101. 题目: Comparing laboratory and airborne hyperspectral data for the estimation and mapping of topsoil organic carbon: Feature selection coupled with random forest
期刊: Soil and Tillage Research
作者: Yongsheng Hong, Songchao Chen, Yiyun Chen, Marc Linderman, Abdul M. Mouazen, Yaolin Liu, Long Guo, Lei Yu, Yanfang Liu, Hang Cheng, Yi Liu
摘要: Rapid monitoring of soil organic carbon (SOC) with fine sampling resolution is vital for further understanding of the global carbon cycle and sustainable management of soil resources. Proximal visible and near-infrared (Vis–NIR) spectroscopy is an effective approach to analyze SOC. However, this technique can only be used for point-to-point monitoring and not for grid pixels evenly spread throughout the area. Airborne hyperspectral imagery with high-spectral- and spatial-resolution provides a promising tool for mapping topsoil SOC at a fine scale, but suffers from the interference of some external factors. Using 45 topsoil samples collected from an agricultural field in the United States, this study aimed to compare the potential of airborne hyperspectral image in estimating and mapping of bare topsoil SOC with that derived from proximal laboratory Vis–NIR spectral data. Random forest (RF) along with two advanced feature selection algorithms, namely, continuous wavelet transform (CWT) and competitive adaptive reweighted sampling (CARS), was applied to optimize the performance of the prediction models. Results showed that laboratory and airborne spectra presented similar spectral shapes and strengths, but laboratory spectral curves were smoother than airborne spectral curves, which were noisier. Laboratory spectra (R2 = 0.79–0.87) performed better than airborne hyperspectral imagery (R2 = 0.49–0.76) in cross-validation, regardless of feature selection algorithms. The CWT-RF models resulted in the highest cross-validation results for laboratory (R2 = 0.87) and airborne (R2 = 0.76) spectra, suggesting their robustness in SOC prediction. The SOC maps retrieved from full-spectrum-RF, CWT-RF, and CARS-RF models all exhibited similar spatial distribution patterns. With airborne hyperspectral imagery serving as a valuable data source at pixel level for digital soil mapping, the methodological framework proposed in this paper could improve the accuracy and reduce the prediction uncertainty of SOC maps by selecting and adopting the optimal subset of spectral variables.
102. 题目: Sources of Particulate Organic Matter across Mangrove Forests and Adjacent Ecosystems in Different Geomorphic Settings
作者: Daniel A. Saavedra-Hortua, Daniel A. Friess, Martin Zimmer, Lucy Gwen Gillis
摘要: Mangrove forests are among the world's most productive ecosystems and provide essential ecosystem services such as global climate regulation through the sequestration of carbon. A detailed understanding of the influence of drivers of ecosystem connectivity (in terms of exchange of suspended particulate organic matter), such as geomorphic setting and carbon stocks, among coastal ecosystems is important for being able to depict carbon dynamics. Here, we compared carbon stocks, CO2 fluxes at the sediment-air interface, concentrations of dissolved organic carbon and suspended particulate organic carbon across a mangrove-seagrass-tidal flat seascape. Using stable isotope signatures of carbon and nitrogen in combination with MixSIAR models, we evaluated the contribution of organic matter from different sources among the different seascape components. Generally, carbon concentration was higher as dissolved organic carbon than as suspended particulate matter. Geomorphic settings of the different locations reflected the contributions to particulate organic matter of the primary producers. For example, the biggest contributors in the riverine location were mangrove trees and terrestrial plants, while in fringing locations oceanic and macroalgal sources dominated. Anthropogenic induced changes at the coastal level (i.e. reduction of mangrove forests area) may affect carbon accumulation dynamics in adjacent coastal ecosystems.
