Soil evaporation of aeolian sandy soil in Gurbantunggut Desert

干旱条件下，水是影响自然环境变异的最重要因子。土壤水分含量决定着植物生存与生长，对遏止沙漠化危害至关重要。土壤水分是将降水、土壤和植被对水分平衡的作用与水分平衡对植被的动态影响综合起来的关键因子。干早、半干早沙地降水先天不足，而潜在蒸散量大，降雨入渗到土壤中并被储存的水分是该地区植被生长、发育的主要水源。沙地土壤蒸发是大气降水的一种无效散失，它的大小直接决定着降水转化为有效土壤水的效率，从而间接决定了植物可利用水分的多寡。在降水稀少的沙漠地区，定量认识土壤蒸发量的大小和其所占降水的比例的多少显得尤为重要。本论文于2004年在植物全生长期（5-9月），应用自制的微型蒸渗仪(Micro-Lysimeter)测定了风沙土（有结皮覆盖的丘间低地和裸露沙丘顶部）和对照的荒漠盐碱土的土壤蒸发。结果表明：在相似的气象条件下，风沙土区的丘间低地和荒漠盐碱土的日平均蒸发量分别约是裸露沙丘（风沙土区）的2倍和3倍。整个生长期裸露沙丘的累积蒸发量为18.7 mm，丘间低地为38.8 mm，荒漠盐碱土为 52.1 mm。根据整个观测期的累积蒸发量和累积降雨量计算得出的蒸发降雨比分别为：裸露沙丘0.20，丘间低地0.42，荒漠盐碱土0.62，表明裸露沙丘由降水转化为土壤水而储存的比率最高。同时，从数据分析中可以看出：在风沙土区0-5 cm土层的含水量对土壤蒸发起决定作用，而盐碱土区的土壤蒸发则受到更深层次土壤水分的影响。裸露沙丘低的土壤蒸发、高的降水转化效率，为植被恢复奠定了良好的基础。因此，裸露沙丘的低蒸发量可以视为植被状况对生态水文过程的一种良性反馈。Abstract:Water is a key factor influenced the environment variation in arid and semiarid region, soil moisture content is the most important limitary factor to plant growth, also have the probability to prevent aggravation of the desertification .soil moisture is the essential to combine the effect of precipitation, soil and vegetation on water balance with the dynamic impact of water balance on vegetation. Precipitation is inadequate in the arid and semiarid sandy land, but the potential evapotranspiration is high, so the main water source for plant growth is the deposited soil moisture. Sandy soil evaporation is an ineffective loss of rainfall, it directly determines the amount of rainfall that will eventually becomes soil water, which is available to plants. In the desert area where rainfall is rare and valuable, study on soil evaporation and its proportion of the rainfall is more important than other region. Experiments were carried out in the whole growing season of 2004 to evaluate the evaporation of aeolian sandy soil and heavy texured saline desert soils using micro-lysimeters. The results indicated that the average daily evaporation of the inter-dune and saline soils are 2 times and 3 times, respectively, of the evaporation from the bare sand dune soil under similar climatic and soil water conditions. Accumulated evaporations from bare sand dune, inter-dune lowland and the desert saline soils for the whole growing season were 18.7 mm, 38.8 mm and 52.1mm, respectively. Based on the accumulated evaporation and precipitation, the evaporation-precipitation ratios for the whole growing season were calculated as 0.20, 0.42 and 0.62 for bare sand dune, inter-dune lowland and desert saline soils, respectively; indicated that bare sand dune has the highest storage ratio for precipitation. Close correlation between soil evaporation between soil water content at 0-5 cm (R2 > 0.90 for sandy soils, R2 ~ 0.81 for heavy textured saline soil) indicated that the soil evaporation was determined by soil water content in top soil layer for sandy soils, and for the heavy textured saline soil, it was also influenced by soil water content at the layers below. Low evaporation, high storage ratio to rainfall in bare sand dune, creates favorable condition for vegetation restoration, and this may be considered as a positive feedback of local vegetation conditions towards eco-hydrological processes

