Is geochemical contamination from urban development contributing to weed invasions in high conservation value wetlands?

![CDATA[Blue Mountains Upland Swamps are unique ecosystems that are restricted to less than 3000ha within the Blue Mountains, NSW and listed as an endangered ecological community under State and Federal legislation. Geochemistry of water, sediment and foliage was assessed within two urbanised and two naturally vegetated swamp catchments. Water in urban swamps exhibited elevated pH by 1.45 pH units and electrical conductivity by 4.5 times compared to naturally vegetated swamps. Calcium, bicarbonate and potassium concentrations differed between catchment types within water, sediment and foliage. The gradual dissolution and mobilisation of ions, including calcium, potassium and bicarbonate, from concrete is suspected to contribute to geochemical contamination within urban catchments. Urban development contributes to erosion, channelisation and water pollution within Blue Mountains Upland Swamps. Urbanisation is associated with Key Threatening Processes including altered natural hydrology, exotic weed invasions and altered fire frequency. However, the ecological implications of urban water chemistry on these sensitive swamps are unclear. We suspect that urban swamp geochemistry may favour exotic plant species. Improving understanding of how urban development may affect these unique ecosystems is essential to guide management practices, for example exploration of alternative materials to concrete for use in sensitive, poorly buffered environments, and promote conservation.]]