103. 题目: Spatial variability of organic matter degradability in tidal Elbe sediments
期刊: Journal of Soils and Sediments
作者: Florian Zander, Timo Heimovaara, Julia Gebert
摘要: Purpose: The microbial turnover of sediment organic matter (OM) in ports and waterways impacts water quality, sonic depth finding and presumably also rheological properties as well as greenhouse gas emissions, especially if organic carbon is released as methane. As a consequence, sediment management practices as a whole are affected. This study aimed to discern spatial OM degradability patterns in the Port of Hamburg and investigated correlations with standard analytical properties as a basis for future predictive modelling. Materials and methods: Sediments in the Port of Hamburg were repeatedly sampled at nine locations along an east-west transect using a 1-m corer. In a stratified sampling approach, layers of suspended particulate matter (SPM), fluid mud (FM), pre-consolidated sediment (PS) and consolidated sediment (CS) were identified and individually analysed for long-term aerobic and anaerobic degradation of organic matter, DNA concentration, stable carbon isotope signature, density fractions and standard solids and pore water properties. Results and discussion: The investigation area was characterised by a distinct gradient with a 10-fold higher OM degradability in upstream areas and lower degradability in downstream areas. Concomitantly, upstream locations showed higher DNA concentrations and more negative δ13C values. The share of bulk sediment in the heavy density fraction as well as the proportion and absolute amount of organic carbon were significantly larger at downstream locations. A depth and hence age-related gradient was found at individual locations, showing higher degradability of the upper, younger material, concomitant with higher DNA concentration, and lower OM turnover in the deeper, older and more consolidated material. Deeper layers were also characterised by higher concentrations of pore water ammonium, indicative of anaerobic nitrogen mineralisation. Conclusions: Organic matter lability is inversely linked to its stabilisation in organo-mineral complexes. The observed degradability gradient is likely due to the different OM quality in relation to its origin. Downstream OM enters the system with the tidal flood current from the direction of the North Sea whereas upstream locations receive OM originating from the catchment, containing more autochthonous, plankton-derived and more easily degradable components. At individual sampling points, depth-related degradability gradients reflect an age gradient, with easily degradable material in top layers and increasing stabilisation of OM in organo-mineral compounds with depth.
104. 题目: Spent mushroom substrates affect soil humus composition, microbial biomass and functional diversity in paddy fields
期刊: Applied Soil Ecology
作者: Fangliang Li, Qingbo Kong, Qing Zhang, Huangping Wang, Limin Wang, Tao Luo
摘要: Spent mushroom substrate (SMS) is the residue after mushroom production. The aims of this work were to analyze the effects of continuous application of SMS for nearly 10 years on soil organic carbon (SOC), soil humus composition, microbial biomass and functional diversity in paddy fields and to provide a theoretical basis for scientific application of SMS. A continuous application of SMS from Agaricus bisporus experiment was established in paddy field of southeastern China in 2007. Soils were collected from 6 treatments in 2016. The results showed that application of SMS could significantly increase the contents of SOC, soil total alkali-soluble humic carbon (HEC), humic acid carbon (HAC), especially the treatment of with high quantity of SMS, but not significantly increase the content of fulvic acid carbon (FAC). The microbial biomass carbon and nitrogen contents of MR3 (the amounts of SMS were 9574.5 kg hm−2, converted to pure nitrogen were 180 kg hm−2) were the largest, it illustrated that the amount of SMS was not the more the better. The average well color development (AWCD), the Shannon index, Simpson index and McIntosh index of MR3 treatment were the highest. Microorganisms of MR3 treatment could make better use of carbon sources. Carboxylic acids, carbohydrates and polymers were the main carbon source types. Sufficient but not excessive application of SMS was beneficial to the carbon source utilization of fast-growing microorganisms and was considered to be a good way to improve the productivity of paddy soil.
105. 题目: Relevance of biochar to influence the bacterial succession during pig manure composting
期刊: Bioresource Technology
作者: Mukesh Kumar Awasthi, Yumin Duan, Tao Liu, Sanjeev Kumar Awasthi, Zengqiang Zhang
摘要: The influence of pig manure biochar amendment (PMBA) during the pig manure (PM) and wheat straw (WS) composting was evaluated. Five concentration of PMBA (0%, 2%, 4%, 6% and10%) were applied to explore the bacterial distributions in PM compost by 16SDNA amplicons sequencing. The results showed that the addition of 6% PMBA could significantly enhanced the bacterial community abundance compared with other composts, while control has relative less bacterial population (332 OTU). The visualization of phylogenetic tree and krona demonstrated the distinctive distribution of each composts, suggested that biochar dosages have an influence on bacterial communities’ variation during co-composting. Beta-diversity of distance matrix heat-map and principal component analysis confirmed that bacterial communities were considerably correlated with increasing PMBA. Redundancy also confirmed the similarity and discrepancy among all treatments and environmental factors. This work considered as the potential of PMBA as a booster in composting, where T4 has most plentiful bacterial community and diversity.
