Topsoil（0～10 cm） samples were collected from typical plant communities in the lower reaches of the Yalong River in the southeastern Tibetan Plateau.The contents of total carbon,total nitrogen,particulate organic carbon,dissolved organic carbon,dissolved inorganic carbon and stable carbon isotopic composition(δ 13 C org ) were measured.The δ 13 C org and stoichiometry were employed to investigate soil carbon storage and its driving factors in hot dry valley.The results show that:（1） The topsoil carbon storage is 121×10~9kg C in the lower Yalong River.Of which,particulate organic carbon storage （95×10~9kg C） accounts for 79.48%,particulate inorganic carbon storage（26×10~9kg C） comprises 20.05%.Dissolved organic carbon and dissolved inorganic carbon reserves are negligible.（2） By comparison,there are considerable soil carbon content and carbon sink potential in the study area.Higher soil organic carbon （SOC） content （21.23 g/kg）,especially mixed woodlands site SOC content （49.71 g/kg）,revealing that contribution of species diversity to SOC content in the study area.A variety of plant communities and a strong photosynthetic carbon assimilation（higher carbon nitrogen ratio（C/N,31.21） of vegetation leaves） carbon sequestration ability provided sufficient plant source carbon guarantee for the higher SOC content in the study area.Higher soil inorganic carbon content and pedogenic inorganic carbon export fluxes（2.065×10~8kg C/a）,implying that there is considerable potential of carbon sink and storage of pedogenic inorganic carbon in the study area.It is suggested that the export fluxes of pedogenic inorganic carbon carried by runoff should be considered in the calculation of pedogenic inorganic carbon sink on a basin scale.（3） The gradient differences of the soil C/N ratio and δ 13 C org were not significant （p＞0.05）,indicating that there is no significant difference in soil microbial metabolic activity among the plant communities.The SOC content was coupling controlled by abiotic factors（temperature,precipitation and slope） and biological factors （community productivity and microbial metabolic activity） in the study area.This study can provide basic data for the discussion of soil carbon sink/source regulation mechanism and the realization of Chinese“carbon neutrality”goal.

Damming significantly influences silicon (Si) biogeochemical cycles in river system. Its mechanism, however, is still not clear to date. We here carried out spatial and temporal field observations over a complete hydrological year in the Xinfengjiang Reservoir on a tributary of the Pearl River to explore the influence of the reservoir on the biogeochemical cycles of Dissolved Silicon (DSi) by exploring in different functional zones. The results showed that DSi concentration was temporally and spatially different, showing variable behaviors in different functional zones. In the Riverine zone, the DSi concentration was largely controlled by input from chemical weathering of silicate minerals in the watershed and seasonal changes in precipitation. In the Transition zone, the biological activity of phytoplankton was the key to control the DSi change, especially during the wet season. In the Lacustrine zone, the effect of the 'biological pump' was limited but some other factors influenced the Si and C cycle, such as phytoplankton settlement/re-decomposition, input of terrigenous substances. In the Dammed zone, the spatial distribution of DSi concentrations was significantly influenced by water regulation of the reservoir. Based on these observations, the DSi interception efficiency of the Xinfengjiang Reservoir was estimated to be about 40.5% and 16.3% when selecting Up-Dammed zone and Down-Dammed zone as output endmember, respectively, over a complete hydrological year. Such DSi sink significance was mainly contributed from the Riverine zone during the wet season. Our studies benefit the understanding of the spatial and temporal heterogenic effects on DSi biogeochemical cycles in a reservoir.

元素硒是许多生物(包括土壤微生物,植物、动物和人类)机体必需的微量营养元素之一,而且对植物、动物和人具有双重生物效应.半个多世纪以来土壤—植物系统元素硒的迁移、转化和富集过程一直备受关注.土壤硒的存在形态包括可溶态硒、可交换态及碳酸盐结合态硒、铁锰氧化物结合态硒、有机物结合态硒和残渣态硒5种形态,其中可溶态硒和可交换态及碳酸盐结合态硒具生物有效性,有机物结合态硒随着有机质分解可转化为可溶态硒而成为土壤潜在有效硒源.不同植物硒含量水平取决于区域土壤有效硒含量和不同植物的硒吸收和富集水平.因此,土壤硒的生物有效性是决定食物链硒含量的关键,同时土壤有效硒通过调节根际环境和植物代谢过程提高植物抗逆性.土壤—植物系统元素硒的迁移和转化是一个复杂的生物地球化学过程,受地壳运动、母岩性质、气候、地貌、土壤环境(物理、化学和微生物活动)条件、土壤硒含量及其化学性质、植物种类及其生理习性、田间管理过程等因素的耦合作用影响.为充分合理利用土壤硒资源,将来应加强植物体内,尤其是主要粮食作物、蔬菜、果树和地道药材叶片、果实中硒迁移、转化和富集研究,为缺硒地区硒的生物强化、富硒地区农作物种植选择和居民食品选择及其风险评价提供基础数据.

