河流拦截筑坝形成蓄水河流,逐渐向“湖泊型”生态系统演化,加强了生物地球化学循环并进一步影响水体碳循环.为了更准确地进行全球碳循环的预算并预测碳循环变化,必须确定对河流系统产生影响的碳来源.因此,通过测定库区水体c(DIC)(DIC为...河流拦截筑坝形成蓄水河流,逐渐向“湖泊型”生态系统演化,加强了生物地球化学循环并进一步影响水体碳循环.为了更准确地进行全球碳循环的预算并预测碳循环变化,必须确定对河流系统产生影响的碳来源.因此,通过测定库区水体c(DIC)(DIC为溶解性无机碳)及其δ13 C(稳定碳同位素),分析了DIC的主要来源及其影响因素.结果表明:①水体c(DIC)为1.80~5.02 mmol/L,而δ13 C DIC(溶解性无机碳的稳定碳同位素)为-7.45‰^-1.26‰.c(DIC)与EC(电导率)、TA(总碱度)均呈正相关,与水温呈负相关.表水层δ13 C DIC与c(DIC)、TA均呈正相关,与EC在入库河流处呈负相关;而滞水层δ13 C DIC与EC、p CO 2(二氧化碳分压)、TA、c(DIC)均呈正相关.②水平方向上,表水层各指标变化明显,TA、EC、SIc(方解石饱和指数)和c(DIC)整体上呈降低趋势,δ13 C DIC从上游至下游逐渐偏正,受碳酸盐矿物溶解影响显著;垂直方向上,热分层和化学分层现象对水的碳循环产生了显著影响.有机质分解在深水层释放大量CO 2致使c(DIC)、p CO 2逐渐升高及δ13 C DIC逐渐降低,c(DIC)及其δ13 C在整个水柱上存在显著的空间异质性.研究显示,光照水库DIC的来源主要有两种,即生物源的土壤CO 2和有机物呼吸产生的溶解CO 2形式的DIC源、碳酸盐矿物风化所产生的碳酸氢盐形式的DIC源.展开更多
Multi-proxies of lacustrine sediments, such as total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), hydrogen index (HI), oxygen index (OI) and stable car...Multi-proxies of lacustrine sediments, such as total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), hydrogen index (HI), oxygen index (OI) and stable carbon isotopic composition of organic matter (δ^(13)C_(org)), were analyzed using a 7.3 m core from Zige Tangco. The source of the organic matter in the sediment was mainly from autochthonous phyto-plankton, therefore the significances of proxies can be interpreted as that high TOC, TOC/TS, HI and δ^(13)C_(org) values, low TC, TIC values corresponded to warm and wet climatic condition, and vice versa. The process of climatic development in the Zige Tangco region was hence recovered. During the early and Mid-Holocene, the climate was warm and wet and intensive cold events occurred during the periods of 8600 to 8400 cal a BP and 7400 to 7000 cal a BP. In the second half of Holocene, the climate became cold and dry gradually. The palaeoclimatic process during Holocene in Zige Tangco region matched well with that in Co Ngoin region which is ca 40 km to the south-east. Therefore this palaeoclimatic process represents the Holocene climatic feature in the Central Tibetan Plateau which has the same pattern in the Northern Tibetan Plateau, but the time and duration of some climatic events might be different. We can conclude that in Holocene solar insolation controlled the climatic pattern on the central Tibetan Plateau.展开更多
全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13...全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13)C)和水分利用效率(iWUE)对气候变暖和大气CO2浓度急剧上升的响应缺乏研究。本研究利用天山西部伊犁河流域的雪岭云杉树轮样本,使用树木年代学方法和树轮稳定碳同位素技术,建立树轮宽度年表、稳定碳同位素(δ^(13)C)以及内禀水分利用效率(iWUE)序列,分析了树轮δ13C和iWUE的长期变化特征,探讨了树轮δ13C和iWUE对气候的响应规律以及iWUE与树轮宽度的关系。结果表明,主要的气候因子并没有强烈地限制树木径向生长;夏季平均气温对树轮δ^(13)C分馏有重要影响,iWUE的长期变化受到全球Ca增加和升温趋势影响,但直接影响iWUE年际变化的主要因素是饱和水汽压亏缺(VPD)。全球升温和Ca增加导致了iWUE的持续升高,但并没有导致雪岭云杉树木径向生长的明显增加。展开更多