106. 题目: Release of colloidal biochar during transient chemical conditions: The humic acid effect
期刊: Environmental Pollution
作者: Yang Wang, Scott A. Bradford, Jianying Shang
摘要: Our understanding of colloidal biochar (CB) transport and release is largely unknown in environments with transient chemical conditions, e.g., ionic strength (IS), pH, and especially humic acid (HA). In this study, column experiments were conducted to investigate CB transport and retention in the presence and absence of HA, and CB release under transient IS and pH conditions in saturated sand. Step reductions in solution IS from 25 to 0.01 mM produced significant release peaks of CB due to a reduction in the depth of the primary minima on rough surfaces with small energy barriers. In contrast, step increases of solution pH from 4 to 10 only slightly increased CB release presumably due to the strong buffering capacity of CB. The CB retention was diminished by HA during the deposition phase. However, the release of CB with transients in IS and pH was not influenced much when deposition occurred in the presence of HA. These observations indicate that HA increased the energy barrier during deposition but did not have a large influence on the depth of the interacting minimum during transient release. Potential explanations for these effects of HA on CB retention and transient release include enhanced repulsive electrostatic interactions and/or altering of surface roughness properties. Our findings indicated that the release of retained CB is sensitive to transient IS conditions, but less dependent on pH increases and CB deposition in the presence of HA. This information is needed to quantify potential benefits and/or adverse risks of mobile CB in natural environments.
107. 题目: Soil Organic Carbon across Mexico and the conterminous United States (1991‐2010)
期刊: Global Biogeochemical Cycles
作者: Mario Guevara, Carlos Arroyo, Nathaniel Brunsell, Carlos O. Cruz, Grant Domke, Julian Equihua, Jorge Etchevers, Daniel Hayes, Tom Hengl, Alejandro Ibelles, Kris Johnson, Ben de Jong, Zamir Libohova, Ricardo Llamas, Lucas Nave, Jose L. Ornelas, Fernando Paz, Rainer Ressl, Anita Schwartz, Arturo Victoria, Skye Wills, Rodrigo Vargas
摘要: Soil Organic Carbon (SOC) information is fundamental for improving global carbon cycle modeling efforts, but discrepancies exist from country‐to‐global scales. We predicted the spatial distribution of SOC stocks (topsoil; 0‐30 cm) and quantified modeling uncertainty across Mexico and the conterminous United States (CONUS). We used a multi‐source SOC dataset (>10000 pedons, between 1991‐2010) coupled with a simulated annealing regression framework that accounts for variable selection. Our model explained ~50% of SOC spatial variability (across 250m grids). We analyzed model variance, and the residual variance of six conventional pedotransfer functions for estimating bulk density (BD) to calculate SOC stocks. Two independent datasets confirmed that the SOC stock for both countries represents between 46 and 47 Pg with a total modeling variance of ±12 Pg. We report a residual variance of 10.4 ±5.1 Pg of SOC stocks against the six pedotransfer functions. When reducing training data to defined decades with relatively higher density of observations (1991‐2000 and 2001‐2010, respectively), model variance for predicted SOC stocks ranged between 41 and 55 Pg. We found nearly 42% of SOC across Mexico in forests and 24% in croplands; whereas 31% was found in forests and 28% in croplands across CONUS. Grasslands and shrublands stored 29 and 35% of SOC across Mexico and CONUS, respectively. We predicted SOC stocks >30% below recent global estimates that do not account for uncertainty and are based on legacy data. Our results provide
108. 题目: The use of amino sugars for assessing seasonal dynamics of particulate organic matter in the Yangtze River estuary
期刊: Marine Chemistry
作者: Chengzhe Ren, Huamao Yuan, Jinming Song, Liqin Duan, Xuegang Li, Ning Li, Bu Zhou
摘要: The particulate amino sugars (PAS), organic carbon (POC) and nitrogen (PN), the chlorophyll a (Chl-a), and the heterotrophic bacterial cell count (HBC) in the Yangtze River Estuary (YRE) were determined to study the biological source, bioavailability and bacterial contribution of particulate organic matter (POM) under the influence of algal bloom during the spring and autumn of 2017. The contents of PAS were 2.6–69.6 nmol/(mg dw) and made up 5.29 ± 2.55% of POC and 5.39 ± 2.77% of PN. The strong positive correlations between Chl-a and POC, PN and PAS and their similar distributions indicated that phytoplankton was a major source of POM and PAS in the YRE. When algal blooms occurred, the high ratios of glucosamine to galactosamine (GlcN/GalN) (~10.9) and the high carbon and nitrogen normalized yields of PAS (%PAS-POC and %PAS-PN, respectively) clearly indicated the planktonic (especially zooplankton) source of POM, although the high muramic acid (Mur) contents implying high contents of fresh bacterial organic matter (OM) were also found. Additionally, the high proportion of fresh plankton- and bacterial-derived OM indicated that the POM was more labile when algal bloom occurred. In contrast, when the primary production was low, the lower %PAS-POC and GlcN/GalN ratios (< 3) in the POM demonstrated the decreased contribution of planktonic OM and the relatively elevated contribution of bacterial OM. In addition, the higher %PAS-PN and the lower DO concentrations in seawater indicated that the POM experienced some degree of degradation but was still at an early stage in the nearshore site in autumn. In spring, the Changjiang diluted water (CDW) carried considerable plankton-derived POM into the estuary and influenced the distribution of POM. In autumn, the terrestrial OM might become more bacterial-derived and had less influence on the bulk POM of the estuary. The bacterial OM estimated by the Mur accounted for an average of 10.8 ± 3.7% and 40.5 ± 19.1% of the POC in spring and autumn, respectively, which was approximately two times higher than the results based on the heterotrophic bacterial cell count (HBC), indicating that most of the bacterial OM in the POM was detritus. In summary, the content, source and bioavailability of POM were significantly affected by algal bloom and the CDW, and the amino sugars represent a reliable tool to indicate the source and bioavailability of POM.
