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17441. 题目: Alkane variation in peat reveals palaeohydrological changes since the Little Ice Age in eastern China
文章编号: N21103113
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Yang Pang, Bin Zhou, ChunMei Ma, JiaWei Jiang, David Taylor, YueHan Lu
更新时间: 2021-10-31
摘要: The East Asian summer monsoon (EASM) system plays a crucial role in regulating climatic and hydrological variability in East Asia. However, it remains controversial how EASM altered the spatiotemporal patterns of hydrological variability of eastern China during the Little Ice Age (LIA). Here, we established a relatively high-resolution palaeohydrological record over the last 700 years in East China via analyzing n-alkanes from a peat core. Mid- and long-chain (C21–C25 and C27–C31) n-alkanes account for more than 95% of the total odd‑carbon-numbered n-alkanes, with short-chain n-alkanes (C17–C19) accounting for only 2.3% on average, suggesting that organic matter in the peat core originated primarily from vascular plants. Organic geochemical indices, including Paq (an indicator of contributions from aquatic plants), the average chain length (ACL) of long-chain n-alkanes, and C31/C27 and C23/C29 n-alkane ratios, suggest a transition from dry conditions during the middle LIA to wet conditions in the late LIA. Comparing Paq records from the study profile with previous records from the EASM region, we found that the northern and southern parts of eastern China showed contrasting changes in humidity during the LIA. Specifically, the southern part shifted from mid-LIA dry conditions to late-LIA wet conditions, whereas the northern part shifted from mid-LIA wet conditions to late-LIA dry conditions. This spatial heterogeneity in hydroclimate could be attributed to La Niña-like conditions and intense summer monsoons during the middle LIA and El Niño-like conditions and weak summer monsoons during the late LIA. Our study demonstrates the importance of understanding spatial heterogeneity of hydroclimatic changes to probe the mechanisms whereby EASM modulates regional climatic changes during the LIA.

17442. 题目: Nematode communities indicate anthropogenic alterations to soil dynamics across diverse grasslands
文章编号: N21103112
期刊: Ecological Indicators
作者: Li Liu, Shuiyan Li, Gail W.T. Wilson, Adam B. Cobb, Chengyang Zhou, Jinsheng Li, Jiahuan Li, Lizhu Guo, Ding Huang
更新时间: 2021-10-31
摘要: Nematode communities are meaningful biological indicators of soil health and soil processes across different grassland types and management practices and analyses of nematode communities provide insight into structure, function, and sensitivity or resilience across multiple ecosystems. In three model grasslands: meadow steppe (MS), typical steppe (TS), and alpine meadow (AM), this current research examined responses of soil nematode communities and related edaphic characteristics to grazing, mowing, and crop cultivation at two soil depths. The research fills a critical knowledge gap by resolving multidirectional influences between local conditions, grassland management practices, and nematode communities. Across grassland types, nematode abundance in AM was greater than MS and TS grasslands, and nematodes were more abundant near the soil surface. Cultivation resulted in greater nematode abundance compared to all other management practices, and generally, bacterivores were the most dominant nematode trophic group. The TS and MS grasslands had relatively more bacterivores, exhibiting substantial influences on soil mineralization and organic matter decomposition pathways. The AM grassland showed relatively more plant feeding nematodes, driving soil mineralization pathways. Among the three management practices, crop cultivation had the greatest impact on nematode community structure and the soil environment, especially in relatively sensitive AM grasslands. In fact, AM soil environments responded most dramatically to cultivation, with nematode abundance, soil quality, and food web complexity increasing. However, soil ecosystem stability, food web reliance, and food web response to resources decreased in cultivated AM soils. Results indicate that unique environmental characteristics in the Qinghai-Tibet plateau drive substantially different AM grassland nematode community structure and soil conditions compared to TS or MS grasslands. As anthropogenic pressures on these ecosystems mount, it is critical to understand how different management practices influence grassland nematode communities, with cascading effects through soil environments.

