41. 题目: High C input by perennial energy crops boosts belowground functioning and increases soil organic P content
期刊: Agriculture, Ecosystems & Environment
作者: A. Ferrarini, E. Martani, F. Fornasier, S. Amaducci
摘要: C input to soil together with plant-microbial-soil organic matter (SOM) transformations are key ecological drivers for soil functioning in perennial cropping systems. In this study, we assessed the effect of three woody (poplar, black locust, willow) and three herbaceous (giant reed, miscanthus, switchgrass) perennial energy crops (PECs) on SOM pools, soil microbial biomass and metabolism and soil P forms distribution. After 9 y from plantation on a low-grade arable land, PECs significantly increased SOM content as much as 3.9 g kg−1 (+23 %) in the topsoil (0−30 cm). At the same time active C increased by 194 mg kg−1 (+ 43 %) and microbial biomass by 10.7 mg g−1 (+ 80 %). Microbial catabolic activity as measured respectively with twenty enzymes activities (EA) involved in C-, N-, P-, and S- cycling increased by 90 % and C substrate utilization profile (CSU - Microresp™) showed an increase of respiration rate by 13 % on average of all 16 substrates utilized. PERMANOVA and dbRDA analysis indicated that activity of microbial community associated with PECs differed significantly from that of arable land, with herbaceous PECs significantly increasing EA involved in C and N cycling while woody PECs increasing those involved in P-cycling. Interestingly, organic P forms content (monoester- and diester-P) along with its contribution to total NaOH-EDTA extractable soil P increased in all PECs, but more in woody than herbaceous ones. Functional diversity and evenness of microbial community resulted higher under herbaceous than woody PECs. Depth decay relationships of Bray Curtis similarity for EA patterns, more than CSU profile, was significantly smaller in woody and arable land than in herbaceous PECs, indicating a significant control of plant C inputs to soil from deep-rooting systems on proximate agents of belowground functioning. Our investigation highlighted the higher capability PECs, compared to annual cropping systems, in coupling nutrients cycling with C cycling, with the high C input being most probably the driving factor. Therefore, PECs might be ultimately considered not just as energy crops but also as a valuable strategy for revitalizing depleted soils by conventional agricultural practices.
42. 题目: Soil erosion significantly reduces organic carbon and nitrogen mineralization in a simulated experiment
期刊: Agriculture, Ecosystems & Environment
作者: Liping Qiu, Hansong Zhu, Jiao Liu, Yufei Yao, Xiang Wang, Guohua Rong, Xiaoning Zhao, Mingan Shao, Xiaorong Wei
摘要: Soil erosion has important influence on soil processes and particularly soil nutrient dynamics, which in turn affects the terrestrial C and N cycling and greenhouse gases emission. However, the responses of carbon (C) and nitrogen (N) cycling in soils and soil fractions to erosion remain largely unclear, hindering the precise prediction of the fate of C and N in the terrestrial ecosystem. Herein, we compared the mineralization of organic carbon (OC) and N at two different temperatures (15 and 25 °C) in bulk soils and aggregate fractions of 19 soils before and after a simulated rainstorm. The temperature sensitivity (Q10) of OC and N mineralization was calculated. Soil samples were collected from 9 sites across China, with soil types of Alfisols, Inceptisols, Mollisols, Ultisols, and land uses of croplands, grasslands, and woodlands. The soil aggregate fractions were >2, 2-1, 1-0.25 and <0.25 mm, respectively. We hypothesized that erosion will decrease OC and N mineralization due to the loss of labile organic matter from soils and that the effects of erosion would decrease with clay content and vary with different aggregate fractions. In support of these hypotheses, the cumulative mineralized OC and N (Cm and Nm) in the soils and aggregate fractions were decreased of 78-85% and 37-52% after erosion, and the temperature sensitivities of OC and N mineralization were decreased of 80-84% and 4-43%, respectively. The effects of erosion varied with site where the soil was collected. The decreases in Cm and Nm mainly occurred in small aggregate sizes (1-0.25 and <0.25 mm fractions). The Cm and Nm in bulk soils and aggregates increased significantly with the contents of OC, N, labile OC and mineral N but were texture independent. These results highlighted significantly reduction of OC and N mineralization at eroding sites, which should be carefully considered when assessing emissions of greenhouse gases in eroding environments.
