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21.
Healthy watersheds provide valuable services to society, including the supply and purification of fresh water. Because these natural ecosystem services lie outside the traditional domain of commercial markets, they are undervalued and underprotected. With population and development pressures leading to the rapid modification of watershed lands, valuable hydrological services are being lost, which poses risks to the quality and cost of drinking water and the reliability of water supplies. Increasing the scale and scope of programmes to protect hydrological services requires policies that harmonize land uses in watersheds with the provision of these important natural services. This article summarizes key attributes of hydrological services and their economic benefits; presents a spectrum of institutional mechanisms for safeguarding those services; discusses programmes in Quito (Ecuador), Costa Rica and New York City; and offers some lessons learned and recommendations for achieving higher levels of watershed protection.  相似文献   
22.
Effect of mineral and manure phosphorus sources on runoff phosphorus   总被引:3,自引:0,他引:3  
Concern over nonpoint-source phosphorus (P) losses from agricultural lands to surface waters has resulted in scrutiny of factors affecting P loss potential. A rainfall simulation study was conducted to quantify the effects of alternative P sources (dairy manure, poultry manure, swine slurry, and diammonium phosphate), application methods, and initial soil P concentrations on runoff P losses from three acidic soils (Buchanan-Hartleton, Hagerstown, and Lewbeach). Low P (12 to 26 mg kg(-1) Mehlich-3 P) and high P (396 to 415 mg kg(-1) Mehlich-3 P) members of each soil were amended with 100 kg total P ha(-1) from each of the four P sources either by surface application or mixing, and subjected to simulated rainfall (70 mm h(-1) to produce 30 min runoff). Phosphorus losses from fertilizer and manure applied to the soil surface differed significantly by source, with dissolved reactive phosphorus (DRP) accounting for 64% of total phosphorus (TP) (versus 9% for the unamended soils). For manure amended soils, these losses were linearly related to water-soluble P concentration of manure (r2 = 0.86 for DRP, r2 = 0.78 for TP). Mixing the P sources into the soil significantly decreased P losses relative to surface P application, such that DRP losses from amended, mixed soils were not significantly different from the unamended soil. Results of this study can be applied to site assessment indices to quantify the potential for P loss from recently manured soils.  相似文献   
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24.
Surface coal mining in Appalachia has caused extensive replacement of forest with non-forested land cover, much of which is unmanaged and unproductive. Although forested ecosystems are valued by society for both marketable products and ecosystem services, forests have not been restored on most Appalachian mined lands because traditional reclamation practices, encouraged by regulatory policies, created conditions poorly suited for reforestation. Reclamation scientists have studied productive forests growing on older mine sites, established forest vegetation experimentally on recent mines, and identified mine reclamation practices that encourage forest vegetation re-establishment. Based on these findings, they developed a Forestry Reclamation Approach (FRA) that can be employed by coal mining firms to restore forest vegetation. Scientists and mine regulators, working collaboratively, have communicated the FRA to the coal industry and to regulatory enforcement personnel. Today, the FRA is used routinely by many coal mining firms, and thousands of mined hectares have been reclaimed to restore productive mine soils and planted with native forest trees. Reclamation of coal mines using the FRA is expected to restore these lands’ capabilities to provide forest-based ecosystem services, such as wood production, atmospheric carbon sequestration, wildlife habitat, watershed protection, and water quality protection to a greater extent than conventional reclamation practices.  相似文献   
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26.
江西武夷成矿带铜多金属矿产资源远景评价与展望   总被引:1,自引:0,他引:1  
华南武夷山地区处于扬子、华夏两大构造单元交接叠加地段,构造变形复杂,中生代岩浆活动强烈,具有十分优越的成矿条件,矿产资源潜力巨大.本文以正在武夷山成矿带开展的矿产远景调查工作和资源评价工作所取得的阶段性成果为基础,分析了武夷山成矿带的成矿地质背景、主要矿床类型及近几年的找矿勘查成果,并对武夷成矿带江西省境内铜多金属矿产资源潜力进行了初步评价,划分了十七个找矿远景区.  相似文献   
27.