文摘河流拦截筑坝形成蓄水河流,逐渐向“湖泊型”生态系统演化,加强了生物地球化学循环并进一步影响水体碳循环.为了更准确地进行全球碳循环的预算并预测碳循环变化,必须确定对河流系统产生影响的碳来源.因此,通过测定库区水体c(DIC)(DIC为溶解性无机碳)及其δ13 C(稳定碳同位素),分析了DIC的主要来源及其影响因素.结果表明:①水体c(DIC)为1.80~5.02 mmol/L,而δ13 C DIC(溶解性无机碳的稳定碳同位素)为-7.45‰^-1.26‰.c(DIC)与EC(电导率)、TA(总碱度)均呈正相关,与水温呈负相关.表水层δ13 C DIC与c(DIC)、TA均呈正相关,与EC在入库河流处呈负相关;而滞水层δ13 C DIC与EC、p CO 2(二氧化碳分压)、TA、c(DIC)均呈正相关.②水平方向上,表水层各指标变化明显,TA、EC、SIc(方解石饱和指数)和c(DIC)整体上呈降低趋势,δ13 C DIC从上游至下游逐渐偏正,受碳酸盐矿物溶解影响显著;垂直方向上,热分层和化学分层现象对水的碳循环产生了显著影响.有机质分解在深水层释放大量CO 2致使c(DIC)、p CO 2逐渐升高及δ13 C DIC逐渐降低,c(DIC)及其δ13 C在整个水柱上存在显著的空间异质性.研究显示,光照水库DIC的来源主要有两种,即生物源的土壤CO 2和有机物呼吸产生的溶解CO 2形式的DIC源、碳酸盐矿物风化所产生的碳酸氢盐形式的DIC源.
基金National Natural Science Foundation of China (Grant Nos. 40471001 and 90411017)
文摘Multi-proxies of lacustrine sediments, such as total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), hydrogen index (HI), oxygen index (OI) and stable carbon isotopic composition of organic matter (δ^(13)C_(org)), were analyzed using a 7.3 m core from Zige Tangco. The source of the organic matter in the sediment was mainly from autochthonous phyto-plankton, therefore the significances of proxies can be interpreted as that high TOC, TOC/TS, HI and δ^(13)C_(org) values, low TC, TIC values corresponded to warm and wet climatic condition, and vice versa. The process of climatic development in the Zige Tangco region was hence recovered. During the early and Mid-Holocene, the climate was warm and wet and intensive cold events occurred during the periods of 8600 to 8400 cal a BP and 7400 to 7000 cal a BP. In the second half of Holocene, the climate became cold and dry gradually. The palaeoclimatic process during Holocene in Zige Tangco region matched well with that in Co Ngoin region which is ca 40 km to the south-east. Therefore this palaeoclimatic process represents the Holocene climatic feature in the Central Tibetan Plateau which has the same pattern in the Northern Tibetan Plateau, but the time and duration of some climatic events might be different. We can conclude that in Holocene solar insolation controlled the climatic pattern on the central Tibetan Plateau.
文摘全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13)C)和水分利用效率(iWUE)对气候变暖和大气CO2浓度急剧上升的响应缺乏研究。本研究利用天山西部伊犁河流域的雪岭云杉树轮样本,使用树木年代学方法和树轮稳定碳同位素技术,建立树轮宽度年表、稳定碳同位素(δ^(13)C)以及内禀水分利用效率(iWUE)序列,分析了树轮δ13C和iWUE的长期变化特征,探讨了树轮δ13C和iWUE对气候的响应规律以及iWUE与树轮宽度的关系。结果表明,主要的气候因子并没有强烈地限制树木径向生长;夏季平均气温对树轮δ^(13)C分馏有重要影响,iWUE的长期变化受到全球Ca增加和升温趋势影响,但直接影响iWUE年际变化的主要因素是饱和水汽压亏缺(VPD)。全球升温和Ca增加导致了iWUE的持续升高,但并没有导致雪岭云杉树木径向生长的明显增加。
