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221. 题目: Physicochemical fractionation reveals increased soil organic carbon storage in a wolfberry orchard under cover cropping
文章编号: N24112015
期刊: Plant and Soil
作者: Fang Wang, Haonan Chen, Yamiao Gao, Wenhui Li, Lizhen Zhu, Liu Yang, Ray R Weil, Xiongxiong Nan
更新时间: 2024-11-20
摘要:

Background and aims

Characterizing the responses of soil organic carbon (SOC) fractions to agricultural management practices is essential for understanding SOC stability in agroecosystems. To establish a rational soil management regime for wolfberry (Lycium barbarum L.) production, this study investigated the long-term effects of cover cropping with manure on the storage of SOC and its fractions in a wolfberry orchard in Ningxia, Northwest China.

Methods

A field experiment was conducted using wolfberry grown as a monocrop or cover cropped with forage radish under zero, moderate, and high rates of animal manure.

Results

After seven years of cover cropping, SOC concentrations in the topsoil (0–20 cm) were higher than those under monocropping, and the difference was most pronounced under moderate manure application. The annual SOC accumulation rates reached ~ 1.00 t ha^–1a^–1 under cover cropping with moderate and high manure application, and the SOC storage efficiency of exogenous organic carbon input was 33.0%. Cover cropping also increased the concentrations of unprotected coarse particulate organic carbon fraction, as well as physically protected particulate organic carbon, chemically protected clay-sized, and biochemically protected silt-sized fractions in the topsoil. Unprotected SOC was the predominant form of organic carbon accumulated. A positive linear association emerged between SOC stock and exogenous organic carbon input in the topsoil. Despite weak responses of SOC and its fractions in the subsoil (20–40 cm), their trends were basically consistent with those observed in the topsoil.

Conclusions

Organic carbon inputs from multiple sources boosted SOC storage in the wolfberry orchard. Cover cropping with moderate manure application effectively improved SOC concentrations in the coarse and intra-aggregate particulate fractions, showing great potential for enhancing SOC storage. Future studies should delve deeper into the response mechanisms of SOC fractions from a microbiological perspective to decipher the role of cover crops and manure in the accumulation and transformation of SOC fractions.

222. 题目: Impact of pyrolysis temperature on heavy metals environmental risk in biochar derived from co-pyrolysis of Alternanthera philoxeroides and sludge
文章编号: N24112014
期刊: Journal of Environmental Chemical Engineering
作者: Tong Xiao, Pikun Zhou, Yun Liu, Kaike Zhang, Fangyu Liu, Ge Guo, Fuquan Ni, Yu Deng
更新时间: 2024-11-20
摘要: Resource utilization of dried livestock sewage sludge (SS) and invasive plants, e.g. Alternanthera philoxeroides (AP) is the focus of cracking the environmental challenges. In this study, AP and sludge were used as raw materials to prepare co-pyrolysis biochar at 300-800 °C. The total amount of heavy metals, BCR forms, and leaching toxicity were analyzed to evaluate the environmental risk of heavy metals in biochar. The results showed that the proportion of unstable states and leaching toxicity of six heavy metals decreased, and the total amount and proportion of stable states increased with the increasing pyrolysis temperature. Compared with SS and SBCs, the unstable fraction and leaching toxicity of heavy metals in SABCs were significantly reduced, and the values of RAC and RI were lower. The RI value of SS was 1001.40, which belongs to a very high-risk level, while the RI of SABC800 was low risk with a value of 51.69, indicating that the co-pyrolysis of AP and SS at high temperatures could effectively reduce the environmental risk of biochar. In addition, the E_r value of Cd in SBCs was significantly higher than that of SS, but it was lower in SABCs than in SS, which suggested that AP addition is beneficial to reducing the ecotoxicity and environmental risk of Cd in livestock sewage sludge. This study demonstrates the superiority of AP addition in reducing the environmental risk of heavy metals, especially Cd in SS, and provides a new idea of resource utilization for invasive plants and livestock sewage sludge disposal.

