A Pollution Case Study:

The Black Sea

Background

Enclosed sea with only the Bosphorus as communicating waterway with Aegean and Mediterranean

Bosphorus

Danube

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

Danube Dneiper and Dniester are major river inputs and all in NWAdjacent shelf (<200m) circa 25% of total area of Black Sea

Danube conveyor belt collecting pollution from countries en routeMost of these countries are heavily industrialised and very poor treatment of wastes

Nutrient inputs to the NW shelf and EutrophicationRivers major input

Increased release to Black Sea of N and P (mid 70s)

Average dissolved N & P in Romanian coastal waters

0

50

100

150

200

250

300

1960 1965 1970 1975 1980 1985 1990

Date

µg

/L

Phosphates

Nitrates

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

Increased phytoplankton biomass, reduction in species diversity, red-brown-green tides

0

5000

10000

15000

20000

25000

30000

mg

.cu

bic

met

re

1950s 1960s 1970s 1980s

Increase in biomass in NW shelf of Black Sea

•Decrease in oxygen

•Si fluxes to coastal waters decreased due to dams

0

200

400

600

800

1000

1200

1400

1600

1800

1960 1965 1970 1975 1980 1985 1990

Silicon

Average dissolved Si in Romanian coastal waters

Impact on ecosystemChanges in zooplankton:

Some species common pre 1970s, almost goneLarger planktonic crustacea replaced by smaller speciesExplosion in gelatinous species- e.g. Aurelia aurita increased 1000X from 60s to 80sAlien species introduced- bloom in gelatinous ctenophore mnemiopsis Increase in jelly fish likely due to removal of predator (mackerel)

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

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 levelsBetter 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

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

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