Fate in the Environment and Long-Range Atmospheric Transport of the Organophosphorus Insecticide, Chlorpyrifos and Its Oxon - Reviews of Environmental Contamination and Toxicology - page 39

Table 4 Numbers and approximate percentage distributions of reported concentration levels
expressed as percentages of reported data

Air
ng m −3

Rain
ng L −1

Snow
ng L −1

Water
ng L −1

Sediment
ng g −1

Soil

ng g −1 Biota Phase ng g −1

Number and conc. ~100 15 18 30 8 2 10
% >10 15 20 11 0 0 0 0
% 1-10 14 40 17 46 20 0 10
% 0.1-1.0 36 20 11 27 40 100 10
% 0.01-0.1 27 20 61 10 40 0 80
% 0.001-0.01 8 0 0 17 0 0 0
Note that concentrations in air and rain appear similar numerically because the air-water partition
coefficient of 0.00034 is similar to the 0.001 factor conversion from m 3 to L

frequency of detection. The key issue in this context is not one of presence/absence,
because CPY and CPYO can be monitored in air at concentrations as little as
0.001 ng m −3 , which are much less than thresholds for adverse effects. Risk depends
on the magnitude of concentrations, especially in media where organisms might be
exposed and thus are potentially at risk. It can be difficult to assimilate ranges in
concentrations in the atmosphere and the variety of concentration units of differing
magnitudes in sampled media. Accordingly, here, the feasibility was assessed of
compiling a more readily comprehendible depiction of multi-media environmental
concentrations by expressing the concentrations as ranges and converting concen-
trations in various media to fugacities. Fugacity is essentially partial pressure and
can be deduced for all media and compared directly, without difficulties introduced
by the use of different concentration units for individual compartments of the envi-
ronment. Using fugacity as a synoptic descriptor of concentrations in the ecosys-
tem has been applied previously to multi-media concentrations of organochlorines
in the Great Lakes (Clark et al. 1988 ). It is, of course, possible to calculate multi-
media equilibrium concentrations using partition coefficients directly, rather than
using fugacity as an intermediate, but the equilibrium status of two phases with
units such as ng m −3 in air and mg kg −1 in vegetation may not be obvious.
Ideally, to demonstrate directly the trend of decreasing concentrations, the data
should be plotted as a function of distance from source, but because sources are
often uncertain and concentrations vary with time as a function of transformation of
the material at the location of release, this is rarely possible. The approach adopted
here was to compile a distribution of reported concentrations to gain perspective on
the range in magnitude of concentrations at various distances from points of release,
at least for ecosystems for which sufficient monitoring data have been compiled.
Accordingly, Table 4 depicts the distribution of reported concentrations for air, rain,
snow, water bodies, soils, sediments, and biota on a decade scale. In some cases,
products of transformation are included and in others they were specifically
excluded. Some of the data were reported graphically or as ranges, so numerical
values were sometimes difficult to establish. Locations for which information was
available varied geographically and often lacked information on current and recent
meteorology such as wind speed, temperature, and precipitation. Some values
reported for each concentration range are approximate because reports gave only