223. 题目: Anthropic dark soils horizons in western Siberian taiga: origin, soil chemistry and sustainability of organic matter
文章编号: N24112013
期刊: Geoderma
作者: Daria S Derbilova, Priscia Oliva, David Sebag, Sergei Loiko, Asap Idimeshev, Eugeniy Barsukov, Liudmila S Shirokova, Jean-Jacques Braun, Oleg S Pokrovsky
更新时间: 2024-11-20
摘要: The impact of human activity on soil carbon stock and soil fertility is at the forefront of scientific research. In the past, human practices improved soil fertility and increased carbon storage over long periods of time. Studying the resulting anthrosols provides access to their evolution over time scales that are unavailable otherwise. These archeological Anthrosols have been extensively investigated in Amazonia and Europe, but are virtually unknown in Siberia. Here we examined four soil profiles from two archeological sites in western Siberia, along with two corresponding control profiles. The first site, Ketskii Ostrog, is an ancient 18th century fortress occupied by an agricultural population. The second site, Shaitan III, is a historical settlement of metallurgists and horse-breeders active from the 10th through the 17th century. We aimed to understand whether human activity at these two sites modified soil carbon and chemical fertility, and to compare these soils with other studied global anthrosols. We revealed a contrasting impact of human activity for these two sites. At Ketskii Ostrog, ancient agricultural practices improved soil chemical fertility, with the effects persisting until present day. Human activities exhibited a beneficial influence on deep horizons through improvements in their cation exchange capacity, pH and nutrient (P and Ca) concentrations. The Ketskii Ostrog soils were similar to plaggic soils documented in Northern Europe, which are characterized by the addition of fresh organic matter (OM) in the form of manure which was purposefully added to improve soil fertility. At Shaitan III, chemical fertility has also been improved, but to a lesser extent. In contrast to Ketskii Ostrog, Shaitan III soils are rich in charred organic matter and strongly resemble Amazonian Dark Earths with their physico-chemical properties. The Shaitan III soils also have a different origin, as the result of unintentional human impact. Anthropisation has increased carbon stocks in the soil at both sites; however, Shaitan III soils prove to be a more effective carbon sink than at Ketskii Ostrog. This two-fold dichotomy (intentional/unintentional vs. fresh OM/charred OM) is not limited by geographical borders (Amazonia, Europe, or Siberia) and soil typology as currently proposed in the WRB. This highlights the need for concerted studies on anthropised archaeological soils in regard to their importance for both soil fertility and carbon storage.

224. 题目: Organic carbon recycling for net zero emissions and sustainable organic carbon flow between urban and rural areas
文章编号: N24112012
期刊: Environmental Technology & Innovation
作者: Wenhai Luo, Konrad Koch, Quan Wang
更新时间: 2024-11-20
摘要: This virtual special issue (VSI) compiles recent cutting-edge research on organic carbon recycling (OCR) for net zero emissions and sustainable organic carbon flow between urban and rural areas from the perspectives of advanced technologies, techno-economic assessment, and case studies. Organic residues, including food waste, sewage sludge, livestock manure and agricultural biomass, are not waste but rather a vein of essential resources in a modern circular economy. From these materials, energy, nutrients, and even biopolymers have been derived and produced at an industrial scale. However, the current management practice is often in silos with notable disconnection between areas, where food is consumed (urban) and produced (rural). This disconnection is further hampered by various technical, regulatory, and behaviour challenges. Recognizing the importance of organic carbon preservation, recent and significant efforts have been dedicated to developing efficient technologies, engineering facilities, regulatory frameworks, and management practices to enhance resource recovery from organic residues while promoting green, low-carbon and high-quality development in urban-rural areas. With the great support from the editorial team of Environmental Technology & Innovation, the guest editors, Dr. Wenhai Luo from China Agricultural University, Dr. Konrad Koch from the Technical University of Munich, and Dr. Quan Wang from Northwest A&F University, initiated the OCR VSI in January 2023 to collect novel studies on advanced technologies for organic waste treatment and/or resource recovery. The VSI provides a platform for researchers and practitioners to disseminate and share new knowledge for the rapid and sustainable development of organic waste recycling. The VSI was highly welcome in the field with the submission of reviews, case studies, and research papers spanning the life cycle of organic waste recycling from pre-treatment, main treatment, and product application, for example, to farmland. The main treatment processes include anaerobic digestion, aerobic composting, pyrolysis, and incineration, of which physical, chemical, and biological mechanisms for carbon recycling toward net zero emissions have been investigated. More importantly, the performance of organic waste recycling to farmland soil has been highlighted to couple organic carbon flow between urban and rural areas. With the progress in targeting organic transformation, carbon can be maximumly recycled in various forms, such as methane and humus for energy and nutrient recovery in anaerobic digestion and aerobic composting, respectively. For instance, functional materials, such as zero-valent iron as critically highlighted in a review paper in this SVI, can be potentially practiced in industrial anaerobic digestion systems to enhance methane yield from organic waste for producing renewable energy. The VSI provides fundamental and practical knowledge to further promote resource recovery from organic waste toward net zero emission. Thus, the VSI is extremely valuable to academic and industry in waste management and sustainable development. Both breakthrough and practical investigation, such as microbial dynamics and case assessment are highly transferable to boost the development of the organic waste recycling industry.

