Understanding the relationships among wetland types, biomass and environmental factors is fundamental for wetland vegetation restoration. Based on field investigation in coastal areas of Yellow Sea and Bohai, TWINSPAN was used to categorize wetland types, and redundancy analysis was used to determine the major environmental factors affecting the spatial distribution and biomass variation of wetland types, aiming to provide scientific basis for wetland restoration. Results showed that wetland vegetation in coastal areas of Yellow Sea and Bohai could be classified into eleven types. Soil total carbon content and electrical conductivity significantly influenced the spatial distribution of wetland types. The wetlands in coastal areas of yellow Sea and Bohai had high biomass, with the highest (48512 kg&middot;hm^-2) occurring in <em>Spartina alterniflora</em>community, followed by <em>Suaeda salsa</em>, <em>Phragmites australis</em>, and <em>Tamarix chinensis</em> communities(&gt;5000kg&middot;hm^-2), and the lower (&lt;5000 kg&middot;hm^-2) in other communities. Soil organic carbon and total nitrogen contents were the major factors influencing the spatial variation of wetland biomass. Under climatic warming and increased nitrogen deposition, the biomass of wetland vegetation can be enhanced. Therefore, it is an effective way to strengthen wetland conservation and to restore the degraded wetland ecosystems for enhancing coastal wetland carbon sink and coping with climatic change.

理解湿地植被类型、生物量与环境因素间的关系，是湿地植被恢复的基础。本文在野外调查的基础上，采用TWINSPAN对黄渤海滨海湿地进行类型划分，利用冗余度分析来确定影响研究区湿地类型分布和生物量差异的环境因素，以期为湿地的恢复提供科学依据。结果表明：黄渤海滨海湿地可以划分为11种类型；土壤电导率和土壤总碳对黄渤海滨海湿地类型的分布有显著影响；湿地具有较高的生物量，其中，互花米草(Spartina alterniflora)群落的生物量最高（48512 kg&middot;hm^-2），盐地碱蓬（Suaeda salsa）、芦苇(Phragmites australis)和柽柳(Tamarix chinensis)群落的生物量较高，均超过5000 kg&middot;hm^-2，其他类型的生物量较低，小于5000 kg&middot;hm^-2；影响研究区湿地类型生物量的主要因素为土壤有机碳和总氮含量。在气候变暖、氮沉降增加情况下，滨海湿地生物量将进一步增加，滨海湿地具有很大的固碳潜力。因此，加强研究区湿地的保护和退化湿地的生态恢复，是增加滨海湿地碳汇和应对气候变化的有效途径。

在简述碳中和概念的基础上, 重点对碳中和的实现途径及生态系统碳汇的重要性进行了评述, 认为碳减排和碳增汇是实现&#x0201c;碳中和&#x0201d;的两个决定因素; 碳减排的核心是节能、调结构、增效和发展清洁能源, 碳增汇的核心是生态保护、建设和管理。由于植被自然生长和生态建设等因素, 中国陆地生态系统发挥了, 并将在未来继续发挥着重要的碳汇作用。为增强生态系统的固碳能力, 作者提出&#x0201c;三优&#x0201d;生态建设和管理原则, 即&#x0201c;最优的生态系统布局、最优的物种配置、最优的生态系统管理&#x0201d;。此外, 文章还对&#x0201c;后碳中和&#x0201d;时代可能出现的问题和挑战进行了展望, 认为碳中和后, 由于气候变化, 特别是大气CO₂浓度增速减缓甚至下降等因素, 可能导致全球性的植被生产力下降, 对此可能带来的新的环境问题需要提前谋划和应对。

