0 2 L-l yielded respiration regressions significantly different from 0 ( p < 0.05) with nine sample bot,tles. With the present technique, respiration rates of many fresh water, estuarine, and coastal marine waters may be quantified. Excluded from consideration are oligotrophic lakes and most open ocean regions. Respiration rate measurements in these areas require unacceptably long incubations using the present technique, and investigators must rely on concentrating the plankton to obtain measurements within a relatively short incubation period.
L i t e r a t u r e Cited (1) Parsons, T. R., Strickland, J.D.H., Deep Sea Res., 8, 211-22 (1962). (2) Packard, T. T., J . Mar. Res., 29,235-44 (1971).
(3) Azam, F., Holm-Hansen, O., Mar. Biol., 23,191-6 (1973). (4) Pomeroy, L. R., Johannes, R. E., Deep Sea Res., L3, 971-3 (1966). (5) Pomeroy, L. R., Johannes, R. E., ibid., 15,381-91 (1968). (6) Pomeroy, L. R., paper presented a t American Society of Limnology and Oceanography, Savannah, Ga., 1976. (7) Satomi, M., Pomeroy, L. R., Ecology, 46,877-81 (1965). (8) Carpenter, J. H., Limnol. Oceanogr., 10,135-40 (1965). (9) Carritt, D. E., Carpenter, J. H., J . Mar. Res., 24, 286-318 (1966). (10) Bryan, J. R., Riley, J. P., Williams, P.J.LeB., J . Exp. Mar. Biol. E c o ~ .21,191-7 , (1976). (11) Carpenter, J. H., Limnol. Oceanogr., 10, 141-3 (1965).
Receiued for review June 21,1977. Accepted December 6,1977. Research supported by Energy Research and Development Administration contract A T ( 1 1 - I ) 3279 Document No. COO-3279-29 and National Science Foundation Grant OCE76-11399.
Assessment of Damage to Fish Larvae by Entrainment Sampling with Submersible Pumps John J. Ney'" and Paul D. Schumacher Wisconsin Electric Power Co., 231 West Michigan Avenue, Milwaukee, Wis. 53201
White sucker larvae were passed through a submersible pump-plankton net system to assess the physical effects of this sampling device on ichthyoplankton. Larvae destruction was negligible, and incidence of maiming was very low in the collection process. Prolonged (6 h) pumping of water and debris into a plankton net containing larvae resulted in a mean apparent recapture loss of 18%.Approximately half of the sucker fry recovered after prolonged pumping were maimed. The submersible pump-plankton net combination appears to be an effective device to monitor ichthyoplankton entrainment, although frequent removal of collected material may be warranted.
Entrainment of fish eggs and larvae in cooling water intakes presents a potentially severe threat to fish populations ( I , 2). Because design, location, and operation of intakes are not standardized, assessment of impact must be performed on a site-specific basis ( 3 ) .Sampling methodology to determine the magnitude of ichthyoplankton entrainment consists of monitoring a representative portion of intake flow with a static collection device. Either plankton nets suspended horizontally in the intake or submersible sewage pumps in combination with above-water, vertically suspended plankton nets meet requirements for representative, nonselective, and intensive sampling (4).Destruction of ichthyoplankton by the collection device itself could seriously bias entrainment estimates but has not been adequately addressed. McGroddy and Wyman ( 5 ) recently demonstrated that larval fish are mutilated a t high intake velocity (16.5-17.5 cm/s) in a horizontal collection device, but potential for destruction a t higher velocities was not determined. We report here preliminary determinations of the destructiveness of the submersible pump/plankton net system to fish larvae. These results are timely in that adjudicatory decisions regarding mitigation of entrainment impact will soon be made based on studies in which this collection system was used. Present address, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Va. 24061. 0013-936X/78/0912-0715501.00/0
Experimental
The system tested consisted of a KENCo Model 139 submersible sewage pump ( 5 cm i.d. orifice; rated at 500 L min-' with a 2-m dynamic head) that directed water through 5 m of rigid plastic hose into a plankton tow net (333 km mesh, 75-cm mouth diameter, 225 cm deep) suspended over the Milwaukee River. Less damage might be expected if the impact was cushioned by partial immersion of the plankton net; however, this is not feasible in many monitoring situations. In these experiments, the pump was placed on the bottom of a 208-L steel drum filled with water. Three hundred white sucker ( C a t o s t o m u s c o m m e r s o n i ) fry 11-15 mm total length were added to the drum for each test. Pumping was then initiated and continued about 30 s until the pump intake was exposed. Fry remaining in the drum were counted and subtracted from the total to obtain the number pumped. Three experiments were performed: 1) Three consecutive replicates in which the vertical drop from hose orifice to net (point of impact) was 1.5 m 2) Three consecutive replicates in which the vertical drop from hose orifice to net was 2.7 m 3) Two concurrent replicates in which the vertical drop from hose orifice to net was 1.5 m. Experiments 1 and 2 were terminated when the pump intake became exposed. In 3, the pump was removed to the adjacent river when the drum emptied, and pumping continued for 6 h before fry were removed from the net. The first two experiments investigated extent of damage which accrued from passage through the pump and into the plankton net, while the third design incorporated the additional effect of prolonged exposure to turbulent inflowing water and debris. R e s u l t s a n d Discussion
Experimental results are given in Table I. Recovery of 95-100% of larvae used in the first two experiments indicates that destruction in the sampling process was negligible. Many larvae were still motile, and only a few (less than 5%) were maimed. Failure to recover all fry in three of the six replicates may have resulted from concealment in either the sampling drum or in the plankton net, but physical destruction cannot be discounted.
