First draw water sample

A survey by Strain etal. (1981) of 3000 first-draw water samples in the US showed that about 18% of the samples (or about 540) had a selenium content that exceeded the EPA standard of 10pgL and the highest measured level was 450 pgL b These same samples showed elevated concentrations of elements associated with corrosion of household plumbing by soft, acidic water. The potential impact of acid precipitation on selenium was discussed by Mushak (1985) who suggested that altered acidity by both soil and aquatic systems poses a risk for altered biotransformation processes. Lowered pH in soils reduces selenium availability. In the pres-... 

Measures for individual houses consist of lead pipe replacement and flushing before drawing water for eonsumption. The effect of the first measure ean be established using 30-minute stagnation-time sampling and proportional sampling. To assess the efifeetiveness of flushing, the fully flushed protocol can be applied. 

Test water (first-draw and flush samples). 

One is called a FIRST-DRAW sample. This should be taken in the morning before any water has been run in the house, even for Hushing the toilet. This will tell you how much lead is in water that has been sitting in the plumbing in your home for several hours, and has had a chance to dissolve lead from the pipes, solder, and fixtures it has come into contact with. 

A first-draw sample should be taken from any faucet that is commonly used for drinking water. First-draw samples can vary drastically within the same house because of the lead contained in the brass faucet itself. 

The highest lead concentrations occur in standing water first drawn from the tap. They then generally decline after a few litres of water have been drawn off. The measured concentrations of lead in tap water must be viewed in the light of the national and international standards, which have been variously set at 0.05 or 0.1 mg dm" [25]. The preliminary results of a recent survey of tap water in England, Wales and Scotland suggest that 1.7 million households ca. 9.2%) have a first draw lead concentration in excess of even the higher standard. This number falls to 0.8 million households ca. 4.4%) when daytime samples are considered [25]. 

The first draw one litre samples taken will comprise or include any water stood in non-lead pipework, in-situ between a lead service line and the tap outlet, effectively diluting any lead in the water that has stood in the lead service line, again making it easier for compliance with the AL for lead to be achieved (this aspect is considered in more detail in Chapter 3). 

A major weakness in this sampling approach is the dilution of water that has stood in lead pipe-work with water that has stood in non-lead pipe-work between the lead pipe-work and the tap outlet. To illustrate, let us consider a lead pipe joined to a copper pipe up to the tap. A 12 mm internal diameter copper pipe of 8.8 metres length has a volumetric capacity of 1 litre. If the copper pipe between the lead pipe and the tap is 4.4 metres in length, the first draw one litre sample will comprise 50% water that stood in the copper pipe and 50% water that stood in the lead pipe, a 50% dilution effect. If the copper pipe is 8.8 metres in length, or greater, no water that stood in the lead pipe will be capmred by the first draw one litre sample. This assumes simple plug flow in the pipes concerned, which is reasonable at the flow rates normally experienced (about 0.1 litre per second, that is 6 litres per minute) as the flow should be turbulent... 

Clearly, if the lead levels are essentially zero, then the contribution of the brass parts will be essentially zero. As noted in the AWWARF (2008) study, with the exception of the faucets, the other brass materials, meters and fittings, have relatively low impact on the lead in first draw samples from the consumer s water system in typical circumstances. However, when manufacturing processes result in segregation of lead at the water contact surface, high lead release can be observed for some indeterminable length of time from a very low lead content (on the average) alloy or device. 

For the two UK case studies, the most important calibration data were the plumbosolvency of the water, the percentage of houses with lead pipes within the water system, and daily water consumptions. Pipe details, water use patterns and flow rates were less critical and general assumptions were often used (Hayes et al, 2006, 2008). For the North American case studies in Cities A, B, and C, the most important calibration data were the plumbosolvency of the water and the length and diameter distributions of the non-lead pipes used in premise plumbing. In these studies the focus of compliance assessment was either sequential 30 minutes or 6 hours stagnation - first draw sampling. For City C, the limited data available for model calibration constrained the scope of the case study. 

The first samples examined were prepared by the method developed by Smith et al. [70, 71] and by Matsuo [72]. Sample films of a thickness of ca. 100 pm were obtained by drying a gel which was obtained by quenching a 0.4 g/dl decalin solution of linear polyethylene with a molecular weight of 3 x 106 from 140 °C in ice-water. The samples thus obtained could be drawn to a very high extent because of very few intermolecular chain entanglements. However, since they could not be drawn highly in one step, they were drawn 10 times at the first step in a silicon oil bath at 145 °C at a rate of 1.6 times/min and then at the second step they were drawn so that the final draw ratio was 50,100, and 150 times. 

In many instances the chemical composition of oceanic rain has been used to draw conclusions concerning the chemical composition of marine aerosols (3, 52, S3, 54). The first two entries in Table V emphasize the trends with respect to altitude for our data on rain samples collected in Hawaii. The 100-meter sample was collected near the coast, and the 1000-meter sample was obtained several miles inland in the Hawaiian mountains. The results for F/Cl, Cl/Na, and Na/F in the 100-meter sample agree with the results found for marine aerosol salt fractions given in Table II, and differ only slightly from those of sea water. 

The recommendations of the International Commission on Radiological Protection (ICRP) for maximum permissible concentrations of radionuclides in air and water serve as basic criteria for determining radionuclide concentrations in air and water. For the first estimation, measurements of gross a, / , and y activities are sufficient however, in order to draw a responsible conclusion, individual radionuclides in the sample have to be determined. 

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