Aims Studying storage of carbon (C), nitrogen (N) and phosphorus (P) in ecosystems is of significance in understanding carbon and nutrient cycling. Previous researches in ecosystem C, N and P storage have biased towards forests and grasslands. Shrubland ecosystems encompass a wide gradient in precipitation and soil conditions, providing a unique opportunity to explore the patterns of ecosystem C, N and P storage in relation to climate and soil properties. Methods We estimated densities and storage of organic C, N and P of shrubland ecosystems in Northern China based on data from 433 shrubland sites.Important findings The main results are summarized as follows: the average organic C, N and P densities in temperate shrubland ecosystems across Northern China were 69.8 Mg·hm-2, 7.3 Mg·hm-2 and 4.2 Mg·hm-2, respectively. The average plant C, N and P densities were 5.1 Mg·hm-2, 11.5 × 10-2 Mg·hm-2 and 8.6 × 10-3 Mg·hm-2, respectively, and were significantly correlated with precipitation and soil nutrient concentrations. The average litter C, N and P densities were 1.4 Mg·hm-2, 3.8 ×10-2 Mg·hm-2, 2.5 ×10-3 Mg·hm-2 and were significantly correlated with temperature and precipitation. The average soil organic C, N and P densities in the top 1 m were 64.0 Mg·hm-2, 7.1 Mg·hm-2 and 4.2 Mg·hm-2, respectively and the former two were significantly correlated with temperature and precipitation. The total organic C, N and P storage of shrublands in Northern China were 1.7 Pg, 164.9 Tg and 124.8 Tg, respectively. The plant C, N and P storage were 128.4 Tg, 3.1 Tg and 0.2 Tg, respectively. The litter C, N and P storage were 8.4 Tg, 0.45 Tg, 0.027 Tg, respectively. Soil is the largest C, N and P pool in the studied area. The soil organic C, N and P storage in the top 1 meter were 1.6 Pg, 161.3 Tg and 124.6 Tg, respectively.

研究生态系统碳(C)、氮(N)、磷(P)密度分布和储量对于理解生态系统碳循环和养分循环的机制和规律有重要意义。现有的相关研究多集中在森林和草地生态系统。在中国北方, 灌丛生境水分和土壤条件差异很大, 这为研究生态系统C、N、P密度与储量的分布格局提供了良好条件。该研究调查了433个中国北方温带灌丛样地的生物量、凋落物以及土壤等组分的有机C及N、P含量, 据此计算出中国北方灌丛生态系统有机C及N、P密度和储量。结果表明: 中国北方灌丛平均生态系统有机C及N、P密度分别为69.8 Mg&#x000b7;hm^-2、7.3 Mg&#x000b7;hm^-2、4.2 Mg&#x000b7;hm^-2。其中, 生物量C、N、P密度分别为5.1 Mg&#x000b7;hm^-2、11.5&#x000D7;10^-2 Mg&#x000b7;hm^-2、8.6&#x000D7;10^-3 Mg&#x000b7;hm^-2, 生物量C、N、P密度与降水和土壤养分关系显著; 凋落物C、N、P密度分别为1.4 Mg&#x000b7;hm^-2、3.8&#x000D7;10^-2 Mg&#x000b7;hm^-2、2.5&#x000D7;10^-3 Mg&#x000b7;hm^-2, 凋落物C、N、P密度与温度和降水关系显著; 1 m深土壤的平均有机C及N、P密度分别为64.0 Mg&#x000b7;hm^-2、7.1 Mg&#x000b7;hm^-2、4.2 Mg&#x000b7;hm^-2, 土壤有机C及N密度与温度和降水关系显著。中国北方灌丛生态系统的总有机C及N、P储量分别为1.7 Pg、164.9 Tg、124.8 Tg。其中生物量C、N、P储量分别为128.4 Tg、3.1 Tg、0.2 Tg; 凋落物C、N、P储量分别为8.4 Tg、0.45 Tg、0.027 Tg; 土壤是最大的C、N、P库, 1 m深土壤有机C及N、P储量分别为1.6 Pg、161.3 Tg、124.6 Tg。

