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# 所有论文

1. 题目: Enhancing lead immobilization by biochar: Creation of “surface barrier” via bio-treatment

The long-term effectiveness of heavy metal immobilization is always a concern. This study proposes a completely novel approach to enhance the stability of heavy metals by combined biochar and microbial induced carbonate precipitation (MICP) technologies, to create a “surface barrier” of CaCO3 layer on biochar after lead (Pb2+) immobilization. Aqueous sorption studies and chemical and micro-structure tests were used to verify the feasibility. Rice straw biochar (RSB700) was produced at 700 °C, which shows high immobilization capacity of Pb2+ (maximum of 118 mg g−1). But the stable fraction only accounts for 4.8% of the total immobilized Pb2+ on biochar. After MICP treatment, the stable fraction of Pb2+ significantly increased to a maximum of 92.5%. Microstructural tests confirm the formation of CaCO3 layer on biochar. The CaCO3 species are predominantly calcite and vaterite. Higher Ca2+ and urea concentrations in cementation solution resulted in higher CaCO3 yield but lower Ca2+ utilization efficiency. The main mechanism of the “surface barrier” to enhance Pb2+ stability on biochar was likely the encapsulation effect: it physically blocked the contact between acids and Pb2+ on biochar, and chemically buffer the acidic attack from the environment. The performance of the “surface barrier” depends on both the yield of CaCO3 and their distribution uniformity on biochar's surface. This study shed lights on the potential application of the “surface barrier” strategy combining biochar and MICP technologies for enhanced heavy metal immobilization.

2. 题目: Evaluation of secondary effluent organic matter removal by an in-series forward osmosis-ultrafiltration hybrid process using parallel factor analysis with self-organizing maps

This study explores removal of effluent organic matter (EfOM) from secondary municipal wastewater effluent by a custom-devised in-series forward osmosis-ultrafiltration (FO-UF) hybrid system in which naturally-driven osmotic pressure, induced by the concentration difference between the feed solution and the draw solution, is a sole driving force for post UF filtration. Water flux and reverse salt flux are greatly affected by concentration and type of draw solution as well as different FO membrane configurations of the active layer facing feed solution (AL−FS) and the active layer facing draw solution (AL−DS). Maximum fluorescence intensity values obtained from parallel factor analysis (PARAFAC) revealed that the FO-UF hybrid process removes EfOM up to 97% of initial concentration over 2 h experimentation, owing to 6−8% of additional removal by post UF membrane. PARAFAC and self-organizing maps (SOM) modeling revealed that humic-like substances are removed preferentially over protein-like and smaller-sized organics in both AL−FS and AL−DS modes. However, in AL−DS mode, fouling, possibly due to humic-like substances, followed by deteriorating water quality, is observed earlier than in AL−FS mode. During the FO-UF processes, overall properties of EfOM in feed solution are shifted to hydrophilic and smaller-sized organic matter. This work provides a concept of pump-less FO-UF hybrid filtration and demonstrates the proposed system as a feasible option for EfOM removal in water reuse. As the first of its kind, the incorporation of PARAFAC with SOM modeling in FO process gives an insight into the fouling and transport of EfOM in the AL-FS and AL-DS modes.

3. 题目: Earthworms enhance the bioremediation of tris(2-butoxyethyl) phosphate-contaminated soil by releasing degrading microbes

The escalating awareness of the environmental risks posed by organophosphorus flame retardants (OPFRs), e.g., tris(2-butoxyethyl) phosphate (TBOEP), necessitates the development of effective approaches to mitigate their adverse ecological effects. However, research on the remediation of OPFR-contaminated soil remains limited. In this study, a strategy is proposed to enhance the microbial remediation of TBOEP-contaminated soil through the introduction of exotic earthworms (Eisenia fetida). The presence of earthworms led to a substantial increase in the 28-d removal rates of TBOEP at concentrations of 0.05, 0.5, and 5 mg/kg, with improvements of 32.3±2.0%, 33.2±1.3%, and 33.0±5.6% compared to rates in the absence of earthworms, respectively. The underlying mechanisms for this enhancement include the earthworm-mediated enrichment of TBOEP-degrading bacteria, particularly Rhodococcus, Flavobacterium, and Pseudomonas, and the transfer of Rhodococcus from the earthworm gut to the soil, resulting in an increased relative abundance within the soil. Concurrently, the earthworms stimulated soil peroxidase activity, facilitating the oxidative degradation of TBOEP. Furthermore, the rise in dissolved organic matter content following earthworm treatment fostered the growth of degrading bacteria in the soil. Rhodococcus emerged as a dominant contributor to soil TBOEP removal, consuming humic-like compounds in dissolved organic matter. This investigation underscores the significance of gut microbes and offers valuable insights for the application of earthworm-based remediation strategies in OPFR-contaminated soil.

