitrate nitrogen was more than 85%. This study will be conducive to reducing straw carbon emissions and improve CW technical level.
173. 题目: Efficient tetracycline degradation via peroxymonosulfate activation by magnetic Co/N co-doped biochar: Emphasizing the important role of biochar graphitization
期刊: Chemical Engineering Journal
作者: Hui Zhu, An Guo, Siming Wang, Yan Long, Guangyin Fan, Xiaojun Yu
摘要: The accumulation of tetracycline (TC) in aquatic environments raised the risk to ecosystems and human health due to its potential biological toxicity. The development of carbon-based materials with features of low cost, easy isolation and excellent performance for activating peroxymonosulfate (PMS) to generate reactive oxygen species toward TC degradation is essential but remains a grand challenge. Herein, sustainable biomass kelp-derived self-nitrogen doped biochar (KC)-stabilized Co nanoparticles are developed for PMS activation toward TC degradation. The influences of calcination temperature on the microstructure were studied to further optimize the degradation performance for TC. The Co-N/KC-900 exhibits an optimal performance for activating PMS to degrade TC with a removal efficiency of 99% within 15 min. Additionally, the magnetic Co-N/KC-900 has robust recycling stability because of the enhanced interaction between the Co nanoparticles and graphitized biochar. Characterization results indicate that Co nanoparticles, graphite nitrogen, and direct electron transfer process participate in the PMS activation. Quenching experiments and electron paramagnetic resonance analyses reveal the combined radical and non-radical pathways for TC degradation, and the non-radical pathway plays a dominant role. The possible degradation pathway of tetracycline was proposed, and the toxicity of intermediates in the degradation process was evaluated. This study offers a facile and low-cost strategy to prepare an efficient PMS activator for antibiotic wastewater remediation.
174. 题目: Influence of thermal hydrolysis on sludge anaerobic digestion: Release of humic acid promotes electron transport of methanogen
期刊: Chemical Engineering Journal
作者: Cheng Zhao, Hongbo Liu, He Liu, Xinmin Zhan, Xuedong Zhang, Bo Fu, Mingze Shi, Shuailing Lu, Fang Huang, Minhua Cui, Yajie Li
摘要: Thermal hydrolysis pretreatment (THP) has been widely applied to promote anaerobic digestion (AD). Humic acids (HAs) are a group of insoluble organics and often present in the conventional AD of sludge, but are reportedly substantially released during THP. Thus, the influences of the released HAs on AD shall be investigated, in particular on methanogenesis. Our results indicated that the presence of HAs extracted from thermally hydrolyzed sludge improved methanogenesis by 15.8-80.8%. However, HAs harvested at different temperatures presented distinctively different capabilities in enhancing methane production. Seemingly, the promotion efficiency of HAs to methanogenesis did not significantly respond with any individual characteristics of HAs in aspects of molecular weight, electrical activity and electroactive group compositions. However, the efficiency presented an evident correlation with the superimposed effects of the characteristics aforementioned. Therefore, a hypothesis on the mechanism involved in the phenomenon observed above was proposed that only the HAs with low molecular weight, allowing the molecules to penetrate cells could affect methanogenesis, and not all of the electroactive groups of HAs were involved in microbial electron transfer. Moreover, it was found that only the group of quinones (Q1) with side chain of electron withdrawing group played key roles in accelerating methyl acetyl-CoA degradation and promoting methanogenesis. Directional regulation of methanogenesis promotion assisted with HAs was realized by selectively removing or retaining the Q1 groups in HAs, which also evidently sustained the proposed mechanism aforementioned. The findings of this study demonstrate that high temperature was conducive to the release of organics during sludge thermal hydrolysis, whereas the temperature above 160℃ led to changes of HAs structure and then subsequently undermined methane production from sludge.
175. 题目: Activated peroxymonosulfate with ferric chloride-modified biochar to degrade bisphenol A: characteristics, influencing factors, reaction mechanism and reuse performance
期刊: Separation and Purification Technology
作者: Yanjiao Gao, Yu Chen, Tiehong Song, Rui Su, Jiacheng Luo
摘要: Water environment pollution caused by a large amount usage of bisphenol A (BPA) in industry has attracted widespreadattention, which may lead to destroying the endocrine system of organisms and even the human body. Peroxymonosulfate (PMS) catalyzed by biochar (BC) for the removal of emerging pollutants (including BPA) from water body has entered the researcher's field of vision. A ferric chloride- modified rice husk BC was prepared via one pot method and characterized by BET, SEM, XPS, and Raman spectroscopy. A series of batch experiments were conducted to investigate the performance, influencing factors, and reaction mechanism of BC/PMS system for the degradation of BPA. The results showed that more than 97% of BPA was removed with 1.0 g/L F2BC3 and 1.6 g/L PMS from the artificial solution containing 20 mg/L BPA within 150 min at different pH (3, 6, and 10); The degradation of BPA was not associated with humic acid (HA), was inhibited by HCO3-, NO3-, H2PO4-, and Cl- (at low concentration), and was promoted by Cl- (at high concentration) based on the concentration range set in this study; the removal rate of BPA by F2BC3/PMS decreased from 94.3% to 84.8% after four cycles of F2BC3, which means stable performance has been demonstrated. It could be confirmed that BPA was degraded into intermediates and final products H2O and CO2 via co-attack of major free radicals (SO4•-,•OH, and O2•-) and minor non-radical 1O2. Therefore, F2BC3/PMS system could be considered as a potential process for the treatment of BPA.