225. 题目: Effects of Polyethylene and Poly (butyleneadipate-co-terephthalate) contamination on soil respiration and carbon sequestration
文章编号: N24112011
期刊: Environmental Pollution
作者: Mengyu Liu, Yao Yu, Ying Liu, Sha Xue, Darrell W S Tang, Xiaomei Yang
更新时间: 2024-11-20
摘要: To address plastic pollution in agricultural soils due to polyethylene plastic film mulch used, biodegradable film is being studied as a promising alternative material for sustainable agriculture. However, the impact of biodegradable and polyethylene microplastics on soil carbon remains unclear. The field experiment was conducted with Poly (butyleneadipate-co-terephthalate) debris (PBAT-D, 0.5-2 cm), low-density polyethylene debris (LDPE-D, 0.5-2 cm) and microplastic (LDPE-Mi, 500-1000 μm) contaminated soil (0% (control), 0.05%, 0.1%, 0.2%, 0.5%, 1% and 2% w:w) planted with soybean, to explore potential impacts on soil respiration (Rs), soil organic carbon (SOC) and carbon fractions (microbial biomass carbon (MBC), dissolved organic carbon (DOC), easily oxidizable carbon (EOC), particulate organic carbon (POC), mineral-associated organic carbon (MAOC)), and C-enzymes (β-glucosidase, β-xylosidase, cellobiohydrolase). Results showed that PBAT-D, LDPE-D and LDPE-Mi significantly inhibited Rs compared with the control during the flowering and harvesting stages (p<0.05). SOC significantly increased in the PBAT-D treatments at both stages, and in the LDPE-Mi treatments at the harvesting stage, but decreased in the LDPE-D treatments at the flowering stage. In the PBAT-D treatments, POC increased but DOC and MAOC decreased at both stages. In the LDPE-D treatments, MBC, DOC and EOC significantly decreased but POC increased at both stages. In the LDPE-Mi treatments, MBC and DOC significantly decreased at the harvesting stage, while EOC and MAOC decreased but POC increased at the flowering stage. For C-enzymes, no significant inhibition was observed at the flowering stage, but they were significantly inhibited in all treatments at the harvesting stage. It is concluded that PBAT-D facilitates soil carbon sequestration, which may potentially alter the soil carbon pool and carbon emissions. The key significance of this study is to explore the overall effects of different forms of plastic pollution on soil carbon dynamics, and to inform future efforts to control plastic pollution in farmlands.

226. 题目: Enhanced Biofouling Resistance of Polyvinylidene fluoride Ultrafiltration Membranes Using Crayfish Shell Biochar with Calcium Species
文章编号: N24112010
期刊: Journal of Environmental Chemical Engineering
作者: Dawei Zhang, Liqing Ma, Yuewu Da, Weiying Li, Meijuan Chen, Kan Hu, Xiangzhou Meng, Yao Chen, Yu Qin
更新时间: 2024-11-20
摘要: In this study, polyvinylidene fluoride (PVDF) ultrafiltration membranes doped with crayfish shell (CFS) biochar featuring diverse calcium species (C600, C800) were fabricated (C600@PVDF, C800@PVDF) and employed in the ultrafiltration process of two typical microorganisms including Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Compared with the pristine PVDF membrane (293.9 LMH/bar), results indicated that the water flux of the modified C600@PVDF and the C800@PVDF membrane increased to 425.9 and 375.3 LMH/bar, respectively. Meanwhile, the anti-fouling ability was also improved with the final J/J₀ of 0.662, 0.532 and 0.578, 0.349 when filtering S. aureus and E. coli, while the PVDF membrane was 0.475 and 0.329, respectively. The highest anti-fouling performance of the C800@PVDF membrane was achieved by reducing the polysaccharide content in the biofilm through the cross-linking reaction between polysaccharides and the hydroxylated calcium species on the surface of C800. The reduction in polysaccharide content enhanced the acid-base (AB) repulsion between microorganisms and membranes (20243.2 (S. aureus) and 14266.3 kT (E. coli) for C800@PVDF vs 11092.3 (S. aureus) and 7873.9 kT (E. coli) for PVDF membrane), as well as among microorganisms themselves (24924.4 kT (S. aureus) and 14521.8 kT (E. coli) for C800@PVDF vs 14945.1 (S. aureus) and 10216.8 kT (E. coli) for PVDF), resulting in increased water flux and improved resilience of the membrane, thereby improving the anti-biofouling ability. Findings of the study provide the theoretical guidance for the preparation of anti-fouling membrane, and will be beneficial for biofouling control and delivering high-quality water in actual water treatment plants.

227. 题目: Cycling of dissolved organic nutrients and indications for nutrient limitations in contrasting Amazon rainforest ecosystems
文章编号: N24112009
期刊: Biogeochemistry
作者: D Frederik Lange, Simon A Schröter, Fernanda M da Luz, Elaine Pires, Yago R Santos, Jonismar S da Silva, Stefanie Hildmann, Thorsten Hoffmann, Sávio J F Ferreira, Thorsten Schäfer, Carlos A Quesada, Carsten Simon, Gerd Gleixner
更新时间: 2024-11-20
摘要:

