High-resolution ultraviolet spectral irradiance monitoring program in ...
0.0010
0. 0009 0.0008
Figure 3. Daily values of the ratio of ultraviolet-13 to global (UVB/GBL) are plotted against column ozone (in DU) and cloudiness. It can be seen that the ratio of ultraviolet-B to global increases with decreasing ozone concentration (correlation coefficient r2=-0.61), a result to be expected. Further, the ratio of ultraviolet-13 to global increases with increasing cloudiness (correlation coefficient r2 =0.62). At first look, this is an astonishing result. Note, however, that although the absolute value decreases, the relative ultraviolet-B to global concentration increases. This can also be derived from figure 2.
0.0006
0 0.0001
• The ultraviolet-B radiation more than doubled when we entered the "antarctic ozone hole," whereas the ultraviolet-A radiation was hardly affected. This study was supported by National Science Foundation grant OPP 90-17969. The personnel on the Nathaniel B. Palmer as well as the scientific team under the leadership of Martin Jeffries were very helpful; the latter also made valuable comments on this manuscript. D. Abrams and B. Moore did the data reduction, and the National Aeronautics and Space Administration's Goddard Space Flight Center supplied the
total ozone mapping spectrometer data. To all of them we extend our thanks.
References Ambach, W., M. Blumthaler, and G. Wendler. 1991. A comparison of ultraviolet radiation measured at an arctic and an alpine site. Solar Energy, 47(2), 121-126. Jeffries, M.O. 1994. R/V Nathaniel B. Palmer cruise NBP93-5: Sea-ice physics and biology in the Bellingshausen and Amundsen Seas, August and September 1993. Antarctic Journal of the U.S., 29(1), 12-13.
High-resolution ultraviolet spectral irradiance monitoring program in polar regions—Nearly a decade of data available to polar researchers in ozone and ultraviolet-related studies CHARLES R. BOOTH, TIMoThY B. LucAs, TANYA MESTECHKINA, and JOHN TUSSON IV, Biospherical Instruments Inc., San Diego, California 92110
he Antarctic Ultraviolet Spectroradiometer Monitoring T Network was established by the U.S. National Science Foundation (NSF) in 1988 in response to predictions of increased ultraviolet (UV) radiation in the polar regions. It is the first automated, high-resolution UV scanning spectroradiometer network installed in the world. The network consists of five automated, high-resolution spectroradiometers, placed in strategic locations in Antarctica and the Arctic (see
table 1), and one established in San Diego to collect data and serve as a training and testing facility. The network, which makes essential measurements of UV spectral irradiance, has been successfully operated in the harshest environments of Antarctica and the Arctic. It is currently returning data to researchers studying the effects of ozone depletion on terrestrial and marine biological systems, as well as being used to develop and verify models of atmospheric light transmission.
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Biospherical Instruments, Inc. Table 1. Locations of the sites and the time periods when data are available from each (San Diego, California), under contract to Antarctica Support Associates (ASA), directed by the National Science Foundation (NSF), operates and maintains the network and distributes data McMurdo Station, Ants irctica 166.400 E 77.51 0S March 1988 August-April to the scientific community. 2 Palmer Station, Antarc tica 64.03°W 64.46 0S May 1988 Year round The spectroradiometers 0 90.00°S February 1988 September-March 3 South Pole, Antarctica used in the network are Bio68.00°W 54.59 0S November 1988 Year round spherical Instruments, Inc., Ushuaia, Argentinaa 117.1 2°W 32.46°N October 1992 Year round Model SUV-100. Each instru- 5 San Diego, California (except for during ment contains an irradiance difthe occasional fuser, a double holographic grattesting and training ing monochromator, a photoactivities) multiplier tube, and calibration 1 56.47°W 71.1 8°N December 1990 January-November 6 Barrow, Alaskab lamps. The vacuum-formed Teflon diffuser serves as an all- aCADIC: Centro Austral de Investigaciones Cientificas, Argentina. weather irradiance collector, bUIC/NARL: Ukpeagvik lnu piat Corporation/(formerly) Naval Arctic Research Laboratory and it is heated by the system to deter ice and snow accumulalow's (1974) action spectra for DNA damage and the CIE sanction. The tungsten-halogen and mercury-vapor calibration tioned action spectra for human erythema (McKinlay and Dif lamps are used for automatic internal calibrations of the optifey 1987). cal pathway; these calibrations occur two to four times daily. The values in table 2 indicate the maximum recorded levAn IBM-compatible computer controls all instrument funcels of the dose weightings and UV-B irradiance. The occurtions, calibration activities, and data acquisitions. Further rence of these maxima was dependent upon a combination of details on the