scholarly journals Spatial distribution of selenium and other inorganic constituents in ground water underlying a drained agricultural field, western San Joaquin Valley, California

1992 ◽  
2013 ◽  
Vol 14 (2) ◽  
pp. 299-303
Author(s):  
M. Madhukar ◽  
S. P. Manjunath ◽  
Rohini V. Gopal

Ground water has emerged as the primary water deficiency reduction tool in most developing countries. Recently, the quality of ground water has deteriorated due to over-exploitation and contamination resulting from anthropogenic activities. A broad range of physical, inorganic and organic, bacteriological, and radioactive parameters are found in ground waters. The presence of nitrate and hardness-causing ions at elevated levels is of greatest concern currently, as they can have a serious impact on human health and water distribution systems. The conventional methods which are applied to reduce the concentration of these inorganic constituents are found to be inconsistent when the concentration is significantly high. The present study is an attempt to remove nitrate and hardness-causing ions using polystyrene (PS) beads as packed media. The ground water sample had a total hardness between 1,030–1,250 mg/L, which is greater than the permissible limit, and the nitrate concentration was less than 45 mg/L. PS beads packed media was found to respond significantly in reducing nitrate by 88% and total hardness by 38% at an optimum flow rate and particle size of 3 L/min and 4 mm diameter respectively. PS beads can be a promising media in reducing nitrate and total hardness.


2013 ◽  
Vol 13 (10) ◽  
pp. 28225-28278 ◽  
Author(s):  
D. R. Gentner ◽  
T. B. Ford ◽  
A. Guha ◽  
K. Boulanger ◽  
J. Brioude ◽  
...  

Abstract. Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. Ground site measurements in Bakersfield and aircraft measurements of reactive gas-phase organic compounds were made in this region as part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions from these prominent sources that are relatively understudied compared to motor vehicles We also developed a statistical modeling method with the FLEXPART-WRF transport and meteorological model using ground-based data to assess the spatial distribution of emissions in the San Joaquin Valley. We present evidence for large sources of paraffinic hydrocarbons from petroleum extraction/processing operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes that have limited previous in situ measurements or characterization in emissions from petroleum operations. Observed dairy emissions were dominated by ethanol, methanol, and acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well-correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The good agreement of the observed petroleum operations source profile with the measured composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil suggests a fugitive emissions pathway during petroleum extraction, storage, or processing with negligible coincident methane emissions Aircraft observations of emission hotspots from operations at oil wells and dairies are consistent with the statistical source footprint determined via transport modeling and ground-based data. At Bakersfield, petroleum and dairy operations each comprised 22–23% of anthropogenic non-methane organic carbon and were each responsible for ~12% of potential precursors to ozone, but their direct impacts as potential SOA precursors were estimated to be minor. A comparison with the California Air Resources Board emission inventory supports the current relative emission rates of reactive organic gases from these sources in the region.


Author(s):  
P. Prakash ◽  
A. Kumar Das ◽  
C. V. S. Sandilya

The state of Andhra Pradesh, India falls in water stress<sup>4</sup> area. The primary objective of this study is to examine the spatial distribution of different chemical elements with respect to its contamination level. About 70 % of drinking water needs in rural areas and 40 % drinking water needs in urban areas are met from groundwater resources. In the last decades, rapid population growth coupled with agricultural expansion due to subsidized power to agriculture has significantly increased demand on groundwater resources. Combined to this, the effect of Global warming has put stress on ground water which is resulting in declines in water levels and deterioration of ground water quality. This may be evidenced by the fact that the phreatic aquifer which was in use two decades ago, is existing no more now in some of the parts of the study area and the water is being drawn from deeper aquifers beyond phreatic aquifers. The study has been carried out for which one or more elements are contaminated and to study its spatial distribution.


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