sludge is considered a prime source of heavy metals (Clark 1977). In Maine, 

 pulp plants are major sources of heavy metals (Fink et al. 1976). Chromium, 

 lead, copper, and zinc are the principal metals discharged from these plants. 

 Also, naturally occurring sediments derived from metal ore deposits contain 

 toxic heavy metals, including chromium, manganese, cobalt, nickel, copper, 

 zinc, lead, arsenic, mercury, silver, cadmium, and vanadium. 



Very little site-specific data on heavy metal concentrations are available for 

 coastal Maine waters. Fink and coworkers are sampling five Maine estuaries 

 for heavy metal contamination (personal communication from L. K. Fink, 

 University of Maine, Walpole, ME; January, 1979). Their data will establish 

 baseline levels for 10 metals. A Maine Department of Marine Resouces (MDMR) 

 study indicates that concentrations of heavy metals in macroalgae and 

 shellfish are elevated at sites near mining operations (see "Mineral 

 Extraction " above). 



Fink's preliminary conclusions indicate that the heavy metals in coastal 

 waters are industrial in origin. Levels of five metals found by Fink and 

 coworkers (1976) in suspended particulate matter in the St. Croix River 

 estuary, which is subjected to paper mill effluent, are listed below: 



Element Range (ppb) Mean (ppb) 



Chromium 40- 373 117 



Copper 21-2153 507 



Iron 4-69 38 



Manganese 139-1059 605 



Lead 21-1799 324 



Maine Department of Environmental Protection waste-water discharge licenses 

 specify the amounts of various heavy metals that a discharger may release; 

 these data are given in appendix A. The amount of heavy metal input from acid 

 precipitation is unknown. Acid precipitation is further discussed under "Air 

 Pollution" below. Heavy metals have been found to contaminate landfill sites 

 in Maine (Emmons 1978). Heavy metal levels in vascular plants are used to 

 measure contamination. 



Concentrations of heavy metals approaching or exceeding EPA standards for 

 toxicity to several organisms have been found in several Maine estuaries that 

 are near metal ore bodies and mining operations (Hurst and Dow 1972) and that 

 receive pulp manufacturing effluent (Fink 1977). 



Heavy metals tend to be associated with the organic fraction of estuarine 

 bottom sediments (Fink et al. 1976). Metals are transported through the 

 environment by sorbing (adsorbing and absorbing) onto the organic solids and 

 the subsequent sedimentation, resuspension, or current dispersion of the 

 particulate organics (Clark 1977). However, dispersal of heavy metals from 

 the source of input generally does not occur. Thus, little exchange of heavy 

 metals takes place between the estuarine and marine systems. However, the 

 movement of sediments in dredging operations may transport heavy metals from 

 estuaries to marine environments (see "Ports and Navigation" above). The most 

 frequently dredged areas in Maine receive drainage from the most 

 industrialized portions of the State. 



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