盐生荒漠与绿洲农田土壤CO_2通量的对比研究

为定量确定干旱区土地利用变化对土壤CO2通量的影响,采用LI-8100观测了原始盐生荒漠和垦荒农田的土壤CO2通量.结果表明:在整个生长期内,农田土壤CO2通量平均速率为3.19μmol.m-2.s-1,盐生荒漠为0.08μmol.m-2.s-1.农田土壤CO2通量的日过程呈单峰型,盐生荒漠则呈双峰型;农田土壤CO2通量远高于盐生荒漠,盐生荒漠夜间的土壤CO2通量均为负值.绿洲农田最高月均值出现在7月(4.67μmol.m-2.s-1);荒漠最高出现在6月(0.17μmol.m-2.s-1),9月后荒漠土壤CO2通量的月均值降为负值.进一步研究表明:盐生荒漠垦荒前后土壤CO2通量与土壤温度的相关性都随土壤深度增加而减小,而与近地面10cm气温关系最密切;湿润事件对土壤CO2通量具有促进作用.盐生荒漠开垦为农田后不仅改变了土壤CO2通量的量级,且在一定程度上改变了通量的方向

古尔班通古特沙漠风沙土土壤蒸发特征

土壤表面蒸发是降水的无效损失,其大小直接决定着降水转化为有效土壤水的效率,从而间接决定了植物可利用水分的多寡。在降水稀少的沙漠区,定量认识土壤蒸发的大小和其所占降水的比例显得尤为重要。在2004年全生长期(5~9月)应用自制的微型蒸渗仪(Micro-Lysime-ter)测定了风沙土(有结皮覆盖的丘间低地和裸露沙丘顶部)和对照的荒漠盐碱土的土壤蒸发。结果表明:在相似的气象条件下,风沙土区的丘间低地和荒漠盐碱土的日平均蒸发量分别约是裸露沙丘(风沙土区)的2倍和3倍。整个生长期裸露沙丘的累积蒸发量为18.7mm,丘间低地为38.8mm,荒漠盐碱土为52.1mm。根据整个观测期的累积蒸发量和累积降雨量计算得出的蒸发降雨比分别为:裸露沙丘0.20,丘间低地0.42,荒漠盐碱土0.62,表明裸露沙丘由降水转化为土壤水而储存的比率最高。同时,从数据分析中可以看出:在风沙土区0~5cm土层的含水量对土壤蒸发起决定作用,而盐碱土区的土壤蒸发则受到更深层次土壤水分的影响。裸露沙丘低的土壤蒸发、高的降水转化效率,为植被恢复奠定了良好的基础。因此,裸露沙丘的低蒸发量可以视为植被状况对生态水文过程的一种良性反馈

