新疆节水灌区农田排水措施分析

随着膜下滴灌技术在新疆的大力推广应用,灌排模式发生了改变,从而导致了新的土壤次生盐渍化问题。在阐述新疆3种排水措施——明沟排水、暗管排水和竖井排灌发展的基础上,分析了目前新疆节水灌区农田排水措施存在的问题,结合南疆某一节水灌区灌排试验,分析了排水措施对土壤盐分及地下水位、矿化度的影响,为当地灌排模式提出合理化建议,且为减轻节水灌区的土壤盐渍化提供参考借鉴。     

A preliminary study of an alternative controlled drainage strategy in surface drainage ditches: Low-grade weirs

This study examined hydrological characteristics of low-grade weirs, an alternative controlled drainage strategy in surface drainage ditches. Chemographs of vegetated and clear scraped (control) replicates of weir vs. non-weir treatments were compared to determine differences in time to peak (T_p) and time to base (T_b). Drainage ditches T_p and T_b were affected by both vegetation and weir presence. The order of treatment efficiency for T_p was observed to be: non-vegetated non-weir < vegetated non-weir < non-vegetated weir < vegetated weir. Furthermore, T_b for each ditch was the reverse relationship from T_p where vegetated weir > non-vegetated weir > vegetated non-weir > non-vegetated non-weir. Low-grade weirs increase chemical retention time (vegetated and clear scraped), the average time a molecule of contaminant remains in the system. Future research in water quality improvement and weir management will yield useful information for non-point source pollutant reduction.     

淮河流域(安徽段)主要湿地维管植物研究

淮河流域(安徽段)主要湖泊湿地维管植物有68科165属259种;科、属、种分别占全省维管植物科的30.2%、属的13.4%、种的7.1%。包含5种以上的11个较大科构成了淮河流域湿地植物的主体,其中禾本科和莎草科种类最多。区系分布区类型:蕨类植物主要有4种分布区类型,世界分布为主要类型;种子植物属有14种分布类型,其中温带分布类型占总属数的38.4%,该区湿地维管植物具有典型温带性质。湿地植物资源包括食品类,工业原料类,绿肥类,观赏类,环保类及种质资源类等。     

Variability in feeding ecology of a South American cichlid: a reason for successful invasion in mediterranean‐type rivers?

Abstract –  Ecological attributes behind the success of the South American cichlid Australoheros facetus in mediterranean-type rivers remain unclear. This study addresses this issue, by analysing its abundance and feeding patterns in the lower Guadiana drainage (Portugal), during the dry season of 2003. Despite slight spatial variations in abundance and individual size, A. facetus seemed well established in the Guadiana, Vascão and Ardila rivers. No seasonal or size-related changes in feeding intensity were found, but the diet changed across rivers, over time and throughout ontogeny. Feeding seemed highly generalist, with fish apparently reacting to both spatial and temporal changes in food supply and tending to use the most abundant and easily accessible food items. Overall prey breadth was broad relative to that of other native and non-native species. It is suggested that a generalist feeding strategy may play a significant role in the establishment of non-native fish in mediterranean-type rivers.     

Water-table management in lowland UK peat soils and its potential impact on CO2 emission

The rate of oxidation of peat soils is highly seasonal and varies with temperature and soil moisture content. Large variations in soil moisture content result in wet–dry cycles that can enhance peat degradation. Water‐table management plays a crucial role in controlling and damping the effect of these environmental factors. However, maintaining high ditch water levels in fields bounded by ditches does not guarantee a high field groundwater level. The effect of installing subsurface irrigation at different spacings on water table elevation was studied in a low‐lying peat grassland. The water table elevation data were compared against values predicted with a water balance model. In addition, greenhouse experiments were carried out on undisturbed soil core samples collected from the peat grassland as well as a low‐lying peatland under intensive arable faming to measure CO₂ evolution under different water regimes. The field data from the peat grassland suggest that sub‐irrigation spacing as low as 10 m is necessary during summer periods to maintain groundwater levels similar to those in the ditches. Over the same period of observation, the difference in water level between the ditches and the non‐irrigated fields is as high as 0.7 m. Modelled outputs are in good correlation with the field observations, and demonstrate that simple water balance models can provide an effective tool to study the effect of water management practices and potential changes in subsurface conditions, climate and land use on water‐table levels. The measurement of CO₂ emission from undisturbed peat soil columns shows that the rate of oxidation of soil organic matter from peat soils is highly seasonal and that drainage exacerbates the rate of peat mineralization.     

大口径埋地塑料排水管的应用前景

结合塑料排水管材的自身特点及目前这一管材在市政排水领域的应用现状，通过多年的工程实践，从国家相关的法律法规及经济技术比较等角度出发，笔者认为大口径埋地塑料排水管替代传统的钢筋混凝土排水管将成为市政工程管网建设中的新趋势。     

湘西北山区“长防林”生态效益研究初报

湘西北山区长江防护林生态效益监测站，分别就“长防林”对小流域小气候、坡面产流量、产沙量、输沙率、林地最大涵水能力及保土效果进行了定位观测，资料分析表明，长防林生态效益十分显著。     

Distribution and richness of diadromous fish assemblages in Western Europe: large-scale explanatory factors

Abstract –  The aim of this study was to analyse the distribution of 14 diadromous fish at the beginning of the 20th century in western Europe. This study was conducted on a set of 41 water basins. Five environmental variables were selected and we used generalised additive models for explaining the presence–absence of species. The richest basins were located in the centre of the study area. Six main assemblage types were identified along a latitudinal gradient; they were constituted of a common species basis but differed by the absence or presence of other species. The 10 single species models produced have moderate to very good discrimination level and they can correctly predict both absence and presence. Temperature is included in all but one model, response curves vary according to the species; surface area is included in six models.     

基于DEM的西辽河流域河网水系提取研究

河网水系是对流域进行水文分析的重要数据,其生成的准确性会直接影响水文模型模拟的精度。以西辽河流域为研究区,在ARCGIS软件操作平台上对研究区的数字高程模型数据进行河网水系提取,设定不同的流域汇流累积阈值,分别计算出各模拟河网的分形维数及河网密度,取二者拟合趋势变化相同处阈值对应的河网与实际河网进行比较,发现此处的模拟河网与实际河网具有较高的拟合度,从而避免阈值确定的随机性、主观性等问题,有效地提高流域河网水系提取的精度。