4. 题目: Labile carbon and soil texture control nitrogen transformation in deep vadose zone

Understanding transient nitrogen (N) storage and transformation in the deep vadose zone is critical for controlling groundwater contamination by nitrate. The occurrence of organic and inorganic forms of carbon (C) and nitrogen and their importance in the deep vadose zone is not well characterized due to difficulty in sampling and limited studies. We sampled and characterized these pools beneath 27 croplands with different vadose zone thicknesses (6–45 m). We measured nitrate and ammonium in different depths for the 27 sites to evaluate inorganic N storage. We measured total Kjeldahl nitrogen (TKN), hot-water extractable organic carbon (EOC), soil organic carbon (SOC), and δ13C for two sites to understand the role of organic N and C pools in N transformations. Inorganic N stocks in the vadose zone were 21.7–1043.6 g m−2 across 27 sites; the thicker vadose zone significantly stored more inorganic N (p < 0.05). We observed significant reservoirs of TKN and SOC at depths, likely representing paleosols that may provide organic C and N to subsurface microbes. The occurrence of deep C and N needs to be addressed in future research on terrestrial C and N storage potential. The increase of ammonium and EOC and δ13C value in the proximity of these horizons is consistent with N mineralization. An increase of nitrate, concurrent with the sandy soil texture and the water-filled pore space (WFPS) of 78 %, suggests that deep vadose zone nitrification may be supported in vadose zones with organic-rich layers such as paleosol. A profile showing the decrease of nitrate concentrations, concurrent with the clay soil texture and the WFPS of 91 %, also suggests denitrification may be an important process. Our study shows that microbial N transformation is possible even in deep vadose zone with co-occurrence of C and N sources and controlled by labile C availability and soil texture.

5. 题目: Selenium in Soil-plant System: Transport, Detoxification and Bioremediation

Selenium (Se) is an essential micronutrient for humans and a beneficial element for plants. However, high Se doses always exhibit hazardous effects. Recently, Se toxicity in plant-soil system has received increasing attention. This review will summarize (1) Se concentration in soils and its sources, (2) Se bioavailability in soils and influencing factors, (3) mechanisms on Se uptake and translocation in plants, (4) toxicity and detoxification of Se in plants and (5) strategies to remediate Se pollution. High Se concentration mainly results from wastewater discharge and industrial waste dumping. Selenate (Se [VI]) and selenite (Se [IV]) are the two primary forms absorbed by plants. Soil conditions such as pH, redox potential, organic matter and microorganisms will influence Se bioavailability. In plants, excessive Se will interfere with element uptake, depress photosynthetic pigment biosynthesis, generate oxidative damages and cause genotoxicity. Plants employ a series of strategies to detoxify Se, such as activating antioxidant defense systems and sequestrating excessive Se in the vacuole. In order to alleviate Se toxicity to plants, some strategies can be applied, including phytoremediation, OM remediation, microbial remediation, adsorption technique, chemical reduction technology and exogenous substances (such as Methyl jasmonate, Nitric oxide and Melatonin). This review is expected to expand the knowledge of Se toxicity/detoxicity in soil-plant system and offer valuable insights into soils Se pollution remediation strategies.

6. 题目: Composition of sedimentary organic matter in Thrissur Kole wetland, southwest India

