红树林、滨海盐沼和海草床是典型的滨海蓝碳生态系统,具有相当可观的固碳能力。植被碳库和沉积物碳库是蓝碳生态系统有机碳的主要载体,其变化过程决定了生态系统的整体固碳能力。本文尝试从碳库相互作用的角度出发,通过文献梳理,总结不同植被碳库之间、不同沉积物碳库之间以及植被碳库和沉积物碳库之间相互作用的研究进展,指出物种竞争、外源碳输入以及生物地貌学过程在碳库相互作用中所起到的重要作用,并提出滨海蓝碳生态系统碳库研究中存在的问题和未来研究的方向。

Mangroves, coastal salt marshes and seagrass beds, as the typical coastal blue carbon ecosystems, have been widely recognized for their remarkable capacity in carbon storage. Vegetation carbon pool and sediment (or soil) carbon pool were considered to be the major carbon pools within the coastal blue ecosystems and their variations determined the overall carbon sequestration of the ecosystems. From a perspective of carbon pool interactions, this study summarized the previous research work based on literature review, including the interactions within various vegetation carbon pools and within various sediment carbon pools, as well as the interactions between vegetation and sediment carbon pools. Interspecific competition, allochthonous carbon input and biogeomorphology were found to be the key to understand the carbon pool interactions. Finally, a perspective on the current state-of-the-art of blue carbon pool study is offered, with challenges and suggestions for future directions.

滨海盐沼的碳库变化可为蓝碳碳汇核算提供依据。为量化短时间尺度(季节到年际尺度)内滨海盐沼碳库的固碳速率,基于高分辨率的地表高程监测系统,于2022年在杭州湾南岸典型滨海盐沼开展了季节性的观测和采样分析。研究结果表明,在观测期间,本地种海三棱藨草和外来种互花米草的生长呈现季节性变化特征,植物生长主要集中在3—9月。就植物碳库的地下部分而言,海三棱藨草固碳量达到11 g C·m^-2,互花米草盐沼则较高,为56 g C·m^-2。地表高程监测数据表明,海三棱藨草盐沼的沉积速率为12.30 cm·a^-1,略低于互花米草盐沼的沉积速率(13.02 cm·a^-1)。结合沉积速率与沉积物容重、有机碳含量等数据,可以算得观测期间,海三棱藨草盐沼沉积物碳埋藏速率为460 g C·m^-2·a^-1,互花米草盐沼沉积物碳埋藏速率为588 g C·m^-2·a^-1,这两种滨海湿地的碳埋藏速率也具有季节性,在夏、秋季达到高值。结合植物碳库和沉积物碳库结果可知,杭州湾南岸滨海盐沼生态系统具有较高的固碳速率,外来种生态系统固碳速率(644 g C·m^-2·a^-1)高于本地种生态系统固碳速率(471 g C·m^-2·a^-1)。在将来的滨海湿地蓝碳管理工作中,需要考虑不同物种之间的差异性。

Carbon stock variation observation forms the basis for coastal saltmarsh blue carbon sink accounting. In order to accurately estimate the carbon sequestration rate of coastal saltmarshes over a short-term scale (seasonal to annual), this study carried out field observations and sample collections within a coastal saltmarsh on the south bank of Hangzhou Bay, covering different seasons of 2022. This study was primarily based on high-resolution surface monitoring by Surface Elevation Table (SET) systems. The results revealed a seasonal plant growth pattern between March and September for both the native species <i>Scirpus mariqueter</i> and the exotic species <i>Spartina alterniflora</i>. In terms of belowground biotic carbon stock changes, over the growing season, the carbon stock increase for <i>Scirpus mariqueter</i> reached 11 g C·m^-2 whilst this value was 56 g C·m^-2 for <i>Spartina alterniflora</i>. The SET data indicated a sedimentation rate of 13.02 cm·a^-1 within the <i>Spartina alterniflora</i> saltmarsh, higher than that of the <i>Scirpus mariqueter</i> saltmarsh, 12.30 cm·a^-1. Calculating the sedimentation rate data with sediment bulk density and organic carbon content, the sediment carbon accumulation rate of <i>Scirpus mariqueter</i> saltmarsh was estimated to be 460 g C·m^-2·a^-1, lower than 588 g C·m^-2·a^-1 of the <i>Spartina alterniflora</i> saltmarsh. Combining the biotic carbon stock increase and sediment carbon stock increase, the carbon sequestration rate for the <i>Spartina alterniflora</i> saltmarsh was found to be 644 g C·m^-2·a^-1, higher than the value of <i>Scirpus mariqueter</i> saltmarsh, 471 g C·m^-2·a^-1. Thus, the difference in carbon sequestration abilities of native and exotic species should be considered for future coastal blue carbon management.