109. 题目: Hydrologic connectivity determines dissolved organic matter biogeochemistry in northern high‐latitude lakes
期刊: Limnology and Oceanography
作者: Sarah Ellen Johnston, Robert G. Striegl, Matthew J. Bogard, Mark M. Dornblaser, David E. Butman, Anne M. Kellerman, Kimberly P. Wickland, David C. Podgorski, Robert G. M. Spencer
摘要: Northern high‐latitude lakes are undergoing climate‐induced changes including shifts in their hydrologic connectivity with terrestrial ecosystems. How this will impact dissolved organic matter (DOM) biogeochemistry remains uncertain. We examined the drivers of DOM composition for lakes in the Yukon Flats Basin in Alaska, an arid region of low relief that is characteristic of over one‐quarter of circumpolar lake area. Utilizing the vascular plant biomarker lignin, chromophoric dissolved organic matter (CDOM), and ultrahigh‐resolution mass spectrometry, we interpreted DOM compositional changes using lake‐water stable isotope (δ18O‐H2O) composition as a proxy for lake hydrologic connectivity with the landscape. We observed a relative decrease in CDOM in more hydrologically isolated lakes (enriched δ18O‐H2O) without a corresponding decrease in dissolved organic carbon (DOC) concentration. Although DOC and CDOM were weakly correlated, a significant positive relationship between lignin and CDOM (r2 = 0.67) demonstrates that optical parameters are useful for estimating lignin concentration and thus vascular plant contribution to lake DOM. Indicators of allochthonous DOM, including lignin carbon normalized yields, CDOM aromaticity proxies, and relative abundances of polyphenolic and condensed aromatic compound classes, were negatively correlated with δ18O‐H2O (r2 > 0.45), suggesting there is little allochthonous DOM supplied to many of these hydrologically isolated lakes. We conclude that decreased lake hydrologic connectivity, driven by ongoing climate change (i.e., decreased precipitation, warming temperatures), will reduce allochthonous DOM contributions and shift lakes toward lower CDOM systems with ecosystem‐scale ramifications for heat transfer, photochemical reactions, productivity, and ultimately their biogeochemical function.
110. 题目: Effect of deashing on activation process and lead adsorption capacities of sludge-based biochar
期刊: Science of The Total Environment
作者: Junjie Zhang, Jingai Shao, Qianzheng Jin, Xiong Zhang, Haiping Yang, Yingquan Chen, Shihong Zhang, Hanping Chen
摘要: To explore the effect of inorganic minerals on activation process and lead adsorption of sludge-based biochar, sludge-based biochar was pre-deashed using hydrochloric acid or hydrofluoric acid followed by potassium acetate activation. The results indicate that hydrochloric or hydrofluoric acid deashing can improve the pore parameters of sludge-based biochars and promote subsequent activation effect of potassium acetate. The specific surface area of biochar activated by potassium acetate after hydrochloric acid and hydrofluoric acid pretreatment increased from 583.36 m2/g to 718.70 m2/g and 991.55 m2/g, respectively. The enhancement of pore structure is conducive to enhancing the physical adsorption of lead on sludge-based biochar, while the chemical adsorption is not significantly affected at the same time. Thereby, the biochar and activated biochar pretreated with hydrofluoric acid showed better lead adsorption capacities (16.70 and 49.47 mg/g) than untreated biochar (7.56 and 38.49 mg/g).
