Author(s): Mike Hannah; Nick Vigar
Linked Author(s): Michael Hannah
Keywords: Total Metals; Dissolved Metals; Treatment; Climatic Conditions
Abstract: There are many different contaminants in stormwater runoff. Of particular concern to sensitive environments is the toxicity of the dissolved fraction of heavy metal contaminants. The characterization and partitioning of metals in stormwater is complex and dynamic with many factors affecting it. The majority of stormwater investigations have occurred in the temperate climates of the USA, Europe and Australia. Temperate climates have 4 distinct seasons (summer, autumn, winter and spring) while tropical climates tend to have two; dry and wet. A tropical climate is typically associated with the tropics and is typically between latitudes 23.4°N and 23.4°S. A tropical climate is defined as having a mean temperature of over 18°C (64.4°F). The term'subtropical'describes the area found adjacent to the tropics. The definition of a subtropical climate is one that has at least eight months with a mean temperature of 10°C (50°F) or above. Tropical and sub tropical environments have higher temperatures, higher intensity rainfall and generally faster growing flora. These climatic conditions greatly influence the characterization of stormwater pollutants. The paper draws on research and results from 3 field studies. One on a highly trafficked arterial road in the world heritage wet tropics rainforest near Cairns in Northern Queensland, Australia (latitude 16°51 south) and two industrial sites is Auckland, New Zealand (latitude36°52 south) This paper investigates the effect of climate conditions on the relationship between solids and dissolved metals, the effect of organic carbon and dissolved metal concentration and the effect of temperature on contaminant removal. The paper also discusses sizing of a treatment system in a 2 season environment as well as treatment train mechanisms suitable for these climates.
Year: 2010