Transcript The Black Sea Case Study

A Pollution Case Study:
The Black Sea
Danube
Background
Enclosed sea
with only the
Bosphorus as
communicating
waterway with
Aegean and
Mediterranean
Bosphorus
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 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
Nutrient inputs to the NW shelf and Eutrophication
Rivers major input
Increased release to Black Sea of N and P (mid
70s)
Average dissolved N & P in Romanian coastal waters
300
Phosphates
250
Nitrates
µg/L
200
150
100
50
0
1960
1965
1970
1975
Date
1980
1985
1990
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
Increase in biomass in NW shelf of Black Sea
30000
mg.cubic metre
25000
20000
15000
10000
5000
0
1950s
•Decrease in oxygen
1960s
1970s
1980s
•Si fluxes to coastal waters decreased due to dams
Average dissolved Si in Romanian coastal waters
1800
1600
1400
1200
1000
800
Silicon
600
400
200
0
1960
1965
1970
1975
1980
1985
1990
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)
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 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
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