Spatio-temporal distribution dynamics of various biochemical components in Thrissur Kole wetland were analyzed to assess the quality of organic matter (OM) and trophic status. Thrissur Kole wetland forms part of the Vembanad wetland system, located on the southwest coast of India. Surface sediment samples were collected from sixteen sites during the pre-monsoon (February 2019) and monsoon (August 2019) seasons. Concentration of biochemical parameters displayed the trend as follows: total carbohydrates > total protein > tannin and lignin > total lipids. Intermediate values of C/N ratios [average: 17.15 ± 0.86 (pre-monsoon), 9.81 ± 0.42 (monsoon)], indicated a mixed origin of OM. The occurrence of high tannin and lignin content substantiated terrestrial vascular plant input to the wetland ecosystem. Elevated levels of PRT were due to anthropogenic inputs via aquaculture activities and guano of birds. Majority of the sites exhibited lower values of protein to carbohydrate ratios (< 1) revealed the occurrence of aged sedimentary OM. Lower values of total lipid to total carbohydrate ratio (< 1) indicated lower nutritional quality of the OM. Lower % contribution of labile OM to total OM, lower biopolymeric carbon to total organic carbon ratio and lower algal contribution to the biopolymeric carbon suggested that a bulk fraction of OM exists as refractory. Based on protein and carbohydrate content, biopolymeric carbon and algal contribution to biopolymeric carbon, trophic state of the wetland system was evaluated as hypertrophic which implies deterioration in ecosystem health.

7. 题目: Biochar-amended compost as a promising soil amendment for enhancing plant productivity: A meta-analysis study

A meta-analysis was conducted to evaluate the effect of biochar-amended compost (BAC) on plant productivity (PP) and soil quality. The analysis was based on observations from 47 peer-reviewed publications. The results showed that BAC application significantly increased PP by 74.9 %, the total nitrogen content of soil by 37.6 %, and the organic matter content of soil by 98.6 %. Additionally, BAC application significantly decreased the bioavailability of cadmium (−58.3 %), lead (−50.1 %), and zinc (−87.3 %). However, the bioavailability of copper increased by 30.1 %. The study explored the key factors regulating the response of PP to BAC through subgroup analysis. It was found that the increase in the organic matter content of the soil was the key mechanism for PP improvement. The recommended rate of BAC application for improving PP was found to be between 10 and 20 t ha−1. Overall, the findings of this study are significant in providing data support and technical guidance for the application of BAC in agricultural production. However, the high heterogeneity of BAC application conditions, soil properties, and plant types suggests that site-specific factors should be considered when applying BAC to soils.

8. 题目: Factors influencing the recovery of organic nitrogen from fresh human urine dosed with organic/inorganic acids and concentrated by evaporation in ambient conditions

To feed the world without transgressing regional and planetary boundaries for nitrogen and phosphorus, one promising strategy is to return nutrients present in domestic wastewater to farmland. This study tested a novel approach for producing bio-based solid fertilisers by concentrating source-separated human urine through acidification and dehydration. Thermodynamic simulations and laboratory experiments were conducted to evaluate changes in chemistry of real fresh urine dosed and dehydrated using two different organic and inorganic acids. The results showed that an acid dose of 1.36 g H2SO4 L−1, 2.86 g H3PO4 L−1, 2.53 g C2H2O4·2H2O L−1 and 5.9 g C6H8O7 L−1 was sufficient to maintain pH ≤3.0 and prevent enzymatic ureolysis in urine during dehydration. Unlike alkaline dehydration using Ca(OH)2 where calcite formation limits the nutrient content of fertiliser products (e.g. <15 % nitrogen), there is greater value proposition in acid dehydration of urine, as the products contain 17.9–21.2 % nitrogen, 1.1–3.6 % phosphorus, 4.2–5.6 % potassium and 15.4–19.4 % carbon. While the treatment recovered all phosphorus, recovery of nitrogen in the solid products was 74 % (±4 %). Follow-up experiments revealed that hydrolytic breakdown of urea to ammonia, chemically or enzymatically, was not the reason for the nitrogen losses. Instead, we posit that urea breaks down to ammonium cyanate, which then reacts with amino and sulfhydryl groups of amino acids excreted in urine. Overall, the organic acids evaluated in this study are promising for decentralised urine treatment, as they are naturally present in food and therefore already excreted in human urine.