17443. 题目: The response of coastal macrobenthic food-web structure to seasonal and regional variability in organic matter properties
文章编号: N21103111
期刊: Ecological Indicators
作者: Marta Szczepanek, Marc J. Silberberger, Katarzyna Koziorowska-Makuch, Edoardo Nobili, Monika Kędra
更新时间: 2021-10-31
摘要: The quantity and quality of organic matter (OM) available for macrobenthos vary on temporal and spatial scale, especially in coastal areas, where the seafloor is supplied by both seasonal pulses of primary production and terrestrial carbon transported by rivers. Human-induced environmental changes will alter OM transport to the seafloor, thus, it is of crucial importance to recognize the impacts of spatio-temporal OM variability on macrobenthic food webs. In this study, the seasonal variability of quantity and quality of OM and its effect on benthic food-web structure were studied at four locations along the southern coast of the Baltic Sea, characterized by similar species pools but different environmental settings and various scales of anthropogenic and riverine influence. Our study shows that temporal changes in the isotopic niche (δ13C and δ15N) of benthic invertebrates follow the patterns of quantity and quality of OM related to seasonal changes of pelagic primary production, riverine discharge of terrestrial OM and the input of anthropogenically enriched sources. In the semi-enclosed bay, exposed to intensive summer blooms, all feeding groups expressed lower δ15N values in autumn, suggesting the incorporation of δ15N-depleted cyanobacteria. At a location supplied by a higher proportion of OM from allochthonous sources (riverine discharge), omnivores occupied higher trophic levels, probably due to a higher abundance of meiobenthic prey. In contrast, at the open Polish coast, where the main food supply occurs during diatom spring bloom, the isotopic niche of omnivorous species showed much higher seasonal variability, underlining the importance of food availability for food-web diversity. Quick adaptation of benthic food-web structure to seasonal variations in OM properties and its modification by local conditions may indicate high plasticity of species feeding behavior that suggests a high capacity of benthic communities to mitigate ongoing changes in the marine environment, at least within the range observed today. Our results confirm that combination of spatial and temporal scales in sampling of the food-web structure is a good indicator of the ecosystem stability and function.

17444. 题目: Degradation mechanism and QSAR models of antibiotic contaminants in soil by MgFe-LDH engineered biochar –activating urea-hydrogen peroxide
文章编号: N21103110
期刊: Applied Catalysis B: Environmental
作者: Qincheng Chen, Zhiwen Cheng, Xiaoying Li, Chen Wang, Lili Yan, Guoqing Shen, Zhemin Shen
更新时间: 2021-10-31
摘要: Developing an in-situ soil remediation technology for simultaneous catalytic degradation of contaminants and nitrogen supplementation is of great importance but remains challenging. Herein, MgFe-LDH engineered biochar (MB) was successfully synthesized by using a simple co-precipitation method. The as-prepared materials were used as catalysts for the first time to activate urea-hydrogen peroxide (UHP) to degrade antibiotic sulfamethoxazole (SMX) and provide nitrogen. The enhanced degradation efficiency of SMX (91%) were mainly attributed to •OH and 1O2-mediated oxidation. Pot experiments showed MB/UHP significantly decreased the SMX concentration from 6.47 to 2.10 mg kg-1 and simultaneously increased NH4+-N and NO3--N concentration. The optimal quantitative-structure-activity-relationship model for 19 antibiotics suggested the dipole moment, energy of the highest occupied molecular orbital, and bond order were the intrinsic influencing factors. This study not only provides a green remediation technology but also offers a theoretical basis for estimating the removal rate of unexplored antibiotics.

17445. 题目: Enhanced Adsorption of Humic/Fulvic Acids onto Urea-derived Graphitic Carbon Nitride
文章编号: N21103109
期刊: Journal of Hazardous Materials
作者: Jianchao Wang, Hongxin Li, Dongbei Yue
更新时间: 2021-10-31
摘要: Since humic substances (HSs) can cause environmental problems, their elimination has been attracting more and more concerns. In this study, we investigated HSs adsorption onto urea-derived graphitic carbon nitride (CNU) and elucidated adsorption mechanisms (i.e. heterogeneity, interface rearrangement, and multiple interactions). The adsorption capacity of CNUs was enhanced as increasing calcination temperature and time. Among CNUs, CNU-575-3 showed the highest adsorption capacity; the maximum adsorption capacities for humic acid (HA) and fulvic acid (FA) were 164.06mgC/g, 14.61L/cm·g, 91.12mgC/g, and 5.34L/cm·g, respectively. The adsorption affinity of CNUs mainly correlated with the amount of amino groups, and that of HSs components was dependent on aromaticity due to π-π interactions. More specifically, terrestrial humic-like and fulvic-like components within HA and FA showed the greatest adsorption affinity, respectively. HSs adsorption was remarkably affected by pH, alkali metals, and alkali earth metals via electrostatic interactions, H-bonding, cation bridge, and configurational effect. In addition, the adsorption of Elliott soil HA (ESHA) and the landfill leachate concentrate by CNUs was also highly efficient. This study shows the great promise of CNUs for HSs adsorption in waters and wastewaters.