地球表层元素硅（Si）的生物地球化学循环影响全球初级生产力和全球碳循环进而影响地球环境变化。土壤生物硅（BSi）因其易溶解而成为岩石圈-土壤圈-生物圈-水圈等圈层之间Si迁移-转化的枢纽。采集海南岛西南部的热带季雨林、经济林（橡胶林、桉树林、芒果林）和农作物（香蕉、甘蔗）土壤样品。采用热碱消化连续提取法萃取BSi;运用相关分析和主成分分析法识别土壤BSi含量变化的主要驱动因素。结果表明：研究区不同植物群落土壤BSi含量从大到小依次为：香蕉地（（2.38±0.72）mg/g）＞热带季雨林（（1.86±1.34） mg/g）＞橡胶林（（1.42±0.81） mg/g）＞桉树林（（1.22±0.28） mg/g）＞芒果林（（0.98±0.71） mg/g）＞甘蔗地（（0.62±0.74） mg/g）;研究区土壤BSi含量存在随群落变化的季节变化：森林群落土壤BSi含量干季大于湿季，农业草本群落（香蕉和甘蔗）土壤BSi含量则出现湿季大于干季的特征。研究区土壤BSi含量变化主要受生物因素（总氮和碳/氮（C/N））和非生物因素（化学风化程度）耦合驱动。在全球尺度上，海南岛西南部土壤BSi含量（1.43 mg/g）低于热带雨林土壤BSi含量（2.5 mg/g）,揭示水热同期的季风气候区山地土壤较活跃的微生物活动和较强的降雨、径流侵蚀作用，均有利于土壤BSi发生迁移-转换，最终以溶解态硅的形式随地表径流注入南海，在一定程度上保持南海生态系统的营养成分结构，确保南海生态系统良性循环。

A large area of lands are subject to soil erosion, which affects the soil ecosystem service by causing soil degradation and soil organic carbon (SOC) changes. Robust estimations of soil loss rates are of key importance to understand relevant controlling factors as well as reducing soil losses. This study utilized complied data derived from Cs-137 inventories and erosion plots to quantify soil loss rates in China as well as investigating controlling factors of soil loss rates. Comparison between results from different methods was also conducted to understand the advantages of each method. Our results showed that soil loss rates of cultivated soils derived from both methods were significantly higher than those of uncultivated soils, and soil loss rates were generally positively correlated with the slope gradient and the slope length. There were discrepancies between soil loss rates derived from Cs-137 inventories and those from erosion plots due to the different erosion processes and spatio-temporal scales that these two methods focused on. The Cs-137 loss ratio was identified as the largest source of variations in the estimated soil loss rates by conversion models. Existing studies have failed to collect enough soil samples to correctly estimate the reference Cs-137 inventory, and considerably overestimated the soil loss rates by assuming a default value of unit for the particle size correction factor.

With the increasing of mining depth, intensity, scale and speed, Ordovician limestone water has become the biggest threat to the safety production of the low group seam. Based on the existing geological data, the hydrogeological characteristics of Ordovician limestone water are analyzed; the risk of Ordovician limestone water inrush is evaluated by using the method of “five maps and double coefficients” and considering the importance of effective protective thickness of floor protective layer in the evaluation results. The results show that there are no non straight through relative safety area (Area I) and non straight type relative risk area (Area II), only non straight type water inrush risk area (Area III) and straight through water inrush risk area (Area IV). According to the evaluation results, the floor grouting reinforcement is directly adopted in Area IV, and the Ordovician limestone may need to be modified in the strong water rich area; in Area III, the grouting transformation of the floor is carried out after the area with water inrush is identified first, but the Ordovician limestone is not needed. Other prevention and control measures should be subsidiary.