9. 题目: Facile fabrication of Zero-valent-iron biochar from red mud for bisulfite activation in wastewater treatment: Performance and mechanism

Bisulfate (BS) has recently attracted increasing attention as a green alternative to persulfates (PS) in sulfate radicals based advanced oxidation processes (SR-AOPs). Moreover, facile fabrication of zero-valent iron (ZVI) biochar composites and disposal of red mud remain challenges. Herein, ZVI biochar was synthesized from red mud (RM) and ginkgo leaves (GLs) by one-step pyrolysis and employed as an effective activator of BS for acid orange 7 (AO7) removal. Characterizations including SEM, BET, XRD and FTIR revealed that porous structure and Fe${}^{0}$ particles of ZVI biochar were gradually developed with the increasing pyrolysis temperature from 400–800 °C. The ZVI biochar synthesized at 800 °C with RM: GLs mass ratio of 2:1 (RMBC2-800) showed optimal performance as that 95.3% of AO7 (60 mg/L) was removed with 2.5 mM of BS and 0.5 g/L of RMBC2-800 under an initial pH of 6 within 60 min. Mechanism studies showed that SO4 ${\cdot }^{-}$, OH$\cdot$, O${}_{2}{\cdot }^{-}$ and 1O2 were the active oxygen species in the catalytic reaction. Both Fe0 and the ketonic functional groups (CO) contributed to the high catalytic activity of RMBC2-800. Based on GC-MS analysis, seven degradation intermediates were identified and a possible degradation pathway was proposed. Furthermore, RMBC2-800 could be easily recycled by magnetic separation after wastewater treatment. This study not only proposed a highly efficient ZVI biochar/BS system in organic wastewater treatment, but also guided for effective utilization of red mud to realize the strategy of “treat waste by waste”.

10. 题目: Risk assessment and source apportionment for metals in sediments of Kaptai Lake in Bangladesh using individual and synergistic indices and a receptor model

Metal enrichment in lake sediments originating from multiple sources can threaten both the aquatic ecosystem and human health. Therefore, assessment of the eco-environmental risks and potential sources of metals in the sediments is essential for effective lake management. Here, we analyzed the sediment metal contents of Kaptai Lake, the largest lake in Bangladesh for the first time with this study. The results indicated that only Cr and Ni contents among the metals studied exceeded the probable effect concentrations (PEC) at 25.42 % and 55.93 % of the sampling stations, respectively. All metals at most sampling stations showed low contamination and low ecological risk based on the individual indices (geoaccumulation index, contamination factor, ecological risk factor, enrichment factor and modified hazard quotient). There was no significant risk from the combined metals in the sediments of the lake according to the synergistic indices (toxic risk index, Nemerow risk index, ecological risk index, Nemerow pollution index and pollution load index). Organic matter and silt were significant sediment parameters that favored the accumulation of Cr, Fe, Cu, Pb and Mn. In the absolute principle component scores-multiple linear regression model (APCS-MLR), five potential sources of metals were identified in the sediments: Zn, Mn, Co and Cd mainly from natural sources and to a lesser extent from agricultural and aquacultural activities, Ni, Cr and Fe from parent materials, Pb and Cu mainly from natural sources and to a lesser extent from vehicle emissions, Hg and U from lithogenic sources, and As from natural sources. This study will improve our knowledge of the sedimentary metal contents of Kaptai Lake and provide helpful information for developing effective lake management and pollution control strategies.

11. 题目: Removal of heavy metals lead and ciprofloxacin from farm wastewater using peanut shell biochar

In this paper, peanut shells were used as the raw material for preparing biochar (PBC), and artificial simulated aging was used to age the PBC. To investigate the effectiveness of biochar before and after aging for the removal of Pb and ciprofloxacin (CIP) alone and the feasibility of simultaneous removal of Pb and CIP. The effects of different aging methods on the physicochemical properties of biochar were investigated by measuring the specific surface area (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared absorption spectrometry (FTIR) of biochar. The results showed that the C content of biochar decreased after aging, while the O/C, H/C, (N+O)/C, and O contents increased. Kinetic adsorption, adsorption isothermal and competitive adsorption experiments were performed to study the adsorption properties of CIP and Pb${}^{2+}$ by aging biochar under single and combined pollution systems. Aging inhibited the adsorption of ciprofloxacin on biochar, and the inhibition size was ranked as high-temperature aging > freeze-thaw cycles aging > natural aging. However, the effect of aging on the adsorption of Pb${}^{2+}$ by biochar was insignificant. Pb${}^{2+}$ in the complex contamination system would compete with CIP for oxygen-containing functional groups and adsorption sites on biochar, indicating that the pollutant adsorption mechanism by biochar is complex and influenced by various factors such as aging methods and pollutant species. This study shows that regional climatic factors and target pollutant species must be considered when applying biochar for pollutant removal, which may affect the long-term effects of pollution remediation.

