A Pollution Case Study: The Black Sea

1. A Pollution Case Study: The Black Sea

2. Danube • Background • Enclosed sea with only the Bosphorus as communicating waterway with Aegean and Mediterranean Bosphorus

3. Small flow of relatively freshwater out and beneath return flow of Aegean water (S~22) • Restricted turnover of deepwater, inputs of carbon • Result is anoxic deep basin • However anoxia developed over many thousands of years; relatively stable, no direct impact on coastal systems • NOTE that no large oxygenated water bodies to dilute any low oxygen waters

4. Danube Dneiper and Dniester are major river inputs and all in NW • Adjacent shelf (<200m) circa 25% of total area of Black Sea • Danube conveyor belt collecting pollution from countries en route • Most of these countries are heavily industrialised and very poor treatment of wastes

5. Nutrient inputs to the NW shelf and Eutrophication • Rivers major input • Increased release to Black Sea of N and P (mid 70s)

6. Corresponds to major industrialisation of central and eastern Europe • For Nitrogen, atmospheric input of N containing gases major input ; • Atmosphere =circa 50% of river source; dispersed in contrast to rivers

7. Increased phytoplankton biomass, reduction inspecies diversity, red-brown-green tides • Decrease in oxygen

9. Si fluxes to coastal waters decreased due to dams

10. Impact on ecosystem • Changes in zooplankton: • Some species common pre 1970s, almost gone • Larger planktonic crustacea replaced by smaller species • Explosion in gelatinous species- • e.g. Aurelia aurita increased 1000X from 60s to 80s • Alien species introduced- bloom in gelatinous ctenophore mnemiopsis • Increase in jelly fish likely due to removal of predator (mackerel)

11. Reduced light due to high phytoplankton destroyed benthic algae (e.g. Phyllophora) • Important as habitat for range of fish and invertebrates Conventional fisheries heavily degraded

12. Heavy Metals • Recent measurements of dissolved (e.g.) Cu, Cd, Ni, Co only 2-5 times higher than e.g. open Mediterranean, so not at directly toxic levels • Better feel for inputs of metals is in sediments NW shelf has highest values (when normalised to Al) • >>Reflects riverine inputs of contaminants to this zone

13. Organic Pollutants • Hydrocarbons high relative to comparable regions, • but mainly old & heavily degraded • Organo-chlorines similar or lower than comparable regions • However very limited high quality data so difficult to assess whole system! • Radio-nuclides • Chernobyl major impact; introduction by both air and specifically river

14. Conclusions • For decades Black Sea used as waste receptacle • Major reduction in quality, particularly in the NW Shelf • Eutrophication most obvious problem • Extent of problems for other contaminants hard to estimate because of limited data (e.g. synthetic organic compounds)- need for baseline studies • Antagonistic and synergistic effects of “pollutant cocktail” unclear • Baseline studies will require trained personnel and well equipped labs • Money major limiting factor to obvious remediation actions