43. 题目: Sources, quality and transfers of organic matter in a highly-stratified sub-Arctic coastal system (Saint-Pierre-et-Miquelon, NW Atlantic)
期刊: Progress in Oceanography
作者: Guillaume Bridier, Tarik Meziane, Jacques Grall, Laurent Chauvaud, Sébastien Donnet, Pascal Lazure, Frédéric Olivier
摘要: In response to ongoing global climate change, marine ecosystems in the northwest Atlantic are experiencing one of the most drastic increases in sea surface temperatures in the world. This warming can increase water column stratification and decrease surface nutrient concentrations, in turn impacting primary productivity and phytoplankton assemblages. However, the exact impacts of these changes on sources and quality of organic matter as well as its transfers to the benthic compartment remain uncertain. This survey characterized organic matter sources and quality within a highly-stratified sub-Arctic coastal system (Saint-Pierre and Miquelon) and described its transfer towards a biomass-dominant primary consumer, the sand dollar Echinarachnius parma. This study analyzed fatty acid and stable isotope (δ13C and δ15N) composition of surface and bottom Particulate Organic Matter (s-POM and b-POM, respectively), Sedimentary Organic Matter (SOM) and sand dollar tissue along a near shore to offshore gradient during two contrasting seasons associated either with sharp or weak water column stratification (i.e. High vs Low Stratification Periods). Results revealed high relative abundances of polyunsaturated fatty acids (notably macro- and microalgae markers) in POM during the Low Stratification Period while the High Stratification Period was characterized by elevated relative abundance of saturated fatty acids indicating a higher organic matter degradation state. In addition, strong seasonal differences were also observed in food availability with four-fold higher concentrations in total suspended solids during Low vs High Stratification Periods. These results suggested thus multiple negative effects of stratification on pelagic-benthic coupling and POM quality. Lower nutrient repletion of surface waters during period of sharp stratification diminishes pelagic-benthic coupling by reducing food availability, POM quality and vertical transfer of organic matter. By contrast, the sediment-based diet of E. parma showed a low spatiotemporal variability reflecting the homogenous composition of the SOM. This study suggests that intensified water column stratification due to increasing sea surface temperatures may modify the pelagic-benthic coupling and future quality and composition of POM pools.
44. 题目: Phosphorus transitions in traditional eco-knowledge versus chemical based agri-amendment systems of stress-prone semi-arid tropics: Finding the real game-changer
期刊: Ecological Indicators
作者: Seema B. Sharma, Abhiroop Chowdhury
摘要: Fixation of Phosphorus into locked forms hampers the availability of this important soil element. Phosphate Solubilising Microorganisms (PSM) play an important role of solubilisation and mineralization of these fixed forms into bio-available forms through reactions that are complex but provide simple solutions to P deficiency in soils. Semi-arid soil may have high total phosphorus concentrations but as most of the P is in an unavailable form, it leads to deficiency of this essential macronutrient in the crop. The use of microbial inoculants (biofertilisers) that possess the Phosphate solubilizing activities in agricultural soils is considered as an eco-friendly alternative to chemical based P fertilizers. The present study is a first of its kind attempt to understand the impact of Traditional Ecological Knowledge (TEK) (A1) vis-à-vis conventional chemical intensive integrated (A2) based agriculture amendment systems in altering/modifying the Phosphorus dynamics of the soil in the semiarid tropical region of Kachchh, Western India. The study was carried out for the pre, mid and post-harvest phases of crops for six seasons spread across 4 years. Higher Phosphorus Activation Coefficient (PAC), which is the ratio of available P (AP) to total P (TP) was observed in A1, that coincided with higher soil organic carbon (SOC) as well, across all seasons. The present study tried to answer questions as to how indigenous knowledge-based systems suited to local supply/demand complex system are precursors/indicators of a better microcosm in agriculture ecology studies that owing to its organic matter content improves SOC and PAC and in turn the overall P availability.
45. 题目: Emissions and Potential Controls of Light Alkenes from the Marginal Seas of China
期刊: Science of The Total Environment
作者: Jian-Long Li, Xing Zhai, Ying-Cui Wu, Jian Wang, Hong-Hai Zhang, Gui-Peng Yang
摘要: Marine-derived reactive gases constitute a substantial fraction of volatile organic compounds and directly impact atmospheric chemistry and the global climate. Light alkene emissions from marginal seas are limited, and their contribution to atmospheric concentrations is likely underestimated. We surveyed oceanic emissions of ethylene, propylene, and isoprene, as well as their potential controlling factors in the marginal seas of China during the cruises in 2014–2015. Significant temporal-spatial variations in ethylene, propylene, and isoprene concentrations were observed, with the highest occurring in summer near the coastal regions. Isoprene concentrations were primarily controlled by phytoplankton biomass (i.e., Chl-a) in coastal regions, while the elevated concentrations of ethylene and propylene were attributed to photochemical reactions with the high levels of dissolved organic matter (DOM). Additionally, the vertical distributions of ethylene and propylene mirrored light penetration, with exponential decrease in concentrations with depth. However, there were high values of ethylene and propylene observed at deep chlorophyll maximum, suggesting the existence of non-photochemical production pathways, most likely biological origin. Emissions of ethylene, propylene, and isoprene from the marginal seas of China were estimated to be 0.022, 0.024, and 0.011 Tg C yr-1, respectively, indicating they are important contributors to global non-methane hydrocarbons. Due to the scarcity of alkene emission data for marginal seas, current global emissions have been underestimated to some extent. It is essential to incorporate the contributions from marginal seas to accurately estimate alkene budgets on global scales.