12. 题目: Differences in ecosystem organic carbon stocks due to species selection and site elevation of restored mangrove forests

Mangrove forests are important blue carbon ecosystems. Site elevation and species selection are very important for successful restoration of mangrove forests. It is vital for calculating carbon sequestration of mangrove forests to know the combined influences of species selection and site elevation on the ecosystem organic carbon stock (EOCS). In this study, the combined effects of site elevation (above or below local mean sea level) and species selection (Kandelia obovata vs Avicennia marina) on the EOCS including vegetation organic carbon stock (VOCS) and soil organic carbon stock (SOCS) were quantified through an in situ planting experiment. The total vegetation biomass decreased approximately 48.79% in the K. obovata forest and 19.71% in the A. marina forest because of changes in each component (leaf, stem, branch and root) biomass with the decreases in site elevation. Due to changes in SOCS and VOCS with the decreases in site elevation, EOCS of the A. marina forest decreased approximately 12.3% and EOCS of the K. obovata forest decreased approximately 40.3%. At the site below local mean sea level, the A. marina forest had higher EOCS than the K. obovata forest. These indicated that in order to maximize carbon sequestration in restored mangrove forests, A. marina should be selected for the projects with site elevation below local mean sea level, while K. obovata should be selected for those with site elevation above local mean sea level.

13. 题目: Impacts of land use conversions on soil organic carbon in a warming-induced agricultural frontier in Northern Ontario, Canada under historical and future climate

Land conversion from forest to agriculture in higher latitude regions such as the Great Clay Belt of northern Ontario, Canada is expected to intensify due to warming. It is critical to minimize soil organic carbon (SOC) loss, but there is limited understanding of best land management practices for these Northern agricultural frontiers. We conducted a measurement campaign to assess changes in SOC after land conversion from native forest to either permanent pasture or to arable cropping by measuring SOC content (0–60 cm) at six farms with different land uses over the past 68 years (1950–2018). The Denitrification-Decomposition (DNDC) model was validated for historical SOC trends and then used to assess the impacts of future climate change on crop yields, SOC stocks, and SOC sequestration rates from 1954 to 2070 under three Shared Socio-economic Pathways (SSPs) scenarios from the Coupled Model Intercomparison Project Phase 6. Three land uses (1) continuous barley-oats (BO), (2) continuous Legume hay-BO, (3) continuous Pasture; and two land use conversions (4) pasture from 1954-2014 and then converted to BO from 2015-2070 (Pasture » BO) and (5) BO from 1954 to 2014 and then converted to pasture from 2015-2070 (BO » Pasture) were considered. Averaged across all six farms, the measured SOC stocks 68 years after conversion from forest were 22.7 and 25.3% higher under pasture than under forest and arable cropping, respectively. The DNDC model demonstrated good performance in simulating yields of annual crops, legume hay and pasture as well as SOC stocks across all sites. Under future climate scenarios, higher SOC stocks were predicted for all land use conversions relative to the historical period. Under different land use, predicted SOC stocks were highest for continuous pasture, followed by BO » Pasture, Pasture » BO, Legume hay-BO and lowest for continuous BO. We predicted that the SOC sequestration rate would decrease for all land uses in the period 2015–2070 relative to 1954–2014, except for BO » Pasture. The predicted change declined from 0.35 to 0.22–0.28 Mg C ha−1 yr−1 for continuous pasture, but when change in management occurred from BO to pasture the rate of SOC gain increased. This underscores the potential role of pasture and crop diversification in avoiding SOC losses in agricultural frontiers induced by climate-warming.

14. 题目: Functionalization of the biochar from melon seed shell via introducing nitrogen species

The biochar from the pyrolysis of melon seed shell (MSS) not only can be used as solid fuel but also can be used as catalysts. However, the low nitrogen content in the biochar results in low activity for photocatalytic hydrogen production from water. In this study, melamine was used as an externally added nitrogen source to dope the MSS-derived biochar. The results indicated that melamine could react with MSS during their self-assembly at low temperatures, while the reactions between their derivatives became more intensive during their co-pyrolysis. The presence of the N-containing intermediates enhanced the condensation while suppressed the craking reactions in the pyrolysis, producing more bio-oil but less gases. The bio-oil contained abundant N-containing organics resulting from the reactions of amines with the carboxylic acids, ketones, aldehydes, etc. The biochar also contained abundant N-containing functionalities in the form of C-N, C=N, and N-H in C-N polymer and heptazine structure, formed through similar reaction pathways. These nitrogen-containing species not only could improve the pore structure and band gap of the biochar, but also increase its density and mobility of charge carriers. These rendered the biochar, especially the one produced at the pyrolysis temperature of 400°C, with superior activity for catalyzing H2 generation at a rate of 6.9 μmol/g·h from the photocatalytic splitting of water.

