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21.
本文比较全面地阐述了近年来我国海洋环境保护工作所取得的主要成就,并针对未来沿海经济的迅速发展将给海洋环境带来的压力,探讨深入开展海洋环境保护工作。  相似文献   
22.
Natural zeolite was modified by loading cetylpyridinium bromide (CPB) to create more e cient sites for humic acid (HA) adsorption. The natural and CPB modified zeolites were characterized with X-ray di raction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The e ects of various experimental parameters such as contact time, initial HA concentration, solution pH and coexistent Ca2+, upon HA adsorption onto CPB modified zeolites were evaluated. The results showed that natural zeolite had negligible a nity for HA in aqueous solutions, but CPB modified zeolites exhibited high adsorption e ciency for HA. A higher CPB loading on natural zeolites exhibited a larger HA adsorption capacity. Acidic pH and coexistent Ca2+ were proved to be favorable for HA adsorption onto CPB modified zeolite. The kinetic process was well described by pseudo second-order model. The experimental isotherm data fitted well to Langmuir and Sips models. The maximum monolayer adsorption capacity of CPB modified zeolite with surfactant bilayer coverage was found to be 92.0 mg/g.  相似文献   
23.
在对小清河沿岸水文、地质资料分析的基础上,用I131作为示踪剂,进行了潜水水质野外模拟试验,首次求出了小清河纵向弥散度为0.42m,污染物质向潜水扩散的速度约为2.8m/a。   相似文献   
24.
为探讨水滑石类材料对水体中氟、砷离子的同时去除效果,采用共沉淀法合成(Mg∶Al=2∶1)纳米类水滑石(LDHs),用傅立叶转换红外光谱、电子扫描透射电镜、X射线晶体衍射等手段对合成的材料进行了表征,并研究纳米材料在不同初始浓度、pH、吸附时间、阴离子干扰条件下其同时除砷氟性能。结果表明,煅烧后的水滑石(LDOs)对砷最大吸附量为51.02 mg/g,对氟最大吸附量为36.63 mg/g。吸附动力学实验表明,煅烧水滑石对砷的吸附在前6 h内基本完成,对氟的吸附在前10 h内基本完成。砷氟共存溶液保持pH=4~10及pH=6~8时,水滑石分别对砷、氟保持良好的吸附效率。对比不同阴离子对水滑石共除砷氟效率的影响,水滑石除砷速率受到阴离子影响力大小为:HPO2-4CO2-3NO-3Cl-SO2-4;水滑石除氟速率受到阴离子影响力大小为:CO2-3HPO2-4SO2-4Cl-NO-3。材料再生循环利用4次后,对砷和氟的吸附效率均能达到90%以上。实验结果表明,所合成的水滑石是一种优秀的能共除砷氟的吸附剂。  相似文献   
25.
热喷处理污泥及其复混肥的养分效率与生物效应   总被引:12,自引:1,他引:12  
采用室内分析和田间生物试验,研究了热喷处理污泥及其复混肥的养分供应能力及它们在农地上施用对土壤肥力、青菜产量及其品质的影响。结果表明:热喷处理能有效杀灭污泥中病原物,除自,并可使污泥中水溶性有机碳和速效氮含量分别提高87%,19%和35%,施用热喷污泥制成的复混肥不但比等养分的无机复合肥多增产38%,而且青菜体内Vc和水溶性总糖等营养品质也有明显的提高,NO3^-却只有无机复合肥处理的一半左右,污泥经势喷处理有利于提高污泥中养分的生物有效性,特别是热喷污泥制成的复混肥氮磷养分利用率显著高于无机复合肥,施用污泥和污泥复混肥还能提高土壤肥力,比单纯大量施用污泥要安全得多,土地使用年限可延长40倍。  相似文献   
26.
Nitrous oxide (N2O) is a greenhouse gas that can be released during biological nitrogen removal from wastewater. N2O emission from a sequencing batch reactor (SBR) for biological nitrogen and phosphorus removal from wastewater was investigated, and the aims were to examine which process, nitrification or denitrification, would contribute more to N2Oemission and to study the effects of heterotrophic activities on N2O emission during nitrification. The results showed that N2O emission was mainly attributed to nitrification rather than to denitrification. N2O emission during denitrification mainly occurred with stored organic carbon as the electron donor. During nitrification, NaO emission was increased with increasing initial ammonium or nitrite concentrations. The ratio of N2O emission to the removed ammonium nitrogen (N2O- N/NH4-N) was 2.5% in the SBR system with high heterotrophic activities, while this ratio was in the range from 0.14% to 1.06% in batch nitrification experiments with limited heterotrophic activities.  相似文献   
27.