Permanganate oxidation of sorbed polycyclic aromatic hydrocarbons   总被引:6,自引:0,他引:6  
The polycyclic aromatic hydrocarbons (PAH) that contaminate soils at many industrial and government sites are resistant to natural biotic and abiotic degradation processes. The recalcitrant nature of these compounds may require aggressive chemical treatment to effectively remediate these sites. This study was conducted to assess the viability of permanganate oxidative treatment as a method to reduce PAH concentration in contaminated soils. Study results demonstrated a reduction in soil sorbed concentration for a mixture of six PAHs that included anthracene, benzo(a)pyrene, chrysene, fluoranthene, phenanthrene, and pyrene by potassium permanganate (KMnO4) oxidative treatment. The greatest reduction in soil concentration was observed for benzo(a)pyrene, pyrene, phenanthrene, and anthracene at 72.1, 64.2, 56.2, and 53.8%, respectively, in 30 min at a KMnO4 concentration of 160 mM. Minimal reductions in fluoranthene and chrysene concentration were observed at 13.4 and 7.8%, respectively, under the same conditions. A relative chemical reactivity order of benzo(a)pyrene>pyrene>phenanthrene>anthracene>fluoranthene>chrysene towards permanganate ion was observed. Aromatic sextet theory was applied to the degradation results to explain the highly variable and compound-specific chemical reactivity order.  相似文献   
28.
  针对目前生态气象监测轨道业务的特点,结合工作的实际需要,运用C和C++语言建立了生态气象监测评估业务平台。在程序设计中,采用了生成中间交换文件的结构组织,能够对各模块的输出结果进行详尽直观的分析,并提供了等值线色斑图与区域填充等多种图形绘制方式。该系统可处理AVHRR和EOS/MODIS卫星遥感资料,对气象观测报文进行解译、数据分类管理和质量控制,统计计算水体密度指数、湿润指数、植被覆盖指数、土地退化指数、灾害指数和生态质量综合评价指标,以图形、图像的形式输出生态气象监测评估产品,实现了卫星遥感与生态气象地面监测数据的有效组织和智能化管理。将系统应用于湖南省生态质量气象评价,业务化运行的结果表明,该系统具有较好的业务实用性。〖HJ1〗〖HJ〗
〖HT5”H〗  相似文献   
29.
Samples of benthic invertebrates from four pairs of streams in southwestern Ontario collected monthly from May through August 1991, and once during the subsequent autumn and winter, demonstrated that conservation tillage practices have a remedial effect on the water quality of adjacent streams as indicated by biotic, rather than physical or chemical, parameters. One stream of each pair drained a basin under conventional tillage (CONV, mainly mouldboard ploughing), the other primarily under conservation tillage (CONS). The paired drainage basins were otherwise similar to one another in type of crops grown, as well as size, topography, soils and hydrology. CONS streams yielded a greater variety of Insecta but fewer taxa of Mollusca, Annelida and Crustacea than did samples from CONV streams. Both kick-net and Surber samples from CONS streams yielded significantly more taxa, more kinds of Ephemeroptera, Plecoptera and Trichoptera, and lower Hilsenhoff Biotic Index scores than did samples from CONV streams. Kick samples from CONS streams were significantly more similar to expected reference communities in overall taxonomic composition. Surber samples from CONS streams contained significantly larger numbers of invertebrates. The relatively greater abundances of infaunal species, especially Tubificidae and Chironomini, in CONV streams suggest greater accumulation of fine sediment particles. Conditions during low flow appear to have the greatest influence on the composition of benthic invertebrate communities. The results of the study indicate that conservation tillage practices have a beneficial effect on the quality of surface waters.  相似文献   
30.
Hydrops fetalis and fetal death caused by fetal parovirus B19 infection have been reported to be associated with elevated maternal serum alpha-fetoprotein (AFP), based on a total of six cases. It has been suggested that the absence of AFP elevation may be reassuring. Maternal serum levels of the Down syndrome screening markers unconjugated oestriol and human chorionic gonadotropin in cases of fetal parvovirus infection have not been previously reported. We report four cases of hydrops fetalis and fetal death caused by fetal parvovirus infection, each with unremarkable second-trimester levels of AFP, unconjugated oestriol, and human chorionic gonadotropin.  相似文献   
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