12801. 题目: Glacier loss impacts riverine organic carbon transport to the ocean
Lateral transport of organic carbon (OC) to the coastal ocean is an important component of the global carbon cycle because rivers transport, mineralize, and bury significant amounts of OC. Glaciers drive water and sediment export from many high‐elevation and high‐latitude ecosystems, yet their role in watershed OC balances is poorly understood, particularly with regard to particulate OC. Here we evaluate seasonal water, sediment, and comprehensive OC budgets, including both dissolved and particulate forms, for three watersheds in southeast Alaska that vary in glacier coverage. We show that glacier loss will shift the dominant size fraction of riverine OC from particulate toward dissolved and potentially alter the provenance of particulate OC. Glacier coverage also controls whether OC export is source (C stock) or transport (runoff) limited at the watershed scale. These findings provide insight into the future trajectory of OC export in glacierized regions.
12802. 题目: Errors induced by spectral measurement positions and instrument noise in soil organic carbon prediction using vis-NIR on intact soil
Soil spectroscopy potentially would become a routine method for the measurement of soil properties in the field on soil cores. However, many factors could lead to errors in the measurement of spectra from intact soil cores. So far, errors induced by spectral measurement positions and instrument noise have rarely been quantified. The present study evaluated these errors based on 160 intact ring core samples collected from 20 profiles in a forest, southwest China. Each ring sample was scanned using a visible near-infrared (vis-NIR) spectrometer at nine evenly distributed positions at both ends of the ring to characterize within-sample variability. In addition, 10 scans were made at each position to characterize instrument error. A position spectrum was then calculated by averaging the 10 scans at each position, while a sample spectrum was calculated by averaging all 180 scans of each sample. The samples were then tested for soil organic carbon (SOC) content using the wet oxidation method. Based on the sample spectra and SOC content, a partial least squares regression (PLSR) model was calibrated. The modeling error was empirically calculated. Each scan, position spectrum, and sample spectrum was then fed into the calibrated PLSR model to predict SOC content, and the prediction results were evaluated for errors induced by instrument noise and different spectral measurement positions. Results showed that the error induced by different spectral measurement positions was about 75% of the modeling error, while the error induced by instrument noise was small and negligible. These three errors in terms of standard error of prediction (SEP) accounted for 18.6%, 23.8% and 1.46% of the average measured SOC content of the samples, respectively. Besides, the error due to different soil core sampling positions was also considerable. In terms of SEP, this error accounted for 12.5% of the average measured SOC content. These quantified error budgets would help to account for uncertainty in the measurement of soil properties using spectroscopy in the field.
12803. 题目: Rapid PXRF soil organic carbon and organic matter assessment using novel modular radiation detector assembly
Soil organic matter and organic carbon are variables of critical environmental importance in terms of soil productivity and function, global food security, and climate change mitigation. Rapid and accurate assessment of these variables is central to national programs and international agreements. Portable X-ray fluorescence instruments are widely used to rapidly quantify and map soil elements, however quantification of light elements that constitute the majority of organic materials is not yet possible with this technique (e.g. carbon). We developed a novel attachment for portable X-ray fluorescence instrumentation enabling concurrent volumetric soil organic matter and organic carbon quantification during PXRF analyses. This primary prototype outperformed more expensive visible-near infrared instrumentation using parsimonious soil specific simple linear regression (R2 ranged 0.85–0.97) enabling rapid, parallel, nondestructive, cost-effective acquisition of soil elemental concentrations together with soil organic carbon and soil organic matter data.