17446. 题目: Simulated root exudates stimulate the abundance of Saccharimonadales to improve the alkaline phosphatase activity in maize rhizosphere
文章编号: N21103108
期刊: Applied Soil Ecology
作者: Guiwei Wang, Zexing Jin, Xinxin Wang, Timothy S. George, Gu Feng, Lin Zhang
更新时间: 2021-10-31
摘要: Plants promote the mineralization of soil organic phosphorus by secreting phosphatase into the rhizosphere, in addition they promote the growth of bacteria which also release phosphatase to the rhizosphere. Sugars are the main component of root exudates and a key driver of soil microbial activity. In this study, we added different concentrations of a range of sugars found in root exudates to the soil during maize growth to investigate whether sugars could stimulate alkaline phosphatase activity. Sugars increased alkaline phosphatase activity in soil, while different sugars increased this activity to different extents. Small concentration of sugars did not stimulate alkaline phosphatase activity in the rhizosphere, change the bacterial community structure or select phosphatase producing species such as Saccharimonadales. However, alkaline phosphatase activity was enhanced by larger concentration of added sugars, which increased indigenous soil Saccharimonadales abundance. Notwithstanding this, Saccharimonadales were rare in the microbial taxa at the order level and their relative abundance was only 2.1%–4.9% at different sugar concentration levels. Our results suggest that addition of sugars selected for indigenous soil Saccharimonadales, enhancing alkaline phosphatase activity in the rhizosphere. These rare microbial taxa may be a key species in soil phosphorus cycling.

17447. 题目: Effect of Solution pH on the Dual Role of Dissolved Organic Matter in Sensitized Pollutant Photooxidation
文章编号: N21103107
期刊: Environmental Science & Technology
作者: Jannis Wenk, Cornelia Graf, Michael Aeschbacher, Michael Sander, Silvio Canonica
更新时间: 2021-10-31
摘要: Dissolved organic matter (DOM) has a dual role in indirect phototransformations of aquatic contaminants by acting both as a photosensitizer and an inhibitor. Herein, the pH dependence of the inhibitory effect of DOM and the underlying mechanisms were studied in more than 400 kinetic irradiation experiments over the pH range of 6–11. Experiments employed various combinations of one of three DOM isolates, one of two model photosensitizers, the model antioxidant phenol, and one of nine target compounds (TCs), comprising several aromatic amines, in particular anilines and sulfonamides, and 4-cyanophenol. Using model photosensitizers without antioxidants, the phototransformation of most TCs increased with increasing pH, even for TCs for which pH did not affect speciation. This trend was attributed to pH-dependent formation yields of TC-derived radicals and their re-formation to the parent TC. Analogous trends were observed with DOM as a photosensitizer. Comparison of model and DOM photosensitizer data sets showed increasing inhibitory effects of DOM on TC phototransformation kinetics with increasing pH. In systems with anilines as a TC and phenol as a model antioxidant, pH trends of the inhibitory effect could be rationalized based on the reduction potential difference (ΔEred) of phenoxyl/phenol and anilinyl/aniline couples. Our results indicate that the light-induced transformation of aromatic amines in the aquatic environment is governed by the pH-dependent inhibitory effects of antioxidant phenolic moieties of DOM and pH-dependent processes related to the formation of amine oxidation intermediates.

17448. 题目: Middle-late Holocene climate and hydrologic changes in the Gulf of Saros (NE Aegean Sea)
文章编号: N21103106
期刊: Marine Geology
作者: Cerennaz Bozyiğit, Kürşad Kadir Eriş, Marie-Alexandrine Sicre, Memet Namık Çağatay, Gülsen Uçarkuş, Vincent Klein, Luca Gasperini
更新时间: 2021-10-31
摘要: A multi-proxy analyses was applied on the sediment core from the Gulf of Saros (GoS) to identify and characterize climate and hydrological changes during the middle-to-late Holocene. The formation of two discrete Holocene sapropel layers in the GoS sediments was documented for the first time in the sediment core based on total organic carbon analysis. According to our paleo-proxy records, the lower Holocene sapropel was deposited under warm and humid climate conditions that gave rise to high delivery of terrestrial organic matter by numerous rivers in the northern catchment of the GoS. Biomarker and μ-XRF data were used to decipher climate variations during the middle to late Holocene. The general trends of sea-surface temperature records from the GoS and Sea of Marmara (SoM) at the beginning of late Holocene are in good agreement, underlying the influence of the Black Sea inflow. A relatively warm and wet climate together with a high sedimentation rate during the mid-Holocene Climatic Optimum resulted in high organic productivity and ensuing formation of the younger Holocene sapropel between 5.4 and 3.0 cal ka BP. Late Holocene European climate periods are evident in the Saros core records. The Roman Humid Period is represented by high variation in climate, indicating an earlier (2.5–2.3 cal ka BP) dry and a later (2.3–1.55 cal ka BP) wet periods. The abrupt return to drier condition during the Dark Ages Cold Period (1.6–1.3 cal ka BP) was followed by a wetter Medieval Climate Anomaly (1.1–0.7 cal ka BP). The paleo-proxy record of the core indicates a passage from a wetter to drier climate during the cold Little Ice Age period (730–110 cal yr BP), and highlights the influence of deforestation in the catchment of the GoS as a result of human activities during the last three centuries.