111. 题目: Biochar and nitrogen application rates effect on phosphorus removal from a mixed grass sward irrigated with reclaimed wastewater
期刊: Science of The Total Environment
作者: Everald Mclennon, Juan K.Q. Solomon, Dhurba Neupane, Jason Davison
摘要: This 2-year (2017 and 2018) field study evaluated biochar and nitrogen application rates effect on herbage phosphorus (P) and nitrogen (N) removal from a mixed-grass sward of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] and Kentucky bluegrass (Poa pratensis L.) irrigated with treated wastewater. Treatments used in this study carried out at the Main Station Field Laboratory, Reno, NV were three biochar application rates (0, 8.9, and 17.8 Mg/ha), and three N rates (0, 80, and 120 kg N/ha) arranged in a 3 × 3 factorial in a randomized complete block design experiment with four replications of each treatment combination. Responses were considered different P < 0.05. There was a linear increased in soil volumetric water content as biochar rate increased from 0 to 17.9 Mg/ha. However, biochar application rate did not affect the quantity of biomass produced, forage tissue P and N concentrations, P and N removal or interact with the other experimental variables of N rate and year to influence the response variables. There was, however, an N rate effect (P < 0.05) on biomass production and it was greater for the 80 and 120 kg N rate (average = 8.3 Mg DM/ha) relative to the 0 kg N/ha rate (6.0 Mg DM/ha). Further, cumulative P removal for the 80 and 120 kg N rate (average = 48.9 kg/ha) was greater than the 0 kg N/ha rate (38.1 kg/ha), and cumulative N removal was in the order 120 kg N/ha (321.1 kg/ha) > 80 kg N/ha (267.4 kg/ha) > 0 kg N/ha (187.8 kg/ha). There was a trend for a biochar × N rate interaction on soil P concentration and it tended to be greater for the combinations 8.9 and 17.8 Mg/ha biochar rates and 80 and 120 kg N/ha rates compared to the unamended control. Even though our study did not reveal a definitive effect of biochar on the major response parameters (biomass, tissue P and N concentrations) evaluated, the trend for a biochar × N rate interaction on soil P concentration offers hope that biochar-amended soils coupled with appropriate N fertilization will be effective in P retention on agricultural landscapes irrigated with treated wastewater.
112. 题目: Geochemical Multisurface Modeling of Reactive Zinc Speciation in Compost as Influenced by Extraction Conditions
期刊: Environmental Science & Technology
作者: Susan Klinkert, Rob N.J. Comans
摘要: Knowledge on organic matter (OM) concentration and composition is of major importance for predicting Zn speciation and bioavailability in soils, especially for low-Zn soils. However, comprehensive knowledge on the effect of soil-like organic amendments such as compost on metal speciation is limited. For the first time, multisurface modeling is applied on compost to study the effect of solid and dissolved OM composition on the speciation of reactive Zn as influenced by conditions applied in frequently used extractions to estimate Zn bioavailability. First, compost OM composition was determined by fractionation in operationally defined humic, fulvic, and hydrophilic acid pools under various extraction conditions, and subsequently, Zn speciation was modeled using the generic non-ideal competitive adsorption-Donnan (NICA-Donnan) model in addition to adsorption to hydrous ferric oxide (HFO) and clay. The results show a strong effect of extraction conditions on OM concentration and composition and related dissolved Zn speciation. Model predictions show that Zn in solution is mainly bound to dissolved humic acids. Analysis of deviations between measured and modeled Zn concentrations reveal specific limitations of the current generic model parameters, particularly with regard to Zn binding to OM at low concentrations and Ca-Zn competition, that is, typical conditions that occur in low-Zn soils.
113. 题目: The fuel of atmospheric chemistry: Toward a complete description of reactive organic carbon
期刊: Science Advances
作者: C. L. Heald, J. H. Kroll
摘要: The Earth’s atmosphere contains a multitude of emitted (primary) and chemically formed (secondary) gases and particles that degrade air quality and modulate the climate. Reactive organic carbon (ROC) species are the fuel of the chemistry of the atmosphere, dominating short-lived emissions, reactivity, and the secondary production of key species such as ozone, particulate matter, and carbon dioxide. Despite the central importance of ROC, the diversity and complexity of this class of species has been a longstanding obstacle to developing a comprehensive understanding of how the composition of our atmosphere, and the associated environmental implications, will evolve. Here, we characterize the role of ROC in atmospheric chemistry and the challenges inherent in measuring and modeling ROC, and highlight recent progress toward achieving mass closure for the complete description of atmospheric ROC.
