排序方式: 共有55条查询结果,搜索用时 0 毫秒
51.
Hellen Kezia Silva Almada Divino Vicente Silvério Marcia Nunes Macedo Leonardo Maracahipes-Santos Elizabete Carolina Pinheiro Zaratim Karina Pinheiro Zaratim 《水文科学杂志》2019,64(5):620-632
Water quality in streams is determined by several factors, including geology, topography, climate, and anthropogenic changes. This study aimed to assess the effects of watershed physical, morphology, and precipitation seasonality on the water quality of two streams that supply drinking water to rural settlements and urban areas in the Cerrado-Amazonia transition region. We monitored 16 physico-chemical attributes of water at six different sample locations over three years (2013–2016). Our results indicate that eight of these physico-chemical attributes did not meet the standards for safe drinking water established by Brazilian legislation. Precipitation seasonality, degradation of riparian zones, stream length, and watershed slope were the most important predictors of impaired water quality. Our results highlight the importance of restoring and conserving riparian forests in order to maintain drinking water quality. 相似文献
52.
Saline seepage zone development, and hence the onset of dryland salinity, is a major environmental problem occurring within the Spicers Creek catchment. The primary objective of this paper was to identify previously unmapped faults and show the correlation between these faults and groundwater salinization. As identified from this study, there is a close association between geological structural features and the formation of saline seepage zones. The most saline groundwaters in the catchment were encountered where two geological structures join and form a fault intersection. These saline groundwaters are found at various depths within the fractured aquifers, and changes in groundwater chemistry in the aquifers are associated with the presence of fault zones. 18O and δ2H stable isotopes, together with 87Sr/86Sr isotopic ratios, indicate that groundwaters within the fault zones are enriched in 18O and have a strontium signature similar to seawater. This study identifies several geological structures in the Spicers Creek catchment and demonstrates that groundwaters with the highest salinity arise where fault intersections occur. The results of this study may be used to interpret further the mechanisms leading to seepage zone formation in dryland salinity‐affected catchments located throughout the Central West region of New South Wales, Australia. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
53.
54.
55.
Don P. Chambers Anny Cazenave Nicolas Champollion Habib Dieng William Llovel Rene Forsberg Karina von Schuckmann Yoshihide Wada 《Surveys in Geophysics》2017,38(1):309-327
Evaluating global mean sea level (GMSL) in terms of its components—mass and steric—is useful for both quantifying the accuracy of the measurements and understanding the processes that contribute to GMSL rise. In this paper, we review the GMSL budget over two periods—1993 to 2014 and 2005 to 2014—using multiple data sets of both total GMSL and the components (mass and steric). In addition to comparing linear trends, we also compare the level of agreement of the time series. For the longer period (1993–2014), we find closure in terms of the long-term trend but not for year-to-year variations, consistent with other studies. This is due to the lack of sufficient estimates of the amount of natural water mass cycling between the oceans and hydrosphere. For the more recent period (2005–2014), we find closure in both the long-term trend and for month-to-month variations. This is also consistent with previous studies. 相似文献