46. 题目: Metal Chloride-Loaded Biochar for Phosphorus Recovery: Noteworthy roles of Inherent Minerals in Precursor
作者: Fan Yang, Yuchen Chen, Hongyan Nan, Lei Pei, Yuandong Huang, Xinde Cao, Xiaoyun Xu, Ling Zhao
摘要: Phosphorus (P) is a valuable resource, while it is vastly lost with wastewater causing eutrophication. In this study, to recover P, composite biochars were prepared by pyrolyzing biowaste impregnated with FeCl3 or MgCl2. It was found that inherent mineral profiles in the biowastes played important roles in interacting with metal chlorides and determined P sorption and precipitation. Specifically, two biowastes containing distinct mineral contents, sawdust and sediment, were selected as model components, being alone or mixed at 1:1 (w/w) to prepare biochars with low, moderate and high mineral contents. Results showed that biochar itself could not absorb P, while loading FeCl3 or MgCl2 achieved P recovery rates of approximate 60-100% and 50-100%, respectively, via electrostatic attraction or ligand exchange of PO43- with -OH/-COOH, which was attributed to the enhanced positive charges and -OH/-COOH on the materials by these metal chlorides. Inherent minerals inhibited FeCl3 transforming into Fe3O4 in pyrolysis and promoted generation of Fe4(PO4)3(OH)3 in P sorption, thus high-mineral content was more appropriate for FeCl3 loading; however, precursors with low-mineral content was suitable for MgCl2 loading, since the bulk-C in biochar acted as porous structure to support MgO crystals with high superficial area (∼255.85 m2 g-1). Besides, FeCl3 and MgCl2 both drove dissolution of inherent minerals significantly, while inherent minerals inhibited release of soluble Fe and Mg2+ into solution, which minimized secondary pollution. This study implied that in constructing composite biochar for catching P, the type of metal chloride should match the inherent minerals in biowastes to maximize P recovery and minimize secondary pollution.
47. 题目: Effect of soil amendments on molybdenum availability in mine affected agricultural soils
期刊: Environmental Pollution
作者: Xiaoqing Wang, Gianluca Brunetti, Wenjie Tian, Gary Owens, Yang Qu, Chaoxi Jin, Enzo Lombi
摘要: Molybdenum (Mo) contamination of agricultural soils around Mo-mining areas is of emerging environmental concern. This study evaluated potential practical techniques for chemical immobilization of three Mo contaminated agricultural soils via application of up to six amendments from four different types of materials including biosolids, biochar supported nanoscale zero-valent iron (BC-nZVI), drinking water treatment residues (WTR) and ferrous minerals (magnetite and ferrihydrite). The efficacy of the different amendments on soil Mo bioaccessibility and bioavailability was evaluated by monitoring Mo uptake in both monocotyledon (ryegrass) and dicotyledon (alfalfa) plants, soil extractable Mo, and Mo bioavailability as measured by Diffusive Gradient in Thin Films (DGT®). All amendments exhibited no immobilization effect and increased Mo extractability in the severely contaminated soil (264 mg Mo kg-1). In contrast, in lightly and moderately contaminated soils (22 and 98 mg Mo kg-1), biosolids, WTR and magnetite all reduced soil extractable Mo and decreased Mo uptake in both alfalfa and ryegrass shoots relative to controls (CK). Moreover, DGT showed that during incubation experiments while biosolids amendments increased Mo bioavailability from 115 to 378% compared to the CK treatments, all other amendments decreased Mo bioavailability insignificantly.