Developing technologies to reduce the rate of increase of atmospheric concentration of carbon dioxide (CO2) from annual emissions of 8.6 Pg C yr–1from energy, process industry, land-use conversion and soil cultivation is an important issue of the twenty-first century. Of the three options of reducing the global energy use, developing low or no-carbon fuel and sequestering emissions, this manuscript describes processes for carbon (CO2) sequestration and discusses abiotic and biotic technologies. Carbon sequestration implies transfer of atmospheric CO2into other long-lived global pools including oceanic, pedologic, biotic and geological strata to reduce the net rate of increase in atmospheric CO2. Engineering techniques of CO2injection in deep ocean, geological strata, old coal mines and oil wells, and saline aquifers along with mineral carbonation of CO2constitute abiotic techniques. These techniques have a large potential of thousands of Pg, are expensive, have leakage risks and may be available for routine use by 2025 and beyond. In comparison, biotic techniques are natural and cost-effective processes, have numerous ancillary benefits, are immediately applicable but have finite sink capacity. Biotic and abiotic C sequestration options have specific nitches, are complementary, and have potential to mitigate the climate change risks.

本研究以黄河源区玛沁县大武滩不同退化高寒湿地为研究对象，分层采集冻融丘和丘间土层样品，分析土壤有机碳组分的变化及其与土壤因子的关系。结果表明：冻融丘和丘间各层轻组分有机碳、重组分有机碳、可溶性有机碳、微生物碳含量随着退化程度的加剧下降，且在未退化与轻度退化、重度退化样地冻融丘0~10 cm土层间差异显著（PP<0.05），对高寒湿地退化的响应敏感；土壤含水量与有机碳、轻组分有机碳、重组分有机碳、可溶性有机碳和微生物碳含量呈正相关关系。综上所述，高寒湿地退化导致有机碳组分减少，重组分有机碳含量和占比可作为反映土壤有机碳库变化的关键指标，微生物碳含量和占比可作为反映高寒湿地退化的关键指标，均可为高寒湿地生态系统碳库和恢复机理的研究提供数据支撑。

湿地巨大的碳储存能力使其在稳定全球气候变化中占有重要地位,并对全球土壤碳储量做出重要贡献.本文在阐明湿地碳储量估算方法的基础上,分析我国主要湿地区碳储量并讨论气候、植被、土壤性质、土地利用等因素对湿地碳储量的影响.结果表明: 东北湿地区和青藏高原湿地区是八大湿地区中碳储量最高的两大区域;泥炭湿地的高稳定性、低分解率及酚氧化酶的作用使其成为内陆地区碳储量最高的湿地类型;单一因素的双向干扰及多重因素的交互作用使得湿地碳储量的影响因素和作用机理更加复杂.注重多重因素的交互作用,并结合数据同化技术,有利于湿地碳储量及湿地生态系统价值预测与评估.

Wetlands contain a large proportion of carbon (C) in the biosphere and partly affect climate by regulating C cycles of terrestrial ecosystems. China contains Asia's largest wetlands, accounting for about 10% of the global wetland area. Although previous studies attempted to estimate C budget in China's wetlands, uncertainties remain. We conducted a synthesis to estimate C uptake and emission of wetland ecosystems in China using a dataset compiled from published literature. The dataset comprised 193 studies, including 370 sites representing coastal, river, lake and marsh wetlands across China. In addition, C stocks of different wetlands in China were estimated using unbiased data from the China Second Wetlands Survey. The results showed that China's wetlands sequestered 16.87 Pg C (315.76 Mg C/ha), accounting for about 3.8% of C stocks in global wetlands. Net ecosystem productivity, jointly determined by gross primary productivity and ecosystem respiration, exhibited annual C sequestration of 120.23 Tg C. China's wetlands had a total gaseous C loss of 173.20 Tg C per year from soils, including 154.26 Tg CO -C and 18.94 Tg CH -C emissions. Moreover, C stocks, uptakes and gaseous losses varied with wetland types, and were affected by geographic location and climatic factors (precipitation and temperature). Our results provide better estimation of the C budget in China's wetlands and improve understanding of their contribution to the global C cycle in the context of global climate change.© 2019 John Wiley & Sons Ltd.

