Grain size, organic carbon, and trace metal distribution patterns in Mugu Lagoon, California

Mugu Lagoon, a small coastal water body on th Oxnard Plain, is one of the few lagoons along the southern California coast that remains in a relatively natural state. The eastern arm of the lagoon is divided into three parts: western extension, central section, and southeastern extension. The central section was dredged to a depth of 10m in 1963; the remainder of the lagoon is in its natural state. Sediment in the intertidal and subtidal zone of Mugu Lagoon. is derived from two sources: (1) beach sand from coastal erosion, and (2) fluvial mud from Calleguae Creek. Two chemical components of sediment, found concentrated in silt and clay fractions of Mugu Lagoon, total organic carbon and trace metals (chromium, copper, lead, nickel, and zinc). The concentrations of these two components, along with mean grain size of sediment, follow similar distribution patterns: (1) values increase landward from the barrier, and (2) values increase towards the center of deeper subtidal areas. (See more in text.)