114. 题目: Influence of earthworms on apolar lipid features in soils after 1 year of incubation
作者: Thanh Thuy Nguyen Tu, Alix Vidal, Katell Quénéa, Mercedes Mendez-Millan, Sylvie Derenne
摘要: Molecular and compound specific isotope compositions of apolar lipids were characterized in soil mesocosms incubated for 1 year with or without 13C-labelled plant residues and earthworms, in order to investigate, at the molecular scale, the effect of earthworms on the fate of organic matter (OM) in soils. Molecular and isotope composition of long chain alkanes in casts confirmed that earthworms preferentially ingest soil fractions rich in plant debris. Apolar lipid specific isotope composition allowed calculation of the proportion of carbon derived from the labelled residues (Clab). Casts displayed higher Clab values than surrounding soil while soil without earthworm exhibited intermediate Clab. The odd-over-even predominance (OEP) of alkanes suggested they are probably less degraded in casts than in the surrounding soil. Taken together, OEP and Clab values suggested that besides high incorporation of plant residues, earthworms may also favor the preservation of plant apolar lipids in their casts. Additionally, chain length and isotope pattern of alkanes further suggested root lipids were probably less degraded than shoot lipids. High 13C-incorporation level for the bacterial biomarker hopene provided evidence for intense recycling of plant OM and suggested further contribution of bacterial necromass to soil OM.
115. 题目: Comparison of UV/H2O2 and UV/PS processes for the treatment of reverse osmosis concentrate from municipal wastewater reclamation
期刊: Chemical Engineering Journal
作者: Min-Yong Lee, Wen-Long Wang, Ye Du, Qian-Yuan Wu, Nan Huang, Zi-Bin Xu, Hong-Ying Hu
摘要: Reverse osmosis concentrate (ROC) from municipal wastewater treatment contains high concentrations of complex toxic biorefractory pollutants. We studied the mechanisms by which two ultraviolet advanced oxidation processes, UV/H2O2 and UV/PS, degraded pollutants in ROC from municipal wastewater reclamation processes. Both technologies had similar removal efficiencies of bulk dissolved organic matter based on the observed reduction in COD, chromophores, and fluorophores. However, UV/PS decomposed both high and medium molecular weight (MW) fractions (57 and 67.7%), while UV/H2O2 preferentially decomposed only the high MW fraction (60 and 39.1%), suggesting that the two methods operate by different reaction mechanisms. The changes in electron donating capacity resulting from treatment by UV/H2O2 (42.3%) and UV/PS (75.2%) were different. SO4•− primarily decomposed compounds containing electron-donating groups better than •OH. The removal of dissolved organic matter by UV/PS resulted in decreases in both relative electron-donating capacity and relative specific ultraviolet absorbance. The distinct reaction mechanisms were observed between UV/PS and UV/H2O2, being that UV/PS preferentially decomposed the contaminants via electrophilic addition and hydroquinone generation, while UV/H2O2 preferentially decomposed the contaminants via phenolic-ring cleavage reactions. Changes in the UV absorbance (UVA254) and the fluorescence index (FI) were used to monitor the rate of elimination of toxic biocides in the ROC.
116. 题目: Sub-seafloor sulfur cycling in a low-temperature barite field: A multi-proxy study from the Arctic Loki's Castle vent field
期刊: Chemical Geology
作者: Benjamin Eickmann, Tamara Baumberger, Ingunn H. Thorseth, Harald Strauss, Gretchen L. Früh-Green, Rolf B. Pedersen, Andrea Jaeschke
摘要: The Loki's Castle vent field at the ultraslow-spreading Arctic Mid-Ocean Ridge (AMOR) hosts a low-temperature venting area, which is characterized by microbial mats and numerous up to 1 m tall barite chimneys. An actively-venting barite chimney yielded δ18OSO4 and δ34SSO4 values heavier than ambient seawater and sulfide-oxidizing bacteria in microbial mats identified microbial sulfate reduction and sulfide oxidation as the main processes. In order to investigate the chemical and microbial structure below the barite field, we obtained two gravity cores and present chemical composition (e.g., H2S, SO42−, NH4+, DIC) and stable isotope data for the pore fluids (δ34SSO4, δ13CDIC) together with stable isotope (δ13Corg, δ34S, ∆33S) and lipid biomarker data on bulk sediments. The gravity core more distant to the high-temperature vents shows seawater-like pore fluid profiles with only minor vent fluid contribution (<1%), whereas the bulk sediments yield negative δ34S and positive ∆33S values indicative of sulfate reduction. In contrast, the pore fluid data in close proximity to the high-temperature vents (5–9% vent fluid contribution) record distinct horizons showing sulfate depletion, which coincide with δ34SSO4 values that are higher than those for ambient seawater sulfate. The sediments in these horizons record negative δ34S and positive ∆33S values, indicating that both the pore fluids and the sediments are influenced by active sulfate reduction. We also detected a greater abundance of archaeal mono- and dialkyl tetraether lipids (GMGTs, GDGTs) and bacterial fatty acids in the sediments at actively venting sites, pointing to a more diverse microbial community. Moreover, a positive correlation observed between GMGT abundance and sulfur concentration in the sediments indicates that the availability of sulfur is crucial for the presence of GMGT-producing archaea. Our multi-proxy approach suggests that sulfate reduction in the sub-seafloor sediments of the Loki's Castle barite field is largely driven by microbial processes.