In the nutrient-poor soils of the Amazon rainforest, phosphorus (P) emerges as a critical limiting factor for ecosystem productivity. Despite these limitations, the Amazon exhibits remarkable productivity that is maintained by its efficient nutrient recycling mechanisms. Central to this process is the role of organic matter, particularly its dissolved (DOM) fraction, which serves as a crucial nutrient reservoir for both plants and microorganisms. This study delves into the dynamics of nutrient-containing DOM within the soils of two contrasting rainforest ecosystems: clayey terra firme forests, known for their robust nutrient recycling and presumed P-limitation, and sandy white-sand forests, characterized by reduced nutrient recycling capacity and presumed nitrogen (N)-limitation. Utilizing ultra-high resolution mass spectrometry (HR-MS), we analyzed the molecular composition of dissolved organic nutrient species. We evidenced nutrient limitation applying innovative concepts: (1) assessing nutrient depletion in DOM via nutrient-to-carbon ratios, (2) comparing the composition of nutrient-enriched DOM pools across soil depth profiles to infer microbial nutrient processing, and (3) examining the temporal variability of nutrient-containing DOM as an indicator of nutrient uptake and production. Our results corroborate the hypothesis of P-limitation in terra firme forests, with significant processing of N-containing DOM also observed, indicating a synergistic demand for both P and N. Surprisingly, white-sand soils exhibited no signs of N-limitation but instead sulfur (S)-limitation, a novel finding for these ecosystems. This study highlights the diversity of potential nutrient limitations in the central Amazon and the importance of the bioavailable “black box” DOM for tropical nutrient cycles.

228. 题目: Contributions of microbial necromass and plant lignin to soil organic carbon stock in a paddy field under simulated conditions of long-term elevated CO2 and warming
文章编号: N24112008
期刊: Soil Biology and Biochemistry
作者: Yuan Liu, Weijie Li, Hongfan Meng, Qinyu Xu, Liqiang Sun, Long Zhang, Qingsong Ba, Xiaoyu Liu, Cheng Liu, Li Jiang
更新时间: 2024-11-20
摘要: Global climate change has various fundamental impacts on plant productivity and soil microbial communities, altering the formation and sequestration of soil organic carbon (SOC). However, the effect of climate change on different SOC components such as plant- derived C and microbial-derived C, remains poorly understood. A 3-year field experiment was conducted from 2018-2020 to examine the impacts of elevating atmospheric CO₂ levels (550 ppm) and warming (+2°C) on microbial necromass, plant lignin and phospholipid fatty acid (PLFA) in a Chinese rice paddy. Results showed that elevated CO₂ and warming conditions increased the SOC stock by 16.5% and 8.6%, respectively. Elevated CO₂ increased the accumulation of microbial necromass (mainly fungal) C by 24.6% and total lignin phenols by 15.8%, while also increasing the biomass of fungal PLFAs by 33.4%. In comparison, warming increased the accumulation of microbial necromass C (mainly bacterial necromass) by 11.1% and bacterial biomass by 27.1%, while it decreased total lignin phenols and their contribution to SOC by 8.3% and 15.7%, respectively. The reduction in lignin phenols and their contribution to SOC under warming conditions was mainly attributed to the lower level of plant productivity and increased activities of the enzymes β-1,4-glucosidase, β-cellobiohydrolase and xylanase. This resulted in increased plant residue conversion to microbial necromass in warmed soils. Random forest and correlation analysis indicated that soil pH, fungal biomass, root biomass and C-acquiring enzyme activities were the major factors affecting microbial necromass, while lignin phenols were mainly regulated by the ratio of fungal/bacterial necromass and fungal biomass. Overall, the combined effects of CO₂ enrichment and warming conditions increased the storage and sequestration of SOC by enhancing the accumulation of microbial necromass, which was affected by soil properties, plant root C inputs and microbial communities within soil.

229. 题目: Soil-derived dissolved organic matter and nutrient sources from urban stormwater control measures
文章编号: N24112007
期刊: Science of the Total Environment
作者: Katherine Wardinski, Heather Wall, Durelle Scott
更新时间: 2024-11-20
摘要: There has been significant investment in stormwater control measures (SCM) to reduce erosion, filter pollutants, and mitigate peak storm flows within urban watersheds. SCMs have variable hydrologic connectivity to downstream waterbodies where SCMs may rapidly export water during storm events but dry up in-between events and these alternating wet/dry cycles influence the biogeochemical processes that occur in SCM soils. While the performance of SCMs has been evaluated for nutrient removal, less is known about the potential for mobilization of nutrients and dissolved organic matter (DOM) that accumulate in SCM soils. Because of the significant aquatic ecosystem and human health implications related to excess DOM and nutrients, further work is needed to understand how urban SCMs and wetland soils may be impacting downstream water quality. Water-soluble organic matter (WSOM) was extracted from SCM and urban wetland soils located in the Rappahannock River watershed, part of the larger Chesapeake Bay watershed in the Mid-Atlantic region, to assess the potential mobilization of DOM and nutrients from SCM soils. We found low quantities of readily released organic matter and nutrients regardless of SCM type. WSOM concentration and composition did not vary spatially within SCMs. However, SCM surface water had plant-like signatures and was more aromatic compared to WSOM, indicating that organic matter processing occurs as water moves through SCM soil media. Monthly sampling of SCM soils suggests WSOM and nutrient quantities peak when SCMs are dry. When accounting for spatial extent, SCMs likely serve as smaller potential sources of carbon to downstream aquatic ecosystems relative to larger naturally occurring urban wetlands. Exploring the potential soil-derived DOM in SCMs and urban wetlands furthers our knowledge of how urban systems influence DOM concentration and composition, while examining the performance of SCMs relative to natural soil systems.