spectroradiometers and monitoring network factors: the solar zenith angle, cloud cover, and ozone concan be found in Booth, Weiler, and Penhale 1988; Booth et al. centration. Therefore, due to the higher sun angles around 1990, 1992, and 1993. summer solstice, the antarctic maxima did not occur when Data from the UV Monitoring Network have been used to the ozone was most fully depleted, typically in late September support a variety of research programs, including testing or early October but did occur when residual ozone depletion radiative transfer models (Lubin and Frederick 1989, 1990a, persisted toward the start of summer. Meanwhile, the maxi1990b, 1991; Lubin et al. 1989, 1992; Smith and Baker 1989; ma in San Diego occurred on 20 May 1993 rather than at sumSmith, Wan, and Baker 1992; Smith et al. 1991, 1992), deriving mer solstice due to reflections from broken cloud cover on 20 ozone concentrations (Stamnes et al., 1990, 1992; Stamnes, May. Broken clouds were also responsible for the 5 January Slusser, and Boden 1991; Stamnes 1993), and examing the 1990 elevated readings over Ushuaia, which were only slightly biological impact of enhanced UV (Cullen, Neale, and Lesser higher than the readings there for 30 November 1990. 1992; Lubin et al. 1992; Madronich 1993; and Smith et al. Figure 1 contrasts the springtime erythemally weighted 1991, 1992; Smith, Wan, and Baker 1992). As an example, the noon irradiances for Palmer Station and San Diego. These data in table 2 indicate data that support the latter. The UV-B data are expressed as a function of solar angle to remove most measure, frequently defined as the integral of the spectral irradiance between 290 and 320 nanometers (nm), is the irradiance Table 2. Maximum weekly UV inradiances. The peak values in each case are boldfaced. that is potentially harmful to biological systems. The other two Site data types in table 2 are weighting functions that are performed over the UV-B data to South Pole 7.83 11/29/92 68.5 129.4 12/03/92 67.8 0.111 11/29/92 68.5 56.1 0.256 11/19/92 58.5 further explore the McMurdo 14.96 11/19/92 58.5 226.5 12/01/92 Barrow 10.98 06/06/93 48.7 183.1 06/06/93 48.7 0.146 07/19/93 50.8 impact of UV irradi- Palmer 30.1 12/05/90 42.0 382.7 12/02/90 44.0 0.737 10/26/93 52.0 ance. Several weighting Ushuaia 26.9 01/05/90 32.9 384.6 01/05/90 32.9 0.572 11/30/90 33.3 functions have been San Diego 27.52 05/20/93 16.2 368.4 05/20/93 16.2 0.588 07/23/93 13.5 developed, but the two b Solar zenith angle. aAll dates are month-day-year. presented here are Set-
ANTARCTIC JOURNAL - REVIEW 1994
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30
8C 20
I
10
[iIDiego
)( x *d
10 20 30 40 50 60 70 80 Solar Zenith Angle (degrees) Figure 1. Daily noontime erythemally weighted (McKinlay and Diffey 1987) UV irradiance recorded at Palmer Station, Antarctica, and at San Diego, California. Time is expressed as solar zenith angles and is shown from winter to summer solstice to allow comparison of these sites at different latitudes. The impact of the "ozone hole" at Palmer Station caused higher erythemally weighted irradiances than seen in San Diego. (p.W/cm2 denotes microwatts per square centimeter.) of the latitude dependence and range in time from winter to summer solstice of 1993. The absolute maximum erythemally weighted value in our dataset was recorded at Palmer Station in 1990 when antarctic ozone depletion lasted unusally long. As indicated in table 2, however, on 26 October 1993, Palmer Station recorded the highest DNA-weighted irradiance of our dataset. The erythemally weighted and UV-B irradiances for this date nearly tied the dataset maxima and exceeded the irradiances measured in San Diego at summer solstice. The 26 October maxima occurred when the solar zenith angle was 52°—an angle 10° lower in the sky than the solar zenith angles of the previously recorded maxima. Preliminary total ozone mapping spectrometer (Meteor 3, McPeters personal communication) ozone values of 161 Dobson units (DU) were reported for this day over Palmer Station. The data discussed here and all other data recorded by the NSF UV Monitoring Network are available for all qualified researchers. The data are divided into three classes. Level 1 data are in their original, uncorrected binary form, and level 2
data have been referenced to beginning-of-sea son calibration constants. These two classes are available only to NSF-sponsored researchers. Level 3 data are referenced to both beginningand end-of-season calibration constants. These data are distributed on CD-ROM and are available to any researcher, subject to availability. The information available on CD-ROM is illustrated in figure 2. For more information, please contact C.R. Booth at Biospherical Instruments Inc., 5340 Riley Street, San Diego, CA 92110 [Fax: (619) 686-1887 or Internet: [email protected] ]. We thank a variety of contributors to this effort including Sue Weller, John Gress, Susana Diaz, David Norton, Dan Endres, and David Neuschuler.