15. 题目: Biogeochemical Argo floats reveal the evolution of subsurface chlorophyll and particulate organic carbon in southeast Indian Ocean eddies

16. 题目: Sorption Characteristics of Methylene Blue on Medulla Tetrapanacis Biochar and its Activation Technology

As a simple and low-cost sorbent, biochar can effectively remove inorganic and organic pollutants, but the sorption performance of biochar from different biomass sources on pollutants varies greatly. Finding a biochar material with higher sorption capability and activating methods of biochar to further improve the sorption performance should be very important and basic for the promotion of biochar. In this paper, the plant-based biochar (PBC) produced by Medulla tetrapanacis and activated PBCs treated with HCl, NaOH, and KCl were used as sorbents to remove methylene blue (MB). The PBCs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and BET-N2. The effects of the PBC, HCl-PBC, NaOH-PBC, and KCl-PBC on the removal of MB under different contact times, concentrations, pH, and temperature were tested, respectively. Compared with reported biochar samples, the sorption capacity of PBC on MB is the largest, and the method of activated PBC using KCl works best. The maximum sorption capacity of KCl-PBC is increased by 98.71%, reaching 228.62 mg/g, and is much larger than that of PBC (114.87 mg/g). The activation mechanism of the biochar is dredging the pores and dissolving impurities. The PBC and activated PBCs derived from Medulla tetrapanacis are promising and effective sorbent materials for environmental protection.

17. 题目: Heterogeneous characteristics and absorption enhancement of refractory black carbon in an urban city of China

In this study, field measurement was conducted using an integrated online monitoring system to characterize heterogeneous properties and light absorption of refractory black carbon (rBC). rBC particles are mainly from the incomplete combustion of carbonaceous fuels. With the data collected from a single particle soot photometer, thickly coated (BCkc) and thinly coated (BCnc) particles are characterized with their lag times. With different responses to the precipitation, a dramatical decline of 83 % in the number concentration of BCkc is shown after rainfall, while that of BCnc decreases by 39 %. There is a contrast in core size distribution that BCkc is always with larger particle sizes but has smaller core mass median diameters (MMD) than BCnc. The mean rBC-containing particle mass absorption cross-section (MAC) is 6.70 ± 1.52 m2 g−1, while the corresponding rBC core is 4.90 ± 1.02 m2 g−1. Interestingly, there are wide variations in the core MAC values which range by 57 % from 3.79 to 5.95 m2 g−1, which are also closely related to those of the whole rBC-containing particles with a Pearson correlation of 0.58 (p < 0.01). Errors would be made if we eliminate the discrepancies and set the core MAC as a constant when calculating absorption enhancement (Eabs). In this study, the mean Eabs is 1.37 ± 0.11 while the source apportionment shows that there are five contributors of Eabs including secondary aging (37 %), coal combustion (26 %), fugitive dust (15 %), biomass burning (13 %) and traffic-related emissions (9 %). Secondary aging is found to be the highest contributor due to the liquid phase reactions in formations of secondary inorganic aerosol. Our study characterizes property diversities and provides insights into the sources impacting the light absorption of rBC and will be helpful for controlling it in the future.

18. 题目: Soil organic carbon distribution and storage along reclamation chronosequences in a typical coastal farming area, Eastern China

Soil organic carbon (SOC) is an important indicator for soil quality evaluation. It is closely associated with soil fertility, and also has a great impact on the terrestrial carbon cycle. In this study, the distribution and storage of SOC were evaluated at the different reclamation chronosequences [(a) 2004–2007, (b) 1995–2004, (c) 1955–1995, (d) 1024–1955, and (e) < 1024)] in Dongtai City of Jiangsu Province, Eastern China. The results showed that the average SOC content ranged between 3.98 and 8.49 g/kg, which declined with the increase of soil depth. The soil bulk density exhibited the opposite trend, and had only a slight change throughout the entire study area. Both the SOC content and soil density decreased as the reclamation age increased. The SOC content were significantly higher under the 1024–1955 and < 1024 reclamation stages than the other reclamation stages. The storage of SOC in the study area was 8.03 × 105 kg at the 0–40 cm soil depth, with a SOCD of 3.07 kg/m2, which was markedly lower than the mean value in Jiangsu Province. It was concluded that the SOC storage increased proportionally to the reclamation age, and notable potential for carbon sequestration was expectable in the coastal farming area, Eastern China.