230. 题目: The CAZyme family regulates the changes in soil organic carbon composition during vegetation restoration in the Mu Us desert
文章编号: N24112006
期刊: Geoderma
作者: Zhouchang Yu, Wei Zhang, Hongqiang He, Yanrong Li, Zhiguo Xie, AHejiang Sailike, Hongjian Hao, Xingfang Tian, Lin Sun, Yujie Liang, Rong Fu, Peizhi Yang
更新时间: 2024-11-20
摘要: Combatting desertification through vegetation restoration holds significant potential for soil carbon sequestration. However, understanding the effects of different restoration types on soil organic carbon component and the role of carbohydrate-active enzymes (CAZymes) remains limited. This study assessed soils from four distinct vegetation types, namely grassland desert (GD), desert steppe (DS), typical steppe (TS), and artificial forest (AF), in the eastern part of the Mu Us Desert, China, examining physicochemical properties, carbon chemical composition, microbial community composition, and CAZyme gene abundance. Our research findings demonstrated that TS restoration significantly increased the content of various soil organic carbon (SOC) components. Compared to other vegetation types, the proportion of recalcitrant carbon (20–22%) was notably higher and exhibited a strong correlation with lignin and peptidoglycan, as determined by the analysis of CAZyme subfamily composition. GD and DS soils showed enrichment in cellulose and hemicellulose-decomposing CAZymes, leading to higher polysaccharide and aliphatic carbon levels. Significant changes were observed in the methyl carbon component amidst the decomposition of varied organic matter types, correlating strongly with Proteobacteria and Acidobacteria abundances. Our research elucidates the influence of distinct vegetation types on sandy soil carbon sequestration and stabilization, highlighting the crucial function of microbial communities and their CAZyme activities. These insights can guide enhanced land management strategies for improved carbon dynamics in arid ecosystems.

231. 题目: Unraveling the dynamics of lignin chemistry on decomposition to understand its contribution to soil organic matter accumulation
文章编号: N24112005
期刊: Plant and Soil
作者: Aswin Thirunavukkarasu, Mattias Hedenström, Tobias Sparrman, Mats B Nilsson, Jürgen Schleucher, Mats Öquist
更新时间: 2024-11-20
摘要:

Aims

Plant inputs are the primary organic carbon source that transforms into soil organic matter (SOM) through microbial processing. One prevailing view is that lignin plays a major role in the accumulation of SOM. This study investigated lignin decomposition using wood from different genotypes of Populus tremula as the model substrate. The genotypes naturally varied in lignin content and composition, resulting in high and low lignin substrates.

Methods

The wood was inoculated with fresh soil and decomposition was interpreted through mass loss and CO₂ produced during a 12-month lab incubation. Detailed information on the decomposition patterns of lignin was obtained by Two-dimensional Nuclear magnetic resonance (2D NMR) spectroscopy on four occasions during the incubations.

Results

The lignin content per se did not affect the overall decomposition and ~ 60% of the mass was lost in both substrates. In addition, no differences in oxidative enzyme activity could be observed, and the rate of lignin decomposition was similar to that of the carbohydrates. The 2D NMR analysis showed the oxidized syringyl present in the initial samples was the most resistant to degradation among lignin subunits as it followed the order p-hydroxybenzoates > syringyl > guaiacyl > oxidized syringyl. Furthermore, the degradability of β–O–4 linkages in the lignin varied depending on the subunit (syringyl or guaiacyl) it is attached to.

Conclusions

Our study demonstrates that lignin contains fractions that are easily degradable and can break down alongside carbohydrates. Thus, the initial differences in lignin content per se do not necessarily affect magnitude of SOM accumulation.

232. 题目: Insights into the characteristics and toxicity of microalgal biochar–derived dissolved organic matter by spectroscopy and machine learning
文章编号: N24112004
期刊: Science of the Total Environment
作者: Hongjia Li, Yangzhi Liu, , Tiejun Li, Jun Yan, Chenghu Yang
更新时间: 2024-11-20
摘要: Microalgal biochar has potential applications in various fields; however, there is limited research on the properties and risks of microalgal biochar-derived dissolved organic matter (MBDOM). This study examined how different pyrolysis temperatures (200 °C and 500 °C) and extraction solutions (0.1 mol/L HCl, Milli-Q water, and 0.1 mol/L NaOH) affect the characteristics and toxicity of MBDOM from three microalgae using multi-spectroscopy methods. Results showed that higher pyrolysis temperature reduced dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) but increased total potassium (TK) in the MBDOM. Alkaline solution promoted DOC and TN dissolution, while acidic solutions enhanced TP and TK release from biochar. The molecular weight, aromaticity, and fluorescent composition of MBDOM varied based on pyrolysis temperature, extraction solution, and microalgae species. MBDOM from low pyrolysis temperature and alkaline extraction exhibited significant toxicity to Photobacterium phosphoreum T₃. Correlation analysis and machine learning revealed that pyrolysis temperature had a greater influence on the characteristics and toxicity of MBDOM than the extraction solution. The toxicity of MBDOM was primarily associated with TN and DOC contents and also influenced by molecular weight, aromaticity, and humification. These findings are essential for optimizing microalgal biochar production and application.