References Booth, C.R., T.B. Lucas, T. Mestechkina, J. Tusson, DA. Neuschuler, and J. H. Morrow. 1992. NSF Polar Pro-
grams UV Spectro radiometer Network 1991-1992 Operations Report. San Deigo: Biospherical Instruments, Inc.
Booth, C.R., T.B. Lucas, J.H. Morrow, C.S. Weiler, and P.A. Penhale. 1993. The United States National Science Foundation's polar network for monitoring ultraviolet radiation. In C.S. Weiler and P.A. Penhale (Eds), Ultraviolet radiation in Antarctica: Measurements and biological effects (Antarctic Research Series, Vol. 62). Washing-
ton, D.C.: American Geophysical Union. Booth, C.R., T.B. Lucas, J. Yeh, and D.A. Neuschuler. 1990. Antarctic ultraviolet spectroradio meter monitoring program. In W.D. Komhyr (Ed.), Climate Monitoring and Diagnostics Laboratory no. 18. Summary report 1989. Boulder: U.S. Department of Commerce. Booth, C.R., and S. Madronich. 1993. Radiation amplication factors— Improved formulation accounts for large increases in ultraviolet radiation associated with antarctic ozone depletion. In C.S. Weiler and P.A. Penhale (Eds), Ultraviolet radiation in Antarctica: Measurements and biological effects (Antarctic Research Series, Vol. 62).
Washington, D.C.: American Geophysical Union. Booth, C.R., C.S. Weiler, and P.A. Penhale. 1988. Collection and distribution of data from the United States Antarctic Program's UV monitoring network. In C.S. Weiler (Ed.), Workshop on ultraviolet radiation and biological research in Antarctica (NSF publication 88-108). Washington, D.C.: Government Printing Office. Cullen, J.C., P.J. Neale, and M.P. Lesser. 1992. Biological weighting function for the inhibition of phytoplankton photosynthesis by ultraviolet radiation. Science, 258, 646-650. Lubin, D., and J.E. Frederick. 1989. Ultraviolet moni toring program at Palmer Station, spring 1988. Antarctic Journal of the U.S., 24(5), 172-174. Lubin, D. and J.E. Frederick. 1990a. Column ozone measurements at Palmer Station, Antarctica: Variations during the austral springs of 1988 and 1989. Journal of Geophysical Research, 95(D9), 13883-13889. Lubin, D. and J.E. Frederick. 1990b. Observations of ozone and cloud properties from NSF ultravioletmonitor measurements at PalmerStation, tarcruyure . usia avaiiaoie on voiumes 1 tnrough 4 of published CD-ROMs. Note that voltica.AntarcticJournal of the U.S., 25(5), 241-242. ume 4 is still in the preliminary stages of development, and the dates could change Lubin, D., and J.E. Frederick. 1991. The ultraviolet upon final production. On special request, data acquired before publishing volume 1 radiation environment of the Antarctic Peninsula: may also be obtained. Contact the authors for more information.
ANTARCTIC JOURNAL - REVIEW 1994 258
Li
The roles of ozone and cloud cover. Journal of Applied Meteorology, 30(4), 478-493. Lubin, D., J.E. Frederick, C.R. Booth, T.B. Lucas, and D.A. Neuschuler. 1989. Measurements of enhanced springtime ultraviolet radiation at Palmer Station, Antarctica, Geophysical Research Letters, 16(8), 783-785. Lubin, D., B.G. Mitchell, J.E. Frederick, A.D. Alberts, C.R. Booth, T.B. Lucas, and D.A. Neuschuler. 1992. A contribution toward understanding the biospherical significance of Antarctic ozone depletion. Journal of Geophysical Research, 97(8), 7817-7828. Madronich, S. 1993. UV radiation in the natural and perturbed atomosphere. In M. Tevini (Ed.), UV-B radiation and ozone depletion: Effects on humans, animals, plants, microorganisms, and materi als. Boca Raton, Florida: Lewis Publishers.