117. 题目: High resolution multi-annual riverine fluxes of organic carbon, nutrient and trace element from the largest European Arctic river, Severnaya Dvina
期刊: Chemical Geology
作者: Artem V. Chupakov, Oleg S. Pokrovsky, Olga Y. Moreva, Liudmila S. Shirokova, Natalia V. Neverova, Anna A. Chupakova, Ekaterina I. Kotova, Taissia Y. Vorobyeva
摘要: Assessing multi-annual riverine export fluxes of carbon, nutrients and metals from the continent to the Arctic Ocean is crucial for constraining the current status and foreseeing future changes in riverine export induced by climate change. Over 3 consecutive years (2012–2014), we measured daily to weekly concentrations of C, N, P, all major and 45 trace elements (TE) in filtered (<0.45 μm) river water at the terminal station of Severnaya Dvina, the largest European Arctic river, gauged since 1882. There were 3 main groups of elements according to their seasonal behavior, demonstrating distinct links between concentration and the discharge. Dissolved Inorganic Carbon (DIC), major anions (Cl, SO4), alkali and alkaline-earth elements (Li, Na, Mg, K, Ca, Rb, Sr, Ba), and oxyanions (B, Mo, Ge, As) and U exhibited minimum concentrations during spring flood and autumn high flow events, being significantly (p < 0.01) negatively correlated with discharge and dissolved organic carbon (DOC) concentration. These elements reflected the dominant lithology of Severnaya Dvina watershed (carbonates, gypsum) and were controlled by dilution of underground (baseflow) influx by floods. The concentration of DOC, low-soluble trace elements (Al, Ti, Ga, Y, rare earth elements, Zr, Nb, Hf, Th) and organically-bound metals (V, Cr, Co, Ni, Cu, Cd, Pb) had the maximum at the spring flood peak. The input of these elements to the river occurred via surface flow and they were significantly (p < 0.01) increasing with water discharge. Finally, N, P, Si, Mn and Fe originated from both surface and underground sources and were impacted by autochthonous biotic processes in the river channel; they exhibited a strong winter maximum and a summer minimum.The spring flood (May and June) provided 50% of overall water and DOC, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Sb, and Pb flux and 60% of low-soluble TE (Al, Y, Nb, REEs, Ti, Zr, Hf and Th). The nutrients (K, Rb, Si, P, N) exhibited around 40% share of annual export during spring flood, whereas the export of soluble mobile elements (DIC, Cl−, SO42−, Li, B, Na, Mg, Ca, Sr, Mo and U) mainly occurred during winter (35–40%) with only 20–25% of annual flow provided by spring flood.The 3-year mean export fluxes of dissolved components were 30 to 50% lower than (Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cu, Cd, and Pb) or comparable to (±30% for all other elements including DOC and for DIC) previous estimates of this river from 2007 to 2008 and the historic data of major components from 1930 to 1950. In particular, there was no trend in mean monthly seasonal and annual concentrations and export fluxes of DOC, DIC, SO4, Cl since the beginning of chemical analysis between 1929 and 1930 and in Ca, Mg, Si, and Fe since the 1950's through the duration of this study (2012–2014). The lack of seasonal and annual increases in discharge, carbon, and element concentrations in the permafrost-free Severnaya Dvina River for >120 years of discharge and over 60 years of chemical composition measurements is at odds with the reported short-term trend (based on measurements that began in 1970s) showing that element export fluxes increased in other Arctic rivers due to on-going climate warming and permafrost thaw.