233. 题目: Variable organic matter stoichiometry enhances the biological drawdown of CO2 in the Northwest European shelf seas
文章编号: N24112003
期刊: Biogeosciences
作者: Kubilay Timur Demir, Moritz Mathis, Jan Kossack, Feifei Liu, Ute Daewel, Christoph Stegert, Helmuth Thomas, Corinna Schrum
更新时间: 2024-11-20
摘要: . Variations in the elemental ratios of carbon, nitrogen, and phosphorus in marine organic matter (OM) and their influence on the marine carbon cycle remain poorly understood for both the open and coastal oceans. Observations consistently show an enrichment of carbon and a depletion of phosphorus relative to elemental Redfield ratios. However, many biogeochemical models are constrained to Redfield stoichiometry, neglecting the effects of variable stoichiometry on carbon cycling and typically underestimating biological carbon fixation. This impedes the accurate representation of OM cycling and the resulting carbon fluxes, especially in productive temperate shelf seas such as the Northwest European shelf seas (NWES). Here, the efficiency of oceanic CO₂-uptake strongly depends on the biological uptake of inorganic carbon and its export to the North Atlantic, both of which are influenced by OM stoichiometry. In this study, we provide a first comprehensive and quantitative assessment of the effects of variable OM stoichiometry on carbon cycling in the NWES. For this purpose, we integrate two pathways for variable OM stoichiometry, motivated by observational and experimental results, into the regional high-resolution coupled 3D physical-biogeochemical modeling system SCHISM-ECOSMO-CO₂: first, the release of carbon-enriched dissolved OM under nutrient limitation, and second, the preferential remineralization of organic nitrogen and phosphorus. With these extensions we reproduce the observed OM stoichiometry and evaluate its impact on marine carbon cycling with a focus on OM cycling and the resulting air-sea CO₂-exchange. Compared to the reference simulation with fixed Redfield stoichiometry, the variable stoichiometry configurations show an increase of the annual net CO₂-uptake in the NWES by 10–33 % , depending on the relative contribution of the two new implementations. As the main driver of the additional CO₂-uptake, we identify a corresponding intensification of annual and seasonal OM cycling, resulting in higher net autotrophy in surface waters and higher net heterotrophy in sub-surface layers. This enhanced gradient in net community production leads to an increased biological drawdown of inorganic carbon, most pronounced in the Norwegian Trench. By increasing the biological control on the surface partial pressure of CO₂, this leads to higher summer and lower winter uptake. Our results highlight the importance of variable stoichiometry for an accurate representation of the shelf carbon pump mechanism in the NWES, as it significantly influences the efficiency of carbon sequestration. Since the response depends largely on regional physical conditions and pre-existing carbon export mechanisms, regional assessments are essential to understand the sensitivity of the carbon cycle to OM stoichiometry, which should be included in global models to accurately represent the coastal carbon cycle.

234. 题目: Physicochemical protection is more important than chemical functional composition in controlling soil organic carbon retention following long-term land-use change
文章编号: N24112002
期刊: Geoderma
作者: Meghan Barnard, Ram C Dalal, Zhe H Weng, Steffen A Schweizer, Peter M Kopittke
更新时间: 2024-11-20
摘要: Understanding the mechanisms that control soil organic carbon (SOC) persistence is central to soil management and climate change mitigation. In the present study, we utilised a chronosequence of Vertisols which have undergone land use change from native vegetation to cropping for up to 82 y in subtropical Australia. We examined whether the marked changes in SOC concentrations were associated with changes in the physicochemical protection of SOC in aggregate structures (occlusion) and mineral surfaces (adsorption) or with changes in chemical functional composition. Soil samples were fractionated using density and physical fractionation to isolate the free particulate organic matter (fPOM), occluded POM (oPOM) and fine mineral-associated organic matter (fine-MAOM) to assess the impact of land use change on soil organic matter (SOM) fractions with differing degrees of physicochemical protection. The impact of long-term cropping on SOC functional group composition across soil fractions was assessed using synchrotron-based near edge X-ray absorption fine structure (NEXAFS) analyses. We found that although long-term cropping caused a loss of 43 % of bulk SOC after 20 y, this marked loss over time was not associated with a change in C functional group composition. Furthermore, although the SOC retention in the various fractions differed up to 60-fold (fPOM-C decreased by 78 % after cropping for 20y, whilst fine-MAOM decreased by 25 %), there were only comparatively minor differences in SOC functional group composition between these fractions. Together, these findings suggest that the differences in C retention between fractions were less related to SOC functional group composition and more related to SOM’s physicochemical protection.