Phytoplankton Communities in the Northern Yellow Sea in Summer,2011

2011年6月21日至24日在北黄海海域(36°00′~40°00′n,121°00′~125°00′E)30个站位应用uTErM(O|¨)Hl方法进行了浮游植物群落的分析。共发现浮游植物27种,隶属3门23属,其中硅藻门15属17种,占所发现物种数的63.9%;甲藻门6属8种,占所发现物种数的30.6%;金藻门2属。优势物种为:微小原甲藻[PrOrOCEnTruM MInIMuM(PAVIllArd)SCHIllEr]、具槽帕拉藻[PArAlIA SulCATA(EHrEnbErg)ClEVE]、圆筛藻[COSCInOdISCuS SPP.]、直唐氏藻[dOnkInIA rECTA(dOnkIn)grunOW]、渐尖鳍藻[dInOPHySIS ACuMInATA ClAPArEdE&lACHMAnn]和曲舟藻[PlEurOSIgMA SPP.]。浮游植物的表层细胞丰度为0.19x10~3~1885.67x10~3S/l,平均值为77x10~3S/l;甲藻细胞丰度为0.04x10~3~1882.15x10~3S/l,平均值为72.08x10~3S/l;硅藻细胞丰度为0.04x10~3~43.82x10~3S/l,平均值为5.11x10~3S/l。表层分布看,夏季表层浮游植物细胞高值区主要集中在渤海海峡、山东半岛和辽东半岛近岸区域,中部海域较低,优势种以具槽帕拉藻和圆筛藻为主。垂直方向上,浮游植物细胞丰度主要集中在中上层水体;断面分布上,b-f断面硅藻细胞丰度的高值区多出现于冷水团区域,主要由具槽帕拉藻贡献,甲藻细胞丰度的高值区在中上层水体,由微小原甲藻贡献。表层浮游植物群落的SHAnnOn-WIEnEr多样性指数为0.03~2.94,平均值为1.57;均匀度PIElOu指数为0.01~0.91,平均值为0.67。总体来看,渤海海峡和辽东半岛南岸的浮游植物物种多样性较高。典范对应分析(CCA)显示,具槽帕拉藻、圆筛藻、舟形藻、曲舟藻、太平洋海链藻[THAlASSIOSIrA PACIfICA grAn ET AngST]、斯氏几内亚藻[guInArdIA STrIATA(STOlTErfOTH)HASlE]细胞丰度与营养盐条件呈现正相关。Phytoplankton communities of northern Yellow Sea(36°00'-40°00'N,121°00'-125°00'E) were investigated at 30 stations during 21st to 24th in June 2011.With the analysis of Uterm hl method,a total of 27 taxa which belong to 23 genera of 3 phyla were identified.Bacillariophyta(15 genera and 17species were identified) accounted for 63.9%of the species,30.6%were Pyrrophyta(6 genera and 8species were identified),and the left belonging to Chrysophyta.Dominant species included Prorocentrum minimum(Pavillard) Schiller,Paralia sulcata(Ehrenberg) Cleve,Coscinodiscus spp.,Donkinia recta(Donkin) Grunow,Dinophysis acuminata Clapar de & Lachmann,Pleurosigma spp..Cell abundance of phytoplankton ranged from 0.19 10~3 to 1885.67 10~3 s/L,with an average of 77 10~3 s/L.Pyrrophyta ranged from 0.04 10~3 to 1882.15 10~3 s/L(on average of 72.08 10~3 s/L),followed by Bacillariophyta ranging from 0.04 10~3 to 43.82 10~3 s/L(on average of 5.11 10~3 s/L).Phytoplankton cells in the surface water were mainly concentrated in the Bohai strait,coastal area of Shandong Peninsula and Liaodong Peninsula,with low abundance being in the central area of the northern Yellow Sea.Paralia sulcata and Coscinodiscus spp.occurred in the surface water at most stations.Vertically,cell abundance of phytoplankton was concentrated in the middle and upper water layers.From the transect B to transect F,high diatom abundances were found in the cold water mass due to contributions of Paralia sulcata;similarly,Prorocentrum minimum contributed to maximum abundance of dinoflagellate in the middle and upper water.Shannon-Wiener diversity index of surface phytoplankton community ranged from 0.029 to 2.94,with an average of 1.57,with the Pielou's evenness index ranging from 0.01 to 0.91(on average 0.67).The higher Shannon-Wiener diversity index was found in the Bohai strait and the south coast of Liaodong Peninsula.According to canonical correspondence analysis(CCA),abundances of Paralia sulcata,Coscinodiscus spp.,Navicula spp.,Pleurosigma spp.,Thalassiosira pacifica and Guinardia striata positively correlated to nutrients.国家重大基础研究发展计划(2011CB409804); 国家自然科学基金(41176136); 天津市科技计划项目(12JCZDJC30100); 教育部2102年新世纪优秀人才支持计划(NCET-12-1065)资