川中丘陵区小流域产沙的塘库沉积研究--以南充流溪河为例

报道了川中丘陵区小流域产沙塘库沉积研究的初步结果。研究表明,南充流溪河流域内平均小流域淤沙模数762t/(km2.a),淤沙模数随流域面积增大而减少的趋势不明显,小流域泥沙输移比显然远高于前人报道的0.10~0.27,土壤侵蚀速率远低于全国第2次遥感普查值3000~5000t/(km2.a)。     

泥石流流域降雨的产流与产沙研究

泥石流流域产流产沙与其他流域产流产沙不同 ,有其独特的特点。以云南东川蒋家沟为例 ,研究人工降雨下的小坡面产流产沙 ,自然降雨下的大坡面产流产沙 ,降雨的流域无泥石流时产流产沙和降雨的流域有泥石流时产流产沙 ,给出了相应的计算公式 ,并分别对比了各种情况下产流和产沙实测值与计算值 ,取得了较好的结果。     

半干旱雨养农业区集雨补灌对马铃薯田水分运移的影响

采用大田试验方法,研究集雨补灌对旱作马铃薯田水分运移规律和产量的影响。结果表明,对马铃薯有效的土壤水分主要分布在80 cm以上土层,苗期补灌45 mm处理水分利用效率（WUE）最高,且收获后不同土层中滞留的水分较少;在此基础上再增加补灌量,马铃薯产量增加不显著,WUE显著降低。集雨补灌增加了马铃薯棵间蒸发量（E）和植株蒸腾量（T）,90 mm高额补灌处理在前、中期棵间蒸发量较高,收获后80 cm以下深层贮水量显著高于45 mm及45 mm以下补灌处理。45 mm与90 mm补灌处理植株蒸腾量差异不显著,马铃薯生长后期,苗期补灌与薯块膨大期补灌植株蒸腾量差异亦不显著;苗期45 mm补灌处理蒸腾量与蒸发量比率（T/E）比较高,其综合用水效率较高。     

Nitrogen budget and relationships with riverine nitrogen exports of a dairy cattle farming catchment in eastern Hokkaido,Japan

Abstract

Dairy farming regions are important contributors of nitrogen (N) to surface waters. We evaluated the N budget and relationships to riverine N exports within the Shibetsu River catchment (SRC) of a dairy farming area in eastern Hokkaido, Japan. Five drainage basins with variable land-cover proportions within the SRC were also evaluated individually. We quantified the net N input (NNI) to the catchment from the difference between the input (atmospheric deposition, chemical fertilizers, N fixation by crops and imported food and feed) and the output (exported food and feed, ΔS _liv and ΔS _hu, which are the differences between input and output in livestock and human biomass, respectively) using statistical and measured data. Volatilized ammonia (NH₃) was assumed to be recycled within the catchment. The riverine export of N was quantified. Agricultural N was a dominant source of N to the SRC. Imported feed was the largest input (38.1?kg?N?ha^?1?year^?1), accounting for 44% of the total inputs, followed by chemical fertilizers (32.4?kg?N?ha^?1?year^?1) and N fixation by crops (13.4?kg?N?ha^?1?year^?1). The exported food and feed was 24.7?kg?N?ha^?1?year^?1 and the ΔS _liv and ΔS _hu values were 7.6 and 0.0?kg?N?ha^?1?year^?1, respectively. As a result, the NNI amounted to 54.6?kg?N?ha^?1?year^?1. The riverine export of total N from the five drainage basins correlated well with the NNI, accounting for 27% of the NNI. The fate of the missing NNI that was not measured as riverine export could possibly have been denitrified and/or retained within the SRC. A change in the estimate of the deposition rate of volatilized NH₃ from 100 to 0% redeposited would have decreased the NNI by 37%, although we believe that most NH₃ was likely to have been redeposited. The present study demonstrated that our focus should be on controlling agricultural N to reduce the impact of environmental pollution as well as on evaluating denitrification, N stocks in soil and the fate of NH₃ volatilization in the SRC.     

太湖旱地非点源污染定量化研究

采用田间试验方法,研究了太湖地区旱地氮磷向水体排放的年负荷。结果表明,太湖流域典型旱地氮磷向水体迁移的年负荷分别为12.66,4.05 kg/hm2,分别约占年施肥量的5.6%和4.1%。示范区内旱地氮磷向水体迁移的年总量为3.86 t和1.24 t。NO3-—N和PN是氮流失的主要形式,应重点控制NO3-—N和PN的流失;而PP是磷流失的主要形式,占总磷的76%,是控制的重点。氮磷向水体迁移具有明显的季节特征,夏季和秋季为氮磷高负荷季节,6—11月占全年氮磷输出总量的83.4%和79.8%。在当前的非点源污染治理中,应采取有力措施控制农田养分流失。     

Shining a light on the loss of rheophilic fish habitat in lowland rivers as a forgotten consequence of barriers,and its implications for management

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