176. 题目: Organic-matter decomposition in urban stream and pond habitats
期刊: Ecological Indicators
作者: Matthew J Hill, Ian Thornhill, Scott D Tiegs, Ana Castro-Castellon, J. Salvador Hernández-Avilés, Arantza Daw, Victor Hugo Salinas-Camarillo, Sarah Hobbs
摘要: Organic-matter decomposition is a key ecosystem process in freshwater ecosystems as it influences food web dynamics, represents a considerable flux in the global carbon cycle and can provide a useful measure of the ‘health’ of freshwater habitats. While organic-matter decomposition has been well studied among lotic ecosystems, research from small standing waterbodies such as ponds is largely missing, and decomposition studies are usually conducted on a single freshwater habitat type. However, there is a need to consider ecosystem processes across multiple freshwater habitats and connected ecosystems to better characterise ecosystem functioning at the landscape-scale, given the interdependence of landscape elements. This study provides a comparative analysis of organic-matter decomposition using a standardised field assay (cotton-strip assay) in the water column, riparian zone and land zone of urban pond and stream habitats. The average daily tensile-strength loss of the cotton strips (a process that corresponds to the catabolism of cellulose by microbes) was significantly higher in the aquatic habitats than riparian and land zones when all sites were considered, and when stream and pond sites were considered separately. Furthermore, the average decomposition rate was significantly higher within the water column in river habitats compared to pond habitats, although no difference was observed among riparian and land zones. Woody debris had a negative unimodal association with average per day tensile strength loss within streams, and a positive unimodal association within pond sites. Both nitrate and shading had positive unimodal associations with average per day tensile strength loss within stream sites. Among pond habitat, urban land coverage within 250m of each site was identified to have a negative association with average per day tensile strength loss. Here we demonstrated that urban freshwater habitats have heterogeneous organic matter decomposition rates, and that the responses can be complex. Understanding key ecosystem processes at a multihabitat scale will ensure the effective inclusion of ecosystem process in freshwater assessment and conservation protocols and improve the health and resilience of urban freshwater ecosystems.
177. 题目: Resource utilization of rice husk biomass: Preparation of MgO flake-modified biochar for simultaneous removal of heavy metals from aqueous solution and polluted soil
期刊: Environmental Pollution
作者: Anyu Li, Hanquan Xie, Ying Qiu, Lihu Liu, Tao Lu, Weihua Wang, Guohong Qiu
摘要: In general, the remediation performance of heavy metals can be further improved by metal-oxide modified biochar. This work used MgO-modified rice husk biochar (MgO-5%@RHB-450 and MgO-5%@RHB-600) with high surface activity for simultaneous remediation and removal of heavy metals in soil and wastewater. The adsorption of MgO-5%@RHB-450/MgO-5%@RHB-600 for Cd(II), Cu(II), Zn(II) and Cr(VI) followed the pseudo-second order, with the adsorption capacities reaching 91.13/104.68, 166.68/173.22, 80.12/104.38 and 38.88/47.02 mg g−1, respectively. The addition of 1.0% MgO-5%@RHB-450 and MgO-5%@RHB-600 could effectively decrease the CaCl2-extractable Cd concentration (CaCl2–Cd) by 66.2% and 70.0%, respectively. Moreover, MgO-5%@RHB-450 and MgO-5%@RHB-600 facilitated the transformation of exchangeable fractions to carbonate-bound and residual fractions, and reduced the exchangeable fractions by 8.1% and 9.6%, respectively. The mechanisms for the removal of heavy metals from wastewater by MgO-5%@RHB-450 and MgO-5%@RHB-600 mainly included complexation, ion exchange and precipitation, and the immobilization mechanisms in soil may be precipitation, complexation and pore filling. In general, this study provides high-efficiency functional materials for the remediation of heavy metal pollution.