This paper explores the impact of erosion and restoration measures on habitat development and on wave damping by a small salt marsh nestled alongside a dike on the Wadden island of Terschelling. The aim is to advance knowledge about the benefits and possible side-effects of salt-marsh restoration. Analysis of a time series of aerial photographs from 1944 to 2010 indicates that the salt marsh decreased steadily in size after maintenance of accretion works was terminated. In the western part of the marsh, which is accessible to sheep, vegetation is low (5–15 cm) and dominated by Salicornia europaea and by Spartina anglica. In the most intensively grazed parts, vegetation is very scarce. The eastern, inaccessible part of the salt marsh is covered by dense patches of the shrubby perennial Atriplex portulacoides and Spartina anglica (15–25 cm in height). SWAN wave models show that wave height at this location is significantly affected by the areal extent of the salt marsh as well as by the vegetation. High or dense vegetation are in the models nearly as effective in damping waves (with an initial height of 0.15 and 0.5 m) as widening the salt-marsh area by 350 m. A low density of low plants, as observed in the grazed part of the marsh, has almost no wave-damping effect. Even under conditions of sea level rise, a broader salt marsh vegetated with high plants significantly affects modelled wave height. Therefore, salt-marsh restoration is an adaptation measure worth exploring, though an array of effect types must be considered.  相似文献   
28.
Atrazine is one of the most widely applied and persistent herbicides in the world. In view of limited information on the regional contamination of atrazine in soils in China, this study investigated the spatial distribution and environmental impacts of atrazine in agricultural soils collected from the Yangtze River Delta (YRD) as an illustrative analysis of rapidly developing regions in the country. The results showed that the concentrations of atrazine in the YRD agricultural soils ranged from <1.0 to 113 ng/g dry weight, with a mean of 5.7 ng/g, and a detection rate of 57.7 % in soils. Pesticide factory might be a major source for the elevated levels of atrazine in Zhejiang Province. The contamination of atrazine was closely associated with land use types. The concentrations and detection rates of atrazine were higher in corn fields and mulberry fields than in rice paddy fields. There was no significant difference in compositions of soil microbial phospholipids fatty acids among the areas with different atrazine levels. Positive relationship (R = 0.417, p < 0.05, n = 30) was observed between atrazine and total microbial biomass. However, other factors, such as soil type and land management practice, might have stronger influences on soil microbial communities. Human health risks via exposure to atrazine in soils were estimated according to the methods recommended by the US EPA. Atrazine by itself in all the soil samples imposed very low carcinogenic risks (<10?6) and minimal non-cancer risks (hazard index <1) to adults and children.  相似文献   
29.
随着城市化的进程,垃圾处理设施成为影响城市化质量的重要指标。依据人们实际所关注的垃圾处理设施的总成本和负效应两个因素,在前人研究的基础上,建立了垃圾收运多目标模型,使得总成本和负效应最优化。根据模型设计了粒子群算法,该算法属于智能算法,且精度高,收敛快,在许多领域也得到广泛应用。用设计的粒子群算法并结合案例求出了Pareto最优解,给出三种决策方案,验证了模型和算法的有效性和可行性,为决策者提供了一种理论参考。  相似文献   
30.
随着我国天然气发电比例的不断增加,天然气发电的安全问题逐渐引起人们的关注。为定量分析天然气发电的风险预警等级,针对风险评估过程中的小样本问题,引入信息扩散理论确定风险事故发生的概率,并结合故障类型及影响、危险度分析方法,建立了天然气发电风险预警的定量计算数学模型。以某天然气电厂燃气轮机系统为研究对象,将该厂燃气轮机2007—2014年所发生事故的统计数据作为观测样本,利用构建的风险预警数学模型并结合Matlab软件,计算得到该天然气电厂燃气轮机事故的发生概率以及不同事故模式下事故后果的严重度,最终确定该电厂燃气轮机系统的风险预警等级为Ⅲ级。与传统的安全预警方法相比,该风险预警技术更加客观有效。  相似文献   
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