McKinlay, A.F., and B.L. Diffey. 1987. A reference action spectrum for ultra-violet induced erythema in human skin. In W.R. Passchler and B.F.M. Bosnajakovic (Eds.), Human exposure to ultraviolet radiation: Risks and regulations. Amsterdam: Elsevier. McPeters, R. 1994 Personal communication. Setlow, R.B. 1974. The wavelengths in sunlight effective in producing skin cancer: A theoretical analysis. Proceedings of the National Academy of Science, 71(9), 3363-3366. Smith, R.C., and K.S. Baker. 1989. Stratospheric ozone, middle ultraviolet radiation and phytoplankton productivity. Oceanography, 2(2),4-10.
Smith, R., K. Baker, D. Menzies, and K. Waters. 1991. Biooptical measurements from the IceColors 90 cruise 5 Oct-21 Nov 1990 (Scripps Institution of Oceanography Reference 91-13). La Jolla, California: Scripps Institution of Oceanography. Smith, R.C., B.B. Prézelin, K.S. Baker, R.R. Bidigare, N.P. Boucher, T. Coley, D. Karentz, S. Maclntyre, H.A. Matlick, D. Menzies, M. Ondrusek, Z. Wan, and K.J. Waters. 1992. Ozone depletion: Ultraviolet radiation and phytoplankton biology in antarctic waters. Science, 256(5047), 952-959. Smith, R.C., Z. Wan, and K.S. Baker. 1992. Ozone depletion in Antarctica: Modeling its effect under clear-sky conditions. Journal of Geophysical Research, 97(C5), 7383-7397. Stamnes, K. 1993. The stratosphere as a modulator of ultraviolet radiation into the biosphere. Surveys in Geophysics, 14, 167-186. Stamnes, K., Z. un, J. Slusser, C.R. Booth, and T.B. Lucas. 1992. Several-fold enhancement of biologically effective ultraviolet radiation levels at McMurdo Station, Antarctica, during the 1990 ozone hole, Geophysical Research Letters, 19(10), 1013-1016. Stamnes, K., J. Slusser, and M. Boden. 1991. Derivation of total ozone abundance and cloud effects from spectral irradiance measurements, Applied Optics, 30(30), 4418-4426. Stamnes, K., J. Slusser, M. Bowen, C.R. Booth, and T.B. Lucas. 1990. Biologically effective ultraviolet radiation, total ozone abundance, and cloud optical depth at McMurdo Station, Antarctica, September 15, 1988 through April 15, 1989. Geophysical Research Letters, 17(12),2181-2184.
Effects of solar ultraviolet radiation on antarctic phytoplankton during springtime ozone depletion VIRGINIA E. V1LLAFAIE, E. WALTER HELBLING, and OSMUND HOLM-I-IANSEN, Polar Research Program, Scripps Institution of
Livio
Oceanography, University of California at San Diego, La Jolla, California 92093-0202 SALA, Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia, Chubut, Argentina
n recent years, much attention has been given to the forI mation of the seasonal ozone "hole" over Antarctica, with the concomitant increase in ultraviolet-B [UV-B, 280-320nanometer (nm)] radiation levels (see Weiler and Penhale 1994). The enhanced UV-B radiation can be very damaging to biological systems and has been shown to cause a significant decrease in rates of primary production (Smith et al. 1992; Holm-Hansen, Helbling, and Lubin 1993). In this paper, we are concerned with describing the impact of "normal" ultraviolet radiation (UVR), as well as enhanced UV-B radiation, on natural assemblages of phytoplankton as well as on just the nanoplankton fraction [cells less than 20 micrometers (sm)] and the microplankton fraction (cells >20 tm). Our studies also included estimation of the impact of UVR as influenced by the taxonomic composition of the phytoplankton and the mitigating effect of cellular UV-absorbing compounds. All studies were carried out at Palmer Station (64.7 0 S 64.1 0 W) on Anvers Island from early October to the end of December 1993. This period provided excellent opportunities to document the impact of enhanced UV-B radiation on phytoplankton because the ozone hole was very well developed over Palmer Station in the month of October;