Land use changes have a great impact on carbon (C) cycling of terrestrial ecosystems by changing both the C inputs and mineralization rates. It not only results in variations of SOC stocks, but that the SOC properties could also change after vegetation conversions. In this study, we collected soil samples in a series of forests converted from croplands at different times in Southeast China. The effects of the reforestation on SOC pools and stabilities were investigated based on information of SOC contents, SOC fractions (active, intermediate and passive C) and C:N ratios. The organic carbon (OC) contents of the bulk soil and soil fractions increased with the forest ages in both topsoils (0-10 cm) and subsoils (40-50 cm). The increase rates of the active C were higher than those of the intermediate and passive C. As a result, the proportion of the active C increased with the forest ages, which would result in an increase of SOC instabilities. This was confirmed by the observation that the C:N ratio of the bulk soil increased with the forest ages. Our results implied that the C sink potential of the forest soil is to a large extent determined by the forest age.

化学风化是地表岩石矿物向土壤释放营养元素同时形成土壤粘粒组分的地球化学过程,这一过程使土壤具有生态环境功能.本文选择采集青藏高原东南缘的雅砻江下游不同地貌部位和植物群落的表土样品并分析其粒度组成和地球化学特征.结果表明:研究区表土粒度组成以粉砂为主(46.68％),其次是砂粒(34.05％)和粘粒(19.28％);元素组成以Si、Al和Fe为主;K、P和Si相对于上陆壳亏损,与区内沉积岩为主的岩石分布特征一致.研究区表土粘粒含量和化学蚀变指数(CIA)存在明显的空间差异:海拔<1300 m、 坡度较大的南部谷坡地表土粘粒平均含量为6.51％,CIA平均为65,处于脱Ca、Na的中等风化阶段早期;海拔>2400 m、 坡度平缓的西部坡地和宽谷地表土粘粒含量达39.21％,CIA平均达86,风化程度较高.母岩、海拔、坡度和土壤总氮含量对表土CIA值的贡献依次是57.34％、23.46％、10.33％和6.87％.显然,母岩性质是控制研究区表土化学风化过程的主要因素,地貌条件(海拔和坡度)是驱动化学风化过程最重要的外部因素,且海拔高度的影响大于坡度;生物作用对CIA值有一定的贡献.本研究可为深入探讨干热河谷地区土壤生物地球化学过程提供基础数据.

To investigate the variation of the biogeochemical cycle of riverine dissolved inorganic carbon (DIC) and silicon (DSi) with the cascade damming, the bicarbonate ( $$ {\mathrm{HCO}}_3^{-} $$ ), dissolved silicon (DSi), and other environmental factors within the cascade reservoirs of the lower reaches of Yalongjiang River, passing through the southeastern Qinghai-Tibet Plateau, were systematically analyzed by collecting water samples during the wet season and dry season from 2018 to 2019, respectively. The results showed that the lower ratio of DSi to $$ {\mathrm{HCO}}_3^{\hbox{--} } $$ (0.044 ± 0.001) was mainly controlled by the domination of carbonate mineral in the sedimentary rock of the Yalongjiang River drainage basin. The DSi: $$ {\mathrm{HCO}}_3^{\hbox{--} } $$ ratio was positively correlated with discharge (P < 0.05), and negatively correlated with the water retention time (P < 0.01) and chlorophyll a, implying that the variations of DSi: $$ {\mathrm{HCO}}_3^{\hbox{--} } $$ ratio were mainly determined by the rock chemical weathering processes and the hydrologic process outside the reservoirs and the biological processes within the cascade reservoirs. The phytoplankton photosynthetic process stoichiometrically assimilated DSi and $$ {\mathrm{HCO}}_3^{\hbox{--} } $$ , resulted in 3.46 × 104 t·Si a−1 and 1.89 × 104 t·C a−1 sequestering in the cascade reservoirs, respectively. Compared with the situation of dam-free in the lower reaches of Yalongjiang River, the export flux of $$ {\mathrm{HCO}}_3^{-} $$ and DSi at the mouth of Yalongjiang River was reduced by 11.87% and 62.50%, respectively; the ratio of DSi: $$ {\mathrm{HCO}}_3^{\hbox{--} } $$ decreased by 36.01% for only building the Ertan dam and 53.15% for the cascade damming, respectively. The water renewal time prolonged from 45 to 126.6 days due to the regulation of the cascade reservoirs in the mainstream. Ultimately, a conceptual model on migration-transformation of DIC and DSi within the cascade reservoirs in the lower reaches of Yalongjiang River was established. These findings demonstrated that riverine cascade damming could extend the biogeochemical coupling cycle of DIC and DSi within the inland aquatic ecosystems and ensure the ecological environment security in the hot-dry valley.