12804. 题目: The multi-disciplinary study of Early Copper Age lamps from Zgornje Radvanje (NE Slovenia)
This paper focuses on the analysis and identification of two prehistoric lamps from Zgornje Radvanje (NE Slovenia). The analysis of the organic residues and experimental archaeology allowed us to characterize the fuel source and the wick remains of oval-formed ceramic artefacts from the Copper Age settlement. Infrared spectroscopy (ATR IR), GC-MS and GC-C-IRMS were used to study organic compounds in two archaeological samples, with comparative composition data yielding experiments with modern wicks, linseed oil and animal fats. ATR IR showed traces of plant fibres in the sample of charred residues from one of the lamps. A comparably higher frequency of straight-chain compounds with odd numbers of carbon atoms provided the extracted lipids from the ceramics of the second oval-formed ceramic artefact. We interpret these to mean that carbonised organic residues from the inner surface of the ceramic object are the result of smouldering, with the identified residues of plant fibres probably associated with the remnants of the wick. The GC-MS analysis showed a higher frequency of straight-chain compounds with odd numbers of carbon atoms (especially C15:0 fatty acids) together with two double bond positional isomers of C18:1 in the second oval-formed artefact. The presence of C18:2 and C18:3 fatty acids that are typical for linseed oils was also detected. These analysis together with GC-C-IRMS analysis suggest a predominant use of ruminant fat as fuel for lighting possibly in combination with plant oils. Burns similar to those on the original artefact were observed on replicas of the artefact after they were used as lamps.
12805. 题目: Identifying recent sources and fate of sedimentary nitrogen in the Baltic Sea based on organic matter elemental composition and nitrogen and carbon stable isotopes ratios
Sedimentary nitrogen (SN) provenience and fate in surface and subsurface sediments collected from the Baltic Sea were assessed. SN and sedimentary organic carbon (SOC) concentrations, stable isotopic signatures (δ15NSN and δ13CSOC) and SOC/SN molar ratios, were determined in subsequent layers of twenty-four sediment cores dated with 210Pb/137Cs and fifty-seven surface sediments. Sedimentation rates in the range 66–736 g/m2yr−1 (0.05–0.34 cm/year) were measured. Prolonged incubation of sediments in the laboratory led to a 17–37% decrease of SN in surface sediments, and no SN loss in sediments deposited before 1940. Decrease of δ15NSN on incubation (1‰ on average), and gradients of δ15NSN, between recent - surface (3.5‰) vs. 100 years old - subsurface (2.1‰) sediments were attributed to varying contributions of labile nitrogen to the SN pool. Annual deposition of SN to sediment surface and burial in subsurface sediments amounted, respectively, to 5 ± 2 g/m2 and 3.5 ± 1 g/m2.
12806. 题目: Sedimentary organic matter composition from tropical ports with distinct geographic and morpho-hydrodynamic characteristics: Evaluation through multiple biochemical markers
Increasing coastal urbanization and shipping activity-related environmental pollution advocate the importance of assessment of port ecosystems. Fatty acid biomarkers, elemental components, and biopolymers were used to evaluate the composition of sedimentary organic matter and benthic trophic status of Kolkata (freshwater, enclosed docks) and Kandla (seawater, macrotidal) ports of India. The sediment fatty acid composition indicated relatively fresh and energy-rich organic matter of phytoplankton and bacterial origin inside Kolkata port than the outside riverine station and Kandla port. Biopolymeric carbon (BPC), used as an indicator of trophic status, revealed eutrophic condition in Kolkata port with high accumulation of organic matter of autochthonous origin, attributed to poor water flushing and input of anthropogenic wastes. In contrast, Kandla port was meso-oligotrophic, rich in bacteria, and terrestrial plant-derived materials. Such an assessment of ports' trophic status helps to evaluate the health of the ecosystem and in management practices.
12807. 题目: Soil organic carbon controls dissimilatory nitrate reduction to ammonium along a freshwater-oligohaline gradient of Min River Estuary, Southeast China
Quality and source of soil organic carbon controlling DNRA in estuarine wetlands have not been well understood. We used a 15N isotopic tracer approach to investigate DNRA rates and determined the effects of organic carbon quality and source on magnitudes and distribution of DNRA along a freshwater-oligohaline gradient of Min River estuary, Southeast China. DNRA rates ranged from 0.45 to 2.92 nmol g−1 h−1 and were significantly higher in summer than in winter. DNRA was well predicted by dissolved organic carbon (DOC), organic carbon isotope (δ13Corg), total OC as the main predictor variables, which explained 63%, 6.0% and 7.0% of DNRA variances, respectively. Water content and temperature were crucial for DOC availability with important implications on DNRA. Soil δ13Corg increased from freshwater to oligohaline wetlands and showed a positive correlation with DNRA. We therefore conclude that high DOC availability enhances DNRA and can best predict spatial distribution in subtropical estuary.