48. 题目: Long-term stability of a non-adapted aerobic granular sludge process treating fish canning wastewater associated to EPS producers in the core microbiome
期刊: Science of The Total Environment
作者: Ana M.S. Paulo, Catarina L. Amorim, Joana Costa, Daniela P. Mesquita, Eugénio C. Ferreira, Paula M.L. Castro
摘要: The tolerance of aerobic granular sludge (AGS) to variable wastewater composition is perceived as one of its greatest advantages compared to other aerobic processes. However, research studies select optimal operational conditions for evaluating AGS performance, such as the use of pre-adapted biomass and the control of wastewater composition. In this study, non-adapted granular sludge was used to treat fish canning wastewater presenting highly variable organic, nutrient and salt levels over a period of ca. 8 months. Despite salt levels up to 14 g NaCl L−1, the organic loading rate (OLR) was found to be the main factor driving AGS performance. Throughout the first months of operation the OLR was generally lower than 1.2 kg COD m−3 day−1, resulting in stable nitrification and low COD and phosphorous levels at the outlet. An increase in OLR up to 2.3 kg COD m−3 day−1 disturbed nitrification and COD and phosphate removal, but a decrease to average values between 1 and 1.6 kg COD m−3 day−1 led to resuming of these processes. Most of the bacteria present in the AGS core microbiome were associated to extracellular polymeric substances (EPS) production, such as Thauera and Paracoccus, which increased during the higher OLR period. Ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) species were detected in AGS biomass; while AOB were identified throughout the operation, NOB were no further identified after the period of increased OLR. Different polyphosphate-accumulating organisms (PAOs) were detected along the process: Candidatus Accumulibacter, Tetrasphaera and Gemmatimonas. A non-adapted granular sludge was able to treat the fish canning wastewater and to tolerate salinity fluctuations up to 14 g L−1. Overall, a high microbial diversity associated to EPS producers allowed to preserve bacterial groups responsible for nutrients removal, contributing to the adaptation and long-term stability of the AGS system.
49. 题目: How can biochar-based metal oxide nanocomposites counter salt toxicity in plants?
期刊: Environmental Geochemistry and Health
作者: Kazem Ghassemi-Golezani, Salar Farhangi-Abriz, Soheila Abdoli
摘要: Application of biochar-based metal oxide nanocomposites can acquire new composites and combine the benefits of biochar with nanomaterials. For the first time, this research was conducted to evaluate the possible effects of solid biochar (25 g biochar kg−1 soil) and biochar-based nanocomposites (BNCs) of magnesium oxide (25 g BNC-MgO kg−1 soil), manganese oxide (25 g BNC-MnO biochar kg−1 soil) and combined use of these nanocomposites (12.5 g BNC-MgO + 12.5 g BNC-MnO kg−1 soil) on salt (non-saline, 6 and 12 dSm−1 NaCl salinities) tolerance of safflower plants (Carthamus tinctorius L.). Salinity reduced potassium, magnesium and manganese contents in root and leaf tissues, chlorophyll content index, photosynthetic pigments, maximum quantum yield of photosystem II (Fv/Fm) and relative photosynthetic electron transport rate (RETR), leaf water content and plant biomass, but increased the sodium content, reactive oxygen species generation (ROS), oxidative stress and antioxidants and ROS detoxification potential of safflower roots and leaves. Application of biochar and BNCs increased the contents of potassium, manganese and magnesium in plant tissues, photosynthetic pigments, Fv/Fm and RETR, leaf water content and reduced sodium accumulation, ROS generation and oxidative stress under saline conditions, leading to a higher plant biomass in comparison with control. The BNC-MgO + BNC-MnO was the superior treatment on reducing salt toxicity. This treatment reduced oxidative stress by enhancing photosynthetic pigments, Fv/Fm and RETR of safflower under salt stress. These results revealed that BNCs have a great potential for improving salt tolerance of plants through increasing RETR and decreasing sodium accumulation and ROS generation.
50. 题目: Seedbed consolidation and surface sealing for soils of different texture and soil organic carbon contents
期刊: Soil and Tillage Research
作者: Nargish Parvin, Maria Sandin, Mats Larsbo
摘要: The soil structure near the surface of agricultural soils changes with season mainly by land management together with climatic and biological factors. Quantitative analysis of post-tillage changes in soil structure and related hydraulic properties are necessary for evaluating and improving models of soil hydrological and transport processes. The objectives of this study were to quantify changes in soil seedbed structure induced by rainfall and drainage and to estimate the eff ;ects of soil texture and SOC on these changes. We collected samples from the harrowed layer of twenty-six fine to coarse textured Swedish mineral soils. Air-dried soil was placed in cylinders (5 cm high, diameter 5 cm) and exposed to simulated rainfall (5 mm h−1 for 4 h) and drainage (−50 cm pressure potential) cycles in the laboratory. We used X-ray tomography to quantify changes in pore networks in a thin surface layer and in the whole cylinder. Infiltration rates at -5 cm pressure potential were measured using a mini disc tension infiltrometer on replicate air-dried samples and on the samples included in the consolidation experiments at the final state. Total imaged specific pore volumes generally decreased from initial to final state and pore size distributions were shifted towards larger proportions of below image resolution pores (< 80 μm). There was a strong positive correlation between clay content and changes (i.e. final state-initial state) in the specific volume of pores <80 μm. Soils with high clay content and soil organic carbon (SOC) content often have strong aggregates that resist changes. Nevertheless, both clay and SOC contents were negatively correlated with the changes in specific imaged pore volume. These results highlight the importance of swelling, which is largely controlled by clay content, for seedbed consolidation. In line with previous studies, when excluding coarse textured soil, the changes in surface porosity were negatively correlated with silt content. Changes in infiltration capacity were not significantly correlated with any basic soil properties. Our results suggest that shrinking-swelling should be a central part in any model for seedbed consolidation.
