Predicting Disaster: Model Ecosystems and the Prevention of Water Pollution

Partial List of Ecologically Harmful Chemicals Persistent and bioaccumulative: –DDT and its congeners –Cycodienes Aldrin & Dieldrin Endrin Heptachlor & Chlordane Mirex & Chlordecone (Kepone) –PCBs –PBBs –PFOS & PFOA –Cadmium –Selenium –Organic mercury compounds –Organic tin compounds –Hexachlorobenzene Persistent but not bioaccumulative: –Aldicarb –Lead –DES Unduly Toxic –Fenthion –Parathion –Compound 1040 Endocrine disruptors –Vinclozolin –Phthalates –Atrazine? –….. etc

Preventing Ecological Disasters Statement of the problem: –Complex ecosystems –Many chemicals –Ecological consequences take time to show up –Chemicals cannot be retrieved from environment Metcalf Microcosm: –Predicts environmental behavior –Validated 150 chemicals Many with field experience

Metcalf Microcosm Environment –10 gallon aquarium –Sterile sand, 15 kg –Standard reference water, 8L –10 ml aquarium water Organisms –Sorghum vulgare –Daphnia magnum –Snails (Physa spp) –Algae (Oedegonium cardiacum) –Mosquito larvae (Culex pipiens) –Mosquito fish (Gambusia affinis) Preparation: –Water, sand –Plant sorghum – 8 snails –100 Daphnia –Algae Day 0 –Sorghum is 3-5 cm tall –Treat plants (or sand) –Wait 1/2 hour Day 5 –Add caterpillars Day 26 –Add 300 mosquito larvae Day 29 –Add 3 mosquitofish Day 32 –Terminate system Analysis –Measure 14 C in all organisms, water, sand

Tradeoffs in Designing Model Ecosystems Microcosm –Advantages Cheap Fast Repeatable –Disadvantages Unrealistic? Tests 1 or 2 parameters –Which? Mesocosms –Vary tremendously –With increasing size Complexity increases –More variables included –More parameters tested Costs increase Time to completion increases Reproducibility decreases

Mesocosms

Water, Soil and Air Interconnect Fields, parking lots, Roofs, roads bubbles Wells - private & public Municipal water sources Adsorption on solids; Absorption of gases

Water, Air and Soil as Media for Pollutants