12808. 题目: Effects of straw biochar application on soil temperature, available nitrogen and growth of corn
Straw biochar could improve the water holding capacity effectivity of salinized soil, increase soil fertili, enhance crop yield, reduce greenhouse gas emission, and mitigate climate change. The mechanism of using straw biochar for soil improvement is different under various climate and soil texture conditions. To explore the mechanism of using straw biochar to improve soil and its influence on crop yield in the typical arid and semi-arid, a large temperature difference between day and night, soil temperature at different depths, and physiological changes and crop yield of maize at different growth stages were studied. It is assumed that straw biochar can improve the properties of salinized soil including physicochemical indexes, and crop physiological index, stimulates the positive circulation between soil, vegetation, and microorganisms, and plays a role in improving soil quality. The results showed that biochar application increased the average soil temperature (T) by 2 °C and reduced day-night T differences. Application of 30 t/ha biochar increased the average maize leaf T by 2.2 °C and photosynthetic rate by 16.5%. Furthermore, the average transpiration rate doubled compared to control, and the chlorophyll value increased by 21%. The application of biochar improved the utilization rate of nitrogen fertilizer by enhancing ammonification. Biochar application caused a maximum overall yield increase of 11.9% compared to control treatment (CK). Therefore, these results provide a practical basis for improving weakly alkaline farmland soils in arid and semi-arid areas, and provide an effective method to potentially mitigate the environmental crisis and promote sustainable development in agriculture.
12809. 题目: Particulate biogenic barium tracer of mesopelagic carbon remineralization in the Mediterranean Sea (PEACETIME project)
12810. 题目: Insight into the influence of humic acid and sodium alginate fractions on membrane fouling in coagulation-ultrafiltration combined system
Membrane fouling has become the one of main obstacles for the widespread application of membrane technology in water treatment processes. Coagulation as pretreatment is proven to be effective for the alleviation of membrane fouling. In this study, the influence of humic acid (HA)/sodium alginate (SA) fractions in the structure and resistance of cake layer on the membrane surface was investigated. The presence of SA at an appropriate fraction could facilitate the formation of large and loosely branched flocs and thereby form a more permeable cake layer on the membrane surface due to good bridging and charge neutralization abilities of SA molecules. The particle image velocimetry (PIV) technique was employed for monitoring the dynamic formation process of cake layer under different HA/SA fractions. The cake layer with a higher thickness was observed to be rapidly formed on the membrane surface at the presence of SA in water. According to the theoretical analysis, the membrane fouling in coagulation-ultrafiltration (UF) combined system demonstrated to be highly dependent on the size and intra-porosity of flocs. The fractal dimension of flocs might have an impact on the resistance of cake layer through affecting the porosity of aggregated flocs. The SA molecules could be used as the coagulant aid for effective alleviation of membrane fouling and the improvement of filtration performance in a coagulation-UF combined system.
12811. 题目: Complexation of Sn with Boom Clay Natural Organic Matter under repository conditions
126Sn is a long-lived fission product and as such a waste relevant radioisotope. Understanding its fate under deep-geological repository conditions is a requirement for a complete safety assessment. Yet, due to a limited knowledge of its hydrogeochemical properties, the solubility and speciation of tin in a nuclear waste repository remain uncertain. In Belgium, Boom Clay (BC) is investigated as a potential host rock. It contains a significant amount of dissolved organic matter (DOM), which was shown to strongly influence the mobility of several radionuclides and notably of tetravalent actinides. By chemical analogy, the speciation, sorption and mobility of Sn(IV) in BC is also assumed to be controlled by its binding to DOM. However, the Sn-DOM complexation was never quantified in relevant repository conditions. In this work, the complexation of Sn with BC DOM was investigated under present-day BC conditions and in synthetic seawater as representative of more saline conditions. The ultrafiltration technique was used to quantify the amount of Sn bound to DOM. The two investigated repository conditions yielded nearly identical binding constants, evidencing a low influence of salinity on the level of binding of Sn to BC DOM. BC DOM forms strong complexes with Sn that would significantly increase Sn solubility in BC pore waters. The investigated range of Sn and DOM concentration (DOMtot/Sntot = 2.8 × 102 to 5.7 × 103)also showed that the binding constants are dependent on the metal loading (5.0 < logK(Sn-DOM) < 6.0). A two-site Langmuir isotherm correctly described this dependency and highlighted the binding of Sn on both strong and weak sites present on DOM. Overall, the experimental data show that the binding of Sn with BC DOM controls the Sn speciation under BC repository conditions, which reveals the importance of taking it into account in safety assessment calculations.