118. 题目: Formation of calcite in the presence of dissolved organic matter: Partitioning, fabrics and fluorescence
期刊: Chemical Geology
作者: Andrew R. Pearson, Adam Hartland, Silvia Frisia, Bethany R.S. Fox
摘要: Dissolved organic matter (DOM) is omnipresent in natural waters and is commonly incorporated into carbonates. Records of DOM from speleothems (secondary carbonates found in caves) have often been interpreted to reflect groundwater DOM concentrations. However, the fidelity of these records is largely untested. An understanding of the relationship between dripwater and speleothem DOM is thus required to allow speleothems to be reliably used as archives of DOM concentration.We precipitated calcite (CaCO3) crystals from weak solutions of (NH4)2CO3, CaCl2 and NH4Cl. These solutions also contained peat DOM (from 0 to 15 mgC/L). Fluorescence 3D excitation-emission matrix (3D EEM) analysis showed a strong, positive correlation between [DOM] in the parent-solution, and [DOM] in the calcite. Calcite precipitation was reduced at high DOM concentrations, potentially indicating inhibition of crystallisation. Partition coefficient values showed that DOMaq was subtly preferentially incorporated into calcite.Scanning electron microscope images indicated that the crystal structures were heavily influenced by DOM adsorption with finer, smooth-faced, rhombohedral crystals forming in growth solutions with low aqueous [DOM] (0–5 mgC/L), and prismatic, ‘impure’ crystals produced at high aqueous [DOM] (10 and 15 mgC/L).Overall, our results indicate that authigenic carbonates are likely to faithfully record variations in aqueous [DOM] within the natural range of DOM concentrations in representative freshwater systems (caves, soil water), and that crystal habits are altered by aqueous [DOM] within their growth solutions.We also applied our findings to three flowstones collected from three New Zealand caves which vary in climatic, vegetation and hydrological regimes. We conclude that differences in initial aqueous [DOM] do indeed control incorporation of DOM into calcite, and thus 3D EEM fluorescence can be used to reconstruct original aqueous [DOM] from authigenic carbonates.
119. 题目: Techno-economic analysis for extracellular-polymeric substances (EPS) production using activated sludge fortified with crude glycerol as substrate and its application in leachate treatment
期刊: Bioresource Technology
作者: Lalit R. Kumar, Xiaolei Zhang, Rajwinder Kaur, Sravan K. Yellapu, R.D. Tyagi, Patrick Drogui
摘要: Economic assessment of bio-flocculant production process has been carried out by SuperPro Designer where extracellular-polymeric substances (EPS) were produced using activated sludge fortified with crude glycerol in fermenter followed by centrifugation. Considering EPS concentration of 60 g/L in production fermenter at 96 h, the unit production cost for slime EPS was estimated to be $ 0.95/L. The unit price of S-EPS was sensitive to inoculum size and EPS productivity (EPS concentration and fermentation time) in the fermented broth. Economic analysis was also conducted for EPS aided leachate treatment. The unit leachate treatment cost was 7.78 $/m3 and was sensitive to S-EPS unit production cost. To get same leachate treatment cost as current industrial practice (4 $/m3), S-EPS unit production cost should lower down to $ 0.5/L. The process has several advantages: 1) sludge and crude glycerol valorization for bio-flocculant production 2) Leachate treatment using environment friendly bio-flocculant.
120. 题目: Energy recovery and nutrients recycling from municipal sewage sludge
期刊: Science of The Total Environment
作者: Probir Das, Shoyeb Khan, Mohammed AbdulQuadir, Mahmoud Thaher, Muhammad Waqas, Ahmed Easa, Essam Shabaan Mohamed Attia, Hareb Al-Jabri
摘要: Hydrothermal Liquefaction (HTL) could be a promising and better alternative to other techniques for energy recovery from municipal sewage sludge (MSS). However, the nutrients (i.e., N, and P) recovery potential from the byproducts, generated in the HTL of MSS, needs to be studied so that a comprehensive sludge management practice could be adopted. In this study, HTL process temperature (275–400 °C), and reaction time (30–120 min) were first investigated for biocrude yield and release of the nutrients to the aqueous phase liquid (APL) and biochar. The maximum energy recovery (i.e., 59%) and maximum energy return on investment (i.e., 3.5) were obtained at 350 °C and 60 min of holding time. With the increase in HTL reaction time, the concentration of nitrogen in the APL increased (5.1 to 6.8 mg/L) while the concentration of phosphorus decreased (0.89 to 0.22 mg/L); the opposite was observed for the biochar. The nutrient recycling efficiency from the APL using microalgae was found to be strain-specific; nitrogen recycling efficiency by Picochlorum sp. and Chlorella sp. were 95.4 and 58.6%, respectively. The APL, derived from 1 kg MSS, could potentially produce 0.49 kg microalgal biomass. Since the concentrations of various metals in the biochar samples were substantially lower compared to their concentrations in raw MSS, the application of biochar as a soil conditioner could be very promising. Overall, net positive energy could be recovered from MSS using the HTL process, while the nutrients in the APL could be used to cultivate specific microalgae, and biochar could be applied to enhance the soil quality.