ENVIRONMENTAL FACTORS INFLUENCING SUSPENDED SOLIDS IN THE LOXAIIATCHEE ESTUARY, FLORIDA¹

Abstract

A study was initiated to examine the effects of wind speed, wind direction, freshwater inflow, and tide height on suspended solid concentration and distribution in the Loxahatchee estuary, Florida. Recent efforts to increase freshwater flows in this system raised concerns that suspended solid concentrations would increase as well, which might result in negative impacts for the estuary. The data indicated that total suspended solids (TSS) in the estuary are derived primarily from the inlet and not from freshwater tributaries. In addition, total suspended solids and volatile suspended solids were correlated strongly with salinity, suggesting that suspended sediments act conservatively throughout this system. No one environmental factor had an overwhelming influence on suspended solid concentration throughout the estuary; different regions of the estuary were influenced by different factors. Freshwater inflow was negatively related to TSS in the upper reaches of the estuary but was positively related to TSS in the central embayment region of the estuary. We attribute this latter finding to the fact that extremely high inflows both prevented the normal transport upstream of tidal borne suspended sediments and promoted mixing when the freshwater front moving downstream confronted the tidal front moving upstream. Wind speed, wind direction, and tide height had relatively small effects on TSS concentration but were most influential in reaches upstream of the central embayment, where tidal velocity begins to diminish.

Assessment of groundwater input and water quality changes impacting natural vegetation in the Loxahatchee River and floodplain ecosystem, Florida

“…This subtropical estuary, located just east of Lake Okeechobee, FL in a predominantly carbonate geologic environment (McPherson et al, 1982;Wanless et al, 1984;Noel et al, 1995), may consequently have a strong groundwater contribution to the surface-water budget (Russell and McPherson, 1984;Russell and Goodwin, 1987). Therefore, we utilize naturally occurring isotopes of Ra and Rn as tracers of submarine groundwater flow in our investigation of biogeochemical transport in the Loxahatchee River estuary (Cable et al, 1996(Cable et al, , 1997Kelly and Moran, 1999;Krest et al, 1999Krest et al, , 2000Swarzenski et al, 2001;Kelly and Moran, 2002;Krest and Harvey, 2003;Charette and Buesseler, 2004;Purkl and Eisenhauer, 2004).…”

“…The The 699 km 2 Loxahatchee River watershed provides water for three principal distributaries, the Northwest Branch/Fork, and North-and Southwest Forks that discharge through Jupiter Inlet to the Atlantic Ocean (Russell and McPherson, 1984). Natural and anthropogenic change in the watershed since the 1940's has resulted in increased saltwater intrusion up the Loxahatchee River estuary, and consequent dramatic ecosystem change (McPherson et al, 1982;Noel et al, 1995). Compounding the issue of saltwater intrusion may be a gradual decrease in available fresh surface-and groundwater, due to regional construction of extensive canal networks for expansive urban growth centered around Jupiter, FL (McPherson and Sonntag, 1984).…”

“…Shrubs and ground cover consist primarily of processes directly impact the estuarine distribution of many constituents (Chester, 1999). The concentration profile of suspended particulate matter in the estuary indicate that resuspension of particles is greatest within the tidally-flushed waters of Jupiter Inlet (Noel et al, 1995). To evaluate the physical controls of this system, water mass residence times (i.e., flushing times) and the potential contribution of submarine groundwater discharge in the Loxahatchee River estuary were investigated.…”