Sulfate (SO₄)

Status and Trends

Sulfates in the watershed are primarily related to the types of minerals in the soil and bedrock with contributions from acid rain. Industries and utilities that burn coal release sulfur dioxide into the atmosphere that may be deposited as sulfate or scavenged by rainfall or dew. Dissolved sulfate in surface water may also be derived from the dissolution of gypsum or the oxidation of sulfide minerals such as pyrite in association with mining of coal. Dissolved sulfate is stable under oxidizing conditions, however, under reducing conditions, it can be converted to hydrogen sulfide (HS).

Sulfate is sampled at seventeen stations located in the North Branch Potomac (NBP), tributaries to the NBP and MD stations contributing to the Ohio River drainage. No sulfate measurements are made east (downstream of) station POT 2766 near Paw Paw, WV.

Median sulfate concentration ranged for 30 mg/L at the Youghiogheny River station below the confluence with the Little Youghiogheny to 412 mg/L at Georges Creek. Stations with the highest median concentration (SO₄ > 128.9 mg/L) comprise 25% of all stations and were located in the uppermost NBP stations, Georges Creek and Braddock Run.

Stations with lowest median concentration (SO₄ ≤ 56.5 mg/L) comprise 47% of all stations sampled for SO₄ and were located in the Ohio River drainage, Savage River and Town Creek.

Sulfate concentrations decreased at Cherry Creek, on the North Branch Potomac River at Bloomington, at US 220, at Pinto and at Moores Hollow Road. Concentration increased on the North Branch Potomac River at Oldtown Rd. and on the Little Youghiogheny River.

Sulfate (SO₄) data for sampled locations are summarized in these plots.

• Land use/site map

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This page was updated on 12/5/2005