17449. 题目: Particulate organic carbon exports from the terrestrial biosphere controlled by erosion
文章编号: N21103105
期刊: CATENA
作者: Xuling Luo, Xiaoyong Bai, Qiu Tan, Chen Ran, Huan Chen, Huipeng Xi, Fei Chen, Luhua Wu, Chaojun Li, Sirui Zhang, Xin Zhong, Shuang Tian
更新时间: 2021-10-31
摘要: The transport of particulate organic carbon (POC) through rivers from land to sea affects the redistribution of global organic carbon. However, because of the limitation of the quantity and quality of monitoring data, the POC magnitude, scale and global distribution pattern of land-sea migration are still not well understood. Therefore, based on an updated GEMS-GLORI database and other reanalysis data, we use the soil erosion model (Ferosion), total suspended solids model (Ftss), and runoff model (Frunoff) to re-analyze and generate the POC flux of major rivers in the world dataset. The major results are as follows: the POC flux from global terrestrial biosphere rivers exports approximately 0.12–0.20 Pg C to oceans every year, including 0.20 Pg Ferosion, 0.17 Pg Ftss, and 0.12 Pg Frunoff. In contrast to earlier studies that the Pacific and Arctic Oceans are the main recipients of POC flux, we find that the Pacific and Atlantic received more POC flux and received 30.76%–62.51% and 26.77%–53.95%, respectively. This difference may be related to the combined effects of soil erosion, total suspended solids, and runoff. Asia exports more POC than other continents (60.50%–61.69%). The Amazon basin is the major contributor to the Atlantic POC, contributing 53.30%–58.68%. Furthermore, because of the intense human activities and the widespread distribution of many large watersheds in the highly eroded area, it was found that the POC flux has two key zones (25.75–41.5°N and 4.50°N–13.50°S) in the latitude zone. In summary, the above findings increase our understanding of the spatial redistribution of global organic carbon from land to sea.

17450. 题目: Comparison of different valent iron on anaerobic sludge digestion: Focusing on oxidation reduction potential, dissolved organic nitrogen and microbial community
文章编号: N21103104
期刊: Frontiers of Environmental Science & Engineering
作者: Zecong Yu, Keke Xiao, Yuwei Zhu, Mei Sun, Sha Liang, Jingping Hu, Huijie Hou, Bingchuan Liu, Jiakuan Yang
更新时间: 2021-10-31
摘要: This study compared effects of three different valent iron (Fe0, Fe(II) and Fe(III)) on enhanced anaerobic sludge digestion, focusing on the changes of oxidation reduction potential (ORP), dissolved organic nitrogen (DON), and microbial community. Under the same iron dose in range of 0–160 mg/L after an incubation period of 30 days (d), the maximum methane production rate of sludge samples dosed with respective Fe0, Fe(II) and Fe(III) at the same concentration showed indiscernible differences at each iron dose, regardless of the different iron valence. Moreover, their behavior in changes of ORP, DON and microbial community was different: (1) the addition of Fe0 made the ORP of sludge more negative, and the addition of Fe(II) and Fe(III) made the ORP of sludge less negative. However, whether being more or less negative, the changes of ORP may show unobservable effects on methane yield when it ranged from −278.71 to −379.80 mV; (2) the degradation of dissolved organic nitrogen, particularly proteins, was less efficient in sludge samples dosed with Fe0 compared with those dosed with Fe(II) and Fe(III) after an incubation period of 30 d. At the same dose of 160 mg/L iron, more cysteine was noted in sludge samples dosed with Fe(II) (30.74 mg/L) and Fe(III) (27.92 mg/L) compared with that dosed with Fe0 (21.75 mg/L); (3) Fe0 particularly promoted the enrichment of Geobacter, and it was 6 times higher than those in sludge samples dosed with Fe(II) and Fe(III) at the same dose of 160 mg/L iron.