column ozone concentrations ranged from 140 to 220 Dobson units (DU). During the period of study, incident solar radiation was monitored continuously (and recorded every minute) using a spectroradiometer (model PUV-510; Biospherical Instruments, Inc.) with sensors for photosynthetically available radiation (PAR, 400-700 nm), and four UV wavelengths (305, 320, 340, and 380 nm). Phytoplankton samples were taken at a coastal site at 1-meter depth with a 5-liter Go-Flo bottle and were used for chlorophyll-a (chl-a) analysis, determination of absorption spectra (250-750 nm) of the particulate fraction, floristic analysis, and carbon-14 ( 14c) incorporation. Chl-a analyses were performed by fluorometric techniques (Holm-Hansen et al. 1965; Holm-Hansen and Riemann 1978). The chl-a of the nanoplankton fraction was obtained by prefiltering the sample through a nylon mesh fabric (Nitex®) with a mesh opening of 20 rim; the filtrate was treated in the same way as for total chl-a concentrations. For absorption spectra analysis, a variable amount of seawater (between 5 and 9 liters) was filtered through a Whatman GF/F filter (47-millimeter). The pigments were extracted in 10 milliliters of absolute methanol, and the extract was used
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Figure 3. Daily values of the ratio of ultraviolet-13 to global (UVB/GBL) are plotted against column ozone (in DU) and cloudiness. It can be seen that the ratio of ultraviolet-B to global increases with decreasing ozone concentration (correlation coefficient r2=-0.61), a result to be expected. Further, the ratio of ultraviolet-13 to global increases with increasing cloudiness (correlation coefficient r2 =0.62). At first look, this is an astonishing result. Note, however, that although the absolute value decreases, the relative ultraviolet-B to global concentration increases. This can also be derived from figure 2.
0.0006
0 0.0001
• The ultraviolet-B radiation more than doubled when we entered the "antarctic ozone hole," whereas the ultraviolet-A radiation was hardly affected. This study was supported by National Science Foundation grant OPP 90-17969. The personnel on the Nathaniel B. Palmer as well as the scientific team under the leadership of Martin Jeffries were very helpful; the latter also made valuable comments on this manuscript. D. Abrams and B. Moore did the data reduction, and the National Aeronautics and Space Administration's Goddard Space Flight Center supplied the
total ozone mapping spectrometer data. To all of them we extend our thanks.
References Ambach, W., M. Blumthaler, and G. Wendler. 1991. A comparison of ultraviolet radiation measured at an arctic and an alpine site. Solar Energy, 47(2), 121-126. Jeffries, M.O. 1994. R/V Nathaniel B. Palmer cruise NBP93-5: Sea-ice physics and biology in the Bellingshausen and Amundsen Seas, August and September 1993. Antarctic Journal of the U.S., 29(1), 12-13.
High-resolution ultraviolet spectral irradiance monitoring program in polar regions—Nearly a decade of data available to polar researchers in ozone and ultraviolet-related studies CHARLES R. BOOTH, TIMoThY B. LucAs, TANYA MESTECHKINA, and JOHN TUSSON IV, Biospherical Instruments Inc., San Diego, California 92110
he Antarctic Ultraviolet Spectroradiometer Monitoring T Network was established by the U.S. National Science Foundation (NSF) in 1988 in response to predictions of increased ultraviolet (UV) radiation in the polar regions. It is the first automated, high-resolution UV scanning spectroradiometer network installed in the world. The network consists of five automated, high-resolution spectroradiometers, placed in strategic locations in Antarctica and the Arctic (see
table 1), and one established in San Diego to collect data and serve as a training and testing facility. The network, which makes essential measurements of UV spectral irradiance, has been successfully operated in the harshest environments of Antarctica and the Arctic. It is currently returning data to researchers studying the effects of ozone depletion on terrestrial and marine biological systems, as well as being used to develop and verify models of atmospheric light transmission.