Transport fluxes and properties of riverine organic carbon in the tropical monsoon region were the vital parameters in the global riverine organic carbon fluxes budget. The study focused on the riverine organic carbon in the Changhuajiang River (CHJR), locating at the mid-west of the Hainan Island, China. Dissolved organic carbon (DOC) concentrations in the CHJR ranged from 0.22 mg/L to 11.75 mg/L with an average of 1.75 mg/L, which was lower than the average of global rivers and had a significantly temporal and spatial variation. Output flux of riverine DOC was calculated as 0.55 t/km2/y, which could be revised up to 1.03 t/km2/y, considering that the riverine discharge before dam construction. A linear model of riverine DOC flux suitable in CHJR basin was established, which involved the factors, such as soil organic carbon, runoff depth and slope, etc. There was a large variation of POC concentrations in the CHJR where the average POC concentration in the dry season was 2.41 times of the wet season. Riverine POC flux in CHJR basin was calculated as 1.78 t/km2/y, higher than the average of global rivers and far lower than those in other domestic larger rivers. About 8.28 × 103 t POC were exported yearly in CHJR, of which, 7.15 × 103 t originated from terrestrial ecosystem and 1.13 × 103 t stemmed from aquatic ecosystem. Meanwhile, about 87.74% of terrestrial source happened in the wet season and 12.26% in the dry season. This research revealed that the riverine organic carbon mainly stemmed from the surface erosion processes in the drainage basin during the wet season.

天然水体中存在同化二氧化碳(CO2)的光合作用,也存在释放CO2的微生物呼吸过程.地球表层水体与大气之间的CO2交换构成全球碳循环的一个重要环节.水-气之间CO2交换的方向和通量主要受大气圈和水体表层CO2分压(pCO2)的制约.水体pCO2值可以通过对近水面气体成分变化过程的现场仪器检测或者根据测定的水体化学参数运用经验公式计算求得.迄今对陆地水体,尤其河流筑坝形成的“蓄水河流”(下称水库)水体CO2动态研究中,由于水域及其近表层大气成分的时空多变,一般采用水化学参数计算方法求得水体的pCO2值.全球约70.97％的水库表层水体pCO2高于大气pCO2.全球尺度上水库表层水体pCO2自热带向寒温带逐渐递减;单个水库水体的pCO2一般呈现“出库＞入库＞库中”、pCO2随深度而增加的变化规律.水库表层水体pCO2的时间变化一般表现为“冬季＞夏季、消融期＞冰冻期、黑夜＞白天”.水库水体的pCO2是其水化学平衡的结果,受水温、水体pH、水生生物活动以及外来水体的混合等多种因素影响,变化较为复杂.为精确量化水库水-气界面CO2交换通量,水文学、湖沼学、生态学和地球化学等领域的学者有必要合作,共同努力进行水库流域尺度的实地观测,完善水体溶解无机碳计算模型,深入探讨水库水体碳动力学机制,为全球碳循环研究和气候变化预测提供可靠的基础数据.

为研究湿热中小流域岩石化学风化与化学径流组成的关系,选取硅酸盐岩为主的东江一级支流西枝江流域,分别于2011年1月和7月采集干流和支流水样品并测量其化学组成,运用图解法和正演模型对西枝江流域水化学组成进行分析和定量计算.结果表明,Na+和HCO3-为西枝江流域水体的主要阳离子和阴离子,两者分别占总阳离子和总阴离子的55％以上.硅酸盐矿物的化学风化对水体阳离子的贡献最大(45.8％),其次是人类活动和碳酸盐矿物风化的贡献(分别是24.7％和22.0％),大气输入对阳离子的贡献相对较少(7.5％).受碳酸盐矿物风化和人类活动影响较大的支流水化学组成季节变化较大,受硅酸盐矿物化学风化影响的河流水化学组成季节变化不明显.西枝江流域硅酸盐矿物和碳酸盐矿物化学风化速率分别是8.27和56.95 t/(km2·a),二者化学风化对大气CO2的消耗速率分别为0.80×105和8.52×105 mol/(km2·a).

