Sustainable Water Management - Sustainable Practices in Geoenvironmental Engineering - page 88

analysis of triazine herbicides in water samples. Detection levels by this ELISA-based tech-
nique are 0.1 μg/L for atrazine and 0.5 μg/L for triazine. Other methods have now been
developed to analyse enantiomeric pesticides. Studies were performed by enantioselective
GC/MS from 1997 to 2001 on a lake that received agricultural runoff in Switzerland (Poiger et
al., 2002). Pre-1998, samples showed the dominance of the racemic metolachlor, whereas sam-
ples collected in 2000 to 2001 showed a clear dominance of the S -isomer. This coincided with
the commercial switch from the racemic to the S form for agricultural use. Pharmaceutically
active compounds and other personal care products have also been identiied in surface run-
off from ields irrigated with wastewater treatment efluents (Pedersen et al., 2002).
Methods such as GC, HPLC, GLC, and atomic absorption spectrometry (AA) are accu-
rate, and limits of detections are continually decreasing due to combined techniques (e.g.,
GC/MS, LC/MS, CE/MS, CE/ICP-MS, and ICP-MS). Polar compounds, prior to LC/MS
were extremely dificult to detect. Improved methods of sample preparation have reduced
solvent usage and are more environmentally friendly and rapid. Although efforts have
also been made to automate and simplify many of the technologies, they must continue to
enable more widespread use of the technology. Recoveries from SPE will need to improve
to enable one to obtain more reliable data from this technique. More extensive testing
needs to be done with real environmental samples, not just standards, to more fully under-
stand interferences within the samples. This will enable one to (a) monitor water quality,
(b) determine the origin or source of biological and chemical contaminants, and (c) deter-
mine the transport and fate of the contaminants in the environment.
3.3.2.2 Biomonitoring
Biomonitoring is used to indicate the effect and extent of contaminants in the water. It
includes determining changes in species diversity, composition in a community, and in the
mortality rates of a species. Buildup of contaminants in the tissues of individuals can also be
evaluated, in addition to physiological, behavioral, and morphological changes in individu-
als. The effect of speciic contaminants is dificult to determine. Biomonitoring involves the
determination of the numbers, health, and presence of various species of algae, ish, plants,
benthic macroinvertebrates, insects, or other organisms as a way of determining water
quality (USEPA, 2000). Knowledge of background information is essential. Attached algae
(known as periphyton) are good indicators of water quality since they grow on rocks and
other plants in the water. The advantages for using these as indicators are (a) high numbers
of species are available, (b) their responses to changes in the environment are well known,
(c) they respond quickly to exposures, and (d) they are easy to sample. An assessment could
include (a) determination of the biomass by chlorophyll or on an ash-free dry basis, (b) spe-
cies, (c) distribution of species, and (d) condition of the attached algae assemblages. As yet,
their use has not been widely incorporated in monitoring programs.
Benthic macroinvertebrates have numerous advantages as bioindicators (protocols). They
do not move very far and thus can be used for upstream-downstream studies. Their life
span is about a year, enabling their use for short-term environmental changes. Sampling is
easy. They are numerous, and experienced biologists can easily detect changes in macro-
invertebrate assemblages. In addition, different species respond differently to various con-
taminants. They are also food sources for ish and other commercial species. Many states
in the United States have more information on the relationship between invertebrates and
contaminants than for ish (Southerland and Stribling, 1995).
Fish are good indicators of water quality because (a) they always live in water, (b) they live
for long periods (2 to over 10 years) (Karr et al., 1986), (c) they are easily identiiable and easy