Ambient water sample

Hexachloroethane is rarely detected in ambient water. Data reported in the STORET database indicate that the chemical was detectable in only 1 of 882 (0.1%) ambient water samples (Staples et al. 1985). The median concentration for all samples was <10 pg/L. Hexachloroethane was detected in Lake Ontario water, but not in Lake Erie (International Joint Commission 1983). The concentration of hexachloroethane in Lake Ontario was reported at 0.02 ng/L (Oliver and Niimi 1983). It was also identified in leachate from a hazardous waste site in Niagara Falls, New York (Hauser and Bromberg 1982). Hexachloroethane was not detected in 86 samples of urban runoff from 15 cities analyzed for the National Urban Runoff Program (Cole et al. 1984). 

Hexachlorobutadiene has been detected in some surface waters but the incidence of detection is low. It was detected in 0.2% of 593 ambient water samples in the STORE database with a median level for all samples of less than 10 ppb (Staples et al. 1985). Hexachlorobutadiene was detected in 1 of 204 surface water sites sampled across the United States with a concentration of 22 ppb (Ewing et al. 1977). Low levels of hexachlorobutadiene were detected in the Niagara River at 0.82 ppt (Oliver and Charlton 1984). Hexachlorobutadiene was not detected in rainwater (Pankow et al. 1984) or urban storm water runoff (Cole et al. 1984) in a number of U.S. cities. It has not been detected in open ocean waters however, the coastal waters of the Gulf of Mexico were reported to contain 3-15 ppt (Sauer 1981). 

Epichlorohydrin may be released to the atmosphere and in wastewater during its production and use in manufacture of epoxy resins, glycerine and other chemicals and other uses. It has been detected at low levels in wastewater, groundwater and ambient water samples (United States National Library of Medicine, 1997). 

Overall there appears to be considerable uniformity in the concentration of di- -butyl phthalate in the surface waters of the United States, if locally contaminated areas are excluded. The National Drinking Water Contaminant Occurrence Database (NDOD), which contains data from ambient water samples, lists... 

Ambient water samples usually contain chloride ions. Their presence can be detected through the silver chloride precipitate obtained with silver nitrate reagent in acidic solution. 

Table 16.1.4. Summary of organic solvent concentrations detected in ambient water samples. Data from confirmed and suspected point sources, precipitation, sea water, and wastewater treatment samples were excluded. [Data from HSDB]. ...

As summarised in Table 3.4, some electroanalytical methods have been certified by standardisation bodies for the chemical characterisation of ambient water samples, mostly in the class of inorganic substances. Conductometric detection is used in direct method for ionic constituents and also as chromatographic detector for individual cations and anions. Total, inorganic and organic carbon in water can be also assayed by conductometric detection. Amperometric detection has been certified for dissolved oxygen and cyanide. ISE potentiometry is used for standardised measurements of a set of ions and also for the evaluation of water oxidation-reduction potential. Voltammetric detection is the base for diverse methodologies oriented to the determination of trace elements including the most relevant elemental pollutants. 

The widespread use of -hexanc as an extractant in the laboratory creates problems in interpreting concentration readings at low levels. Even with good quality control, it may often be impossible to determine whether to attribute a measured value to the actual levels in a sample or to contamination from M-hexanc in the laboratory environment (Otson et al. 1994). For the most part, -hexane is not a common target analyte from water or soil samples. While data based on ambient air samples or sampling in the air of various workplace or residential environments are more numerous, most EPA regulatory programs rely on bulk measurements of total hydrocarbons or total volatile compounds rather than on measurements of specific compounds such as -hexane (Bishop et al. 1994 DeLuchi 1993). 

Very little recent information on concentrations of endrin in water could be found in the available literature. Unlike DDT, chlordane, aldrin/dieldrin, and a variety of other chlorinated pesticides, endrin was never used extensively in urban areas. This is reflected in the results from EPA s Nationwide Urban Runoff Program, which showed no detections in 86 high-flow water samples from 51 urbanized watersheds from 19 cities (Cole et al. 1984). Analysis of EPA STORET monitoring information from ambient surface water showed a significant percentage of detections for endrin (32% of 8,789 samples), but most were near the detection limits, with a national median concentration of 0.001 ppb (Staples et al. 1985). A similar analysis of STORET data for endrin aldehyde showed that this compound was not found in 770 samples of ambient surface water. More recently, endrin was not detected (detection limit 49 ng/L [0.045 ppb]) in surface water from the Yakima River Basin, Washington (Foster et al. 1993). However, in... 

Periodic monitoring points should include extraction, injection, and monitoring points. When sampling injection wells, the injection system should be shut down for approximately 24 h to allow ambient conditions to be reestablished. Monitoring wells should be purged and sampled according to standard procedures. Extracted fluid material (pumped water) can be sampled by the same procedures as collecting a surface water sample. 

R96011 Method 1669 Sampling Ambient Water for Trace Metals at EPA Water Quality Criteria Levels... 

Data maintained in the STORET database for 1980-1982 included heptachlor and heptachlor epoxide concentrations in industrial effluent and ambient water. Median values for heptachlor in effluent and water samples were <0.007 ppb detected in 3% (n=671) and 0.001 ppb in 34% (n=4,650) of the samples, respectively. Median values for heptachlor epoxide in effluent and water samples were <0.007 ppb detected in 4.2% (n=672) and 0.001 ppb in 36% (n=4,632) of the samples, respectively (Staples et al. 1985). 

The pH measurements of the mixed contents were made immediately after taking the soil and liquid samples. The presence of a very large amount of suspended sediment affected the accuracy and reproducibility of these pH measurements. The average values for each container are summarized in Table II. The deposited pesticides, the formulating agents and the decomposition products did not change the pH from that observed for ambient water except for... 

All the experiments summarized in Table I were conducted with the water sample at ambient temperature, about 22°C. Purging at elevated temperatures has been investigated and clearly affects recoveries of some compounds. However,... 

Low levels of hexachlorobutadiene can be detected in air, water, and sediment. Atmospheric levels of hexachlorobutadiene in rural and urban air samples typically range from 2 to 11 ppt, with a mean value of 2-3 ppt. Higher levels can be detected at areas near industrial and chemical waste disposal sites and production sites. Hexachlorobutadiene is infrequently detected in ambient waters, but has been detected in drinking water at levels of 2-3 ppt. Sediments contain higher levels of hexachlorobutadiene than the waters from which they were obtained. Foodstuffs generally do not contain detectable levels of hexachlorobutadiene, with the exception offish, in which concentrations of 0.1-4.7 mg/kg have been reported. 

AFM can be run in three different modes contact, noncontact, and tapping mode. When AFM is in the contact mode (similar to stylus profilometry), the most common problem encountered is that under ambient conditions, sample surfaces are covered by a layer of adsorbed gases consisting primarily of water vapor and nitrogen. In addition, a dielectric film can trap electrostatic charge, which can contribute to additional attractive forces between probe and sample. These problems may cause friction in probing, which will destroy the sample or distort the resulting data. 

Zn2+, Co2+ and Cu2+ ions were incorporated into calcined (A1)MCM-41 via ion exchange performed using very diluted Zn2+and Co2+ nitrate and Cu2+ acetate solutions at ambient temperature. Samples were carefully washed by distilled water, dried at ambient temperature and grained. Detailed conditions of the sample preparation and chemical composition ofMe -(A1)MCM-41 are given in Table 1. 

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