@ 1978 American Chemical Society
Volume 12, Number 6, June 1978 715
Table I. Recovery of White Sucker Fry in Plankton Nets Following Pass NO.
NO.
Yo
Set
Replicate
pumped
recovered
Recovered
I
1 2 3 1 2 3 1 2
296 286 295 299 290 299 287 272
296 278 293 299 290 283 229 228
II
111
100.0 97.3 99.3 100.0 100.0 94.6 79.8 83.8
% Mean
98.9 98.2 81.8
Analysis of variance showed a significant ( P < 0.001) difference in mean percentage recovery among experiments. Student-Newman-Keuls multiple range comparisons revealed that mean percentage recovery in Experiment 3 was significantly ( P < 0.05) less than in Experiments 1or 2. The lack of consistent difference in percentage recovery between replicates of 1 and 2 indicated that the additional vertical drop from hose orifice to net had no destructive effect. Lower recovery in the third experiment may have been caused by pumping of a heavy debris load (about 1.5 kg) into the plankton nets. Larvae were meticulously separated from masses of debris, and about half of those recovered were maimed.
These results demonstrate that white sucker larvae can be collected by the submersible pump/plankton net system with minor or negligible losses under the conditions employed in entrainment monitoring. Exceptional debris accumulation in the 6-h experiment represented a “worst-case” condition and confounded effects of prolonged exposure to debris and abrasion from constant turbulence. Although about 80% of larvae were collected under these conditions, recovery rate would be improved by frequently removing net contents. Larvae of the size used in this study are fragile, but it is conceivable that other species and life stages may be more vulnerable to destruction. Further experiments with other forms of ichthyplankton and with prolonged pumping are required to completely define the limitation of this monitoring system. L i t e r a t u r e Cited (1) Edsall, T . A., Yocum, T. G., Lake Michigan Enforcement Conf.,
1972. (2) Marcy, B. C., Jr., J. Fish. Res. Board Can., 28,1057 (1971). (3) Environmental Protection Agency, “Development Document for Best Te’chnology Available for the Location, Design, Construction, and Capacity of Cooling Water Intake Structures for Minimizing Adverse Environmental Impact”, GPO, 1976. (4) Meyers, C. D., Bremer, K. E., Eds., Lake Michigan Cooling Water Studies Panel Rep. 1,NTIS, Springfield, Va., 1975. ( 5 ) McGroddy, P. M., Wyman, R. L., J. Fish. Res. Board Can., 34, 571 (1977).
Received for review August 22,1977. Accepted December 7,1977.
Sulfur and Crustal Reference Elements in Nonurban Aerosols from Squaw Mountain, Colorado Douglas R. Lawson and John W. Winchester* Department of Oceanography, Florida State University, Tallahassee, Fla. 32306
Sulfur and the crustal reference elements potassium, calcium, titanium, and iron were determined by PIXE in nonurban aerosols from a remote western USA mountaintop before and after snowfall. Agreement between the sums of element concentrations in size fractions for duplicate impactor samples and between impactor and simultaneous time sequence streaker samples averaged better than 20%,the limit of combined sampling and analysis errors in the methods employed. Potassium, calcium, and iron, found mainly in particles >1 pm diameter, are highly correlated over time as well as in their particle size distributions, and constitute with titanium a crustal reference group. Sulfur, mainly a submicron aerosol constituent, exhibits poor correlation with the crustal group. Crustal element concentrations are markedly suppressed by regional snow cover as well as by falling snow, but sulfur concentrations, usually 3OO-400ng/m3, are suppressed only when precipitation is occurring, evidence that sulfurcontaining aerosol depends less on nearby sources and has a longer average atmospheric transport pathway than the crustal reference group.
To assess the effect of anthropogenic emissions of sulfur compounds to the atmosphere, measurements of regional nonurban background aerosol concentrations and concentration relationships are needed as a reference for comparison. Several recent studies of aerosol composition a t remote loca716
Environmental Science & Technology
tions have been reported (e.g., l-5), although determinations of sulfur are generally lacking. Moreover, most studies have utilized central electric power sources for aerosol sampling equipment and have by necessity been restricted to locations where power was available. The present study was undertaken as a field test of procedures for characterization of sulfur and associated trace elements in aerosols from remote areas so as to overcome some of the restrictions in previous studies. The procedures employed were based on high sensitivity elemental analysis by proton induced x-ray emission (PIXE) for S, K, Ca, Fe, and additional elements, and on aerosol sampling at low air flow rates, less than 1L/min, using cascade impactors for separation of six particle size fractions and “streakers” for continuous time sequence filter sampling with 2-h resolution. Vacuum pumps were DC operated using 12-V storage batteries, thus affording independence from central electric power. PIXE, which can achieve sensitivity at the picogram level (6) or below (7), is a useful multielement analytical method (8) optimized for rapid routine analysis of small samples at nanogram sensitivity (9).Its physical basis and applications to environmental and biological investigation have recently been reviewed (10, 11). The PIXE procedures used in this investigation have been subjected to interlaboratory comparison of specially prepared samples (12, 1 3 ) and of actual aerosol samples collected on Nuclepore filters and Mylar foil from urban and nonurban locations ( 1 4 , 1 5 ) .Sampling procedures have also been eval-
0013-936X/78/0912-0716$01,00/0 @ 1978 American Chemical Society
