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Characteristics of seston in a regulated Appalachian Mountain river, U.S.A

1987; Wiley; Volume: 1; Issue: 4 Linguagem: Inglês

10.1002/rrr.3450010402

1099-1646

Richard F. Kazmierczak, Jackson R. Webster, E. F. Benfield,

Freshwater macroinvertebrate diversity and ecology

Abstract Six size classes of seston were collected seasonally from the New River, Virginia, U.S.A., during three flow regimes: low flow, discharge changes resulting from daily cycles of hydroelectric power generation, and naturally occurring storm discharge cycles. Seston concentration and particle shape, density, and settling velocity were measured for all size classes, seasons, and flow regimes. Seston concentration, density, and settling velocity varied significantly with size class, season, and flow regime. Total concentrations ranged from a low of 0.47 mg litre −1 during autumn base‐flow to a high of 92.6 mg litre −1 during a winter storm. Mean seston densities ranged between 1.60 and 2.02 g cm −1 , which is much lower than previously published measurements for rivers, suggesting that seston in the New River may be mainly organic‐inorganic aggregates. Mean seston settling velocity was lowest during low‐flow and hydroelectric discharges (0.10 cms −1 ) and highest during storms (0.19 cms −1 ). Seston particle shape varied significantly only with size class. The inability of a commonly used transport equation to predict transport during most discharge conditions suggests that, in some systems, seston concentration and transport may be less a function of discharge and power than of long‐term seasonal and short‐term discharge cycle effects on the density and size characteristics of seston.