ALBERT

Notes: Abstract A very precise and accurate new method is described for determination of the Henry coefficient k and the isotopic fractionation of gases dissolved in liquids. It yields fully corrected values for k at essentially infinite dilution. For oxygen the random error for k is less than 0.02%, which is an order of magnitude better than the best previous measurements on that or any other gas. Extensive tests and comparison with other work indicate that systematic errors probably are negligible and that the accuracy is determined by the precision of the measurements. In the virial correction factor (1+λPt), where Pt is the total pressure of the vapor phase, the coefficient λ for oxygen empirically is a linear decreasing function of the temperature over the range 0–60°C. The simple three-term power series in 1/T proposed by Benson and Krause, $$\ln k = a_0 + a_1 /T + a_2 /T^2 $$ provides a much better form for the variation of k with temperature than any previous expression. With a0=3.71814, a1=5596.17, and a2=−1049668, the precision of fit to it of 37 data points for oxygen from 0–60°C is 0.018% (one standard deviation). The three-term series in 1/T also yields the best fit for the most accurate data on equilibrium constants for other types of systems, which suggests that the function may have broader applications. The oxygen results support the idea that when the function is rewritten as $$\ln k = - (A_1 + A_2 ) + A_1 \left( {\frac{{T_1 }}{T}} \right) + A_2 \left( {\frac{{T_1 }}{T}} \right)^2 $$ it becomes a universal solubility equation in the sense that A2 is common to all gases, with T1 and A1 characteristic of the specific gas. Accurate values are presented for the partial molal thermodynamic function changes for the solution of oxygen in water between the usual standard states for the liquid and vapor phases. These include the change in heat capacity, which varies inversely with the square of the absolute temperature and for which the random error is 0.15%. Analysis of the high-temperature data of Stephan et al., in combination with our values from 0–60°C, shows that for oxygen the fourterm series in 1/T, $$\ln k = - 4.1741 + 1.3104 \times 10^4 /T - 3.4170 \times 10^6 /T^2 + 2.4749 \times 10^8 /T^3 $$ where p=kx and p is the partial pressure in atmospheres of the gas, probably provides the best and easiest way presently available to calculate values for k in the range 100–288°C, but more precise measurements at elevated temperatures are needed. The new method permits direct mass spectrometric comparison of the isotopic ratio34O2/32O2 in the dissolved gas to that in the gas above the solution. The fractionation factor α=32k/34k varies from approximately 1.00085 (±0.00002) at 0°C to 1.00055 (±0.00002) at 60°C. Although the results provide the first quantitative determination of α vs. temperature for oxygen, it is not possible from these data to choose among several functions for the variation ofInα with temperature. If the isotopic fractionation is assumed to be due to a difference in the zero-point energy of the two species of oxygen molecules, the size of the solvent cage is calculated to be approximately 2.5 Å. The isotopic measurements indicate that substitution of a34O2 molecule for a32O2 molecule in solution involves a change in enthalpy with a relatively small change in entropy.

Notes: Abstract From 1987–1990, uncontaminated Asiatic clams (Corbicula fluminea) were placed in cages and transplanted into two streams receiving industrial discharges to help identify and quantify polychlorinated biphenyl (PCB) contamination to the streams. Clams accumulated substantial PCB residues at most sites monitored, with the exception of the sites closest to chlorinated discharges. Clams placed nearest to the chlorinated stream reaches consistently underestimated PCB contamination, based on the amount of PCBs found in fish and sediment at those sites. In a separate experiment, clams exposed in stream-side tanks to untreated (total residual chlorine ranged from 0.02–0.07 mg−1 L daily) and dechlorinated stream water exhibited differing degrees of valve movement, growth, and PCB accumulation after a four-week exposure to the two treatments. Clams exposed to untreated (chlorinated) stream water closed their shells more often, exhibited less growth, and accumulated substantially lower PCB concentrations than clams exposed to dechlorinated stream water. Clams apparently close their shells to avoid chlorine exposure, thus isolating clam tissues from PCBs found in the stream water and in the clams' food. Because chlorine and PCBs occur together in many industrial discharges, this finding is a significant consideration for monitoring programs that utilize clams to assess PCB bioavailability.

Notes: Abstract Sunfish and a minnow species were used as indicators of anthropogenic mercury contamination in an east Tennessee stream system receiving multiple point and non-point discharges. The monitoring of bluegill (Lepomis macrochirus) and redbreast sunfish (Lepomis auritus) identified bioavailable mercury near three geographically separate industrial facilities, and was able to detect decreases in contamination with distance away from these facilities. In general, total mercury concentrations in the tissue of sunfish in this study were low in comparison to the most commonly cited human health threshold limits, although concentrations at some sites exceeded 1 μg/g. Caged blacknose dace (Rhinichthys atratulus) were monitored in conjunction with resident fish as an indicator of more discrete sources in selected headwater streams where fish movement was deemed a potential factor affecting mercury body burdens. Mercury concentrations in muscle tissue of caged dace after 12 weeks exposure were generally low (〈0.2 μg/g) at all sites but higher than in fish from reference streams. mercury accumulation varied between species (sunfish vs. dace) and monitoring method (caged vs. resident) at the same site, with sunfish tending to accumulate higher concentrations of mercury than resident dace which, in turn, contained about twofold higher concentrations than caged dace. However, the site-to-site pattern of mercury accumulation was similar. This study demonstrates the utility of using small stream dwelling fish with restricted home ranges as a tool for identifying and evaluating the bioavailability of mercury sources in large industrial or urbanized settings.

