The influence of atmospheric deposition on spatial and temporal variability in stream water chemistry, Mount Desert Island, Maine

Reuter, John

Field work February to August 2007. Water samples were collected monthly from 20 streams during the period. "Acidification of terrestrial and aquatic ecosystems caused by anthropogenic emissions is a major concern because of the negative implications of increased acidity and increased inputs of toxic metals, such as aluminum, for aquatic biota. Twenty low-order streams were sampled in Mount Desert Island, Maine, from February to August, 2007, and analyzed for pH and major ions. GIS mapping was used to quantify landscape variable including slope, elevation, aspect, vegetation and atmospheric deposition of nitrogen and sulfur (as determined by Weathers et al. 2006) in each sampled watershed. Streams experienced acidic episodes in which average stream pH coincided with decreases in acid neutralizing capacity and increases in stream concentrations in Ph coincide with decreases in acid neutralizing capacity and increases in stream concentrations of aluminum. It is hypothesized that the salt effect, in which sea-salt sodium displaces hydrogen from the soil exchange complex, is partially responsible for the acidic episodes. Among sites with lesser marine influence, atmospheric deposition of sulfur accounts for 76% percent of the variability in stream concentrations of sulfate. It is suggested that a better method of determining sea-salt would separate marine and anthropogenic sulfate more accurately than the method used. This will help determine spatial distribution of sea spray, and determine the effect of anthropogenic sulfur deposition in all areas if the inland, including those with significant marine influence." Appendix B lists site characteristics for each of the streams sampled and includes UTM and lat/long coordinates, max and min elevation, average elevation, average slope, maximum and mimimum slope, aspect, S deposition, N deposition, and discharge (April) Research Recommendations: "It is suggested that a better method of determining sea-salt would separate marine and anthropogenic sulfate more accurately than the method used. This will help determine spatial distribution of sea spray, and determine the effect of anthropogenic sulfur deposition in all areas if the inland, including those with significant marine influence." /STUDY LOCATIONS:/ /MOUNT DESERT ISLAND/Bald Peak Trail/Eagle Lake North/ Eagle Lake South/Eagle Lake West/ Great Brook/Goose Cove North/Gilley Field Stream/Hadlock Brook/Hunter's Brook/Hodgdon Pond/Hamilton Pond Stram/ Indian Point Cove/Littel Notch Sluice/Long Pond North/Long POnd West/Mount Mansell Trail/Maple Spring trail/Otter Creek/Steward Brook/Indian Point Cove Stream/Hodgdon Brook/Steward Brook/Great Brook GIS CATEGORY 1 Coordinates for site locations are provided in appendix B, and a simple map displaying the distribution of sites on the island and subsequent ionic concentrations at sites is provided.