19. 题目: Oxidation treatment of shale gas produced water: Molecular changes in dissolved organic matter composition and toxicity evaluation

Produced water (PW) is the largest waste stream generated by hydraulic fracturing in an unconventional shale gas reservoir. Oxidation processes (OPs) are frequently used as advanced treatment method in highly complicated water matrix treatments. However, the degradation efficiency is the main focus of research, whereas organic compounds and their toxicity have not been properly explored. Here, we obtained the characterization and transformation of dissolved organic matters in PW samples from the first shale gas field of China by two selected OPs using FT-ICR MS. CHO, CHON, CHOS, and CHONS heterocyclic compounds associated with lignins/CRAM-like, aliphatic/proteins, and carbohydrates compounds were the major organic compounds identified. Electrochemical Fe2+/HClO oxidation preferentially removed aromatic structures, unsaturated hydrocarbons, and tannin compounds with a double-bond equivalence (DBE) value below 7 to more saturated compounds. Nevertheless, Fe (VI) degradation manifested in CHOS compounds with low DBE values, especially single bond compounds. Oxygen- and Sulfur-containing substances, primarily O4-11, S1O3-S1O12, N1S1O4, and N2S1O10 classes, were the main recalcitrant components in OPs. The toxicity response byproducts need special attention. The toxicity assessment showed the significant DNA damage caused by Fe2+/HClO oxidation. Our results led to discussions on designing appropriate treatment strategies and the development of PW discharge or reuse standards.

20. 题目: Black carbon in contrasting environments in India: Temporal variability, source apportionment and radiative forcing

Analyses of black carbon (BC) data from three different environments in India - Delhi megacity, Srinagar metropolitan and Gulmarg hill station, showed that Delhi had the highest annual average BC concentration (12.3 ± 10.2 μg m−3), followed by Srinagar (4.3 ± 5 μg m−3) and Gulmarg (2.4 ± 2 μg m−3). The inflow of aerosols from the neighbouring agricultural regions, notably during Winter, causes Delhi to have the highest seasonal average BC (16.8 μg m−3). Srinagar had the highest average seasonal BC during autumn (6.3 μg m−3) due to the burning of horticulture residue and hardwood for charcoal making and residential heating. At Gulmarg, on the other hand, the winter season's high BC (2.2 μg m−3) is due to the increased emissions from the tourist traffic, snowmobile/ATVs and wood burning for residential heating. BC concentrations in Delhi and Srinagar were roughly in line with their population size. However, compared to sites with the similar population, BC at Gulmarg was roughly twice higher than the other sites. There was a higher contribution to BC from fossil fuels than biomass burning at all three sites, which indicates that cars are the primary source of BC. Overall, values of BC aerosol optical properties in Delhi are much higher than those in Srinagar and Gulmarg. During the cold season, continental air masses transport BC from the neighboring areas to Delhi and westerlies enhance the local BC loading at Srinagar and Gulmarg. The predominant presence of absorbing aerosols, particularly BC, during late autumn and winter at all three sites leads to an increase in aerosol optical depth (AOD), a reduction in single scattering albedo (SSA) and an increase in asymmetry parameter (AP). As a result, there is a significant increase in the radiative forcing of the atmosphere (RFATM), with the highest values observed in January in Delhi (+71.5 W m−2) and Srinagar (+56.05 W m−2), and in November at Gulmarg (+18.5 W m−2). These findings suggest that small rural towns that are affected by seasonal emissions, low planetary boundary layers, and frequent temperature inversions, can contribute to a substantial amount of radiative forcing. This study provides a larger perspective on increasing BC in Delhi, and urban-rural fringe areas in the Indian Himalayas, which is crucial for identifying what actions must be taken to control BC emissions to reduce impacts on cryosphere, human health and other sectors.

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