235. 题目: Microwave pyrolysis of Choerospondias axillaris seeds with their derived biochar for comprehensive utilization of the biomass
文章编号: N24112001
期刊: Chemical Engineering Journal
作者: Ruolan Zhou, Xiaojie Tian, Xiaofei Wang, Yuan Zeng, Linyao Ke, Qiuhao Wu, Rui Liao, Roger Ruan, Liangliang Fan, Yunpu Wang
更新时间: 2024-11-20
摘要: Lignocellulosic biomass is a promising resource for producing biofuels with improved properties and has been extensively utilized in microwave pyrolysis. This study explores the use of Choerospondias axillaris seeds for bio-oil production, with the derived biochar serving as both a microwave absorber and in-situ catalyst. The research characterized the biochar including SEM, BET, NH₃-TPD, FTIR, etc, and investigated the impact of different heating modes and types of microwave absorbers on the composition and distribution of pyrolysis products. The results demonstrated that the biochar exhibits excellent microwave absorption properties and catalytic performance. The biochar exhibits a dielectric loss tangent of 0.23 and a specific surface area of 154.54 m²·g⁻¹, characterized by a rich hollow porous structure and surface functional groups. It contains metal elements such as Na, K, and Ca, along with Lewis acid sites, making it an excellent microwave absorption catalyst. Furthermore, the study investigated the effects of microwave power and pyrolysis temperature, revealing that optimal conditions of 700 W and 500 °C result in a fast heating rate of 77.7 °C·min⁻¹, a bio-oil yield of 34.5 wt%, and an aromatics relative content of 61.0 %. The stability of the biochar as a microwave absorption catalyst was evaluated through a reuse study, demonstrating its relatively excellent warming characteristics and product distribution even after five cycles. In summary, this paper proposed an innovative method that employs the derived biochar to enhance biomass pyrolysis, thereby achieving the comprehensive and high-value utilization of Choerospondias axillaris seeds and providing a viable pathway for their sustainable development.

236. 题目: Photochemistry of microplastics-derived dissolved organic matter: Reactive species generation and organic pollutant degradation
文章编号: N24111908
期刊: Water Research
作者: Jie Zhang, Xianfeng Hou, Kena Zhang, Quanzhi Xiao, Jorge L Gardea-Torresdey, Xiaoxia Zhou, Bing Yan
更新时间: 2024-11-19
摘要: Dissolved organic matter (DOM) originating from microplastics (MPs-DOM) is increasingly recognized as a substantial component of aquatic DOM. The photochemistry of MPs-DOM, essential for understanding its environmental fate and impacts, remains largely unexplored. This study investigates the photochemical behaviors of MPs-DOM derived from two common plastics: polystyrene (PS) and polyvinyl chloride (PVC), which represent aromatic and aliphatic plastics, respectively. Spectral and high-resolution mass spectrometry analyses demonstrated that photoreactions preferentially targeted poly-aromatic compounds within the MPs-DOM, leading to degradation products that predominantly form N-aliphatic/lipid-like substances. This transformation is characterized by decreased aromaticity and unsaturation. Additionally, irradiation of MPs-DOM generated reactive species (RS), including triplet intermediates (³DOM*) and singlet oxygen (¹O₂), with apparent quantum yields of 0.06–0.16% and 0.16–0.35%, respectively—values considerably lower than those for conventional DOM (1.19–1.56% for ³DOM* and 1.34–1.90% for ¹O₂). Despite this, the RS generated from MPs-DOM significantly enhance the degradation of coexisting organic pollutants, such as antibiotic resistance genes (ARGs). The findings shed light on the photoinduced transformation of MPs-DOM and suggest that MPs-DOM functions as a natural photocatalyst, mediating redox reactions of pollutants in sunlit aquatic settings. This highlights its previously underestimated role in natural attenuation and aquatic photochemistry.

237. 题目: Exploration of nitrogen sources and transformation processes in eutrophic estuarine zones based on DOM and stable isotope compositions
文章编号: N24111907
期刊: Marine Pollution Bulletin
作者: Xiujian Hu, Shengwei Cao, Mengtuo Wen, Yuanjing Zhang, Yuewen Zhao, Yaci Liu, Xiangke Kong, Yasong Li
更新时间: 2024-11-19
摘要: Our study examines nitrogen sources and transformations in Xiamen Bay, where eutrophication has increased due to higher nitrogen levels. By analyzing dissolved organic matter (DOM) and nitrate stable isotopes (δ15N-NO3−and δ18O-NO3−), the study finds that nitrate in low salinity areas is influenced by freshwater-seawater mixing and biogeochemical processes, while in high salinity areas, it is mainly affected by physical mixing. Bayesian mixing model (MixSIAR) results show that the primary nitrate sources are fecal matter and sewage, followed by atmospheric deposition. During the high flow period, DOM may facilitate nitrogen transformation and release through processes such as degradation or mineralization. In contrast, during the low flow period, the system is mainly influenced by the physical mixing of saline and freshwater. Studies have shown that DOM can indicate the biogeochemical intensity in water bodies, further identifying the main factors influencing the distribution and transformation processes of nitrate content, providing a basis for mitigating eutrophication in estuarine areas.