51. 题目: Sulfite enhanced transformation of iopamidol by UV photolysis in the presence of oxygen: Role of oxysulfur radicals
期刊: Water Research
作者: Ying Cao, Wei Qiu, Juan Li, Yumeng Zhao, Jin Jiang, Suyan Pang
摘要: UV/sulfite process in the absence of oxygen was previously applied as an advanced reduction process for the removal of many halogenated organics and inorganics in water and wastewater. Here, it was found that UV/sulfite process in the presence of oxygen could act as an advanced oxidation process. Specifically, the oxysulfur radicals (including sulfate radical (SO4·−) and sulfite/peroxomonosulfate radicals (SO3·−/SO5·−)) played important roles on the degradation of iopamidol (IPM) as a typical iodinated contrast media (ICM). Furthermore, the contribution of SO4·− on IPM removal gradually increased as pH increased from 5 to 7 and that of SO3·−/SO5·− decreased. Besides, all water quality parameters (i.e., chloride (Cl−), iodide (I−) and natural organic matter (NOM)) investigated here exhibited inhibitory effect on IPM removal. Three inorganic iodine species (i.e., I−, reactive iodine species and iodate (IO3−)) were detected in UV/sulfite process in the presence of oxygen, while only I− was detected in that without oxygen. During UV/sulfite/ethanol, UV photolysis and UV/peroxydisulfate (PDS)/tert-butyl alcohol (TBA) processes, thirteen transformation products including eleven deiodinated products of IPM were identified by ultra HPLC quadrupole time of flight-mass spectrometry (UPLC-Q-TOF-MS). Besides, these products generated by direct UV photolysis, SO4·− and SO3·−/SO5·− were further distinguished. The acute toxicity assay of Vibrio fischeri indicated that transformation products by UV/sulfite under aerobic conditions were less toxic than that by direct UV photolysis.
52. 题目: Refractory Humic-like Substances: Tracking Environmental Impacts of Anthropogenic Groundwater Recharge
期刊: Environmental Science & Technology
作者: Yaxin Zheng, Wei He, Binghua Li, Jin Hur, Huaming Guo, Xiaomeng Li
摘要: To unravel the crucial components of natural organic matter that respond to the process of anthropogenic groundwater recharge (AGR) from different recharge water sources, dissolved organic matter (DOM) and base-extractable particulate organic matter (POM) in groundwater and surface water were analyzed using excitation–emission matrix spectroscopy coupled with parallel factor analysis (EEM–PARAFAC). The EEM and traditional spectral indices of samples show that the fluorescent intensity, molecular weight, and humification degree of the DOM were relatively higher than those of the POM, and the groundwater in the reclaimed water recharge area (RWRA) was more contaminated than in the south-to-north water recharge area (SNWRA). PARAFAC analysis indicates that the DOM was dominated by an allochthonous humic-like substance (C1), whereas the POM was dominated by tryptophan-like substances associated with microbial activity (C2). Partitioning of PARAFAC components between DOM and POM showed that the humic-like substances (C1 and C4) were more likely to be distributed into a dissolved phase compared to the protein-like substances (C2 and C3), which suggested the potential use of C1 and C4 as a tracking indicator. In particular, the clear gradient distributions along both the hydrogeological profile and different aquifer systems in terms of the concentration and composition of C1 also discriminated between the RWRA and SNWRA with regard to the effects of various AGRs on the groundwater. The association between C1 and water-quality indicators revealed by principal component analysis further indicated that refractory humic-like substances would track the environmental impacts of intentional AGR processes.
53. 题目: A model of algal organic carbon distributions in the Pearl River estuary using the amino acid carbon isotope values
期刊: Geochimica et Cosmochimica Acta
作者: Peihong Kang, Han Zhang, Zixiang Yang, Yifan Zhu, Biyan He, Qing Li, Cindy Lee, Tiantian Tang
摘要: To better understand the sources and behavior of estuarine labile organic matter, we measured stable carbon isotope patterns of individual amino acids in suspended particles and surface sediments from the Pearl River Estuary in China; samples were taken along a salinity transect in December, 2016. Here we demonstrate that carbon isotope values (δ13C) of individual amino acids in these samples gradually increase with salinity downstream, reflecting the increase in δ13C values of algal-derived organic carbon along the salinity gradient. The isotopic difference between amino acids and bulk organic carbon varies, most likely due to changes in the relative contributions of algal-derived organic matter and refractory terrestrial input. In addition, algal-derived organic matter can consist of labile and semi-labile organic matter in varied proportions depending on decomposition state. This isotopic difference between amino acids and bulk organic carbon is much larger in surface sediments than in suspended particles, suggesting that labile organic carbon contributed more to suspended particles than to sediments. Using the relative abundances and δ13C ratios of amino acids and total organic carbon, a Lability Model was constructed to evaluate the relative contributions of three forms of estuarine organic carbon: labile algal material as amino acids, semi-labile algal material as lipids and acid-insoluble material, and refractory terrestrial organic material. The model suggests highly dynamic contributions of semi-labile algal-derived organic carbon and terrestrial organic carbon to estuarine particulate organic carbon. This evaluation of organic carbon sources illustrates the importance of decomposition in shaping the molecular composition and isotopic signature of particulate organic carbon in the estuary.