17451. 题目: Biochar and its manure-based feedstock have divergent effects on soil organic carbon and greenhouse gas emissions in croplands
文章编号: N21103103
期刊: Science of The Total Environment
作者: Cole D. Gross, Edward W. Bork, Cameron N. Carlyle, Scott X. Chang
更新时间: 2021-10-31
摘要: Applying organic amendments to soil can increase soil organic carbon (SOC) storage and reduce greenhouse gas (GHG) emissions generated by agriculture, helping to mitigate climate change. However, it is necessary to determine which type of amendment produces the most desirable results. We conducted a 3-y field study comparing one-time additions of manure compost and its biochar derivative to a control to assess their effects on SOC and GHG emissions at ten annually cropped sites in central Alberta, Canada. Manure compost and biochar were applied at equivalent carbon rates (7 Mg ha−1) and tilled into the surface 10 cm of soil. Two years post-treatment, biochar addition increased surface (0–10 cm) SOC by 12 and 10 Mg ha−1 relative to the control and manure addition, respectively. Therefore, the biochar led to the sequestration of SOC at a rate of 2.5 Mg ha−1 y−1 relative to the control. No treatment effect on deeper (10–100 cm) or cumulative SOC was found. In 2018 and 2019, manure addition increased cumulative GHG (sum of CO2, CH4, and N2O) emissions by 33%, on average, due to greater CO2 emissions relative to both the control and biochar addition. In contrast, in 2020, biochar addition reduced cumulative GHG emissions by an average of 21% due to lower CO2 emissions relative to both the control and manure addition. Our study shows that the application of biochar, rather than its manure compost feedstock, increased surface SOC sequestration and had either no effect on (first two years) or reduced GHG emissions (year three) relative to the control. We recommend that policy and carbon sequestration initiatives focus on optimizing biochar production-application systems to fully realize the potential of biochar application as a viable climate change mitigation practice in agriculture.

17452. 题目: Linking isotopic signatures of nitrogen in nearshore coral skeletons with sources in catchment runoff
文章编号: N21103102
期刊: Marine Pollution Bulletin
作者: Guy S. Marion, Stacy D. Jupiter, Veronica Z. Radice, Simon Albert, Ove Hoegh-Guldberg
更新时间: 2021-10-31
摘要: We use a multi-tracer approach to identify catchment sources of nitrogen (N) in the skeletons of nearshore Porites corals within the Great Barrier Reef. We measured δ15N, δ13C and C:N ratios of particulate organic matter (POM) sampled from the Pioneer River catchment and identified five distinct end-members: (1) marine planktonic and algal-dominated matter with higher δ15N values from the river mouth and coastal waters; (2) estuarine planktonic and algal matter with lower δ15N values associated with estuarine mixing; (3) lower river freshwater phytoplankton and algal-dominated matter in stratified reservoirs adjacent to catchment weirs, with the 15N-enriched source likely caused by microbial remineralization and denitrification; (4) upper river low δ15N terrigenous soil matter eroded from cane fields bordering waterways; and (5) terrestrial plant detrital matter in forest streams, representing a low δ15N fixed atmospheric nitrogen source. The δ15N values of adjacent, nearshore Porites coral skeletons is reflective of POM composition in coastal waters, with 15N-enriched values reflective of transformed N during flood pulses from the Pioneer River.

