Table 9.
General characteristics of Major Water Quality Issues on a Global Scale
| Quality issue | Waste bodies mostly concerned | Major problem area | Time-lag between causes and effects | Space scale of issue (a) |
|---|---|---|---|---|
| Pathogenic agents | ++rivers +lakes +groundwaters |
++health | <1 year | local |
| Organic pollution | ++rivers +lakes +groundwaters |
++aquatic environment | <1 year | local |
| Salinization (b) | ++groundwaters +rivers |
++most uses +aquatic environment +health |
1 to 10 years | regional |
| Nitrate pollution | ++groundwaters +rivers |
+health | >10 years | regional |
| Heavy metals | all water bodies | +health +aquatic environment +ocean fluxes |
<1 to >10 years | local to global |
| Pesticides and industrial organics | all water bodies | +health +aquatic environment +ocean fluxes |
1 to 10 years | local to global |
| Acidification (a) | ++rivers,lakes +groundwaters |
+aquatic environment +health |
>10 years | regional |
| Eutrophication (c) | ++lakes +rivers |
++aquatic environment +health |
>10 years | local |
| Sediment load (d) | +rivers |
++aquatic environment +most uses +ocean fluxes |
1-10 years | regional |
| Hydrological modifications (e) | ++rivers | ++aquatic environment | 1 to 10 years | regional |
+ important issues on a global scale
++ very important issue on a global scale
(a) including atmospheric transport of pollutants
(b) including high fluoride or arsenic contents
(c) including river nutrient loads
(d) increase or decrease of loads
(e) water diversion, damming and over-pumping of aquifers
see also Table 10., Focal Points of the Canadian Global Change Program (CGCP) in Relation to Key Global Change Issues.