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451.
452.
岷江上游水电开发对环境的影响 总被引:6,自引:0,他引:6
岷江上游水力资源十分丰富,随着西部大开发的进行,它已成为水电开发的重点区域,干流及支流的电站建设加速进行。自源头至汶川上游河段,实行六级梯级开发方案。但由于岷江水电工程主要是涵洞引水式,原来奔腾的河流变成了地下暗流,使得岷江的多处河段变得干涸,河谷的自然生境和景观发生了很大的变化,原来的干旱河谷气候变得更加干旱。也使河流生物系统受到严重影响。作者在对长江上游考察的基础上对岷江上游水电开发现状及其对环境的影响进行了分析,提出应该进行流域统一规划,强化执法监督,水电开发与环境保护建设并重;加强上中下游统一管理,注重流域综合开发等建议。 相似文献
453.
454.
Alkaline ameliorants increase nitrous oxide emission from acidified black soil in Northeastern China
Lime and plant ash are common management used to achieve optimum pH for plant growth and improve soil properties in agricultural soils. Laboratory incubation was conducted to assess N20 emissions as influenced by different soil amendments (lime and plant ash) in a slightly acidic arable soil (pH 5.34). The experimental treatments consisted of CK, lime and plant ash fertilized with NH4+-N or N03?-N as nitrogen resource. The results show that lime and plant ash dramatically increases the soil pH and N20 emission. For N03?-N fertilization, the cumulative N20 emissions from CK, lime and ash are 421, 1669 and 921 μg N20-N/kg, respectively. For NH4+-N fertilization, the cumulative N20 emissions from CK, lime and ash are 361, 576 and 559 μg N20-N/kg, respectively. N03?-N addition leads to more N20 emission than that of NH4+-N addition, and lime increases more N20 emission than that of plant ash. After incubation, N03?-N content decreased largely. The findings suggested that alkaline ameliorants increase N20 emissions due to enhancement of soil denitrification. 相似文献
455.
制备嵌入式多壁碳纳米管修饰石墨电极(ESCFE),利用循环伏安法研究铅(Pb)的电化学行为及反应机理,结果表明,铅在修饰电极表面出现了一对明显的准可逆的氧化还原峰,发生了2质子的电化学氧化反应。用差分脉冲伏安法研究了铅离子浓度与其峰电流的线性关系,线性范围为1.8×10^-7~1.0×10^-5g/L,线性方程为:ipa(μA)=0.12+1.471c×10^6(g/L),r=0.9999,检出限为6.0×10^-8g/L,RSD%为1.015(n=5)。利用本法对湖泊沉积物中铅进行测定,样品铅含量:0.218~0.6317mg/kg,RSD:3.3%~6.2%,加标回收率:94.3%-106.6%。 相似文献
456.
457.
在含有阴离子表面活性剂-十二烷基硫酸钠(SDS)的6NTU高岭土悬浊液中,改变SDS的浓度,投加纳米SiO2与聚合铝PAC进行动态混凝实验与静沉实验,借助图像分析技术与分形理论,探讨了纳米SiO2与PAC处理含SDS低浊水的作用机理、絮凝效果与形态学特征。结果表明:①纳米SiO2与SDS使高岭土粒子表面负电性增强。纳米SiO2的絮凝机理以吸附架桥为主。②纳米SiO2对SDS的去除效果优于PAC。SDS浓度越高,去除效果越显著。但纳米SiO2对无机高岭土粒子的处理能力不如PAC,PAC絮凝后的上清液浊度低。当SDS浓度增至10mg/L时,纳米SiO2对SDS的去除率高,而PAC对SDS的絮凝能力弱,PAC对无机颗粒的去除效果也下降。③助凝剂纳米SiO2较强的吸附活性能加快PAC絮体成长为结构密实的RLCA构型,分维值高,絮凝效果好。 相似文献
458.
太湖水体中氮、磷空间分布特征及环境效应 总被引:32,自引:12,他引:20
研究分析了太湖水体中氮、磷空间分布规律. 结果表明,太湖水体中各种形态氮、磷的空间分布呈现出非均一性特征,梅梁湾、竺山湾、贡湖湾、西岸区和湖心区水体中总氮、总磷浓度显著高于其他湖区,溶解态氮/磷、碎屑氮/磷的空间分布规律与总氮/磷的基本一致. 总氮与溶解态氮、碎屑态氮之间存在显著的线性正相关,且相关系数分别为rDN=0.819 2和rDeN=0.696 9;总磷与溶解态磷、碎屑态磷也存在极显著的线性正相关,对应的相关系数为rDP=0.747 7和rDeP=0.926 0. 水体中叶绿素a的空间分布差异较大,最高浓度出现在太湖的西部(179.2 μg·L-1±25.9 μg·L-1),最低的则出现在东太湖七都水域附近(11.3 μg·L-1±2.7 μg·L-1). 叶绿素a与总氮、碎屑态氮、总磷、溶解态磷、碎屑态磷、高锰酸盐指数、pH值和悬浮质存在显著的线性正相关,对应相关系数为rTN=0.662 2、rDeN=0.873 9、rTP=0.813 0、rDP=0.407 7、rDeP=0.878 1、rCOD=0.868 9、rpH=0.517 3和rSS=0.533 4,与溶解态氮、电导率和碱度之间相关不显著. 相似文献
459.
Possible solutions for sludge dewatering in China 总被引:3,自引:0,他引:3
Wei Wang Yuxiang Luo Wei Qiao 《Frontiers of Environmental Science & Engineering in China》2010,4(1):102-107
In China, over 1.43×107 tons of dewatered sewage sludge, with 80% water content, were generated from wastewater treatment plants in 2007. About 60%
of the COD removed during the wastewater treatment process becomes concentrated as sludge. Traditional disposal methods used
by municipal solid waste treatment facilities, such as landfills, composting, or incineration, are unsuitable for sludge disposal
because of its high water content. Disposal of sludge has therefore become a major focus of current environmental protection
policies. The present status of sludge treatment and disposal methodology is introduced in this paper. Decreasing the energy
consumption of sludge dewatering from 80% to 50% has been a key issue for safe and economic sludge disposal. In an analysis
of sludge water distribution, thermal drying and hydrothermal conditioning processes are compared. Although thermal drying
could result in an almost dry sludge, the energy consumption needed for this process is extremely high. In comparison, hydrothermal
technology could achieve dewatered sewage sludge with a 50%–60% water content, which is suitable for composting, incineration,
or landfill. The energy consumption of hydrothermal technology is lower than that required for thermal drying. 相似文献
460.
Demographic factors such as operational sex ratio (OSR) and local population density (LPD) are temporally and spatially dynamic in the natural environment but the influence of these variables on male mating success and the mechanisms behind it are still poorly understood and highly controversial. Here, we manipulated the OSR and LPD of a seed bug, Nysius huttoni, and carried out a series of mating trials to test how these variables affected male mating success. The two demographic factors had no significant interactions, suggesting that they affect male mating success independently in N. huttoni. In this species male mating success was significantly higher in both male- and female-biased OSR than in even OSR. It is suggested that, in male-biased OSR, the increased intensity of competition and interference does not result in lower male mating success; rather, males may make more effort in courting and females may have more chance to encounter better males, resulting in higher male mating success. In female-biased OSR, females may become less choosy and less likely to reject male mating attempt, leading to the higher male mating success. Lower male mating success in N. huttoni in high LPD may be due to increased interference between males and/or delayed female receptiveness for mating. OSR had a stronger effect on male mating success than LPD in N. huttoni, suggesting that OSR and LPD affect mating success in different ways and intensities. 相似文献