12812. 题目: Transport mechanism and fate of terrestrial materials delivered by a small tropical mountainous river: A case study of the Kelantan River, Malaysia
Tropical mountain river systems that drain rainforests and experience tropical monsoons typically demonstrate high runoff and discharge a disproportionate amount of particulate load to the world's oceans compared with other more temperate river systems. As a typical tropical small mountainous river with an broad continental shelf system and wave dominated environment, the Kelantan River is one of the few north-flowing streams in Southeast Asia that discharges into the broad and shallow continental shelf of South China Sea. The existence of seasonal variations of salinity, turbidity, and sediment composition indicate that coarse-grained sediments are deposited rapidly when terrestrial sediments delivered by the Kelantan River leave the river mouth. They are then reworked by wave action during the rainy season, leading to the development and rapid migration of barrier spits near the west side of the river mouth. Under the influence of the seasonal variations in the river plume, fine-grained sediments discharged into the sea by the Kelantan River are transported both along-shore and cross-shore, and most of them are deposited in the continental shelf area within 10 km of the river mouth, because of rapid removal of sediments from the river plume. The spatial distribution patterns of sediment composition, C/N ratio, terrestrial organic carbon content, and Sr/Al ratio also support our conclusion.
12813. 题目: Contrasting response of organic carbon mineralisation to iron oxide addition under conditions of low and high microbial biomass in anoxic paddy soil
12814. 题目: Dissimilatory nitrate ammonification and N2 fixation helps maintain nitrogen nutrition in resource-limited rice paddies
12815. 题目: Effect of biochar addition on the removal of organic and nitrogen pollutants from leachate treated with a semi-aerobic aged refuse biofilter
12816. 题目: Seasonal contrast of particulate organic carbon (POC) characteristics in the Geum and Seomjin estuary systems (South Korea) revealed by carbon isotope (δ13C and Δ14C) analyses
In this study, we newly investigated surface water samples collected in two contrasting Korean estuary systems (i.e., closed Geum and open Seomjin estuaries) along a salinity gradient in winter (December) in 2016. The main objectives were to determine the source of particulate organic carbon (POC) in winter and to assess the environmental factors inducing seasonal differences in POC characteristics. Concentrations and dual carbon isotopes (δ13C and Δ14C) of POC were analyzed together with concentrations and stable carbon isotopes (δ13C) of dissolved inorganic carbon (DIC) and compared with those obtained in summer (August) in 2016. Our study provided a new insight that for both estuarine systems, the seasonal contrast in POC characteristics was associated with stronger wind-induced estuarine sediment resuspensions in winter than in summer providing a greater contribution of aged POC to the total POC pool in winter.
12817. 题目: Changes in the characteristics of dissolved organic matter during sludge treatment: A critical review
Dissolved organic matter (DOM) of sludge is a heterogeneous mixture of high to low molecular weight organic substances which is including proteinaceous compounds, carbohydrates, humic substances, lipids, lignins, organic acids, organic micropollutants and other biological derived substances generated during wastewater treatment. This paper reviews definition, composition, quantification, and transformation of DOM during different sludge treatments, and the complex interplay of DOM with microbial communities. In anaerobic digestion, anaerobic digestion-refractory organic matter, particularly compounds showing polycyclic steroid-like, alkane and aromatic structures can be generated after pretreatment. During dewatering, the DOM fraction of low molecular weight proteins (< 20,000 Dalton) is the key parameter deteriorating sludge dewaterability. During composting, decomposition and polymerization of DOM occur, followed by the formation of humic substances. During landfill treatment, the composition of DOM, particularly humic substances, are related with leachate quality. Finally, suggestions are proposed for a better understanding of the transformation and degradation of DOM during sludge treatment. Future work in sludge studies needs the establishment and implementation of definitions for sample handling and the standardization of DOM methods for analysis, including sample preparation and fractionation, and data integration. A more detailed knowledge of DOM in sludge facilitates the operation and optimization of sludge treatment technologies.
