An Introduction to Environmental Chemistry

sampled. A clear seasonal cycle is apparent, with highest values of MSA and

nss-SO 42 - in the austral spring and summer. This is exactly what would be expected

if marine biological production of DMS was the dominant source of sulphur, since

the phytoplankton are strongly seasonal in their production of DMS. For this site

it is well established that marine plankton rather than anthropogenic emissions

268 Chapter Seven

5.4

5.1 4.9 4.7

4.5

4.3

4.2 4.1

4.2

4.2

4.7

4.3 4.5

5.3

5.4

4.3

4.4

5.4

4.9

5.1

5.3

Fig. 7.20Mean annual pH values of rain over Europe in 1985. The pH contours compare

well with rates of acid deposition shown in Fig. 5.7. After Schaug et al.(1987). With

permission from the Co-operative Programme for Monitoring and Evaluation of the Long

Range Transmission of Air Pollutants in Europe (EMEP) and the Norwegian Institute for Air

Research (NILU).