<p id="C3"> <strong>【Objective】</strong> The grassland ecosystem plays an important role in the global carbon balance. The study of grassland carbon pool and its driving force is a hot point of vegetation ecology. This study investigated the vegetation carbon density and its spatial pattern in the steppe and agro-pastoral ecotones of northern China. The major factors driving the spatial variation of grassland vegetation carbon density were identified, as well as the relative contribution of climate, soil texture, grazing intensity and other factors to the grassland vegetation carbon pool. <strong>【Method】</strong> Using the survey data of the grassland vegetation in northern grassland during 2002 and 2009, combined with the MODIS/NDVI remote sensing data and 1:1 million grassland type map, the estimation model of above- and below-ground biomass in the main grassland types of northern China was established. Based on 255 county-level administrative units in the study area, the relationship between grassland vegetation carbon density and climate factors, soil texture and livestock carrying capacity were explored, and derived the relative contribution of different driving factors to grassland carbon density using the general linear model (GLM). <strong>【Result】</strong> (1) The average above-ground biomass (AGB) of the steppe and agro-pastoral ecotones of northern China was 36.9 g C·m^-2, and the below-ground biomass (BGB) was 362.9 g C·m^-2, nearly 10 times the AGB. Both the above- and below-ground biomass decreased from east to west, and followed logarithmic normal distribution. The biomass carbon density of grassland types was significantly different. (2) In the whole study region and steppe sub-region, desert sub-region, agro-pastoral sub-region, the AGB showed a significantly positive correlation with mean annual precipitation (MAP) and soil clay content (Clay%), a significantly negative relationship with the mean annual temperature (MAT) and soil sand content (Sand%). The AGB increased with livestock carrying capacity except in the steppe sub-region where were very heavily grazed. (3) General Linear Model (GLM) analysis indicated that the MAP, MAT, Clay% and grazing intensity explained 29.6% (<i>P</i><0.001), 5.8% (<i>P</i><0.001), 0.8% (<i>P</i><0.05) and 1.3% (<i>P</i><0.001) of AGB variation, respectively, and the MAP, MAT and Sand% contributed to 12.1% (<i>P</i><0.001), 6.8% (<i>P</i><0.001) and 1.9% (<i>P</i><0.005) to BGB variation, respectively, and the grazing intensity had minor contribution to BGB. <strong>【Conclusion】</strong> Climate factors especially MAP was the dominate driving factor of grassland vegetation carbon density, and its impact on AGB was more obvious than on BGB. Soil texture also had a significant contribution to the grassland vegetation carbon density, especially on the BGB. Grazing intensity explained only 1.3% of the AGB and had no impact on BGB. This finding indicated that the climate factors were major contributor grassland vegetation carbon density comparing with grazing intensity. </p>