河流筑坝将异养的自然河流转变成自养的“蓄水河流”(下称水库),使得河流生源物质循环过程和输向海洋的物质性质及其通量发生变化.由于生源要素碳(C)、氮(N)、磷(P)、硅(Si)在生物过程中的行为不同,导致水库中生源要素有机碳(OC)、P和Si的循环效率不同,依次是Si＞OC＞P;而全球尺度上水库对生源要素的滞留效率表现为N＞C＞P＞Si.水库的沉积埋藏作用构成河流OC的净汇.元素生态化学计量特征与稳定同位素组成联合使用可有效示踪生源物质在水库中的迁移转化过程.随着人类对清洁能源需求的增加,河流水库群建设强度将会增大,梯级筑坝下流域系统生源物质动力学的变化规律及其生态环境累积效应等科学问题应引起生物地球化学循环研究领域的关注.

In the context of climate change, the input of acid substances into rivers, caused by human activities in the process of industrial and agricultural development, has significantly disrupted river systems and has had a profound impact on the carbon cycle. The hydrochemical composition and which main sources of the Lianjiang River (LR), a subtropical karst river in northern Guangdong Province, South China, were analyzed in January 2018. The objective was to explicate the influence on the deficit proportion of CO2 consumption, resulting from carbonate chemical weathering (CCW), driven by nitric acid (HNO3) and sulfuric acid (H2SO4), which is affected by exogenous acids from the industrial regions in north of the Nanling Mountains and the Pearl River Delta. The response of the riverine carbonate system to exogenous acid-related weathering was also discussed. HCO3− and Ca2+, respectively, accounted for 84.97% of the total anions and 78.71% of the total cations in the surface runoff of the LR, which was characterized as typical karst water. CCW was the most important material source of river dissolved loads in the LR, followed by human activities and silicate chemical weathering (SCW). Dissolved inorganic carbon (DIC), derived from CCW induced by carbonic acid (H2CO3), had the largest contribution to the total amount of DIC in the LR (76.79%), and those from CCW induced by anthropogenic acids (HNO3 and H2SO4) and SCW contributed 13.56% and 9.64% to the total DIC, respectively. The deficit proportion of CO2 consumption associated with CCW resulting from sulfuric acid and nitric acid (13.56%), was slightly lower than that of the Guizhou Plateau in rainy and pre-rainy seasons (15.67% and 14.17%, respectively). The deficit percentage of CO2 uptake associated with CCW induced by sulfuric acid and nitric acid, accounted for 38.44% of the total CO2 consumption related to natural CCW and 18.84% of the anthropogenic acids from external areas. DIC derived from CCW induced by human activities, had a significant positive correlation with the total alkalinity, SIc and pCO2 in river water, indicating that the carbonate system of the LR was also driven by exogenous acids, with the exception of carbonic acid. More attention should be paid to the effects of human activities on the chemical weathering and riverine carbonate system in the karst drainage basin.

The continent ocean transfer of dissolved silica (DSi, formed as Sio(2)) via rivers constitutes an important part of the global silica cycle. The uptake of terrestrial vegetation and riverine phytoplankton are the key process controlling DSi migration within the drainage basin. Anthropogenic activities (including land use change and damming) have been altering DSi export by changing biological uptakes in the basin. A significant artificial lake effect of damming was exhibited on the spatial variations of chlorophyll-a (Chl.a) and DSi, which caused 15.39% of riverine DSi to be detained in the reservoir region of Changhuajiang River basin, Hainan Island, China. The biological uptake of terrestrial vegetation was behindhand responsible for seasonal fluctuations of DSi. The DSi uptake yields ranged from 19.44 t/km(2)/yr to 86.76 t/km(2)/yr during the different terrestrial vegetation types in the basin, in turn, tropical rainforest > crops > artificial economic forests > grassland. The try calculating of the DSi yield released by the silicates weathering was carried out taking biological processes in the basin into account. Taking into the plants uptake within the basin consideration, the corrected DSi yield from the silicates weathering was 18.6 t/km(2)/yr. Accordingly, the silicates weathering rate was up to 41.55 t/km(2)/yr, which was 1.36 times higher than that (30.39 t/km(2)/yr) without consideration of the biological uptake, and close to the fastest weathering rate of the granite basin (Puerto Rico) in the earth surface. Of the DSi released by the silicates weathering, 28.56% was absorbed by terrestrial vegetation, and 31.43% was consumed by riverine phytoplankton, and the rest was drainaged into the South China Sea. (C) 2016 Published by Elsevier Ltd.

