Chemical Contaminants In Water Research Articles

Preliminary Survey of Chemical Contaminants in Water, Sediment, and Aquatic Biota at Selected Sites in Northeastern Florida Bay and Canal C-111

Several actions are under way to alter water management capabilities and practices in south Florida in order to restore a more natural hydroperiod for the Everglades. Because relatively little research has been conducted on contaminants entering Florida Bay, we undertook a preliminary study in June 1995 to determine contaminant concentrations in surface water, sediment, and biota prior to major changes in water management. The areas studied were the C-111 canal (five sites) beginning just above water control structure S-197 and extending to Manatee Bay (part of the Biscayne Bay system), Shell Creek (three sites), the mouth of Taylor River, Trout Creek (two sites), and a site near the Key Largo Ranger Station. Hydrographic observations were made at each site, and samples of water and sediment were collected at each of the five areas except the Key Largo site. Bioresidues were determined for indigenous oysters collected from the C-111 canal and Shell Creek and for transplanted oysters exposed at the Key Largo site, the C-111 canal, Shell Creek, Taylor River, and Trout Creek for 5-29 days. Water samples were analyzed for selected organochlorine pesticides and metals; sediments were analyzed for the same compounds and for polycyclic aromatic hydrocarbons (PAHs). Fish filets and shucked oysters were analyzed for selected organochlorine pesticides, polychlorinated biphenyl (PCB) congeners, and metals. Other than low dissolved oxygen at some C-111 canal sites, water quality was generally good. Most contaminants were below water and sediment quality guidelines designed to protect aquatic life, and contaminant concentrations in oysters were low. Threshold effect levels were exceeded for some organochlorine pesticides and PAHs in some sediment samples, but all values measured were below probable effect levels. Low concentrations of organochlorine pesticides were detected in sediments from the C-111 canal, Shell Creek, Taylor River, and Trout Creek; except for Taylor River, low concentrations of PCB congeners and PAHs were detected from the same areas. The only organochlorine pesticide detected in filets from seven fish was 3.2 v-g DDE/kg (wet weight) in a sea catfish. Total mercury concentrations in filets of four species of fishes ranged from 0.53 to 1.3 μg/g, wet weight, which falls within a limited consumption advisory by the State of Florida.

Application of ultrasonic irradiation for the degradation of chemical contaminants in water

The sonochemical degradation of a variety of chemical contaminants in aqueous solution has been investigated. Substrates such as chlorinated hydrocarbons, pesticides, phenols, explosives such as TNT, and esters are transformed into short-chain organic acids, CO 2, and inorganic ions as the final products. Time scales of treatment in simple batch reactors over the frequency range of 20 to 500 kHz are reported to range from minutes to hours for complete degradation. Ultrasonic irradiation appears to be an effective method for the rapid destruction of organic contaminants in water because of localized high concentrations of oxidizing species such as hydroxyl radical and hydrogen peroxide in solution, high localized temperatures and pressures, and the formation of transient supercritical water. The degradation of chemical compounds by acoustic cavitation is shown to involve three distinct pathways: 1) oxidation by hydroxyl radicals, 2) pyrolytic decomposition and 3) supercritical water oxidation. Detailed reaction mechanisms for the degradation of p-nitrophenol, carbon tetrachloride, parathion, p-nitrophenyl acetate and trinitrotoluene are presented.

Dermal exposure to environmental contaminants in the Great Lakes.

This paper reviews the literature to determine the importance of the dermal route of exposure for swimmers and bathers using Great Lakes waters and summarizes the chemical water contaminants of concern in the Great Lakes along with relevant dermal absorption data. We detail in vivo and in vitro methods of quantifying the degree of dermal absorption and discuss a preference for infinite dose data as opposed to finite dose data. The basic mechanisms of the dermal absorption process, routes of chemical entry, and the environmental and physiological factors affecting this process are also reviewed, and we discuss the concepts of surface slick exposure to lipophilic compounds and the adsorption of contaminants to water sediment. After presenting mathematical constructs for calculating the degree of exposure, we present in vitro data concerning skin absorption of polyaromatic hydrocarbons adsorbed to Great Lakes water sediment to show that in a worst-case scenario exposure via the dermal route can be equally important to the oral route. We have concluded that prolonged exposure of the skin, especially under conditions that may enhance dermal absorption (e.g., sunburn) may result in toxicologically significant amounts of certain water contaminants being absorbed. It is recommended that swimming should be confined to public beaches, people should refrain from swimming if they are sunburned, and skin should be washed with soap as soon as possible following exposure. Future studies should be conducted to investigate the importance of the dermal exposure route to swimmers and bathers.

