EFFECTS OF PLACER GOLD MINING ON PRIMARY PRODUCTION IN SUBARCTIC STREAMS OF ALASKA 1

• Published in: Journal of the American Water Resources Association
• Main Authors: Van Nieuwenhuyse, Erwin E., LaPerriere, Jacqueline D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1986
• Subjects: Earth-Surface Processes; Water Science and Technology; Ecology; Subarctic; Alaska
• Online Access: http://dx.doi.org/10.1111/j.1752-1688.1986.tb01864.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1752-1688.1986.tb01864.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1752-1688.1986.tb01864.x

ABSTRACT: Turbidity, total residues, settleable solids, vertical light extinction, and primary production were measured in mined and unmined streams located in the interior highlands of Alaska. Undisturbed streams had low turbidities (< 1 NTU), total residue concentrations averaging 120 mg 1 −1 , and undetectable settleable solids. During active mining, turbidity, total residues, and settleable solids levels in a moderately mined stream averaged 170 NTU, 201 mg 1 −1 , and < 0.1 ml 1 −1 , respectively. In a heavily mined stream, turbidity and total residues were two orders of magnitude higher than in unmined streams and settleable solids nearly always exceeded 0.2 ml 1 −1 . Vertical extinction coefficients and turbidity were positively correlated. In undisturbed streams gross primary productivity (g‐O 2 m −2 d −1 ) ranged from 0.20 shortly after spring breakup to a maximum of 1.20 in early fall. Productivity in the moderately mined stream was reduced by 50 percent while photosynthetic efficiency doubled. Primary production was undetectable in a heavily mined stream. Maximum standing crops of periphyton measured as chlorophyll a occurred in fall in an undisturbed stream after 13 weeks of exposure and ranged from 4.5 to 11.8 mg‐chl a m −2 . The highest chlorophyll a densities recorded in the moderately mined stream was 3.8 mg m −2 , and no chlorophyl a was detected in the heavily mined stream.