Metals

Metal forms, cycling
Sources
Movement, pathways
Toxicity, Standards
Metals in surface water and ground water

Above is an outline of the main part of the lecture. You should know this material.

http://h2osparc.wq.ncsu.edu/info/hmetals.html
The above is a good general site on metals, (prob 4-6 pages mostly tables). Their main site has a lot of information on many topics we are covering or that you are doing for presentations.

http://water.usgs.gov/pubs/circ/circ1133/

This is a paper about contaminants in the Mississippi River. There is a chapter about metals (7 pg). We will use the larger paper several times in this class.

http://www.atsdr.cdc.gov/

What is the ASTDR? What do they do?

Health Effects
Top 20 Substances
1.Arsenic
2.Lead
3.Mercury
7.Cadmium
16.Chromium (+6)

From the ToxFAQs

Ingestion of metals such as lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), barium (Ba), and chromium (Cr), may pose great risks to human health. Trace metals such as lead and cadmium will interfere with essential nutrients of similar appearance, such as calcium (Ca2+) and zinc (Zn2+).

Lead: Because of size and charge similarities, lead can substitute for calcium and included in bone. Children are especially susceptible to lead because developing skeletal systems require high calcium levels. Lead that is stored in bone is not harmful, but if high levels of calcium are ingested later, the lead in the bone may be replaced by calcium and mobilized. Once free in the system, lead may cause nephrotoxicity, neurotoxicity, and hypertension.

Cadmium: Cadmium may interfere with the metallothionein's ability to regulate zinc and copper concentrations in the body. Metallothionein is a protein that binds to excess essential metals to render them unavailable When cadmium induces metallothionein activity, it binds to copper and zinc, disrupting the homeostasis levels. Cadmium is used in industrial manufacture and is a byproduct of the metallurgy of zinc

Mercury: Mercury poses a great risk to humans, especially in the form of methylmercury. When mercury enters water it is often transformed by microorganisms into the toxic methyl mercury form. Symptoms of acute poisoning are pharyngitis, gasteroenteritis, vomiting, nephritis, hepatitus, and circulatory collapse. Chronic poisoning is usually a result of industrial exposure or a diet consisting of contaminated fish (mercury is the only metal that will bioaccumulate). Chronic poisoning may cause liver damage, neural damage, and teratogenesis.

Arsenic: Arsenic ingestion can cause severe toxicity through ingestion of contaminated food and water. Ingestion causes vomiting, diarrhea, and cardiac abnormalities.

Chromium: The presence of abundant chromium anions in the water is generally a result of industrial waste. The chronic adverse health effects are respiratory and dermatologic.

Examples of adverse effects (abstracts)
These metals can adversely impact aquatic communities. An extreme example of this is the Kesterson Reservoir in the San Joaquin Valley, California, which received subsurface agricultural drainwater containing high levels of selenium and salts that had been leached from the soil during irrigation. Studies in the Kesterson Reservoir revealed elevated levels of selenium in water, sediments, terrestrial and aquatic vegetation, and aquatic insects. The elevated levels of selenium were cited as relating to the low reproductive success, high mortality, and developmental abnormalities in embryos and chicks of nesting aquatic birds.

http://wi.water.usgs.gov/pubs/FS-216-95/
Mercury Contamination of Aquatic Ecosystems

Cadmium toxicity among wildlife in the Colorado Rocky Mountains.
Author(s): Larison, James R.
Likens, Gene E.; Fitzpatrick, John W.; Crock, J.G. Source:
Nature; 7/13/2000, Vol. 406 Issue 6792, p181, 3p, 4 graphs
Academic Search Premiere

http://co.water.usgs.gov/trace/pubs/est_rice_99.html
Rice, K.C., 1999, Trace-element concentrations in streambed sediment across the conterminous United States: Environmental Science and Technology, vol. 33 no. 15, p. 2499-2504.

http://tx.usgs.gov/coring/pubs/wqtrends.html
Water-quality trends in White Rock Creek Basin from 1912-1994 identified using sediment cores from White Rock Lake reservoir, Dallas, Texas

Arsenic

We will be looking at arsenic as a case study because the standard has been recently revised under much controversy.

Readings:
http://www.atsdr.cdc.gov/
ToxFAQ fact sheet
Covers transport, health effects

http://www.who.int/inf-fs/en/fact210.html
WHO fact sheet, an overview

http://co.water.usgs.gov/trace/arsenic/
A USGS site on arsenic in groundwater

http://www.epa.gov/safewater/arsenic.html
The EP web page on arsenic

Questions?
What is arsenic? How does it occur in nature?
What do we use it for?
How much is produced in the US?
How is arsenic transported through the environment?
What are the health risks from arsenic?
What is the occurrence of arsenic in drinking water supplies?

What was originally proposed as an MCL?
What is the MCL going to be?
How much is it going to cost?