【目的】 草地生态系统在全球碳平衡中有重要的意义,草地植被碳库及其变化机制研究是植被生态学的重要命题。本文研究北方草地和农牧交错区草地植被碳密度及其空间格局,解析不同区域草地植被碳密度的关键影响因素,分析了气候、土壤、放牧等因素对地上地下植被碳库的相对贡献。【方法】 基于2002—2009年北方草地及农牧交错带草地植被调查数据,结合同期MODIS/NDVI遥感影像和1﹕100万草地类型图,建立了我国主要草地类型的生物量估算模型;整合野外考察数据和前人研究结果,探讨了研究区地上地下生物碳库及其空间格局;基于研究区255个县级行政单元,分析了不同类型草地植被碳库与气候要素、土壤要素及家畜承载量的关系,应用一般线性模型（GLM）解析了不同影响因素对草地碳密度的相对贡献。【结果】 （1）北方草地与农牧交错区草地地上平均生物碳密度为36.9 g C·m^-2,地下生物碳密度为362.9 g C·m^-2,地下生物碳密度高于地上10倍,均呈从东到西递减的趋势,频率分布图基本服从对数正态分布,不同草地类型的生物碳密度存在明显差异;（2）整个研究区及草原亚区、荒漠亚区、农牧交错亚区内,地上生物量与年降水量（MAP）呈极显著正相关、与年均气温（MAT）均呈极显著负相关,与土壤黏粒含量（Clay%）呈显著正相关、与土壤砂粒含量（Sand%）呈显著负相关,整个研究区家畜承载量与草地地上生物量之间呈极显著正相关;（3）一般线性模型（GLM）分析结果表明,年平均降水量（MAP）、年均气温（MAT）、土壤黏粒含量（Clay%）、放牧强度对地上生物量空间变异的解释率分别达到29.6%（PPPPPPP【结论】 气候条件尤其是年降水量是草地生物量碳库的主要影响因素,但对地上生物量影响更为明显;土壤质地对植被生物碳库也有显著贡献,尤其对地下生物量的影响更加显著;放牧强度只能解释地上生物量变化的1.3%、对地下生物量没有显著贡献,这一发现意味着气候对生物量碳库的贡献远大于放牧影响。

<p>Soils store a large amount of the terrestrial ecosystem carbon (C) and play an important role in maintaining global C balance. However, very few studies have addressed the regional patterns of soil organic carbon (SOC) storage and the main factors influencing its changes in Chinese terrestrial ecosystems, especially using field measured data. In this study, we collected information on SOC storage in the main types of ecosystems (forest, grassland, cropland, and wetland) across 18 regions of China during the 1980s (from the Second National Soil Survey of China, SNSSC) and the 2010s (from studies published between 2004 and 2014), and evaluated whether trends changed over the 30-year period. The SOC storage (0-100 cm) in China was 83.46&plusmn;11.89 Pg C in the 1980s and 86.50&plusmn;8.71 Pg C in the 2010s, and the net increase over 30 years was 3.04&plusmn;1.65 Pg C, with a rate of 0.101&plusmn;0.055 Pg C yr^-1. This increase was mainly observed in the topsoil (0-20 cm). Forest, grassland, and cropland SOC storage increased by 2.52&plusmn;0.77, 0.40&plusmn;0.78, and 0.07&plusmn;0.31 Pg C, respectively, which can be attributed to the several ecological restoration projects and agricultural practices implemented. On the other hand, SOC storage in wetlands declined by 0.76&plusmn;0.29 Pg C, most likely due to the decrease in wetland area and SOC density. These results, combined with those of vegetation C sink (0.100 Pg C yr^-1), show that the net C sink in Chinese terrestrial ecosystems was about 0.201&plusmn;0.061 Pg C yr^-1, which offsets 14.85%-27.79% of the C emissions from fossil fuels from the 1980s to the 2010s. These estimates of soil C sink based on field measured data supported the premise that China's terrestrial ecosystems have a large C sequestration potential, and further emphasized the importance of forest protection and reforestation to increase SOC storage capacity.</p>

土壤作为陆地生态系统有机碳库的主体,在全球碳循环中起着重要作用。然而,当前区域土壤有机碳储量的变化情况及其碳源/汇功能仍然不清楚。利用中国1980s （1979-1985年）第二次土壤普查数据,同时收集整理2010s（2004-2014年）已发表的有关中国土壤有机碳储量（0~20 cm和0~100 cm）的文献数据,综合评估了1980s-2010s中国土壤有机碳储量的变化情况,并分析森林、草地、农田和湿地等生态系统土壤碳源/汇功能;同时结合现有的中国植被碳储量变化研究,进一步探讨了1980s-2010s中国陆地生态系统的碳源/汇效应。研究发现：① 1980s-2010s中国土壤（0~100 cm）有机碳储量净增长3.04&plusmn;1.65 Pg C,增长速率为0.101&plusmn;0.055 Pg C yr^-1,其中表层土壤（0~20 cm）的碳汇效应明显;② 森林土壤是固碳主体,净增长2.52&plusmn;0.77 Pg C,而草地和农田土壤增长有限,分别为0.40&plusmn;0.78和0.07&plusmn;0.31 Pg C;③ 湿地有机碳储量净减少0.76&plusmn;0.29 Pg C;④ 中国陆地生态系统的碳汇效应较强,总碳汇量相当于同期（1980-2009年）化石燃料和水泥生产排放CO₂总量的14.85%~27.79%。随着中国森林和草地生态系统植被和土壤的进一步保护、恢复和重建,中国陆地生态系统具有较大的碳汇潜力,在未来全球碳平衡中将发挥更大的作用。