178. 题目: A green approach towards sorption of CO2 on waste derived biochar
期刊: Environmental Research
作者: Aman Kumar, Ekta Singh, Rahul Mishra, Shang-Lien Lo, Sunil Kumar
摘要: Carbon capture technologies have advanced in recent years to meet the ever-increasing quest to minimize excessive anthropogenic CO2 emissions. The most promising option for CO2 control has been identified as carbon capture and storage. Among the numerous sorbents, char generated from biomass thermal conversion has shown to be an efficient CO2 adsorbent. This study examines various characteristics that can be used to increase the yield of biochar suited for carbon sequestration. This review gives recent research progress in the area, stressing the variations and consequences of various preparation processes on textural features such as surface area, pore size and sorption performance with respect to CO2's sorption capacity. The adjoining gaps discovered in this field have also been highlighted herewith, which will serve as future work possibilities. It aims to analyse and describe the possibilities and potential of employing pristine and modified biochar as a medium of CO2 capture. It also examines the parameters that influence biochar's CO2 adsorption ability and pertinent challenges regarding the production of biochar-based CO2 sorbent materials.
179. 题目: Polyhalogenated Carbazoles in Sediments of Lower Laurentian Great Lakes and Regional Perspectives
期刊: ACS ES&T Water
作者: An Li, Shanshan Zhou, Huan He, Jiehong Guo, Karl J Rockne, Neil C Sturchio, John P Giesy
摘要: This work continued investigations of polyhalogenated carbazoles (PHCZs) in sediments of the Laurentian Great Lakes. A total of 77 Ponar grab samples plus approximately 300 segments from 12 sediment cores from Lakes Erie and Ontario were analyzed for carbazole (CZ) and 26 PHCZs. CZ is widespread in sediments of all five Great Lakes, particularly in Lake Erie where it has accumulated >100 tonnes, which is similar to that of total polychlorinated biphenyls. Among the 26 PHCZs, 3-bromo- (3-BCZ) and 3-chloro- (3-CCZ) carbazoles exhibited the greatest mass loads in Lakes Ontario and Erie, although their stratigraphic sediment records suggest peaking of input occurred before 1980 and are now decreasing. Of emerging concern are several dibromocarbazoles, which exhibit rapid increases in net fluxes to sediment since the 1980s. Accumulation of PHCZs that are considered to be of natural origin decreases in an eastward and southward transect across the region, opposite to the trend for those that are predominantly of human activity related origin. The dependences on water depth and sediment organic matter content differ among PHCZs and their categories. Results presented here demonstrate the inter-related influences of natural processes and human activities on occurrences, fates, and dispositions of PHCZs and likely other organohalogens in the Great Lakes.
180. 题目: Linking soil bacterial community assembly with the composition of organic carbon during forest succession
期刊: Soil Biology and Biochemistry
作者: Qi Zhang, Xing Wang, Zhenjiao Zhang, Hanyu Liu, Yingyi Liu, Yongzhong Feng, Gaihe Yang, Chengjie Ren, Xinhui Han
摘要: Changes in the composition of organic carbon lead to shifts in the selective environment, which in turn contribute to changes in the composition and assembly process of soil bacterial communities at different successional stages. Deterministic and stochastic processes are expected to clarify bacterial community assembly process during long-term ecosystem recovery. Therefore, by studying the bacterial community of the organic horizon and mineral horizon during forest succession, the main role of organic carbon composition in determining soil bacterial community structure and assembly process during forest succession in the arid regions of Loess Plateau, China was revealed. Stochastic assembly was predominant in the organic horizon (75.0%) and mineral horizon (71.6%), and its relative contribution of stochastic assembly was similar in two horizons. In addition, network analyses demonstrated that bacterial nodes (as individual taxa) and connectivity between them was higher in the organic horizon (nodes: 297 and edges: 5242) than mineral horizon (nodes: 251 and edges: 1694). During forest succession, the bacterial community gradually changed to a K-strategy, and the degree of bacterial network connection cross the organic horizon and mineral horizon gradually decreased. The taxon- organic carbon composition cooccurrence network aided in identifying the relationship between the composition of organic carbon and the bacterial community, and ploysaccharide, methyl and aliphatic carbon were the main reason for the differences in the bacterial community. Meanwhile, the relationship between the composition of organic carbon in bacterial assembly was different in the organic horizon and mineral horizon: ploysaccharide, methyl, aliphatic, aromatics and carboxylic carbon were the main factors driving bacterial assembly in the organic horizon, whereas the interaction of them with bacterial traits jointly participated the assembly process in the mineral horizon. Our results highlight the importance of resource availability, particularly the composition of organic carbon, in determining how the microbial community composition assembles during forest succession.