Lakes small particulates

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... 

Krambeck et al. [40] measured small quantities of particulate carbon in lake waters by an automated furnace combustion infrared procedure. The whole sequence of operations was controlled with the aid of an AIM65 desktop computer. The system was successfully operated for routine analysis of samples of lake water with particulate organic carbon values of 100-300ug L 1 carbon a single analysis takes 8min. The relative standard deviation was about 1%. 

In air, endrin is expected to be associated primarily with particulate matter, based on its low vapor pressure and high Koc (Kenaga 1980). However, small amounts of endrin in the atmosphere may exist in the vapor phase (Eisenreich et al. 1981). Because of its low solubility (200 pg/L, see Table 3-2), endrin would not be expected to be removed significantly from the atmosphere by wet deposition. Particle-adsorbed endrin will be removed from the atmosphere by both wet and dry deposition. In recent studies in the Great Lakes area, endrin was found in 5% of 450 wet deposition (rain/snow) samples collected between 1986-1991, at volume weighted mean concentrations ranging from 0.02 to 0.98 ng/L (ppt) (Chan et al. 1994). 

Because mirex is a very hydrophobic compound with a low vapor pressure, atmospheric transport is unlikely (Hoff et al. 1992). These authors reported detecting mirex in only 5 of 143 samples at a maximum and mean concentration of 22 pg/m and 0.35 pg/m, respectively. Based on a vapor pressure of <3x10 mm Hg at 25 °C, mirex is expected to exist mainly in the particulate phase with a small proportion existing in the vapor phase in the ambient atmosphere (IARC 1979c). A mass balance approach to the movement of mirex within Lake Ontario indicates that 5% of the total input of mirex to the lake can be attributed to atmospheric deposition compared with 72% of benzo(a)pyrene (Arimoto 1989). 

Note that for the total (dissolved and particulate) concentration, Ct, the abrupt change of the solid-to-water-phase ratio, rsw (Eq. 9-15), at the sediment surface acts like a phase change. The numerical example given in Table 19.1 demonstrates that the transition from the open water column of a lake or the ocean to the sediments involves an increase of rsw by 5 to 6 orders of magnitude. Typically, in the open water, rs p is of order 10 3 kg m-3 while in the sediment column lies between 102 and 103 kg nr3. Thus, at equilibrium the total (dissolved and sorbed) concentration per unit bulk volume on either side of the interface for compounds with small to moderate solid-water distribution ratios (Ki <10 m3kg ) is approximatively given by (see Box 19.1, Eq. 4) ... 

Esthwaite Water (Tipping and Woof, 1983, a and b) is a softwater lake in the English Lake District. In this lake, humic substances extracted by butan-l-ol were present almost exclusively in the dissolved and colloidal size classes. The small fraction of humic substances in the particulate form should not be discounted, since it may explain a hypolimnetic accumulation of these substances. Humic carbon comprised 60-70% of the DOC in winter and early spring, but only 30-40% in summer. The higher proportion of nonhumic DOC during summer months presumably resulted from increased biological production of DOC. 

With these conditions and c [uestions in mind, why is P more often limiting in lakes than on land, at least in the temperate zone P limits lake productivity because (a) unlike C and N, there are no mechanisms that can increase inputs of P when it is in short supply, as discussed above (b) P is relatively immobile within and through terrestrial ecosystems, so inputs of P to lakes are small and (c) lakes have an uncontrollable loss of P, in the sinking of particulate organic matter out of the euphotic zone. 

Particulate iron and colloidal electro active Fe(III) in lake water forms small amorphous, porous balls of <0.5 tm diameter they consist of about 50% Fe(II), (Buffle et al. 1988), 50% Fe(III) and some... 

---