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91.
Pollution Buildup on Road Surfaces 总被引:1,自引:0,他引:1
Samples of sediment found on an urban road in Aberdeen (Scotland) were collected by washing designated surfaces. This method, called the “wet” method, was capable of collecting sediment of the smallest particle size range that is normally left behind by traditional sampling techniques using dry vacuuming. Over 17 months (mainly on a weekly basis), 66 samples were collected and analyzed for sediment loading, particle size distribution, concentration of heavy metals (Zn, Cu, Pb, Cd) in four sediment size fractions, and several dissolved pollutants in the effluent collected from washing (NO3?,?SO42?,?PO43?,?Cl?,?F?,?NH4+, total organic carbon, total carbon). Standard statistical methods, including multiple regressions, were used to determine relationships amongst different sediment characteristics. It was found that sediment loading, as well as concentrations of Cl? and SO42?, were highest in the winter months, especially when snow was present on the road surface. It was observed that 66% of total road sediment loading was found within a 0.5 m strip next to the curb. The average sediment particle sizes found were smaller than those previously recorded in the literature. As expected, the concentrations of heavy metals were highest in the smallest particle size fraction analyzed (<63?μm), and this occurred during the summer months when less sediment was available on the street surface. The antecedent dry weather period had a very weak and negative influence on the loading rate of the smallest particle size fraction next to the curb. 相似文献
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基于多尺度分析理论,运用Mallat算法和Daubeclfies小波,把时间序列分解为比原始序列更单一的细节和慨貌部分,并利用AR(P)模型能反映时间序列中邻近时刻间联系的特性,对序列分解后的部分进行拟合与预测,然后再由多尺度分析中的重构方法进行序列重构,由此建立耦合的预测模型。通过黄河青铜峡270多年(1724~1997)年径流时间序列的建模及验证,表明拟建的耦合模型与传统单一模型的预测精度相比,由50%提高到90%,可用于实际需要。 相似文献
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芮孝芳 《水利水电科技进展》2017,37(2):1-6
凭借"大数据"可以精细刻画降雨空间分布和下垫面空间变异性的优势,提出了"大数据"背景下考虑降雨空间分布和下垫面空间变异性对流域产汇流影响的计算方法,即单元嵌套网格剖分流域的方法。通过引入"网格水滴"的概念揭示了流域瞬时单位线的物理本质,对由RodriguezIturbe和Valdes所提出R-V地貌瞬时单位线理论进行补充,分析了等流时线法和单位线法的局限性,提出的单元嵌套网格产汇理论既克服了等流时线法和单位线法的缺点,也吸取了它们的优点,为在"大数据"支撑下统一等流时线和单位线法提供了可行性。 相似文献
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Jinzhu Ma Lihua Chen Jianhua He Yurui Zhang Xianghu Li W. Mike Edmunds 《Water and Environment Journal》2013,27(1):86-98
The Mann–Kendall test, wavelet analysis was used to analyse the long‐term trends and periodicities in temperature, precipitation and streamflow in China's Shiyang River Basin since 1950. The Principal components analysis (PCA) was used to quantify the impacts of climate change and human activities on water resources. The annual mean air temperature has increased, consistent with increasing global temperatures. The annual precipitation fluctuated but has generally increased since the 1990s. The air temperature and precipitation showed changes on periods ranging from 2 to 28 years. The correlation between annual runoff and precipitation variation was 0.61 (P < 0.05), indicating precipitation is the main source of the runoff. Human activities played the dominant role in the lower reaches, accounting for 58.5% of the total effect. The results have important implications for water resources management to support harmonisation of the relationship between humans and nature to combat the effect of climate. 相似文献
99.
Sprinkling is often used in Scandinavia to protect round wood stored for industrial use from fungal and insect attack and drying cracks. Log yard runoff can be harmful for the water recipient due to eutrophication and oxygen depletion. A wetland system for treatment of log yard runoff is being evaluated in central Sweden. The purification capacity of a sloping couch grass (Elytrigia repens L.) field was examined when log yard runoff was applied to the field through a sprinkling system. Water samples were taken from groundwater pipes during four summer seasons (May to September, 2002–2005) and analysed for total organic carbon, total phosphorus (TP), total nitrogen and distillable phenols to evaluate the purification capacity of the infiltration wetland. Results from 2002 to 2004 were compared with results from 2005 when the irrigation intensity was considerably lower. Overall, the results showed good purification capacity although the concentrations of TP in the groundwater increased during 2005. The reduced hydraulic load did not increase purification. 相似文献
100.
《Urban Water Journal》2013,10(3):247-257
The current paper is the first study to report quality of urban runoff, focusing on the diffuse sources contributing to pollutant loads in the Delhi watershed. The quality of stormwater runoff from the urban watershed of Delhi was evaluated to assess the effects of different land-use practices on pollutant concentrations. Six sites within the Delhi watershed with different land-use characteristics were selected. The microbial quality of the urban runoff from sub-catchments of Delhi watershed is very poor with Faecal Coliform (FC) levels varying between 6 and 7 log orders. There was a good correlation between the chemical and biological quality of urban runoff with land-use characteristics such as impervious land and population density. Except for chemical oxygen demand all other parameters in urban runoff were found to exceed the effluent discharge standards set by the National River Conservation Directorate (NRCD), India. The public health risks associated with exposure to urban runoff via different routes have also been qualitatively estimated. 相似文献