三峡库区渝巴公路马道子滑坡岸段动态风险评价

水库区公路岸坡属大型线性工程,其灾害评价主要涉及沿线两侧一定宽度范围,总体呈线状或条带状;库水升降及降雨作用,可引起岸坡地下水位的波动,从而导致岸坡稳定性的变化,这一过程是一个动态变化过程;基于以上认识,以三峡库区渝巴公路马道子滑坡段为例,根据线性工程风险评价的特点,采用地下水浸润线简化求解公式,并按照滑坡动态稳定性的理念,对该公路岸坡段的动态风险进行了初步评价,并对治理必要性进行了分析,结果与实际相符。     

SENSITIVITY OF PHYTOPLANKTON SIMULATIONS TO VARIATIONS IN THE HALF SATURATION CONSTANTS1

ABSTRACT In many impoundment dynamic water quality models, the growth of two or more ecologic groups of phytoplankton may be simulated. These ecologic groups are differentiated by growth rates, temperature tolerances, settling rates, and the Michaelis-Menten half saturation constants for necessary nutrients. In this investigation, the effect of variations in the Michaelis-Menten half saturation constant for the limiting nutrient when two competing ecologic groups of algae are simulated is examined. In an idealized case, it is demonstrated that uncertainty in the half saturation constant for the limiting nutrient for one ecologic group of algae can significantly affect the simulation results and in some cases could lead to a poorly designed impoundment restoration program.     

A SATURATION-BASED MODEL OF RELATIVE WETNESS FOR WETLAND IDENTIFICATION1

ABSTRACT: A wetness index that was derived from Beven's distributed hillslope runoff model and based on the concept of relative wetness is introduced as a wetland identification and mapping tool. Data requirements are modified to make the model suitable for use by managers and field agents. The model predicts the relative propensity of any point or small area within a landscape unit to become saturated. This allows an index of relative wetness to be produced. Points on the landscape can then be assigned values of relative wetness. The index has potential utility for: (1) providing more detailed information on wetness conditions than binary (wetland-nonwetland) classification systems now in use; (2) assisting in wetland identification when field indicators are absent or ambiguous; (3) application in dryland environments where common wetland indicators are largely irrelevant; and (4) broad-scale wetland mapping in a geographic information systems environment using existing digital topographic and soils databases.     

A Conceptual Model of Spatially Heterogeneous Nitrogen Leaching from a Welsh Moorland Catchment

Soil- and stream-water data from the Plynlimon research area, mid-Wales, have been used to develop a conceptual model of spatial variations in nitrogen (N) leaching within moorland catchments. Extensive peats, in both hilltop and valley locations, are considered near-complete sinks for inorganic N, but leach the most dissolved organic nitrogen (DON). Peaty mineral soils on hillslopes also retain inorganic N within upper organic horizons, but a proportion percolates into mineral horizons as nitrate (NO ₃ ^– ), either through incomplete immobilisation in the organic layer, or in water bypassing the organic soil matrix via macropores. This NO ₃ ^– reaches the stream where mineral soilwaters discharge (via matrix throughflow or pipeflow) directly to the drainage network, or via small N-enriched flush wetlands. NO ₃ ^– in hillslope waters discharging into larger valley wetlands will be removed before reaching the stream. A concept of catchment nitrate leaching zones is proposed, whereby most stream NO ₃ ^– derives from localised areas of mineral soil hillslope draining directly to the stream; the extent of these zones within a catchment may thus determine its overall susceptibility to elevated surface water NO ₃ ^– concentrations.     

