Water Quality 103: Toxics Monitoring
By: Bryan Duggan, Water and Environmental Specialist
Due to a Oregon Legislative mandate, the Oregon Department of Environmental Quality
(DEQ) in 2008 implemented a statewide water quality toxics monitoring program. DEQ
staff is collecting water quality samples from rotating basins and are due to collect the
first samples in the Coos and Coquille system in 2013. The overall goals of the DEQ
Water Quality Toxics Monitoring Program are to: gather information on the presence and
concentration of chemicals in Oregon’s waters, use this information to identify the
sources of these chemicals, work with community groups and the public to identify the
means of reducing these chemicals, and to make the results available to the public.
But, what are these chemicals, how do they get in our waters, and how do they impact
water quality? Aquatic Toxicology is the study of the effects of manufactured chemicals
and other anthropocentric and natural materials on aquatic organisms at various levels
within the ecosystem. It is important to define a few terms at this point; a toxin is a
contaminant produced by a biological organism (i.e. snake venom), a toxicant is a
contaminant of chemical anthropocentric activities (i.e. PCBs) and is the focus of our
interest. Bioaccumulation is the net accumulation of a contaminant in and on an organism
from all sources including water, air and solid phases in the environment.
The pollutants (or toxicants) of concern in Aquatic Toxicology are: Pesticides,
Polyaromatic Hydrocarbons (PAHs), Polychlorinated Biphenyls (PCBs), Polychlorinated
Dibenzodioxins (PCDDs), Polybrominated Diphenyl Ethers (PBDEs), inorganics (heavy
metals), Pharmaceutical and Personal Care Products (PPCPs), and others and their
mixtures which we do not have the space to delve into.
DDT is the most famous of the group of chemicals referred to as pesticides which in
essence are any chemical or agent whose use is intended to prevent, destroy or repel plant
or animal pests. PAHs are compounds composed of two or more fused aromatic rings,
have a wide occurrence, are carcinogenic, and are found in tobacco smoke, automobile
exhaust, and smoked foods. PCBs are commercially produced chlorinated compounds
that are long lived, persistent and can disperse long distances by air and water. PCDDs
are another commercially produced compound similar to PCBs and are also persistent,
bioaccumulate and contribute to immune dysfunction and reproductive effects. PBDEs
are the flame retardants prevalent in everyday textiles such as furniture, plastics, and
electronic components; highly transferrable by air and water, they are persistent, and
bioaccumulative. Heavy metals are persistent in our environments due to industrial and
commercial activities; the complete impacts of these compounds have yet to be
determined. PPCPs are emerging pollutants that include personal care compounds that are
inadequately disposed of and persisting in the environment.
Fate and Transport refer to two important components to the bioavailability (degree that
the toxicant is free to be taken up into and cause an effect on an organism) of
contaminants in the environment. Fate is where a pollutant is ultimately stored in an
environment (water, soils, organic tissue) and transport is how the pollutant moves
through the environment. Aquatic toxicologists routinely collect sediment and tissue
samples from aquatic organisms to learn about the fate of these chemicals in our
environment; sediment and tissue contaminant levels can also be compared to account for
the transport of these toxicants.
Perhaps easiest for us to contemplate this is the following example: a pollutant is
discharged into the atmosphere (via emissions) and water (point source discharge), a king
salmon accumulates contaminants during the ocean life stages; are the contaminants
transported back as a result of migration? A study of salmon and grayling fish in the
Copper River and spawning lakes in Alaska found that migrating salmon had double
concentrations of PCBs and Pesticides in their gonads (and presumed transfer to roe and
juveniles). Grayling in salmon spawning lakes had higher concentrations of PCB’s and
Pesticides than did graylings in salmon free lakes. Graylings are resident fish in Alaskan
lakes and are predators to juvenile salmon.
Fate, transport and bioavailabilty toxicity are all dependent upon the properties of the
environment, properties of the pollutant, and the properties of the organism. What this
means is that standard water quality parameters such as pH, dissolved oxygen,
temperature and conductivity can influence the speciation (distribution) of the chemical.
So standard water quality parameters mentioned above can modify the behavioral
conditions of organisms present that leads to greater or lesser bioavailability and
accumulation of toxicants in an organism. Water pH values can also have direct impacts
upon the solubility of a pollutant as well.
So what does this all mean for our community? These chemicals clearly show a fate and
transport ability to bioaccumulate up the food chain, and as a lot of hunters like to claim,
humans are at the top of this chain. As recent as 2008, Oregon’s water quality standards
use to direct the human health criteria of toxicants in the environment to be calculated
using a fish consumption rate of 17.5 grams/day. However in Indian Country, where fish
is an integral component of first foods, this rate was too low to protect many fish
consumers. After a five year effort by Oregon Tribes, the DEQ recently raised the human
health toxics criteria based on a higher fish consumption rate of 175 g/day. This in effect
strengthens Oregon’s water quality standards to protect both fish and human
communities.
On March 13, I sat in on a public meeting held in the Coos Bay City Hall to hear what
Pam Blake and Lori Pillsbury of the Oregon DEQ had to say about local toxics
monitoring. The DEQ are performing routine public meetings to gather input from
citizens and local stakeholders to suggest monitoring sites for toxicology testing. The
DEQ plans on sampling sediments and fish tissue samples at 13-18 sites within the Coos
and Coquille basins; the results of these tests will guide agency efforts to reduce these
pollutants. With the prevalence of these toxicants in our environment and the
understanding of their fate, transport, and toxicity, local knowledge of their presence and
sources can only be a positive step toward a truly healthy community and environment.