238. 题目: Diel dissolved organic matter patterns reflect spatiotemporally varying sources and transformations along an intermittent stream
文章编号: N24111906
期刊: Limnology and Oceanography
作者: Rebecca L Hale, Sarah E Godsey, Jenna M Dohman, Sara R Warix
更新时间: 2024-11-19
摘要: Stream dissolved organic matter (DOM) is a globally important carbon flux and a locally important control on stream ecosystems, and therefore understanding controls on stream DOM fluxes and dynamics is crucial at both local and global scales. However, attributing process controls is challenging because both hydrological and biological controls on DOM are integrated and may vary over time and throughout stream networks. Our objective was to assess the patterns and corresponding controls of diel DOM cycles through a seasonal flow recession by using reach‐scale in situ sensors in a non‐perennial stream network. We identified five characteristic diel variations in DOM with differing phase and amplitude. During snowmelt flows, diel variations in DOM were consistent among sites and reflected diel flowpath shifts and photodegradation. Evapotranspiration‐driven diel stage oscillations emerged at two upstream sites, shaping diel DOM patterns indirectly, by creating conditions for instream DOM processing. At a spring‐fed site, minimal diel variation was observed throughout the summer whereas at an intermittent reach, daily drying and rewetting created biogeochemical hot moments. This research demonstrates that controls on DOM vary over time and space, even in close proximity, generating asynchronous fDOM patterns during low flows, illuminating shifts in biogeochemical processes and flowpaths.

239. 题目: Nitrogen mineralization/immobilization dynamics across the river-estuary-sea continuum: Effects of organic matter and microorganisms
文章编号: N24111905
期刊: Marine Pollution Bulletin
作者: Hengchen Wei, Peiyi Wang, Jing Li, Qingyan Wang, Fengwei Zhang, Dongyao Sun, Dengzhou Gao, Zhuhong Ding, Wei Du, Guoling Zhang, Xianbiao Lin
更新时间: 2024-11-19
摘要: N mineralization and immobilization are important N cycling pathways. While they are widely studied in individual coastal habitats, they are rarely compared across different habitats along the river-estuary-sea continuum. We addressed this gap by investigating gross nitrogen mineralization (GNM) and gross ammonium immobilization (GAI) in urban rivers, estuary, and adjacent sea of the Yangtze River-Estuary-East China Sea system. We sampled 30 stations during winter and summer, quantifying GNM and GAI rates using enriched 15N stable isotopes. We observed a 65 % decrease in total organic C concentrations and a three-fold increase in fungi/bacteria ratios from river to sea. Along the gradient, GNM decreased from 5.41 to 2.41 μg N g−1 d−1 and GAI decreased from 6.08 to 3.27, with their ratios generally >1, indicating nitrogen limitation. Redundant analyses identified temperature and Fe as significant environmental variables. This study highlights the importance of cross-habitat comparisons to N cycling studies in coastal systems.

240. 题目: Enhanced soil carbon storage and arbuscular mycorrhizal fungal biomass in a long-term nutrient management under soybean-based cropping system
文章编号: N24111904
期刊: Environmental Science and Pollution Research
作者: Richa Agnihotri, Ashu Pandey, Mahaveer P Sharma, Anil Prakash, Aketi Ramesh, Hemant Singh Maheshwari, Rakesh Kumar Verma, Raghvendra Nargund, Sunil Datt Billore
更新时间: 2024-11-19
摘要:

To ensure the sustainability of crop production and ecosystem functioning, a thorough understanding of the mechanisms governing soil carbon (C) sequestration and soil health is essential. This study examined the effects of three nutrient management practices (organic, inorganic, and integrated) and two cropping systems (soybean-wheat and soybean-chickpea), on arbuscular mycorrhizal fungi (AMF) and soil C-sequestration in a long-term (12 years) field experiment. We measured the stocks of soil organic carbon, total glomalin–related soil protein, pertinent soil quality parameters such as microbial biomass carbon, and β-glucosidase activity along with AMF biomass [microscopic parameters and 16:1ω5cis phospholipid fatty acid (AM PLFA) and neutral lipid fatty acid (AM NLFA)]. It was observed that the measures of AMF biomass were positively correlated with the soil organic carbon stocks, total glomalin–related soil protein stocks, and soil quality parameters. Organic practice recorded significantly higher AMF spores, mycorrhizal colonization percentage, AM PLFA (2.58 nmol g⁻¹ soil), AM NLFA (7.95 nmol g⁻¹ soil), soil organic carbon stocks (15.78 Mg ha⁻¹), total glomalin–related soil protein stocks (2.10 Mg ha⁻¹), and soil quality parameters such as microbial biomass carbon, and β-glucosidase activity than inorganic and integrated practices. In comparison to soybean-chickpea, C-sequestration was higher in soybean-wheat. Principal component analysis validated the said results and differentiated soybean-wheat under organic practice from the rest of the treatments. In conclusion, our results suggest that organic management in conjunction with soybean-wheat crop rotation enhances AMF and can be recommended for improving soil quality and C sequestration without compromising crop yield.