Freshwater Streams

Calcium chloride is found in the marine environment. The elemental composition of seawater is 400 ppm calcium, 18,900 ppm chlorine, and many organisms and aquatic species are tolerant of these concentrations. Toxicity arises either from the invasion of freshwater in otherwise saltwater environments or possible toxic doses of calcium chloride from spills, surface mnoff, or underground percolation into typically freshwater streams or aquifers. Various agencies have guidelines for calcium and chloride in potable water (41). The European Economic Community (EEC) is the only agency to have a minimum specification for calcium in softened water. 

Pignatello JJ, MM Martinson, JG Steiert, RE Carlson, RL Crawford (1983) Biodegradation and photolysis of pentachlorophenol in artificial freshwater streams. Appl Environ Microbiol 46 1024-1031. 

Wakelin SA, Colloff MJ, Kookana RS (2008) Assessing the effect of wastewater treatment pLANT effluent on microbial function and community structure in the sediment of a freshwater stream with variable seasonal flow. Appl Env Microbiol 74 2659-2668... 

In a study involving several contaminated freshwater streams in New Jersey Pinelands, Ross and Sherrell [8] have used CFF, with a 10 kDa (ca. 3 nm) cutoff, to separate the filtrate (<0.45 pm) into colloidal and truly dissolved fractions in freshwater systems. The colloidal fraction,/cou, was calculated by difference ... 

The body of flatworms (phylum Platyhehninthes) consists of two external cell layers (endoderm and ectoderm) with a third layer between. A distinct excretory system is present. In addition to a nerve net resembling that of the Cnidaria, there are a cerebral ganglion and distinct eyes. One large group of flat-worms, the planaiians (typically about 15 mm in length, Fig. 1-14), inhabit freshwater streams. They are said to be the simplest creatures in which behavior can be studied. 

A freshwater stream may look sparkling and clean, but it s probably not safe for drinking. Many rivers and lakes in the United States are polluted. Bacteria and viruses enter water supplies through contamination by sewage and industrial wastes. Wastes from landfills and mines leak into groundwater reservoirs. Pesticides, herbicides, and fertilizers are picked up by rainwater and carried into streams. Streams flow into rivers, and rivers empty into oceans. In addition, coastal cities pump waste directly into the oceans. For this reason, much of the oceans pollution is found along the coasts of continents. 

Merz-Preiss, M. Riding, R. (1999) Cyanobacterial tufa calcification in two freshwater streams ambient environment, chemical thresholds and biological processes. Sedimentary Geology 126, 103-124. 

Gypsum is a relatively inert by-product of wet process acid production. However, it may pose an environmental problem to wet process acid operations simply because some 5 to 7 tonnes are produced for each tonne of phosphoric acid (100% basis). Years ago, disposal by some facilities was simply into the nearest watercourse via a slurry pipeline. However, with the realization that even inactive suspended solids in freshwater streams can have severe smothering and siltation effects on both water quality and the diversity of stream life, this practice has been largely discontinued. Use of the gypsum for wallboard manufacture has been studied [54], and is used where supplies of natural gypsum are scarce, such as in the U.S. [55, 56]. Application of... 

Observed short-term responses of MPB photosynthesis to ambient UV levels are less clear-cut, when compared with supplemented UV-B, and appear to vary with substrate type and community density. For a muddy sediment, no significant effects of ambient UV-B on either carbon uptake or oxygen microprofiles of a diatom mat (dominated by large motile species) were found [46]. In a sandy sediment, on the other hand, both carbon uptake and allocation of a community dominated by small (mainly non-motile) diatoms and cyanobacteria decreased significantly under ambient UV-B, although only at the end of a 3-week experiment [47]. Finally, no effects of ambient UV-B on photosynthetic rates were observed in freshwater stream periphyton [150]. 

BIOLOGICAL PROPERTIES will persist until natural alkalinity precipitates as oxide attaches to small particulates in air and remains for many days most ends up in soil and attaches to particulates containing iron, manganese, or aluminum found in low levels in rivers, lakes, and streams 35 ppt of salinity 0.3 pg/L in seawater and at 1.1 pg/L in freshwater streams highly persistent in water with a half-life of longer than 200 days can be detected in water by atomic absorption 0.2 pg/L found in tap water found in some foods in the parts per million range... 

Thus the presence of 10" M Cl" has increased the total dissolved cadmium concentration even further. Although the increase is approxi mately 2 percent in this example because of the 01 concentration selected, quite significant increases in solubility are observed in solutions such as seawater, where the Cl- concentration is approximately 20 g/liter or 0.56 M. In seawater of pH 8 the solubility of cadmium hydroxide including all hydroxo and chlorocomplexes) is approximately 10+°-39 compared with lO- - M if no Cd(II) complexes were formed. This is an increase of 110 times in cadmium solubility. In seawater the major dissolved species is CdCla . The solubilization of metals such as cadmium and mercury by the formation of soluble chloro complexes has significance in relation to marine waste disposal. The discharge of freshwater streams containing these metals in suspension to a saline environment could well result in increased dissolved metal levels because of the formation of dissolved chloride complexes. 

Our studies indicated rapid photolysis of trichlorophenol, di-chlorophenol, and pentachlorophenol in both distilled and estuarine water. We can compare our results of pentachlorophenol with those of other investigators who have studied the photolysis of this compound in both fresh and marine waters O, 17-20). The photolysis rate constant kp for pentachlorophenol in a freshwater stream was 0.29 hr ( 1/2 2.4 hr) at 3.8 cm in the summer ( W), while we found a kp of 0.37 hr ( 1/2 " 2 hr, light hours) at a depth of 3.0 cm in the summer (Table I). The half-life of pentachlorophenol in a 1 m deep freshwater pond was 1.5 to 3 days (17) while in 5.5 m deep marine mesocosm the half-life was 22 days (18). Using lamps to simulate sunlight the pentachlorophenol in surface seawater was found to have a half-life of 2.4 hr. ( 5), Thus our rate constant and half-life for pentachlorophenol photolysis was similar to one determined by others in surface waters. Due to attenuation of light by substances in the water longer half-lives, i.e., days rather than hours, are found for pentachlorophenol when distributed throughout the water column. 

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