Metal migration through roadside ditch systems.

摘要

The purpose of this research was to understand the concentration and location of metals released by traffic related processes in three different roadside ditch systems in the Binghamton, NY urban corridor. To achieve this goal metal concentrations were used (1) to compare the three ditch locations from traffic type and speed perspectives, (2) the distance from roadway relation between cross sectional segments of the ditch was established, (3) the differences along the flow path of the ditch, (4) differences between soil depths, (5) and the seasonal and yearly changes in metal concentrations were determined, (6) where metal concentrations may have negative ecosystem impacts based on Dutch Soil Standards was established, (7) the relationship between particle size and metal concentrations was assessed, and (8) the phase metals in stormwater were transported through the ditch was determined. These objectives were addressed through the collection of soil cores and stormwater samples.;The ditch soils and stormwater samples underwent a 1% HNO3 cold acid leach to determine the short term metal availability (24 hour time point) and a longer term metal availability (30 day time point). The ditch soils were also microwave digested to determine the acid extractible metal concentrations. The extracts from these three leaching methods were analyzed on an Inductively Coupled Plasma -- Optical Emission Spectrometer for aluminum, calcium, cadmium, chromium, copper, iron, manganese, nickel, lead, strontium, vanadium, and zinc. The ditch soils were also analyzed using X Ray Fluorescence to determine the total metal concentrations. The analytical results and those from the dissolved and particulate phase in stormwater samples were used to determine the location and mobility of these metals in the ditches.;All three ditch locations had metal concentrations above the Dutch target standards for cadmium, copper, nickel, lead, vanadium, and zinc in roadside soils. Two of the three ditches sampled had metal concentrations above the Dutch intervention levels for lead, vanadium, and zinc indicating the need for remediation to avoid negative ecosystem impacts. Roadside ditches require further scrutiny at other sites in order to better understand location specific metal mobility threats to surface water quality in the United States.