秦岭火地塘3种主要林型林冠层对不同pH值降雨水质的影响

[目的]研究秦岭火地塘林区3种主要林型林冠层对不同pH值降雨水质的影响过程,为研究酸沉降对森林生态系统的影响提供基础。[方法]以林区油松林、华山松林、锐齿栎林为研究对象,自制人工降雨器模拟降雨,分析各林分林冠穿透雨水化学物质浓度随降雨时间及降雨酸度的变化规律。[结果]①模拟降雨10 min或20 min 3种林分林冠穿透雨中NH4^(+),NO3^(-),K+,Ca^(2+),Mg^(2+),Pb,Zn,Cd浓度达到峰值,降雨20~30 min后浓度降低并趋于稳定,随降雨时间延长总体上呈先升高后降低并趋于稳定的规律。②针叶林、阔叶林不同的叶组织特性影响林冠中化学物质淋洗量。相同pH值降雨淋洗,油松、华山松林冠穿透雨中NH4^(+),NO3^(-),K+,Ca^(2+),Mg^(2+),Pb,Zn,Cd浓度多表现为大于锐齿栎。③酸雨能促进林冠中化学物质淋失。对于同一树种,不同pH值降雨淋洗,林冠穿透雨中NH4^(+),K+,Ca^(2+),Mg^(2+),Pb,Cd浓度值及浓度变化幅度大小大体表现为:pH 4.0>pH 5.0>pH 7.0。[结论]根据林冠穿透雨水化学物质浓度随降雨时间动态变化规律,将林冠对穿透雨水质影响过程划分为降雨淋洗(降雨开始至降雨10 min或20 min)和降雨淋溶(降雨约20~30 min以后)两个阶段。降雨淋洗阶段,林冠层对水质变化影响大。

城市土壤特征对降雨径流控制的影响

城市范围土壤受到人为扰动而出现生态功能退化,总结了城市土壤的物理化学和水文生态特征,分析了城市土壤对降雨径流量和水质的影响,探讨了低影响开发(LID)工程土的要求,以期为改善LID措施控制降雨径流效果提供理论依据和参考。研究表明:以下渗为主的LID措施,土壤饱和导水率是重要参数;以去除污染负荷为主的LID措施,土壤质地、容重是重要参数,pH及本底养分、重金属含量也是影响因素;应以此为基础设计改良工程土配方;施工过程中,应避免场地土壤的机械人为压实;定期清理设施区域的垃圾,防止阻塞土壤表层;在污染严重区域,定期检测土壤污染物浓度,若超过土壤负载需更换土壤。

西安市不同下垫面雨水水质分析及道路雨水利用设计

针对西安市面临的水资源短缺、雨水资源浪费以及径流污染严重等问题,对西安高新区不同下垫面降雨径流水质进行了监测,选取了如下采样点:直接降雨、屋顶、路面、绿地及停车场等,并根据不同区域划分,分析了水中污染物浓度及特征.结果表明,西安市降雨径流中有机污染物含量均有超出《地表水环境质量标准》(GB3838-2002)V类水质,超标率达75%;屋面、路面SS含量超出国外城市3~4倍,超出国内其他城市2~4倍,污染十分严重.雨水资源化利用对于西安市具有极大的意义及潜在优势,故本文将选取西安高新技术开发区某路段雨水利用改造设计为例,介绍生态滤沟技术在道路径流雨水的滞蓄与利用中的应用.

基于SWMM的不同降水量对城市降雨径流TSS的影响分析

受物理、化学、生物等多重因素的影响,城市降雨径流水质的模拟研究比较模糊。以TSS(总悬浮固体量)为例,利用SWMM的污染物模块及其土地利用模块、污染物累积模块和污染物冲刷模块进行城市雨水径流水质模拟;考虑了不同土地利用情况对污染物的累积及冲刷的影响,针对不同的降水量,利用EMC法(平均浓度法)以及指数方程法进行污染物的冲刷模拟,指数方程法的模拟精度大于EMC法的模拟精度,与监测值更接近。指数方程法的模拟结果表明:当降水量小于2.5mm时,其TSS冲刷量增长幅度较缓;而当降水量大于3.5mm时,其TSS冲刷量呈显著线性增加关系,从而表明,降水量较大的降水事件对于TSS的冲刷量影响更为显著。

兰州地区雨水径流中污染物特征研究

参照兰州地区已有的降雨雨水径流污染物含量资料,收集了兰州交通大学内地表径流、屋面径流,检测了其中污染物真实含量,得出两种雨水径流中污染物含量特点,研究了初期雨水径流污染物的浓度较高的冲刷效应特点,以期为城市雨水处理提供可靠的实际数据依据。

Influence of Polymer Binder on the Physical Properties and Stability of Engineering Spoil on a Slope

An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.

Studies on Material Cycling in Evergreen Broad-Leaved Forest Ecosystem in Hangzhou: Ⅰ. Precipitation Distribution

Through the long-term plot studies on the precipitation distribution in the evergreen broad-leaved forest ecosystem in Hangzhou for two years, it was indicated that the pattern of precipitation distribution included larger amounts of penetration water and stemflow and a lower amount of interception water. The results revealed that the main factors to infulence the percentages of penetration and stemflow were the air temperature and the leaf area of the forest. The quantity of seepage through the litter layer was much larger than that through the soil layers which decreased sharply with soil depth. The output of water from the ecosystem by surface runoff and deep infiltration through the soil was much lower, only being 5.20 percent of the rainfall, while the water evapotranspiration loss was as large as more than 90 percent of it. The losses by the soil evaporation and plant evapotranspiration were the largest part of output in this forest ecosystem.