John G. Lyon

Assessing mine drainage pH from the color and spectral reflectance of chemical precipitates

The pH of mine impacted waters was estimated from the spectral reflectance of resident sediments composed mostly of chemical precipitates. Mine drainage sediments were collected from sites in the Anthracite Region of eastern Pennsylvania, representing acid to near neutral pH. Sediments occurring in acidic waters contained primarily schwertmannite and goethite while near neutral waters produced ferrihydrite. The minerals comprising the sediments occurring at each pH mode were spectrally separable. Spectral angle difference mapping was used to correlate sediment color with stream water pH (r 2 =0.76). Band-center and band-depth analysis of spectral absorption features were also used to discriminate ferrihydrite and goethite and/or schwertmannite by analyzing the 4 T1 6 A1 crystal field transition (900– 1000 nm). The presence of these minerals accurately predicted stream water pH (r 2 =0.87) and provided a qualitative estimate of dissolved SO4 concentrations. Spectral analysis results were used to analyze airborne digital multispectral video (DMSV) imagery for several sites in the region. The high spatial resolution of the DMSV sensor allowed for precise mapping of the mine drainage sediments. The results from this study indicate that airborne and space-borne imaging spectrometers may be used to accurately classify streams impacted by acid vs. neutral-to-alkaline mine drainage after appropriate spectral libraries are developed. Published by Elsevier Science Ltd.

Historical aerial photographs and a geographic information system (GIS) to determine effects of long-term water level fluctuations on wetlands along the St. Marys River, Michigan, USA

Abstract The water levels of the Great Lakes fluctuate as much as ± 1 m from their respective long-range mean elevations in response to changes in climatic conditions. Coastal wetland areas on each Great Lake expand or contract in response to the long-term water level fluctuations. The water level of the St. Marys River, a connecting channel between Lakes Superior and Huron, is largely controlled by the level of Lake Huron. The St. Marys River wetlands expand and contract in a fashion similar to wetlands on the lakes. Data on St. Marys River wetland areas were derived from historical aerial photographs and placed in a Geographic Information System (GIS) to analyze the effects of water level fluctuations. The GIS was used to measure wetland area changes between the years for which photographic data were available. Use of GIS allowed quantification of wetland area changes, estimation of response rates and description of inter-class transfer dynamics, for five coastal wetland classes influenced by long-term water level fluctuations.

Determinations of suspended sediment concentrations from multiple day landsat and AVHRR data

Abstract A combination of satellite data, on-site sampling, and hydrodynamic and water quality model simulations was used to evaluate surface sediment concentrations in Sandusky Bay, Lake Erie. Both satellite brightness values and categorizations of total suspended sediment concentrations from Landsat and AVHRR data were evaluated for the period of 10–28 June 1981. The satellite data products displayed many of the trends in concentration recorded by the on-site data, and were similar to the results of hydrodynamic and water quality (HWQ) model simulations reported elsewhere.

Use of a geographic information system data base to measure and evaluate wetland changes in the St. Marys River, Michigan

A digital data base was constructed by photo interpretation, mapping, and digitizing seven dates of aerial photography on the St. Marys River, Michigan, USA. The data base was used in conjunction with geographic information system software to examine historical changes in wetland area. Total wetland area between 1939 and 1985 ranged from 7 200 to 7 317 ha over a 46-year period of high and low water. There was greatest variation in areas of emergent wetland and scrub-shrub wetland, which appeared to be responding primarily to changes in water level.