Zinc [Zn, 30]
359
Sediments of Sergipe river estuary (Brazil) contain Zn from 7.4 to 89.7 mg/kg (Garcia
et al. 2011). The Zn concentration in the wetland sediments from the effluent at the
Savannah River Site (Aiken, SC) is 602 mg/kg, and its highest amounts, 425.9 mg/kg,
are fixed in SOM fraction. High amounts of Zn (114.4 mg/kg) in these sediments occur
as amorphous oxides (Knox et  al. 2006). Zinc content of surface-bottom sediments
of harbor in Klaipeda (Lithuania) depends also on granulometric composition and is
(in mg/kg, average and maximum, respectively): in sand, 28.6 and 79.8, and in mud,
40.5 and 185.2 (Galkus et al. 2012).
The assessment limits for Zn in sediments are established as follows (in mg/kg):
effect range low—150, effect range median—410, probable effect level (PEL)—315,
severe effect level—820, and toxic effect threshold—540 (EPA 2000, 2013). The
Environment Canada sediment-quality guidelines (USGS 2001) gave the following values for Zn in the lake-bottom sediments (in mg/kg): threshold effect level—123, PEL—
315, threshold effect concentration—121, and probable effect concentration—459.
Zinc may enter into river systems from numerous sources, such as mine drainage,
industrial and municipal wastes, urban runoff, and soil erosion waters. The largest, up to about 30% Zn discharge to aquatic environments in the EU countries, is
from the manufacturing of basic industrial chemicals. The estimated total Zn load
(in 1990) into the Baltic Sea was 168 t/yr, of which about 80% was from anthropogenic sources (Matschullat 1997).
The median Zn concentration in bottled waters of the EU countries is 1.2 μg/L and
is much lower than in tap waters, estimated to be 23.5 μg/L (Birke et al. 2010). The
guide value for Zn in the United States is 3 mg/L, and a maximum level is 5 mg/L
(EPA 1999). The World Health Organization (WHO) has not yet established a guideline value for Zn in drinking water, because it is not of health concern. However,
drinking water containing Zn at levels >3 mg/L may not be acceptable to consumers
(WHO 2011a).
Zinc contents of aquatic organisms vary greatly and are influenced mainly by
sites of sampling. Fish of the Baltic Sea contain Zn within the range of 1.4–48 mg/kg
fresh weight (FW), whereas soft tissues of mussels contain from 50 to 600  mg/kg
(Szefer 2002).
Zinc in waters is not very toxic to the biota; however, concentrations above
240 μg/L may have adverse effects on some sensitive organisms, for example,
salmons. The limit for safe Zn concentration to aquatic biota is established to be
180–570 μg/L, for soft and very hard water, respectively (Peganova and Eder vide
Kabata-Pendias and Mukherjee 2007).
Rainwaters collected in Sweden, during 1999, contain Zn at an average value of
11 μg/L, within the range of 1.6–24 μg/L. Its wet deposition has been estimated to
be 110 g/ha/yr (Eriksson 2001a).
55.4 AIR
General levels of Zn in the atmosphere are relatively fairly constant. Its worldwide
median concentrations are estimated to be 0.04 and 900 ng/m 3 , for remote and polluted regions, respectively. However, air of some industrial areas may contain up
to 16,000 ng/m 3 (Table 55.1). Aerosol samples from over the North Sea contain Zn