Geomorphic features,climate characteristics and dam construction are the main factors controlling the cycling and export of riverine carbon to the ocean.The Zengjiang River (ZJR) is a second-order tributary of the Pearl River system,with an area of 3160km2.Silicate rocks dominated the bedrock within the drainage basin.The landforms within the drainage basin are dominated by mountains and hills covered with a thick layer of red weathering crusts on the surface.The soil is mainly of Udic Ferralisols,with parts of mountain areas covered by Peruelic Ferrallisols and Gleysol-Paddy soils.Annual mean temperature and precipitation is 21.6℃ and 2188mm,respectively.The vegetation is southern subtropical evergreen broad-leaved forest,with about 70％ of forest coverage.The river water is clear at the usual time due to the low soil erosion rate within the basin,and is relatively turbid only during the bursting flood periods.The averaged annual discharge is 3.82×109m3 from 1954 to 2009,with 83.3％ of which was discharged from April to September.A dam was built up and impounded in March 2008 at the lower reaches of the river,which led to a backwater section extended up to 22km.The Qilinzui Hydrological Station (QLZ:23°20.734′N,113°50.399′E;6m a.s.1.) controls 91％ of the catchment area and located at the backwater section.Water samples were monthly collected at the QLZ section from December 2008 to January 2010.Water samples were also collected in July 2009 (flood season) and January 2010 (dry season) at other 23 sections on the mainstream or its tributaries.The analyzed water physical-chemical parameters include:the total alkalinity,temperature,pH,electrical conductivity,the concentrations of DOC,POC and chlorophyll-a,and other ions.The partial pressure of CO2 of the surface water was calculated using the CO2SYS program using measured parameters.In the flooding season,a flushing effect by rainfall enhanced the contribution of allochthonous DOC to the riverine carbon in the ZJR,meanwhile the higher atmospheric temperature also promoted the flourishing of autochthonous DOC in the ZJR.The concentration of DOC at the QLZ section varied from 0.76mg/L to 4.75mg/L,with an average of 2.37± 1.13mg/L,which is much lower than the global averaged value.The low DOC concentration in the ZJR is a consequence of its mountainous and hilly topography within the drainage basin.However,the higher DOC concentration in the flood season than in other seasons is most likely explained by the significant scouring effect of the DOC pools stored in the forests and soils.The polluted effluents from more densely residential land at the lower reaches of the river basin in winter may be responsible for the higher DOC concentration in those sampling sections.Concentration of total suspended substance (TSS) in the ZJR was positively correlated significantly with the discharge.The photosynthesis in the river became faint with increasing concentration of TSS,which limited the production of autochthonous carbon.The content of organic carbon of TSS decreased exponentially with the concentration of the TSS for the ZJR.In the QLZ section,the C/N molar ratio of the riverine particulate organic matter is 6.43±1.04,which is significantly less than that collected from March 2002 to February 2003 at the same sampling section,i.e.,9.80± 1.66,which demonstrates that the contribution from aquatic biomass to total POC had increased after the construction of the dam.The calculation results shown that the contribution from aquatic biomass to the POC from 2009 to 2010 at the QLZ section reached (93.0±6.5)％.Some time,the dam construction also led to a lower partial pressure of CO2 in the backwater area relative to that in the atmosphere.Annual POC and DOC specific yields of the ZJR basin were estimated to be 11.58×105g/km2·a and 25.08×105g/km2· a for 2009,respectively.Compared with other global rivers,the ZJR had a relatively high level of TOC yield,and with DOC being the dominating form of riverine organic carbon,which is similar to the carbon dynamics in the Amazon and Orinoco rivers in South America,and different to that in the Xijiang and Beijiang rivers which with a similar climate and latitude zones to the ZJR.

