Modeling salinization and recovery of road salt-impacted lakes in temperate regions based on long-term monitoring of Lake George, New York (USA) and its drainage basin.

Road salt mitigates winter highway icing but accumulates in watershed soils and receiving waters, affecting soil chemistry and physical, biological, and ecological processes. Despite efforts to reduce salt loading in watersheds, accumulated cations and Cl- continue to impact tributaries and lakes, and the recovery process is not well understood. Lake George, New York (USA) is typical of many temperate lakes at risk for elevated Cl- concentrations from winter deicing; the lake salt concentration increased by ~3.4% year-1 since 1980. Here, we evaluated the ionic composition in Finkle Brook, a major watershed draining to Lake George, studied intermittently since 1970 and typical of other salt-impacted Lake George tributaries. Salt loading in the Lake George basin since the 1940s displaced cations from exchange sites in basin soils; these desorbed cations follow a simple ion-exchange model, with lower sodium and higher calcium, magnesium and potassium fluxes in runoff. Reduced salt application in the Finkle Brook watershed during the low-snow winter of 2015-2016 led to a 30-40% decline of Cl- and base cations in the tributary, implying a Cl- soil half-life of 1-2 years. We developed a conceptual model that describes cation behavior in runoff from a watershed that received road salt loading over a long period of time, and then recovery following reduced salt loading. Next, we developed a dynamic model estimating time to steady-state for Cl- in Lake George with road salt loading starting in 1940, calibrating the model with tributary runoff and lake chemistry data from 1970 and 1980, respectively, and forecasting Cl- concentrations in Lake George based on various scenarios of salt loading and soil retention of Cl-. Our Lake George models are readily adaptable to other temperate lakes with drainage basins where road salt is applied during freezing conditions and paved roads cover a portion of the watershed.

The evaluation of pelvic injury in the female athlete.

The differential diagnosis of pelvic pain and possible injury in the female athlete is quite broad and must include gastrointestinal and genitourinary aetiologies, as well as musculoskeletal injuries. These considerations reflect the anatomical complexity of the female pelvis. The pelvic bones house the lower gastrointestinal and genitourinary viscera and transmit stress from the lower extremities to the upper body. The innervation of the pelvic structures also complicates evaluation and diagnosis when somatic and visceral afferent information affects the athlete's interpretation of pain. An algorithmic approach can facilitate evaluation and rehabilitation of pelvic injuries in the female athlete in the contest of previously described mechanisms of musculoskeletal injury.

The effect of lithium on the membrane molecular dynamics of normal human erythrocytes.

Erythrocytes from normal adults with no personal or family history of bipolar affective disorder were analyzed by fluorescence spectroscopy to determine what effect, if any, acute in vitro incubation with lithium had on erythrocyte membrane dynamics. The effects on erythrocyte membrane molecular dynamics of varying concentrations of Li2CO3 (0.25-2.0 meq/liter), varying incubation temperatures (25-40 degrees C), and varying incubation times (5-185 min) were investigated. Following incubation with Li2CO3, the erythrocytes were labeled with either 4-phenylspiro-[furan-2(3H),--1'phthalan]--3,3'-dione (fluorescamine), which binds to membrane surface primary amines, or 12(9)anthroyl stearate [12(9)AS], which inserts deep in the membrane hydrocarbon core. The membrane molecular dynamics were then determined by fluorescence anisotropy measurements. These studies demonstrate that clinically relevant concentrations of Li+ incubated with intact normal human erythrocytes significantly alters molecular dynamics on the erythrocyte membrane surface, with less striking changes in the hydrocarbon core. A possible interpretation of these findings is that hydrated Li+ alters the electrostatic interaction of membrane surface molecules, as well as the surrounding solvent (water) structure, with a resultant increase in the molecular motion of these molecules. Alterations in membrane receptor motion could potentially alter receptor functional activity. If similar motional alterations were to occur in the interior of a membrane channel, such as an ionophore, the functional activity of the channel could also be potentially altered. These findings provide additional insight into possible biological actions of Li+, as well as potential molecular alterations in bipolar affective disorder erythrocytes.