污染排放造成的外部性分析及其对资源配置的影响

污染排放对环境造成了外部不经济性,本文对环境的外部不经济性的起因进行了分析,并对由此引起的资源配置失误作了详细解释。还提出了一些意见来减少外部不经济性,从而达到资源的优化配置。     

水化煤饱和-风干过程的自燃特性实验研究

为了掌握水化煤饱和-风干过程中不同风干时间煤样的自燃特性,对水化煤样进行不同风干时间的实验煤样预处理,形成不同风干时间的水化煤样。通过煤样含水率测试、物理吸附实验和程序升温实验,对不同饱和-风干时间的水化煤样以及原煤样的吸氧量和CO,CO2,CH4,C2H4,C2H6,C3H8气体浓度随煤温的变化规律进行实验研究。研究结果表明:不同风干时间水化煤样随着煤温的逐渐升高,吸氧量呈先减小后增大趋势;不同风干时间的水化煤样的自燃标志性气体析出速率随煤温的升高均呈指数增大的变化趋势;在低温氧化阶段,水化煤样比原煤反应时间提前,且反应速率更快,这表明水化煤样比原煤样更加容易发生自燃,且风干时间为20 min的水化煤危险性更大。     

一种湿度试验中计算露点温度的方法

目的研究在气候环境试验中如何把露点温度作为控制目标的方法。方法选择干湿球温度表作为测量湿度的传感器,饱和水汽压是计算湿度量的一个重要参数,探究出便于在微控制器上应用的计算饱和水汽压的公式,然后建立露点温度计算模型,得出水汽压与露点温度的关系式。结果通过0~100℃的100组样本值的验证,与《湿度查算手册》值比较,平均误差较小。结论该公式适用于湿度试验箱中微控制器中露点温度的处理问题。     

Effect of water regimes and organic matters on transport of arsenic in summer rice （Oryza sativa L.）

The arsenic contamination in soil-water-plant systems is a major concern of where, the groundwater is being contaminated with arsenic (above 0.01 mg/L) in the Indian subcontinent. The study was conducted with organic matter to find out the reducing e ect on arsenic load to rice (cv. Khitish). It was observed that intermittent ponding reduced arsenic uptake (23.33% in root, 13.84% in shoot and 19.84% in leaf) at panicle initiation stage, instead of continuous ponding. A decreasing trend of arsenic accumulation (root > straw > husk > whole grain > milled grain) was observed in di erent plant parts at harvest. Combined applications of lathyrus + vermicompost + poultry manure reduced arsenic transport in plant parts (root, straw, husk, whole grains and milled grain) which was significantly at par (p > 0.05) with chopped rice straw (5 tons/ha ) + lathyrus green manuring (5 tons/ha) in comparison to control and corresponding soils. A significant negative correlation of arsenic with phosphorus (grain P with arsenic in di erent parts R2= 0.627–0.726 at p > 0.01) was observed. Similarly, soil arsenic had a negative correlation with soil available phosphorus (R2 = 0.822 at p > 0.001) followed by soil nitrogen (R2= 0.762 at p > 0.01) and soil potassium (R2 = 0.626 at p > 0.01). Hence, e ective management of contaminated irrigation water along with organic matter could reduce the arsenic build up to plants and soil.     

海洋大气氯离子采集过程饱和现象研究

采用我国大气网站规定的连续法,以(10±2)d和(30±2)d 2种采样周期对万宁试验站近海暴露场的大气氯离子进行了为期1 a的监测。研究证实,我国现行氯离子测试方法在海洋大气氯离子采集过程中存在饱和现象,风速对饱和程度的影响很复杂,既能加重饱和程度也能减轻饱和程度。     

污泥水富集硝化菌的群落结构及动力学参数研究

采用序批式反应器处理富含高氨氮的污泥水并培养富含硝化菌的活性污泥,利用荧光原位杂交技术解析硝化菌的群落结构,并分别测定了氨氧化菌、亚硝酸盐氧化菌的基质半饱和常数、温度修正系数.结果表明,污泥中氨氧化菌的含量（AOB/DAPI）为15.7%±3.7%,优势菌属为Nitrosomonas europaea-Nitrosococcus mobilis;亚硝酸氧化菌的含量（NOB/DAPI）为12.9%±3.2%,优势菌属为Nitrobacter spp..氨氧化速率在10～40℃之间的温度修正系数τN为1.092,亚硝酸盐氧化速率在15～30℃之间的温度修正系数τN为1.061,氨氧化菌（以NH⁺₄-N计）和亚硝酸盐氧化菌（以NO^－₂-N计）在20℃的基质半饱和常数KN分别为(1.60±0.29) mg/L、(2.78±0.30) mg/L.