. The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove forests) to the global level and a top-down approach derived from considerations of global sediment balance and a compilation of the organic carbon content of vegeatated sediments. Up-scaling of individual burial estimates values yielded a total carbon burial in vegetated habitats of 111 Tmol C y-1. The total burial in unvegetated sediments was estimated to be 126 Tg C y-1, resulting in a bottom-up estimate of total burial in the ocean of about 244 Tg C y-1, two-fold higher than estimates of oceanic carbon burial that presently enter global carbon budgets. The organic carbon concentrations in vegetated marine sediments exceeds by 2 to 10-fold those in shelf/deltaic sediments. Top-down recalculation of ocean sediment budgets to account for these, previously neglected, organic-rich sediments, yields a top-down carbon burial estimate of 216 Tg C y-1, with vegetated coastal habitats contributing about 50%. Even though vegetated carbon burial contributes about half of the total carbon burial in the ocean, burial represents a small fraction of the net production of these ecosystems, estimated at about 3388 Tg C y-1, suggesting that bulk of the benthic net ecosystem production must support excess respiration in other compartments, such as unvegetated sediments and the coastal pelagic compartment. The total excess organic carbon available to be exported to the ocean is estimated at between 1126 to 3534 Tg C y-1, the bulk of which must be respired in the open ocean. Widespread loss of vegetated coastal habitats must have reduced carbon burial in the ocean by about 30 Tg C y-1, identifying the destruction of these ecosystems as an important loss of CO2 sink capacity in the biosphere.

红树林是地球上固碳效率最高的生态系统之一,对于应对全球气候变化、实现我国“双碳”目标具有积极意义。本研究以浙江沿浦湾红树林为研究区域,于2018—2019年春季和秋季采集表层(0~25 cm)沉积物样品,对其有机碳、总氮、总磷含量和沉积物粒度进行分析。结果表明:沉积物有机碳含量为6.50~11.90 g/kg,总氮含量为1.08~1.36 g/kg,总磷含量为0.57~0.74 g/kg。通过相关性分析发现,沉积物有机碳与总氮呈显著正相关(p<0.05),表明两者的潜在来源具有相似性;有机碳也与黏土含量呈极显著正相关(p<0.01),即细粒沉积物更有利于有机碳的固存;相反,有机碳与总磷、平均粒径、砂和粉砂含量呈极显著负相关(p<0.01)。层次分割分析表明,沉积物中砂和粉砂的含量是影响红树林表层有机碳分布的关键环境因子。此外,红树植物品种及成林时间、地表径流分布、台风影响和养殖塘清塘也是影响沉积物有机碳分布的驱动因素。

Mangroves are among the most effective carbon sequestration ecosystems on earth, which is crucial in addressing global climate change and achieving China’s “dual carbon” goals. This research focused on the Yanpu Bay mangroves in Zhejiang, where surface (0-25 cm)sediment samples were collected in the spring and autumn of 2018-2019 to analyze organic carbon, total nitrogen, total phosphorus, and sediment particle size. The findings revealed that the sediment organic carbon content ranged from 6.50 to 11.90 g/kg, the total nitrogen content ranged from 1.08 to 1.36 g/kg, and the total phosphorus content ranged from 0.57 to 0.74 g/kg. Correlation analysis revealed a significant positive correlation between sediment organic carbon and total nitrogen (p<0.05), indicating their potential sources shared similarities. The sediment organic carbon also showed a highly significant positive correlation with clay content (p<0.01), indicating that fine-grained sediments were more conducive to organic carbon sequestration. Conversely, it exhibited a highly significant negative correlation with total phosphorus, mean particle size, sand and silt content (p<0.01). Hierarchical segmentation analysis suggested that the sand and silt content in the sediment were key environmental factors affecting the distribution of organic carbon in the surface of mangroves. Additionally, mangrove species composition, stand age, surface runoff distribution, typhoon impacts, and pond dredging in aquaculture areas were also identified as driving factors influencing sediment organic carbon distribution.

Will warming lead to an increased use of older soil organic carbon (SOC) by microbial communities, thereby inducing C losses from C-rich alpine soils? We studied soil microbial community composition, activity, and substrate use after 3 and 4 years of soil warming (+4 °C, 2007-2010) at the alpine treeline in Switzerland. The warming experiment was nested in a free air CO2 enrichment experiment using depleted (13)CO2 (δ(13)C = -30‰, 2001-2009). We traced this depleted (13)C label in phospholipid fatty acids (PLFA) of the organic layer (0-5 cm soil depth) and in C mineralized from root-free soils to distinguish substrate ages used by soil microorganisms: fixed before 2001 ('old'), from 2001 to 2009 ('new') or in 2010 ('recent'). Warming induced a sustained stimulation of soil respiration (+38%) without decline in mineralizable SOC. PLFA concentrations did not reveal changes in microbial community composition due to soil warming, but soil microbial metabolic activity was stimulated (+66%). Warming decreased the amount of new and recent C in the fungal biomarker 18:2ω6,9 and the amount of new C mineralized from root-free soils, implying a shift in microbial substrate use toward a greater use of old SOC. This shift in substrate use could indicate an imbalance between C inputs and outputs, which could eventually decrease SOC storage in this alpine ecosystem.© 2013 John Wiley & Sons Ltd.

