BIOGEOCHEMICAL METAL CYCLING IN ROADSIDE ENVIRONMENTS

The purpose of this research was to understand the concentration and location of metals released by traffic related processes in roadside ditch systems. Soils and plants from roadside environments and their metal concentrations can be indicators of wider environmental and health problems to their surrounding ecosystems. Typha, an aquatic plant that is common along flooding prone areas, such as drainage ditches, could be a good bio-indicator of how traffic related pollution is affecting the environment, because Typha is a potential accumulator of metals and nutrients reflecting soil concentrations. To test this possibility, Typha and soil samples were collected from roadside ditches at 8 locations with varying traffic intensity in Broome County, New York.

The ditch soils and Typha samples underwent a 1% HNO3 cold acid leach for 24 hours to determine short term metal leachability. The ditch soils and Typha samples were also microwave digested to determine the acid extractible fraction of the total metal concentrations. The extracts were analyzed on an ICP-OES to determine aluminum, calcium, cadmium, chromium, copper, iron, manganese, nickel, lead, strontium, vanadium, and zinc concentrations. Preliminary results from soil concentrations indicate several sources of pollution including elevated sodium from road salt, and calcium, magnesium, and strontium from road abrasion, as well as cadmium, copper, lead, nickel, and zinc from vehicle sources. Based on plant/soil partitioning ratios the Typha are preferentially incorporating both macro- and micro–nutrients, but presently not metal concentrations at toxic levels. However metal concentrations in Typha do reflect traffic intensity, with higher metal concentrations in plant tissues adjacent to busier roadways. Roadside ditches along urban-rural gradient should be further studied in order to better understand and ultimately reduce their threat to surface water quality in the United States.