12818. 题目: Chlortetracycline hydrochloride removal by different biochar/Fe composites: A comparative study
In the last years, the synthesis and applications of biochar/Fe composites have been extensively studied, but only few papers have systematically evaluated their removal performances. Herein, we successfully synthesized and structurally characterized Fe0, Fe3C, and Fe3O4-coated biochars (BCs) for the removal of chlortetracycline hydrochloride (CH). Evaluation of their removal rate and affinity revealed that Fe0@BC could achieve better and faster CH removal and degradation than Fe3 and Fe3O4@BC. The removal rate was controlled by the O–Fe content and solution pH after the reaction. The CH adsorption occurred on the O C groups of Fe0@BC and the OC and OFe groups of Fe3 and Fe3O4@BC. Electron paramagnetic resonance analysis and radical quenching experiments indicated that HO and 1O2/ O2− were mainly responsible for CH degradation by biochar/Fe composites. Additional parameters, such as effects of initial concentrations and coexisting anions, regeneration capacity, cost and actual wastewater treatment were also explored. Principal component analysis was applied for a comprehensive and quantitative assessment of the three materials, indicating Fe0@BC is the most beneficial functional material for CH removal.
12819. 题目: Effect of terminal temperature on the morphology and potentially toxic metals concentrations of biochars derived from paper and kitchen waste
This study investigated the morphology and potentially toxic metal concentrations of paper waste-based biochar (PB) and kitchen waste-based biochar (KB) obtained at 500 and 700 °C. The morphology and potentially toxic metals (Cr, Mn, Cu, Cd, Pb, Zn, Ag, and Ba) concentrations in the biochars were determined by SEM and FT-IR analysis. The Cr, Mn, Cu, and Cd concentrations in PB were low, while the Ba content was relatively high at 0.1 mg∙kg−1. An increase in the terminal temperature led to an increase in the concentrations of Fe/Mn oxide-bound potentially toxic metals of PB, and a decrease in the concentrations of organic matter-bound potentially toxic metals. The Fe/Mn oxide-bound Cr, Mn, Cu, Pb, and Zn concentrations of KB decreased with an increase in the terminal temperature. Therefore, increasing the terminal temperature could reduce the bioavailability of potentially toxic metals in PB and KB. The environmental risk of the different biochars when used for soil remediation was assessed by the potential ecological risk index (RI), and a case study of a Tibetan soil was also conducted. The potentially toxic metal concentrations leached from both PB and KB were lower than the relevant standards. The findings showed that both PB and KB can be safely used for soil remediation.
12820. 题目: Effectiveness of different approaches for in situ measurements of organic carbon using visible and near infrared spectrometry in Poyang basin
Research on soil carbon dynamics and content in the Poyang Lake area is important because of their effects on the soil carbon pool and soil carbon cycle. Visible and near infrared (VNIR) diffuse reflectance spectroscopy can provide analytical dense soil data reflecting multiple physical and chemical properties of soil under in situ conditions. The effective use of in situ VNIR in Poyang Lake would greatly improve the collection of high‐resolution and spatially explicit soil data and, thus, hasten the monitoring process. We collected two data sets S1 and S2 in 2016‐2018. A dataset from S1 was used to develop the in situ correction matrix using laboratory and in situ spectra. Spectra from the Chinese soil spectroscopic database (CSSD) and dataset of S1 in dry laboratory condition were used for calibration (CSSD‐local calibration). The dataset from S2 was utilized as the validation dataset. Four in situ correction methods, external parameter orthogonalization (EPO), piecewise direct standardization, direct standardization, and generalized least squares weighting, were used to remove the in situ effect on the spectra. In addition, partial least squares regression and support vector machine (SVM), were used to test the effectiveness of the prediction. We also compared the prediction results by calibration of the CSSD, CSSD‐local and CSSD combined with four in situ samples from the validation datasets with extra‐weighting (CSSD‐EX). The results showed that EPO was the most effective method for removing the in situ effect. EPO and SVM with the calibration of CSSD‐EX yielded the best prediction result with the lowest root mean squared error at 1.71 g kg‐1 and the highest Lin's concordance correlation coefficient at 0.88. The CSSD with EPO and SVM would allow the in situ estimation of soil organic carbon in the Poyang Lake area at a reasonable cost.
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