Water-borne contaminants

For the monitoring of water-borne contaminants, the main advantages of passive sampling are convenience and the fact that sampling is time integrated and is... 

Enviromiiental contaminants fall into three categories (1) microorganisms (bacteria and viruses), (2) manufacturing contaminants, (3) air or water-borne contaminants. 

In recent years, the use of solvent-borne adhesives has been seriously restricted. Solvents are, in general, volatile, flammable and toxic. Further, solvent may react with other airborne contaminants contributing to smog formation and workplace exposure. These arguments have limited the use of solvent-bome adhesives by different national and European regulations. Although solvent recovery systems and afterburners can be effectively attached to ventilation equipment, many factories are switching to the use of water-borne rubber adhesives, hot melts or 100% solids reactive systems, often at the expense of product performance or labour efficiency. 

Even if the assumed evaporation and drift rates were perfecdy accurate, the calculated blow-down rate of 98 gpm might still not be quite enough because of the effects of air-borne contaminants, which are usually incalculable. Once the approximate level of blow-down has been determined, the circulating water quality should be regularly monitored and appropriate adjustments made. 

The biological contamination and the hardness of underground water are the two very serious problems of water. Dissolved salts deteriorate water quality and may cause diseases related to joints and bones, while infected water may cause many water-borne diseases such as cholera, dysentery, typhoid etc. Ultrasound may disinfect the potable water by blasting off micro organisms such as zooplanktons, phytoplanktons, pathogenic bacteria and produce germ-free water in few minutes of... 

The natural occurrence of mercury in the environment means that mercury is likely to occur in surface waters, even when anthropogenic sources of mercury are absent. Freshwaters without known sources of mercury contamination generally contain less than 5 ng/L (ppt) of total mercury in aerobic surface waters (Gilmour and Henry 1991). Mercury levels in water-borne particulates in the St. Louis River estuary... 

Hepatitis A virus (HAV) accounts for about one fourth to one third the cases of clinical acute hepatitis in the United States and 20% to 25% worldwide. Although most commonly an infection of children and adolescents, the disease tends to be more virulent in middle-aged and older people. Most sporadic cases occur from person-to-person contact, such as occurs in children in day care centers. Epidemics have been associated with waterborne and food-borne contamination. Ingestion of raw shellfish from contaminated waters has caused both sporadic and epidemic cases. Although not as common a cause of liver infection as hepatitis B, it is more frequently associated with jaundice when occurring in adults than either hepatitis B or C an estimated 50% to 70% of infected adults develop jaundice. In contrast, hepatitis A infection in children is rarely associated with jaundice, and thus is usually not detected clinically. The incidence of the disease is declining in the developed world with introduction of hepatitis A vaccine complete immunization of less than half the at-risk population has been shown to reduce incidence of acute hepatitis A infection by more than 90% in areas of high endemicity. Universal vaccination of... 

Bioavailability of contaminants in waters and sediments also changes in temporal and spatial scales. For example, because sediments are at best mixtures, rather than solutions like most water-borne pollutants, the conditions that influence the bioavailability of a contaminant in two similar sites may change from day to day as well as be considerably different even though they are in close proximity to each other. In general, the characteristics of the water above the sediment (overlaying water) and the interstitial water (water in-between the particles of the sediment, often referred to as pore water) most influence the bioavailability of the contaminants in the sediment. It is believed that pore water has the greatest influence on the bioavailabihty of contaminants in sediments (Suter et al. 2000). One way to think of contaminants in water is that they are today s pollution issue, whereas contaminants in sediments are both today s and yesteryear s issues. 

Food- and water-borne illnesses may be caused by toxins created by growing bacteria toxins produced by the harmful algal species or contamination of food and/or water with certain bacteria, viruses or parasites. Many cases of food poisoning happen when someone eats food that has harmful bacteria in it. The bacteria or the toxins produced by them can then make the person sick. Bacteria also can get into the water supply and make someone sick. 

Food- or water-borne bacteria as weapons The use of these bacteria is less likely than using bacteria that can be spread through the air because it is hard to expose a lot of people at the same time. However, all of the above bacteria may be used to contaminate public water supplies or food at large events. Standard treatment of public water supplies would most likely kill the bacteria before people were able to drink it. 

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