Enhancing the terrestrial ecosystem carbon sink (referred to as terrestrial C sink) is an important way to slow down the continuous increase in atmospheric carbon dioxide (CO) concentration and to achieve carbon neutrality target. To better understand the characteristics of terrestrial C sinks and their contribution to carbon neutrality, this review summarizes major progress in terrestrial C budget researches during the past decades, clarifies spatial patterns and drivers of terrestrial C sources and sinks in China and around the world, and examines the role of terrestrial C sinks in achieving carbon neutrality target. According to recent studies, the global terrestrial C sink has been increasing from a source of (-0.2±0.9) Pg C yr (1 Pg=10 g) in the 1960s to a sink of (1.9±1.1) Pg C yr in the 2010s. By synthesizing the published data, we estimate terrestrial C sink of 0.20-0.25 Pg C yr in China during the past decades, and predict it to be 0.15-0.52 Pg C yr by 2060. The terrestrial C sinks are mainly located in the mid- and high latitudes of the Northern Hemisphere, while tropical regions act as a weak C sink or source. The C balance differs much among ecosystem types: forest is the major C sink; shrubland, wetland and farmland soil act as C sinks; and whether the grassland functions as C sink or source remains unclear. Desert might be a C sink, but the magnitude and the associated mechanisms are still controversial. Elevated atmospheric CO concentration, nitrogen deposition, climate change, and land cover change are the main drivers of terrestrial C sinks, while other factors such as fires and aerosols would also affect ecosystem C balance. The driving factors of terrestrial C sink differ among regions. Elevated CO concentration and climate change are major drivers of the C sinks in North America and Europe, while afforestation and ecological restoration are additionally important forcing factors of terrestrial C sinks in China. For future studies, we recommend the necessity for intensive and long term ecosystem C monitoring over broad geographic scale to improve terrestrial biosphere models for accurately evaluating terrestrial C budget and its dynamics under various climate change and policy scenarios.© 2022. Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.

Increasing soil organic carbon (SOC) sequestration is not only an efficient method to address climate change problems but also a useful way to improve land productivity. It has been reported by many studies that land-use changes can significantly influence the sequestration of SOC. However, the SOC sequestration potential (SOCP, the difference between the saturation and the existing content of SOC) caused by land-use change, and the effects of land-use optimization on the SOCP are still not well understood. In this research, we modeled the effects of land-use optimization on SOCP in Beijing. We simulated three land-use optimization scenarios (uncontrolled scenario, scale control scenario, and spatial restriction scenario) and assessed their effects on SOCP. The total SOCP (0-20 cm) in Beijing in 2010 was estimated as 23.82 Tg C or 18.27 t C/ha. In the uncontrolled scenario, the built-up land area of Beijing would increase by 951 km2 from 2010 to 2030, and the SOCP would decrease by 1.73 Tg C. In the scale control scenario, the built-up land area would decrease by 25 km2 and the SOCP would increase by 0.07 Tg C from 2010 to 2030. Compared to the uncontrolled scenario, the SOCP in 2030 of Beijing would increase by 0.77 Tg C or 0.64 t C/ha in the spatial restriction scenario. This research provides evidence to guide planning authorities in conducting land-use optimization strategies and estimating their effects on the carbon sequestration function of land-use systems.