Notes: Abstract The effect of salinity on survival, osmoregulation and oxygen consumption was determined on coastal young-of-the-year (YOY) largemouth bassMicropterus salmoides by exposing them to saline media of 0, 4, 8, 12, and 16‰. The data indicated a decrease in survival with longer exposure time and increased salinity. There were no significant differences in plasma osmolality with increased salinity from 0 to 8‰ but osmolality was significantly greater at 12‰ than 0‰ and osmolality from 16‰ was greater than all other salinity treatments. No significant differences in hematocrits were detected between 0 and 12‰, but hematocrits in the 16‰ treatment were significantly reduced compared to all other treatments. YOYM. salmoides are good osmoregulators up to 8‰ but increased salinity caused measurable osmoregulatory dysfunction. Oxygen consumption rate increased significantly as salinity increased, suggesting that adaptation of this species to hypersaline media is in part accompanied by increased energy expenditure.

Notes: Synopsis Female Gambusia affinis were collected from low salinity/near-neutral pH and tidal freshwater/low pH localities to document life history variation between these two habitats. Mosquito fish were 2.7 times more abundant in low salinity/near-neutral pH (2.37 ± 0.72 ppt; pH = 5.73 ± 0.11) than in tidal freshwater/low pH (0.27 ± 0.19 ppt; pH = 4.46 ± 0.18) habitats in Old Fort Bayou, a black-water tidal river of the Biloxi Bay estuary, Mississippi. Fish were common in both areas from June 1985 through February 1986. There were no significant differences between habitats in the length-weight relationships during the reproductive season with the exception of February. However, there were significant differences in life histories, although the areas were only 4 km apart. Ovarian recrudescence was observed in fish from both areas in February, but ovaries of low salinity fish were more developed than ovaries of freshwater fish. All fish from both areas had regressed ovaries by late September. The monthly slopes of the brood size vs. standard length regressions were significantly different between areas throughout the reproductive season with the exception of June. Although freshwater fish produced heavier tail-free embryos, fish from low salinity had significantly higher GSI values and brood size throughout the reproductive season. These observations suggest that Gambusia affonis may have a greater reproductive effort in low salinity/near-neutral pH environments than in freshwater/low pH habitats.

Notes: Synopsis Juvenile bluegill,Lepomis macrochirus, collected from Mississippi coastal drainages were held at 0, 5, and 10% S and fed diets containing 0, 2, and 4% dietary NaCl. Over a 58 day period, fish from each of the nine treatments (salinity x diet) were fed ad libitum twice daily for 5 min. Mean treatment growth rates did not differ when adjusted for initial wet weights. Hematocrit and intestinal Na+/K+-ATPase activity also did not differ. All fish maintained in 0% S had a marginally lower plasma osmolality compared to fish held in 5 and 10% S. Plasma Cl concentration of fish held in 0% S receiving the 0% NaCl diet was lower than that of the other eight treatments. Results indicate that coastal juvenile bluegill can exploit waters up to 10% S while consuming prey items containing up to 4% NaCl with no influence on growth or certain osmoregulatory characteristics.

Notes: Abstract Approximately 250 000 kg of mercury was lost towater and soils at the U.S. Dept. of Energy Y-12 Plantin Oak Ridge, Tennessee in the 1950s and early 1960s. A creek originating within the plant receivedcontinuous inputs of waterborne mercury, predominantlyas dissolved inorganic mercury, from groundwater,streambed contamination, and sump and process waterdischarges to the contaminated storm sewer network.These produce aqueous total mercury concentrations of1–2 μg L-1 in the upper reaches of the stream,decreasing to about 0.1–0.2 μg L-1 in its lowerreaches. A program to reduce mercury concentrationsin the creek identified specific sources (buildingsumps, contaminated springwater seeps, foundationdrains, and contaminated piping) and rerouted wateraround contaminated portions of the drain system orcollected and treated mercury-contaminated waterbefore discharging it. As a result, waterbornemercury concentrations in the creek and total mercuryloading were reduced from 1.8 μg L-1 to0.6 μg L-1 and 100 to 20 g d-1, respectively, in the last 5 yr.Mean mercury concentrations in fish nearest sourceareas in the creek headwaters decreased at roughly thesame rate as waterborne total mercury concentrationsover the past five years, but at the facility boundarydownstream the decline in mercury bioaccumulation wasmuch less. At sites 5–15 km farther downstream, nodecrease was evident. Dissolved methylmercury tendedto increase with distance downstream in a patterninverse to that noted for its dissolved inorganicmercury precursor.Improvements in water quality and modification ofweirs to allow the passage of fish have resulted inthe establishment of large populations of fish inmercury-contaminated headwater areas previously devoidof fish. It may be that the accumulation, retention,and eventual downstream transport of this reservoir ofbiologically incorporated methylmercury has acted tobuffer against expected reductions in mercury in fishat downstream sites.