Movement of DOC and P from soils to streams, reservoirs and the ocean

David Chittleborough | Wayne Meyer | Jim Cox
Ann McNeill| Cameron Grant

Fresh water streams in southern Australia generally have high levels of dissolved organic carbon (DOC) and many streams and water storages have environmentally significant amounts of phosphorus. These two agents are significant contributors to low water quality in southern Australian reservoirs, waterways and water storages and are sufficiently high in DOC to warrant removal by water treatment. This carbon and phosphorus contributes to pollution in the near marine environment of the Gulf St Vincent and, along with sediment from soils in the Mount Lofty Catchments, is having deleterious effect on the marine biological system. Some streams draining the Mount Lofty Ranges watershed, for example, have four times the recommended US Environmental Protection Agency levels of phosphorus and dissolved organic carbon above 20 mg/L. In some streams nitrate is also unacceptably high. Eutrophication is a growing threat, largely because of the P levels in water storages and streams. Whereas climate and soil type are significant factors in the movement of these components from soils to waterways, there is little doubt that diverse human activities in catchments have exacerbated this transport. Soil and land management offer the prospect of significantly reducing the problem.

The issue being addressed by the Hydropedology Research Program is to quantify the loss of DOC and P from catchments and to test methods of reducing the movement of these components from their source (soils) to streams, reservoirs and ocean.