17453. 题目: Storage or loss of soil active carbon in cropland soils: The effect of agricultural practices and hydrology
文章编号: N21103101
期刊: Geoderma
作者: Josette Garnier, Gilles Billen, Julien Tournebize, Pierre Barré, Bruno Mary, François Baudin
更新时间: 2021-10-31
摘要: Few studies have simultaneously addressed the issue of the short- and long-term hydrological control of organic carbon (OC) export from soils and the role of the leaching process in the long-term dynamics of the soil OC pool. We combined short- and long-term approaches by investigating dissolved organic carbon (DOC) at the outlet of a small drainage catchment and establishing a relationship between DOC concentrations (3.5 ± 1.8 mgC L-1 on average) and subsurface runoff (175 mm yr−1 on average). We then calculated the annual DOC export as a function of average annual water runoff for a 9-year period. We assumed that the annual flux of leaching is proportional to the active soil OC stock, which we compared with data from the literature. We added a leaching function to the AMG two-compartment model of soil carbon dynamics. The innovative use of the Rock–Eval method for agricultural soils made it possible to determine the stable and active carbon fractions (OCp and OCA, respectively), necessary to characterize the system in the model, for 52 plots in organic and conventional agricultural farms in the Seine Basin. No significant difference was found in OC for the two agricultural systems (11.4 ± 2.5 gC kg−1 vs. 12.3 ± 4.2 gC kg−1, respectively, for the 0 to 30 cm layer). Using the AMG model with its leaching function, we calculated the equilibrium value of OCA, representing the size of the OCA pool that would be reached in the long term under constant farming practices and hydrological conditions in a given plot. Deviation from this equilibrium indicates whether carbon storage or loss occurs. Overall, for the plots sampled in the Seine Basin, an annual carbon loss of ∼−0.24 % yr−1 of the total OC pool was found. This may increase by 15% (i.e., to ∼−0.28% yr−1) under higher subsurface runoff, which is plausible under ongoing climate change (e.g., 600 mm yr−1 vs. 175 mm yr−1 currently observed).

17454. 题目: Field-scale decentralized domestic wastewater treatment system: Effect of dynamic loading conditions on the removal of organic carbon and nitrogen
文章编号: N21103017
期刊: Journal of Environmental Management
作者: Guru R. Munavalli, Pratap G. Sonavane, Mitil M. Koli, Bhargavi S. Dhamangaokar
更新时间: 2021-10-30
摘要: The field–scale decentralized wastewater treatment system (DWTS) was developed with an anaerobic baffled reactor (ABR) and a newly configured hybrid constructed wetland (HCW) vegetated with Typha angustifolia and Canna indica to treat 42 kLd of domestic wastewater. Biorack baffled constructed wetland (BBCW) and baffled vertical flow constructed wetland (BVFCW) were used in the first and second stage of HCW respectively. DWTS was assessed for its efficiency to remove COD, BOD and TKN under high (varying flow and varying COD) and moderate (constant flow and varying COD) dynamic loading conditions. The tracer study and pertinent computation showed the good performance of DWTS in its hydraulic efficiency. COD of raw wastewater was the treatment-limiting step in ABR. BBCW sustained larger fluctuations in loading rates [hydraulic (0.43–10.29 m3/m2.d) and organic (0.08–2.30 kgCOD/m2.d)]. The draining (unsaturated) conditions enhanced COD and BOD removal in BVFCW. DWTS was found to be efficient for the average removal of COD (70–90%) and TKN (40–65%). HCW contributed 50–60% and 70–80% to COD and TKN removal respectively. The quantification of impacts on treatment efficiency and sustainability of DWTS was demonstrated at field-scale under high and moderate dynamic conditions.

17455. 题目: Effect of humic acid on the single-stage nitrogen removal using anammox and partial nitritation (SNAP) process: performance and bacterial communities
文章编号: N21103016
期刊: Journal of Environmental Chemical Engineering
作者: Changhao Lu, Chunli Yuan, Tong Zhu, Youzhao Wang
更新时间: 2021-10-30
摘要: The present research investigated the effect of humic acid on nitrogen removal performance and microbial community structure in a single-stage nitrogen removal using anammox and partial nitrification (SNAP) reactor. The results showed that 576mg·L-1 humic acid enhanced nitrogen removal efficiency maximally to 96% and nitrogen removal rate to 1.61 kgN·m-3·d-1. COD concentration (provided by humic acid) of 120-233mg·L-1, the nitrogen removal rate (NRR) was 1.27 kgN·m-3·d-1. COD concentration (provided by humic acid) of 259-658mg·L-1 enhanced the NRR above 1.5 kgN·m-3·d-1, and COD concentration increased to 691-1637mg·L-1, the average NRR decreased to 1.45 kgN·m-3·d-1. The results indicated COD concentration of 691-1637mg·L-1 has the strongest positive effect on the anammox reaction. The analysis of high throughput sequencing presented COD concentration of 500mg·L-1 promoted the growth of Candidatus_brocadia, and 1500mg·L-1 COD concentration improved Candidatus kuenenia growth. Functional genes from KEGG and COG database showed that the expressions of nitrate reductase and nitrite reductase (NADH) were highly promoted with the increase of humic acid concentration, which proved the nitrification enhanced by humic acid. All findings in this study were inferred that humic acid enhanced nitrogen removal in SNAP reactor. This result will improve the practical and effective use of the SNAP process to treat landfill leachate in engineering application.

