Ecological responses to the discharge of polluted coal mine wastewater

Abstract

The discharge of coal mine generated wastewater has degraded the Georges River downstream of the discharge point. This study measured the water quality, sediment quality and macroinvertebrate community of the upper Georges River to determine the impact of the influx of wastewater from an underground coal mine. The investigation revealed that the wastewater discharge from the West Cliff Colliery into the Georges River was highly polluted. The pollution of the river is characterised by increases in electrical conductivity, pH levels and a suite of metals including; antimony, aluminium, arsenic, barium, boron, cobalt, lithium, molybdenum, nickel, strontium, titanium, uranium and zinc. The elevated concentrations of metals downstream of the wastewater discharge point has caused a suite of metals including; aluminium, barium, chromium, cobalt, copper, iron, lead, lithium, manganese, nickel, strontium, titanium, uranium and zinc to accumulate within the sediment. The altered water chemistry downstream of the wastewater discharge point is expected to be the salient factor in the significant loss of biodiversity within the macroinvertebrate community. The aquatic macroinvertebrate community downstream of the wastewater discharge is characterised by a loss of pollution sensitive taxa and an increase in pollution tolerant taxa. A laboratory experiment has identified that a suite of metals including aluminium, boron, barium, cobalt, copper, iron, lithium, manganese, molybdenum, nickel, strontium and uranium present in the coal mine wastewater discharge are able to bioaccumulate within plants that are exposed to the wastewater. This research has demonstrated that the current implementation of environmental protection legislation has failed to protect one of Sydney's major waterways from the effects of coal mining. Consequently, it is essential that we better manage our aquatic ecosystems to avoid further instances of degradation and to preserve ecosystem functions and services.

Date of Award	2019
Original language	English