Assessment of exposure to chemical contaminants in water and food

The main questions on the validity of the studies and routine monitoring (e.g., in the scope of the WHO/UNEP GEMS programme) assessing exposure to chemicals through water and food (i.e., through digestion) relate to the following. (a) Sampling: variations due to sampling strategy and approach usually exceed analytical errors. (b) Measurement: quality assessment and quality control (QA/QC) procedures are essential. However, potential limitations of measurement errors resulting from implementation of these procedures should be kept in perspective with other errors and confounding factors. (c) Methodology: which depends on the variability of the intake patterns in the population, as well on the adequacy of the information on the consumption of food of a specified type as an indicator of the intake of a specific chemical. These factors should be considered in particular in studies using ‘food basket’ methods. Whenever possible, structure of the population in respect to the factors determining typical diet should be registered. (d) Form of reporting: limiting possibilities for re-analysis of the exposure estimates. In conclusion, the routinely collected data on exposure through food and water should be used with care in epidemiological studies. Assessment of the exposure conducted specially for the epidemiological study should consider possible changes of the diet with time. The data on confounders are crucial for exposure estimates.

Assessment of chemical contaminants in water and sediment samples from Degh Nala in the province of Punjab, Pakistan

Twenty water samples and 18 underlying sediment samples were collected near effluent discharges along 30 km of a surface stream, Degh Nala, Pakistan, which receives effluents from two major industrial areas. Water quality parameters were very poor, except for reference samples collected upstream from the industrial areas and from a freshwater canal into which the Nala flows. Mercury (Hg) concentrations were extremely high in waters (up to 72 mg/L) and sediments (up to 887 μg/g) from the upper reaches, and minor influxes from other sites maintained Hg at alarming levels. Concentrations of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) and its metabolites were greater than 1.0 μg/g in two sediment samples. The acute toxicity of water samples to the freshwater planarian, Dugesia dorotocephala, was generally consistent with degree of contamination.

Water Quality and Health (Review of the Internationaal Drinking Water Supply and Sanitation Decade)

A review is presented of the development of the International Drinking Water Supply and Sanitation Decade (IDWSSD) launched in 1981 and terminated in 1990. Health aspects of drinking water quality in relation to chemical water contamination are investigated and an outlook to the future is presented as far as the tasks of water pollution control are concerned.

Investigation of potential health effects associated with well water chemical contamination in Londonderry Township, Pennsylvania, U.S.A.

A community health survey was conducted by the Pennsylvania Department of Health in Londonderry Township, Dauphin County, Pennsylvania, in response to concerns about potential health effects associated with residential exposure to chemical contaminants in well water. The data indicate that there were no observable adverse health effects in the exposed group of residents, compared with the control group, which could be ascribed to long-term, low-level exposure to trichloroethylene (TCE) and other volatile organic chemicals. Significantly more individuals in the exposed group than in the control group experienced eye irritation, diarrhea, and sleepiness during the 12-month period prior to the survey. This indicated the possibility of an association of contaminated water with the manifestation of symptoms. It is hypothesized that the increased rate of symptoms observed in the exposed group, when compared to the control group, may have been caused by one or more of the following factors: (1) effect of TCE at a threshold level higher than 28 ppb, (2) effect of a single chemical entity other than TCE, and (3) additive or synergistic effects of several chemicals. It is also possible that there are factors other than water contaminants associated with the recorded symptoms, e.g., stress, that may have had an important influence in the exposed group but not in the control group.

Environmental pollution problems in Africa

Environmental pollution is increasingly a problem in Africa, where the environmental consequences of development cannot be ignored. Although development is desirable, it can result in health problems in humans; an inadequate supply of clean water; the chemical contamination of water and air and threats to various ecosystems and living resources.

Effect of artefact pollution on the viability of seabird colonies on Long Island, New York

Colonies of several species of seabirds and freshwater birds persist on Long Island, even in close proximity to metropolitan New York City. Habitat destruction, chemical contamination of water and food sources, and direct interference by man, pose the main hazards to these birds. Efforts have been made to minimise the impact of such well-known disturbances and, in certain areas, the colonies seem to be thriving. Studies of breeding success and mortality have revealed that human artefacts, such as trash scattered on the beaches or jetsam washed ashore, may contribute significantly to the mortality of certain species. This is a readily controllable form of environmental contamination which involves no philosophical or economic conflicts.

Relation of Raw‐Water Quality to Treatment Plant Design

Walton's studies have shown that well‐designed and well‐operated treatment plants can produce a water virtually free of coliform organisms, even though the raw water contains coliform‐organism concentrations far higher than the recommended limits proposed by U.S. Public Health Service. Careful attention to disinfection has been the key to this success. Uncertainty about the significance of viruses and organic chemical contaminants in water, rather than bacterial loadings, would seem also to cause uncertainty about the degree of pollution that treatment plants can remove. At this time there is no adequate basis for prescribing the limits of pollution that various processes can remove.