17456. 题目: Tracking of Realistic Nanoplastics in Complicated Matrices by Iridium Element Labeling and Inductively Coupled Plasma Mass Spectroscopy
文章编号: N21103015
期刊: Journal of Hazardous Materials
作者: Qi Gao, Yunqing Wang, Yunxia Ji, Xizhen Zhao, Panpan Zhang, Lingxin Chen
更新时间: 2021-10-30
摘要: Herein, we proposed a protocol to track realistic nanoplastics (NPs) by labeling them with an iridium-containing organic molecular agent (denoted as Ir) followed by inductively coupled plasma mass spectroscopy detection, as exemplified by polyethylene terephthalate (PET) NPs prepared from water bottles. The Ir showed satisfactory labeling stability in typical environmental and biological matrices. After 3d’s incubation, the leaching ratios were less than 3% in water, phosphate buffered saline, sea water, cell culture medium, artificial gastric juice, artificial intestinal fluid, sediment resuspension, and around 5% in fetal bovine serum. On this basis, in vivo distribution of PET NPs in mice was analyzed. The intravenously injected NPs widely distributed in liver, spleen, lung and kidney. Comparatively, NPs could hardly be detected in these organs after intragastric administration, suggesting that they could not penetrate the intestinal barriers. The temporal and spatial distribution of the NPs in an intertidal zone sediment resuspension model was also investigated. The NPs mostly deposited at the overlying deposit, implying the absorption-driven sinking behavior of NPs with natural organic matters. This work provided an effective way to quantitatively track realistic NPs, which could promote the understanding of the fate and effect of NPs in natural environments and organisms.

17457. 题目: Influence of environmental factors on tree species diversity and composition in the Indian western Himalaya
文章编号: N21103014
期刊: Forest Ecology and Management
作者: Shinny Thakur, Vikram S. Negi, Rupesh Dhyani, I.D. Bhatt, A.K. Yadava
更新时间: 2021-10-30
摘要: Understanding patterns in forest communities and its driving factors play a critical role in ecological studies. In view of this, present study attempts to understand the role of environmental and anthropogenic factors towards shaping species diversity and composition along the altitudinal gradient (700–3800 m asl) in Indian western Himalaya. A total of 51 tree species (28 families) were recorded; Pinaceae (5) and Fagaceae (5) were the species rich families. α-diversity indices i.e., Margalef's richness index (R), Shannon index (Hʹ) and Simpson index showed a humped shaped distribution, whereas Evenness index (E) showed an inverted humped shaped distribution along the altitude range. Based on non-metric dimensional scaling (NMDS), four different community types were identified. Redundancy analysis (RDA) revealed a strong relationship of tree species composition with environmental (41.73% variation) and anthropogenic factors (17.35% variation). RDA further indicated that the bulk density (BD), disturbance index (DI), mean diurnal temperature range (Bio2) and solar radiation (SR) are significantly associated with sub-tropical (below 1200 m) and lower temperate forest (1200–1700 m) types. Likewise, soil organic carbon (SOC), precipitation of the driest quarter (Bio17) and pH were significantly associated with upper temperate (1700–2900 m), and subalpine forest composition (>2900 m). Both NMDS classification and RDA ordination clearly demonstrate spatial variability in composition of tree community and environmental properties.

17458. 题目: Ultrafiltration concentrated biogas slurry can reduce the organic pollution of groundwater in fertigation
文章编号: N21103013
期刊: Science of The Total Environment
作者: Weishen Zeng, Jinrong Qiu, Dehan Wang, Zhaoyun Wu, Lintong He
更新时间: 2021-10-30
摘要: Biogas slurry has the problems of having a low concentration, having a large production volume, and containing many small-molecule organic pollutants. During the fertigation process of biogas slurry, many small-molecule organic pollutants may pose potential pollution risks to groundwater. In this study, the ultrafiltration membrane technology was used to separate small-molecule organics in the biogas slurry to prepare ultrafiltration concentrated biogas slurry (UCBS). To research the impact of UCBS and raw biogas slurry (RBS) on the small-molecule organic pollution of groundwater, a laboratory soil column simulation leaching device was used to conduct leaching experiments with 4 types of UCBS and RBS in acric ferralsols and hydragric anthrosols for two quarters (8 fertilization periods). The results of the study show that both UCBS and RBS caused nitrate pollution to groundwater. UCBS has a lower risk of organic pollution to groundwater than RBS. Irrigating UCBS in hydragric anthrosols has a higher risk of organic pollution of groundwater than that in acric ferralsols. Analysis of the molecular weight distribution of dissolved organic matter (DOM) in the leaching solution showed that the organic pollutants were mainly small molecules <10 kDa. According to 3D excitation-emission matrix (3D-EEM) analysis, the main organic pollutants in the leaching solution were fulvic acid, microbial protein metabolites and humic acid organic compounds. The research results show that the pretreatment of biogas slurry by ultrafiltration can reduce the risk of small-molecule organic pollution of groundwater in land application, which can provide a new scientific basis to standardize biogas slurry land application technical guidelines and reduce groundwater pollution.