On the basis of the meteorological database including monthly cumulative sunshine hours, temperature and precipitation (1 971 -201 3)from Qinyang Meteorological Bureau,Henan province,the climatic change characteristics and its effect on the growth and production of the Huai medicine were ana-lyzed by the methods of moving average,M-K mutation test and multiple linear regression.The results showed that the average temperature increased at the average speed of 0.3 ℃/1 0 a in the period of the Huai medicine growth.The average temperature increased 0.4 ℃ /1 0 a and 0.5 ℃/1 0 a in winter sea-son and spring season,respectively.Accumulated temperature ≥1 0℃ presents significantly increasing trend (P <0.05)and delaying sustained time.The mean annual precipitation decreased slightly.The seasonal distribution of precipitation was corresponding to the water requirement of the Huai medicine in different growth processes,and the frequency of strong precipitation has decreased,which resists the de-caying roots or tubers to a certain extent.The cooperative function of the atmospheric temperature and precipitation significantly affects the production of the Huai medicine (P <0.05)in the growth period and in the inflated period of roots and /or tubers.The atmospheric temperature change comprised a crucial factor on the Huai medicine production in Qinyang County.To ensure the Huai medicine quality,produc-tion and the market demand,the responding measures need to be adopted in the Huai medicine origin re-gion with the global warming.

To evaluate the carbon sink capacity caused by rock chemical weathering processes and its controlling factors in the tropical monsoon region, the hydrochemistry of the granite-hosted Changhuajiang River (CHJR) basin in Hainan Island, China, were systematically investigated by collecting water samples from the river mouth to headwater in the dry season and the wet season, respectively. The results show that Na+, Ca2+ and HCO3 − are dominant in the chemical runoff of the CHJR. The spatial and temporal variations of major ions imply the influence of the multi-sources. The concentrations of Ca2+, Mg2+, HCO3 − and DSi, mainly sourcing from rock (silicates and carbonates) weathering, are lower in the wet season than those in the dry season. However, the concentrations of K+, Cl−, SO4 2−and NO3 −, mainly sourcing from the atmospheric precipitation and human activities, are significantly controlled by the monsoon rainfall and hydrological stage in the CHJR basin. The contributions of the silicates chemical weathering, human activities, atmospheric input, evaporites dissolution and carbonates chemical weathering to the chemical runoff are 82.62, 9.05, 5.24, 2.05 and 1.05 % in the CHJR, respectively. The chemical weathering rates of silicates, carbonates and evaporites are 16.25, 0.40 and 0.62 t km−2 year−1, respectively. Chemical weathering rates in global granite-hosted basins significantly correlate with temperatures (P < 0.01) and rapidly increase when temperatures are up to 24 °C. There are two kinds of relationship between chemical weathering rates and runoff depths: logarithmic pattern (temperatures <10 °C) and linear pattern (temperatures >10 °C). On a regional scale, we find that the chemical weathering rates in the southern China appear a weak positive correlation with normalized differential vegetation indexes (NDVI), which need to be confirmed by enough data. The flux of atmospheric CO2 consumption from rock weathering in the CHJR basin is 2.71 × 105 mol km−2 year−1 by the discharge water of 2014, with being close to that (2.9 × 105 mol km−2 year−1) in the other tropical basins and far from that (5.06 × 105 mol km−2 year−1) calculated by the averaged discharge water of over years in the CHJR. The silicates weathering intensity lies at the moderate phase, implying that the weathering processes are still developing in global tropical granite basins. Hence, how the atmospheric CO2 consumption from rock weathering will change with increasing the atmospheric CO2 level and dam construction altering water cycle in the tropical monsoon area is expected to be deserved.

根据2014年1月实测的海南岛昌化江径流化学组成,运用物质平衡法和相关分析法估算化学径流组成的来源和控制因素,探讨流域化学风化产物HCO3-和溶解性硅(DSi)的输出及生态环境意义.结果表明昌化江流域水体呈中偏弱碱性,化学径流组成阴离子以HCO3-为主,阳离子以Ca2+、Na+为主.其中,77.30％的离子源于流域内硅酸盐岩的化学风化,1.38％的离子来源于碳酸盐岩风化,大气沉降对化学径流的贡献为5.45％,人类活动对干、支流化学径流的贡献分别为15.90％与21.04％,差异显著(P＜0.01).地貌条件、岩性及径流深度是影响流域化学径流组成的关键因素.昌化江流域干季输入南海的HCO3-和DSi量分别为2.12×108 mol、1.38×108 mol,是南海海洋生态系统初级生产力的主要物质来源之一,在南海生态系统物质循环预算中不可忽视.