54. 题目: Groundwater dating with dissolved organic radiocarbon: a promising approach in carbonate aquifers
期刊: Applied Geochemistry
作者: Florian Heine, Florian Einsiedl
摘要: A complete hydrogeological understanding of the deep Upper Jurassic carbonate aquifer in the South German Molasse Basin is essential for the future development of this important drinking water resource and geothermally used system. Water chemistry data, δ13CDIC, 14C of the dissolved inorganic carbon (14CDIC) and stable water isotope (δ18O and δD) measurements have been used to evaluate a promising groundwater dating approach with 14C of dissolved organic carbon (14CDOC). The pre-concentration of dissolved organic matter (DOM) was performed by the easy applicable solid phase extraction (SPE) with a styrene-divinylbenzene copolymer sorbent (PPL). Based on the sampling campaign of seven groundwater wells conducted between 2017 and 2019, it was shown that the groundwater is mainly of Ca-HCO3 type with some evidence of ion exchange between Ca2+ and Na+ at two of the investigated wells. The δD values ranged from -89.4 ‰ to -70.9 ‰ while δ18O values varied between -12.5 ‰ and -9.8 ‰. The obtained stable water isotope signatures indicated that the groundwater is of meteoric origin and was recharged during warm climate (Holocene), intermediate climate and cold climate (Pleistocene) infiltration conditions. The measured 14CDOC activities varied from 5.7 pmC to 51.1 pmC and the calculated piston-flow water ages (ORAs) ranged from 4,200 years to 25,248 years using an initial 14C0DOC of 85 pmC. The calculated ORAs showed a very good correlation to the infiltration temperature-sensitive δ18O values which were affirmed with noble gas infiltration temperatures for two wells after Weise et al. (1991) and were also in good accordance with the atmospheric temperature record of the northern hemisphere from Dokken et al. (2015). The results reflect a consistent hydrogeological picture of the carbonate aquifer, which also supports the applicability of the SPE-PPL method for 14CDOC dating in groundwater with a low DOC content (<1 mg/l). In contrast, 14CDIC activities of 1.4 pmC to 21.3 pmC led to geochemically corrected piston-flow ages between 8,057 years and >30,000 years and generally to an overestimation of the apparent water ages. This study gives insights into the promising approach of 14CDOC groundwater dating in carbonate aquifers with low DOC contents and allows future sustainable groundwater resource management of the investigated aquifer system.
55. 题目: Responses of soil organic carbon components and their sensitivity to karst rocky desertification control measures in Southwest China
期刊: Journal of Soils and Sediments
作者: Jiacheng Lan
摘要: Purpose Adequate karst rocky desertification control measures are very important in enhancing the soil quality and soil organic carbon (SOC) sequestration in the karst regions of Southwest China. This study aims to assess the responses and sensitivity of SOC and its components to karst rocky desertification control measures in degraded karst ecosystems. Materials and methods Two karst rocky desertification control measures, namely, conversion of cropland to secondary forest (SF) and the Chinese prickly ash planting (CPP), were chosen with cropland (CL) as reference soil. Soils in 0–10- and 10–20-cm layers were sampled. Then, SOC, easily oxidizable organic carbon (EOC), non-liable organic carbon (NLOC), particulate organic carbon (POC), mineral-associated SOM (MOC), and the carbon pool management index (CPMI) were determined. Results and discussion Karst rocky desertification control measures caused SOC to increase significantly through the increase in active (EOC, POC), non-liable (NLOC), and stable carbons (MOC). Significant relationships between the changes in SOC and the changes in its components were observed in the depths of 0–20cm. The responses of POC were more sensitive than SOC and other soil C components under CPP and SF. The EOC and POC ratios to SOC were highest in SF soils, followed by CPP as compared with soils under CL. The values of the CPMI and C/N ratios in CPP were lower than those in SF. The sensitivity index (SI) value of POC was highest, followed by EOC, SOC, NLOC, and MOC. Redundancy analysis (RDA) showed the C/N, CPMI, and POC/SOC ratios had significant effects on changes in soil C components. Conclusions The results indicated that karst rocky desertification control measures not only enhanced SOC quality but may also be beneficial for soil C sequestration. Conversion of cropland to natural SF could be a more suitable control measure for enhancing SOC quality and storage in the karst regions of southwestern China. POC was the most sensitive SOC fraction to karst rocky desertification control measures and can best reflect the dynamics of SOC. C/N ratio and CPMI may be considered as useful soil quality indicators for the overall C change in different karst rocky desertification control measures in degraded karst systems.
