Resolution and Analysis of Spatial Variations and Patterns in an Urban Lake with Rapid Profiling Instrumentation

Abstract

Rapid response vertical profiling instrumentation was used to document spatial variability and patterns in a small urban lake, Onondaga Lake, associated with multiple drivers. Paired profiles of temperature, specific conductance (SC), turbidity (T n ), fluorometric chlorophyll a (Chl f ), and nitrate nitrogen (NO 3 À ) were collected at >30 fixed locations (a "gridding") weekly, over the spring to fall interval of several years. These gridding data are analyzed (1) to characterize phytoplankton (Chl f ) patchiness in the lake's upper waters, (2) to establish the representativeness of a single long-term site for monitoring lake-wide conditions, and (3) to resolve spatial patterns of multiple tracers imparted by buoyancy effects of inflows. Multiple buoyancy signatures were resolved, including overflows from less dense inflows, and interflows to metalimnetic depths and underflows to the bottom from the plunging of more dense inputs. Three different metrics had utility as tracers in depicting the buoyancy signatures as follows: (1) SC, for salinity-enriched tributaries and the more dilute river that receives the lake's outflow, (2) T n , for the tributaries during runoff events, and (3) NO 3 À , for the effluent of a domestic waste treatment facility and from the addition of NO 3 À solution to control methyl mercury. The plunging inflow phenomenon, which frequently prevailed, has important management implications.

Coupling Suspect and Nontarget Screening with Mass Balance Modeling to Characterize Organic Micropollutants in the Onondaga LakeThree Rivers System

“…Water quality parameters for lake, tributary, and river water samples (i.e., temperature, specific conductance, pH, dissolved oxygen (DO), turbidity, and fluorometric chlorophyll a) were measured in situ at each sampling site by the UFI sampling crew with a YSI 6600 multiparameter sonde. 1,2 Water quality parameters (i.e., temperature, specific conductance, 5-day biochemical oxygen demand (BOD5), DO, turbidity, and ammonianitrogen (NH3-N)) for wastewater effluent samples were monitored by the regional WWTP in compliance with the New York State Pollutant Discharge Elimination System Permit.…”