This review presents a comprehensive discussion of the key technical issues in woody biomass pretreatment: barriers to efficient cellulose saccharification, pretreatment energy consumption, in particular energy consumed for wood-size reduction, and criteria to evaluate the performance of a pretreatment. A post-chemical pretreatment size-reduction approach is proposed to significantly reduce mechanical energy consumption. Because the ultimate goal of biofuel production is net energy output, a concept of pretreatment energy efficiency (kg/MJ) based on the total sugar recovery (kg/kg wood) divided by the energy consumption in pretreatment (MJ/kg wood) is defined. It is then used to evaluate the performances of three of the most promising pretreatment technologies: steam explosion, organosolv, and sulfite pretreatment to overcome lignocelluloses recalcitrance (SPORL) for softwood pretreatment. The present study found that SPORL is the most efficient process and produced highest sugar yield. Other important issues, such as the effects of lignin on substrate saccharification and the effects of pretreatment on high-value lignin utilization in woody biomass pretreatment, are also discussed.Published by Elsevier Ltd.

The species identity, composition, distribution, and evolution of plant community can reflect the development direction of wetland ecosystem, and affect the proper functioning of main ecological functions. To investigate plant community structure, a transect with a width of about 500 m perpendicular to the community transition zone was established in the Yellow River Estuary in 2021. The results showed that there were 15 species of higher plants which belonged to 11 families and 15 genera. The plant communities with strip distribution from the river to the sea could be divided into seven types. <em>Spartina alterniflora</em>&nbsp;dominated the vegetation. Species composition of the vegetation was relatively simple, mainly composed of herbaceous species. The Shannon diversity index increased first and then decreased along the river to the sea direction. In the past 10 years, plant community of wetlands in the Yellow River Estuary had shown dramatic changes. The species number of plant community declined, the top two species in terms of importance value changed considerably, and the established species of some communities gradually disappeared or were replaced by new species. This study highlights the rapid evolution of plant community, providing scientific reference for biodiversity conservation and ecological management of newborn wetlands in the Yellow River Estuary.<br><div> <br></div>

以中国土种志资料为基础，分析了土壤有机质含量变异与空间尺度的关系及土类内和土类间的变异程度，探讨了不同空间尺度单元下，土壤有机质平均含量与土壤性质的相关性。结果表明，以土壤剖面为单元，随着土壤剖面数的增加，土壤有机质含量的变异系数增大；行政区域尺度单元内部土壤有机质变异程度大于单元间土壤有机质含量的变异程度。以土壤分类单元为空间单元，土类内的有机质含量变异程度小于土类间的变异程度。随着统计单元空间尺度的增大，土壤有机质含量与土壤性质之间的相关性减弱。因此，采用网格法或行政区划分空间区域，获得空间区域单元内土壤有机质含量或贮量的精确估算需要较多的剖面，但外推至数据不足的空间区域时，估算的不确定较小；采用土壤分类单元为空间区域单元，结果则相反。

有机碳在海洋环境中的长期保存机制一直是海洋碳循环研究的重点,也是研究气候变化与全球碳循环之间作用和反馈的关键。据估算,表层海洋沉积物中约20%的有机碳是通过与氧化铁的结合而保存下来的,因此与氧化铁结合是有机碳长期保存的关键因素之一。研究表明,有机碳—氧化铁复合物的形成主要通过吸附和共沉淀这2种机制,共沉淀反应是有机碳与氧化铁在海洋环境中结合的主导机制。不同来源的有机物在发生与铁氧化物的共沉淀或吸附作用时是有选择性的,在大部分海洋环境中铁氧化物优先与海洋有机碳结合,但在河口三角洲区域,铁氧化物优先与陆源有机碳结合。大量的陆源输入,较高的初级生产和频繁的再悬浮活动使河口边缘海特别适于开展有机碳—氧化铁结合的相关研究,这也是今后研究的重点方向。

Understanding the mechanisms responsible for long-term storage of organic carbon (OC) in marine environment is important for studying the marine carbon cycling and predicting how the global carbon cycle will respond to climate change. It is estimated that more than 20% of the OC in marine sediments is associated with iron oxides and thus these complexes are one of the most important factors in the long-term storage of OC. The OC-iron oxide (OC-Fe) association can be formed through either adsorption or co-precipitation, but the dominant mechanism of OC-Fe association in marine environments is co-precipitation. The combination of OC from different sources with iron oxides is selective. Iron oxides preferentially combine with marine OC in most marine environments, but in estuarine delta regions they prefer terrestrial OC. Due to large inputs of terrestrial materials, high primary production and frequent re-suspension, estuarine and marginal seas are suitable sites for OC-Fe association studies, which should be emphasized in the future.