56. 题目: Reevaluation of the contributions of reactive intermediates to the photochemical transformation of 17β-estradiol in sewage effluent
期刊: Water Research
作者: Lushi Lian, Chenyong Miao, Zhenyu Hao, Qian Liu, Yingjie Liu, Weihua Song, Shuwen Yan
摘要: Photodegradation of the natural steroid 17β-estradiol (E2), an endocrine-disrupting hormone that has been widely detected in aquatic environments, was investigated in wastewater effluents at various pH ranges under simulated solar irradiation. The rate of E2 degradation in the sewage effluents was stable at pH 6.0-7.0 but suddenly increased from pH 8.0-10.0. The second-order reaction rate constants of E2 with 3EfOM* and CO3•− were measured to increase 11.0-fold and 18.0-fold from pH 6.0 to 10.0, respectively. Two main reasons are proposed for this sharp increase. First, the change in the ionization state of E2 made it susceptible to oxidation by triplet-state effluent organic matter (3EfOM*) and carbonate radicals (CO3•−). Second, the steady-state concentration of CO3•− increased with increasing pH. Indirect photolysis was suggested to be the main degradation pathway in the sewage effluents, and 3EfOM* was proposed to play a major role at pH 8.0-9.0, while CO3•− played a significant role at pH 10.0. In this study, EfOM was shown for the first time to inhibit the oxidation of E2 initiated by 3EfOM* and CO3•−. Thus, we suggest that EfOM plays a dual role in the photodegradation of E2: EfOM can not only be activated as 3EfOM* to degrade E2 but also can inhibit the degradation of E2 by reducing the E2 oxidation intermediate back to E2. The estrogenic activity of the photodegradation products was also studied. The in vitro estrogenic activity of E2 solutions decreased approximately as fast as the E2 photodegradation occurred in the effluent water at various pH values, suggesting that solar photodegradation in sewage effluents reduces the risk of endocrine disruption in waters impacted by E2 and subject to continuing inputs. The results of this study are important for predicting the environmental fate of endocrine-disrupting chemicals and developing methods for their removal from aquatic environments.
57. 题目: Fire–vegetation relationships during the last glacial cycle in a low mountain range (Eifel, Germany)
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Arne Kappenberg, Wulf Amelung, Nadine Conze, Frank Sirocko, Eva Lehndorff
摘要: Lake sediments can provide useful archives to reconstruct past vegetation changes or fire history. To comprehend how vegetation and fire history have correlated during the last 130,000 years, we used two lake sediment records with known patterns of pollen and botanical macro remains and supplemented this data by analyses of lignin-derived phenols as markers for local vegetation inputs and by benzene polycarboxylic acids (BPCAs) as markers for total fire residue inputs (black carbon, BC). The two sediment archives originated from two maar lakes in the Eifel, which is part of the low mountain ranges in central Germany. A lignin-derived phenol index showed woody angiosperms and gymnosperms as fire fuel in the periods with the highest BC amounts. We recorded 3 g BC per kg sediment for phases covered by forest, while BC contents during colder and drier climates were much smaller (≤0.2 g BC per kg sediment), confirming the hypothesis that fires mostly occurred during humid periods in which forest were established. Both records pointed to forested phases with strong fire activity from 48,000–60,000 years before the year 2000 (b2k). Furthermore, the record reaching back to 130,000 years showed a strong fire activity at about 28,000–30,000 yr b2k, and was free of vegetation macro remains and fire markers from 60,000–118,000 yr b2k. All paleobotanical and chemical biomarker results documented the next oldest forested and fire interval, from 118,000 to 130,000 yr b2k, which includes the Eemian of the last interglacial. Thus, nearly all forested phases were accompanied by fire peaks. Overall, biomarker analyses confirmed that analyses of pollen and botanical macro remains. Fire events were highest during warm and humid forested phases.
