We established a budget model of nitrogen （N） inputs and outputs between watersheds and waterbodies to determine the sources of riverine N in the Changjiang （Yangtze） River drainage area. Nitrogen inputs in the bu...We established a budget model of nitrogen （N） inputs and outputs between watersheds and waterbodies to determine the sources of riverine N in the Changjiang （Yangtze） River drainage area. Nitrogen inputs in the budget included N from synthetic fertilizer, biological fixation by leguminous and other crops, wet/dry atmospheric deposition, excreta from humans and animals, and crop residues. The total N input was estimated to be 17.6 Tg, of which 20% or 3.5 Tg N was transported into waterbodies. Of the total N transported into waterbodies, the largest proportion was N from animal waste （26%）, followed by N from atmospheric wet/dry deposition （25%）, synthetic fertilizer N （17%）, N in sewage wastes （17%）, N in human waste from rural areas （6%） and industrial wastewater N （9%）. We studied the spatial patterns of N inputs and outputs by dividing the Changjiang River drainage area into four sub-basins, from upstream to downstream： the Tongtian River drainage area （TTD, the headwater drainage area, 138 000 l^n2, less disturbed by human activities）; the Jinsha River drainage area （JSD, 347 000 km2, less disturbed by human activities, approx. 3 500 km upstream of the Changjiang estuary）; the Pingshan-Yichang drainage area （PYD, 520 500 krn2, large-scale human disturbance, about 2 000 km upstream of the Changjiang estuary）; and the Yichang-Datong drainage area （YDD, 699 900 km^2, large-scale httman disturbance, approx. 620 km upstream of the Changjiang estuary）. The average N input into waterbodies was 2.3, 7.3, 24.1, and 28.2 kg N/ha in the TTD, JSD, PYD, and YDD sub-basins, respectively, suggesting an increase of N-components of more than 10 times from upstream to downstream areas.展开更多
本文通过调研长江、黄河流域全新世古洪水研究相关文献,开展了两大流域全新世古洪水发生频次空间对比研究。现有资料表明,两大流域全新世古洪水在6000 a BP以前发生较少;6000-4000 a BP古洪水频次上升,在4000 a BP、3000 a BP前后均出...本文通过调研长江、黄河流域全新世古洪水研究相关文献,开展了两大流域全新世古洪水发生频次空间对比研究。现有资料表明,两大流域全新世古洪水在6000 a BP以前发生较少;6000-4000 a BP古洪水频次上升,在4000 a BP、3000 a BP前后均出现一个洪水多灾期;3000 a BP-1000 a BP两大流域古洪水记录频次呈递减趋势;1000 a BP以来,两大流域整体上表现为递增的趋势,而值得注意的是1000 a BP后,两大流域古洪水记录频次呈现出反相位变化的趋势。与太阳活动记录对比,发现两个流域洪水发生均与太阳活动相关,但是两个流域洪水发生对太阳活动的响应相反,长江流域在太阳活动较弱的时期,洪水多发,而黄河流域在太阳活动较强的时期,洪水多发。展开更多
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX2-YW-Q07-02)the National Basic Research Program of China (973Program)(No.2010CB428706)+1 种基金the Fund for Creative Research Groups of NSFC(No.41121064)the National Natural Science Foundation of China (No.41106090)
文摘We established a budget model of nitrogen （N） inputs and outputs between watersheds and waterbodies to determine the sources of riverine N in the Changjiang （Yangtze） River drainage area. Nitrogen inputs in the budget included N from synthetic fertilizer, biological fixation by leguminous and other crops, wet/dry atmospheric deposition, excreta from humans and animals, and crop residues. The total N input was estimated to be 17.6 Tg, of which 20% or 3.5 Tg N was transported into waterbodies. Of the total N transported into waterbodies, the largest proportion was N from animal waste （26%）, followed by N from atmospheric wet/dry deposition （25%）, synthetic fertilizer N （17%）, N in sewage wastes （17%）, N in human waste from rural areas （6%） and industrial wastewater N （9%）. We studied the spatial patterns of N inputs and outputs by dividing the Changjiang River drainage area into four sub-basins, from upstream to downstream： the Tongtian River drainage area （TTD, the headwater drainage area, 138 000 l^n2, less disturbed by human activities）; the Jinsha River drainage area （JSD, 347 000 km2, less disturbed by human activities, approx. 3 500 km upstream of the Changjiang estuary）; the Pingshan-Yichang drainage area （PYD, 520 500 krn2, large-scale human disturbance, about 2 000 km upstream of the Changjiang estuary）; and the Yichang-Datong drainage area （YDD, 699 900 km^2, large-scale httman disturbance, approx. 620 km upstream of the Changjiang estuary）. The average N input into waterbodies was 2.3, 7.3, 24.1, and 28.2 kg N/ha in the TTD, JSD, PYD, and YDD sub-basins, respectively, suggesting an increase of N-components of more than 10 times from upstream to downstream areas.
文摘本文通过调研长江、黄河流域全新世古洪水研究相关文献,开展了两大流域全新世古洪水发生频次空间对比研究。现有资料表明,两大流域全新世古洪水在6000 a BP以前发生较少;6000-4000 a BP古洪水频次上升,在4000 a BP、3000 a BP前后均出现一个洪水多灾期;3000 a BP-1000 a BP两大流域古洪水记录频次呈递减趋势;1000 a BP以来,两大流域整体上表现为递增的趋势,而值得注意的是1000 a BP后,两大流域古洪水记录频次呈现出反相位变化的趋势。与太阳活动记录对比,发现两个流域洪水发生均与太阳活动相关,但是两个流域洪水发生对太阳活动的响应相反,长江流域在太阳活动较弱的时期,洪水多发,而黄河流域在太阳活动较强的时期,洪水多发。