黄河泥沙是黄河下游陆地地貌类型形成的物质来源,泥沙沉积改变了地表土壤结构和有机碳含量水平。基于室内外实验和空间地统计分析方法,文中对开封—周口土壤有机碳组分的空间特征和影响因素进行了分析。在0~100 cm土壤中TOC、AOC、NOC的含量分别为0.05~30.03 g/kg、0.01~8.86 g/kg和0.02~23.36 g/kg,表层0~20 cm的TOC、AOC、NOC高于下层,同一土层中TOC的变化幅度和含量差异性最大,AOC最小,NOC介于二者之间。NOC的含量对TOC的贡献大于AOC。空间地统计学研究显示,TOC、AOC、NOC的块金系数在0.50~0.67之间,具有中等程度的空间相关性,TOC、AOC、NOC的含量受结构因素和随机因素的共同作用,且二者的作用强度接近。空间上,自表层向下层,土壤TOC、AOC和NOC的整体变化趋势较为一致,高值区与低值区之间过渡明显,NOC和AOC的含量及空间变化能较好地反映TOC的空间变化和碳积累区域。分析发现,黄河泥沙冲/沉积区分布、农业耕作过程和耕作历史是影响区内土壤有机碳及其组成含量和空间分布的主要因素,而有机物的输入量、土壤颗粒物组成及二者的动态关系是影响土壤结构体形成和有机碳含量的关键因素,提高有机物的含量和改善土壤结构是提升土壤质量、实现区内农业持续发展的有效途径。

The interfaces of the Earth&rsquo;s critical zones are the place where organic carbon is dramatically decomposed and transformed. The dynamics and fate of organic carbon serve as an important foundation of revealing the material transportation and energy transfer in the critical zones, which is of great significance to support the ecological system. The geochemical characteristics of organic carbon in riverine system is reviewed in this study, including the research methods, sources, storage, dynamics and turnover process of organic carbon. It is suggested that the the dynamics of organic carbon in the critical zones should be studied well for understanding carbon cycling in the riverine systems. Various technical methods, short-term high-frequency observation, long-term observation research in the multiinterface with multitime scales should be conducted in typical critical zones, in order to reveal the key factors and its mechanisms of organic carbon dynamics and processes in the riverine systems. Furthermore, the response and feedback mechanism of organic carbon cycle to global change and human activities on longtime scales should be studied. Besides, the carbon exchange between interfaces of atmosphere-plant-litter-soil-river and the dynamics of organic carbon in watersheds should be further analyzed under different disturbance intensities of human activities. Understanding the impacts of environmental changes and human activities on the geochemical cycling of organic carbon in critical zones would benefit the optimization of carbon cycling model and climate change predictions.

地球关键带的各个界面是有机碳发生剧烈分解转化的场所，探讨关键带有机碳的动态变化、归趋及其控制过程，是揭示地表流域中物质运输和能量传递规律的重要基础，对维持生态系统平衡具有重要意义。本文介绍了国内外关于流域不同关键带有机碳的研究方法、来源、储量及其动态、周转过程等地球化学特征的研究进展，以及现有研究存在的问题。建议将典型关键带作为一个整体来研究，综合使用多种技术方法，将短期高频次观测和长期定位观测研究相结合，在典型小流域开展多界面、多过程、多时间尺度的长期同步观测和系统研究，揭示控制关键带有机碳地球化学循环的关键因子及其作用机制。同时重视长时间尺度下有机碳循环对全球变化和人类活动的响应及反馈机制；分析不同人为活动下，大气植物凋落物土壤河流之间的碳交换特征及流域有机碳动态变化规律；定量区分环境变化和人类活动对关键带有机碳地球化学行为的影响，为碳循环模型优化及气候变化预测提供科学依据。