Sources of alkalinity and acidity along an acid mine drainage remediated stream in SE Ohio: Hewett Fork
Abstract
In the remediation of acid mine drainage impacted streams, it is important to locate and quantify the sources of acidity and alkalinity inputs. These parameters affect the long-term recovery of the stream habitat. Previous studies have focused on treating the remediation of AMD as point source pollution, targeting the main acid seep for remediation. However, in the interest of biological and chemical recovery, it is important to understand how sources of alkalinity and acidity, throughout the stream, affect water and sediment quality. The Hewett Fork watershed in Southeastern Ohio is impacted by AMD from the AS-14 mine complex in Carbondale, Ohio. In attempts to remediate the stream, the water is being treated with a continuous alkaline input from a calcium oxide doser. While the section of watershed furthest downstream from the doser is showing signs of recovery, the water chemistry and aquatic life near the doser are still impacted. The objective of this study is to examine and model the chemistry of the tributaries of Hewett Fork to see how they contribute to the alkalinity and acidity budgets of the main stem of the stream. By examining the inputs of tributaries into the main stem, this project aims to understand processes occurring during remediation throughout the entire stream. Discharge was measured during a dry period in October, 2012 and at a high flow in May, 2013. Field parameters such as pH, TDS, DO, alkalinity and acidity were also determined. Low flow data collected during fall sampling shows variable flow along the stream path, the stream gains water from ground water at some points while it loses water at others, potentially due to variable elevation of the water table. Flow data collected during spring sampling shows that Hewett Fork is a gaining stream during that period with inputs from groundwater contributing to increasing flow downstream. When using this data to calculate the net alkalinity load along the stream, there are areas with alkaline and acidic inputs that do not seem consistent with the water budget. This indicates the need to examine sediment-water interactions along the stream in order to fully understand the implications of the acidity and alkalinity budgets. The precipitation and dissolution of Fe, Al and Ca minerals along the path can explain changes in the alkalinity and acidity budgets that cannot be understood when looking only at the water chemistry. The flow and inputs of water, transport of sediments, and chemical reactions happening within the stream have to be considered together to understand variations in chemical loads and stream chemistry.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.H41H1340S
- Keywords:
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- 1009 GEOCHEMISTRY Geochemical modeling;
- 1806 HYDROLOGY Chemistry of fresh water;
- 1876 HYDROLOGY Water budgets