17459. 题目: Variability and composition of amino acids and amino sugars in sediment cores of the Changjiang Estuary
文章编号: N21103012
期刊: Organic Geochemistry
作者: Jin-E Wei, Yan Chen, Ning Zhang, Jun-Qi Yang, Rong Chen, Hong-Hai Zhang, Gui-Peng Yang
更新时间: 2021-10-30
摘要: Understanding the sources, compositions and degradation states of sedimentary organic matter (SOM) in estuarine regions can provide significant information about regional carbon and nitrogen cycles. Amino acids (AAs), amino sugars (ASs), total organic carbon (TOC), total nitrogen (TN) and stable carbon isotopic composition (δ13OC) were investigated in six sediment cores of the Changjiang Estuary. The concentrations of ASs ranged from 0.60 to 3.11 μmol g-1, and accounted for 1.7 ± 0.7% of TOC and 2.1 ± 0.9% of TN. The concentrations of AAs ranged from 5.18 to 11.66 μmol g-1 and accounted for 8.1 ± 1.7% of TOC and 17.4 ± 3.9% of TN. Relatively coarse and fresh SOM was mainly deposited in the nearshore (e.g., station B6), whereas fine and degraded SOM occurred in the offshore area (e.g., station A7-4). The relationships between median grain size and AA-C% and degradation index (DI) revealed that fine-grained particles adsorbed older SOM, but sandy sediments were correlated with relatively fresh SOM. Diatoms were the main contributor of marine SOM and high primary production increased the burial of fresh SOM. TOC and TN contents and their degradation states did not exhibit distinct trends with core depth, possibly due to frequent vertical disturbance. Additionally, bacterial OM contributed 0.4–23.7% to TOC and 0.6–30.6% to TN in the sediment cores. The hypoxia of the water might have further promoted the proportion of bacterial OM in the sediments.

17460. 题目: The Relationship between Molecular Size and Polarity of Atmospheric Organic Aerosol in Singapore and Its Implications for Volatility and Light Absorption Properties
文章编号: N21103011
期刊: ACS Earth and Space Chemistry
作者: Liudongqing Yang, Sri Hapsari Budisulistiorini, Guorong Chen, Xianfeng Wang, Mikinori Kuwata
更新时间: 2021-10-30
摘要: Organic aerosol, which is a complex mixture, has been categorized by both chemical (e.g., degree of oxygenation and molecular weight (MW)) and physical (e.g., water solubility and optical) characteristics. However, the inter-relationships among these characteristics have not been well-established yet. This study developed a novel framework on the inter-relationship among volatility, water solubility, and MW. The framework suggests that water-soluble organic matter (WSOM) can have relatively small MW (<200) because highly polar species tend to have lower volatility. On the other hand, water-insoluble organic matter (WISOM) needs to have larger MW than the threshold, as less polar species tend to be highly volatile. The idea was tested by analyzing aerosol samples collected at Singapore. Both WSOM and WISOM were extracted from the samples. The WSOM fraction was further classified by polarity using the 1-octanol–water method. The samples were analyzed by atmospheric pressure chemical ionization mass spectrometry (APCI-MS). APCI-MS is a soft-ionization technique that dominantly provides [M–H]− ions. The APCI-MS data validated the newly developed idea on the MW distributions for WSOM and WISOM. The positive matrix factorization (PMF) analysis was applied to the APCI-MS data. The analysis for WSOM also supported the inverse relationship between polarity and MW. The PMF outputs were combined with the ultraviolet–visible absorption data for obtaining absorption Ångstrom exponents (AAE) for each factor. The result suggests that highly polar WSOM factors have relatively small values of average MW (≤205) and higher values of AAE (>8.5), connecting polarity and optical properties of OM.