Springs, groundwater sampling

A third example of OXC is taken from field observations. In response to the recommendation by Hostcttler (7) that the most reliable characterization of the redox status of a natural water is a complete chemical analysis of all redox-active species, the Illinois State Water Survey (10) collected and analyzed groundwater samples from a pristine aquifer on a monthly basis for one year. Table III lists calculated values of OXj, RDj, and OXC for samples taken from depths of 35,50, and 65 feet. OXC is greatest in the most shallow samples and it decreases with depth. In addition, the lowest values at a constant depth occur in the winter samples and OXC varies little from April to September. This seasonal effect is the result of a decrease in total reductants RDj values for December through February are more than three times those for the spring and summer months. OXj is relatively constant throughout the entire sampling period. It is uncertain whether or not the... 

The solubility of methyl parathion is not sufficient to pose a problem in runoff water as determined by an empirical model of Wauchope and Leonard (1980). Some recent monitoring data, however, indicate that methyl parathion has been detected in surface waters (Senseman et al. 1997). In a study to determine the residue levels of pesticides in shallow groundwater of the United States, water samples from 1,012 wells and 22 springs were analyzed for methyl parathion. No methyl parathion was detected in any of the water samples (Kolpin et al. 1998). In a study of water from near-surface aquifers in the Midwest, no methyl parathion was detected in any of the water samples from 94 wells that were analyzed for pesticide levels (Kolpin et al. 1995). Leaching to groundwater does not appear to be a significant fate process. 

Echols, K.R. Meadows, J. Schwartz, T. Borsuk, P. Carline, R. Tillitt, D. 1996, Comparison of SPMDs, Caged Fish, and Hexane Filled Dialysis Bags for Sampling PCBs in Groundwater from a Spring at Sherman s Dale, PA. Presented at the 4th Annual SPMD International Workshop Kansas City, MO. June 11-13, 1996. 

Sulfide (S ) is a bivalent monoanion produced from the decomposition of metal sulfide salts. It occurs in groundwaters, hot springs, and wastewaters. It is also formed from the bacterial reduction of sulfate. Sulfide salts in solid wastes in contact with an acid can produce hydrogen sulfide. H2S, which is highly toxic. In an aqueous sample, sulfide may be present as dissolved H2S and HS , dissolved metallic sulfide, and acid-soluble metallic sulfide contained in suspended particles. All these soluble and insoluble sulfides and dissolved H2S and HS together are termed as total sulfide. The sulfide remaining after the removal of suspended solids is termed the dissolved sulfide. Copper and silver sulfides are insoluble even under acidic conditions. Therefore, these two sulfides are not determined in the following tests. 

Many stages of the water cycle are described by specific information implanted into surface water and groundwater. Yet, field hydrochemists have limited access to the water, being able to measure and sample it only at single points—wells and springs. Their task is to reconstruct the complete water history. A list of pertinent topics is given below. 

Figure 8 Early spring samples from four streams at Sleepers River Watershed, Vermont, have 5 0 values intermediate between the compositions of snowmelt collected in pan lysimeters and groundwater. Diurnal fluctuations in discharge correlate with diurnal changes in 5 0, especially at W-2. W-2, a 59 ha agricultural basin, shows much greater contributions from snowmelt than the other three catchments. The three mixed agricultural/forested nested catchments—W-9 (47-ha), W-3 (837-ha), and W-5 (11,125)—show increasing contributions from new snowmelt as scale increases (after Shanley et al., 2001).

Table 13 Average concentrations of groundwater and stream/spring samples from the Soan-Sakesar Valley,...

With few exceptions, most blind U deposits and other potential sources of He are situated below the water table, so that He must be released into the groundwater prior to its escape to the soil gas and the atmosphere. In consequence, groundwater, or at least groundwater as represented by water in drill holes and wells, has been sampled extensively as a means of determining the dispersion of He. Surface waters, however, tend to be equilibrated with the atmosphere and are unsuitable as sample media, except when collected from springs and at depth from lakes. 

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