58. 题目: Active phoD-harboring bacteria are enriched by long-term organic fertilization
期刊: Soil Biology and Biochemistry
作者: Wenbo Liu, Ning Ling, Gongwen Luo, Junjie Guo, Chen Zhu, Qicheng Xu, Manqiang Liu, Qirong Shen, Shiwei Guo
摘要: PhoD harboring microorganisms are crucial for the regulation of soil phosphorus (P) cycling through the secretion of alkaline phosphomonoesterases and are also known to be sensitive to fertilizer inputs. However, the impacts of long-term mineral and organic fertilizer inputs on active phoD-harboring functional communities in soils remain largely unknown. In the present study, 18O-DNA-stable isotope probing coupled with high-throughput sequencing was utilized in order to characterize active phoD-harboring functional bacterial communities in soils subjected to long-term no-fertilizer (Control), mineral-only fertilizer (NPK), organic-only fertilizer (M), and the combination of mineral and organic fertilizer (NPKM) amendments. Total and active phoD gene abundance decreased in soils amended with long-term mineral fertilizer, but increased in soils under organic fertilizer amendment, compared with the non-fertilized soils. A total of 51 active phoD-harboring bacterial OTUs, mainly belonging to Actinobacteria, were identified in this study. Organically amended soils harbored a higher diversity of active bacterial community. In the active phoD-harboring functional community, Rhodococcus comprised approximately 99% of the total relative abundance in the unfertilized soil, whereas Nocardiopsis and Bacillus accounted for approximately 62% and 24%, respectively, in mineral-only fertilized soils. Active phoD-harboring communities were dominated by members of the genera Streptomyces (26-60%), Nocardia (5-9%) and Gordonia (23-41%) in all organically fertilized soils, including M and NPKM. Overall, these long-term fertilization regimes altered the abundance, richness and composition of the active phoD-harboring functional microbial community. This study provides novel insights into the responses of the active functional bacterial community that is responsible for soil P mineralization to differing long-term fertilization regimes.
59. 题目: Deciphering Dissolved Organic Matter: Ionization, Dopant, and Fragmentation Insights via Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry
期刊: Environmental Science & Technology
作者: Martin R. Kurek, Brett A. Poulin, Amy M. McKenna, Robert G. M. Spencer
摘要: Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) has been increasingly employed to characterize dissolved organic matter (DOM) across a range of aquatic environments highlighting the role of DOM in global carbon cycling. DOM analysis commonly utilizes electrospray ionization (ESI), while some have implemented other techniques, including dopant-assisted atmospheric pressure photoionization (APPI). We compared various extracted DOM compositions analyzed by negative ESI and positive APPI doped with both toluene and tetrahydrofuran (THF), including a fragmentation study of THF-doped riverine DOM using infrared multiple photon dissociation (IRMPD). DOM compositions followed the same trends in ESI and dopant-assisted APPI with the latter presenting saturated, less oxygenated, and more N-containing compounds than ESI. Between the APPI dopants, THF-doping yielded spectra with more aliphatic-like and N-containing compounds than toluene-doping. We further demonstrate how fragmentation of THF-doped DOM in APPI resolved subtle differences between riverine DOM that was absent from ESI. In both ionization methods, we describe a linear relationship between atomic and formulaic N-compositions from a range of DOM extracts. This study highlights that THF-doped APPI is useful for uncovering low-intensity aliphatic and peptide-like components in autochthonous DOM, which could aid environmental assessments of DOM across biolability gradients.
60. 题目: Photochemical Oxidation of Water-Soluble Organic Carbon (WSOC) on Mineral Dust and Enhanced Organic Ammonium Formation
期刊: Environmental Science & Technology
作者: Tao Wang, Yangyang Liu, Yue Deng, Hanyun Cheng, Yang Yang, Yiqing Feng, Liwu Zhang, Hongbo Fu, Jianmin Chen
摘要: Water-soluble organic carbon (WSOC), which is closely related to biogenic emissions, is of great importance in the atmosphere for its ubiquitous existence and rich abundance. Levoglucosan, a typical WSOC, is usually considered to be stable and thus used as a tracer of biomass burning. However, we found that levoglucosan can be photo-oxidized on mineral dust, with formic acid, oxalic acid, glyoxylic acid, 2,3-dioxopropanoic acid, dicarbonic acid, performic acid, mesoxalaldehyde, 2-hydroxymalonaldehyde, carbonic formic anhydride, and 1,3-dioxolane-2,4-dione detected as main products. Further, we observed the heterogeneous uptake of NH3 promoted by the carboxylic acids stemming from the photocatalytic oxidation (PCO) of levoglucosan. The mineral-dust-initiated PCO of levoglucosan and enhanced heterogeneous uptake of NH3, which are highly influenced by irradiation and moisture conditions, were for the first time revealed. The reaction mechanisms and pathways were studied in detail by diffuse reflection infrared Fourier transform spectroscopy (DRIFTS), high-pressure photon ionization time-of-flight mass spectrometry (HPPI-ToF-MS) and flow reactor systems. Diverse WSOC constituents were studied as well, and the reactivity toward NH3 is related to the number of hydroxyl groups of the WSOC molecules. This work reveals a new precursor of secondary organic aerosols and provides experimental evidence of the existence of organic ammonium salts in atmospheric particles.