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Biospherical Instruments, Inc. Table 1. Locations of the sites and the time periods when data are available from each (San Diego, California), under contract to Antarctica Support Associates (ASA), directed by the National Science Foundation (NSF), operates and maintains the network and distributes data McMurdo Station, Ants irctica 166.400 E 77.51 0S March 1988 August-April to the scientific community. 2 Palmer Station, Antarc tica 64.03°W 64.46 0S May 1988 Year round The spectroradiometers 0 90.00°S February 1988 September-March 3 South Pole, Antarctica used in the network are Bio68.00°W 54.59 0S November 1988 Year round spherical Instruments, Inc., Ushuaia, Argentinaa 117.1 2°W 32.46°N October 1992 Year round Model SUV-100. Each instru- 5 San Diego, California (except for during ment contains an irradiance difthe occasional fuser, a double holographic grattesting and training ing monochromator, a photoactivities) multiplier tube, and calibration 1 56.47°W 71.1 8°N December 1990 January-November 6 Barrow, Alaskab lamps. The vacuum-formed Teflon diffuser serves as an all- aCADIC: Centro Austral de Investigaciones Cientificas, Argentina. weather irradiance collector, bUIC/NARL: Ukpeagvik lnu piat Corporation/(formerly) Naval Arctic Research Laboratory and it is heated by the system to deter ice and snow accumulalow's (1974) action spectra for DNA damage and the CIE sanction. The tungsten-halogen and mercury-vapor calibration tioned action spectra for human erythema (McKinlay and Dif lamps are used for automatic internal calibrations of the optifey 1987). cal pathway; these calibrations occur two to four times daily. The values in table 2 indicate the maximum recorded levAn IBM-compatible computer controls all instrument funcels of the dose weightings and UV-B irradiance. The occurtions, calibration activities, and data acquisitions. Further rence of these maxima was dependent upon a combination of details on the spectroradiometers and monitoring network factors: the solar zenith angle, cloud cover, and ozone concan be found in Booth, Weiler, and Penhale 1988; Booth et al. centration. Therefore, due to the higher sun angles around 1990, 1992, and 1993. summer solstice, the antarctic maxima did not occur when Data from the UV Monitoring Network have been used to the ozone was most fully depleted, typically in late September support a variety of research programs, including testing or early October but did occur when residual ozone depletion radiative transfer models (Lubin and Frederick 1989, 1990a, persisted toward the start of summer. Meanwhile, the maxi1990b, 1991; Lubin et al. 1989, 1992; Smith and Baker 1989; ma in San Diego occurred on 20 May 1993 rather than at sumSmith, Wan, and Baker 1992; Smith et al. 1991, 1992), deriving mer solstice due to reflections from broken cloud cover on 20 ozone concentrations (Stamnes et al., 1990, 1992; Stamnes, May. Broken clouds were also responsible for the 5 January Slusser, and Boden 1991; Stamnes 1993), and examing the 1990 elevated readings over Ushuaia, which were only slightly biological impact of enhanced UV (Cullen, Neale, and Lesser higher than the readings there for 30 November 1990. 1992; Lubin et al. 1992; Madronich 1993; and Smith et al. Figure 1 contrasts the springtime erythemally weighted 1991, 1992; Smith, Wan, and Baker 1992). As an example, the noon irradiances for Palmer Station and San Diego. These data in table 2 indicate data that support the latter. The UV-B data are expressed as a function of solar angle to remove most measure, frequently defined as the integral of the spectral irradiance between 290 and 320 nanometers (nm), is the irradiance Table 2. Maximum weekly UV inradiances. The peak values in each case are boldfaced. that is potentially harmful to biological systems. The other two Site data types in table 2 are weighting functions that are performed over the UV-B data to South Pole 7.83 11/29/92 68.5 129.4 12/03/92 67.8 0.111 11/29/92 68.5 56.1 0.256 11/19/92 58.5 further explore the McMurdo 14.96 11/19/92 58.5 226.5 12/01/92 Barrow 10.98 06/06/93 48.7 183.1 06/06/93 48.7 0.146 07/19/93 50.8 impact of UV irradi- Palmer 30.1 12/05/90 42.0 382.7 12/02/90 44.0 0.737 10/26/93 52.0 ance. Several weighting Ushuaia 26.9 01/05/90 32.9 384.6 01/05/90 32.9 0.572 11/30/90 33.3 functions have been San Diego 27.52 05/20/93 16.2 368.4 05/20/93 16.2 0.588 07/23/93 13.5 developed, but the two b Solar zenith angle. aAll dates are month-day-year. presented here are Set-
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30
8C 20
I
10
[iIDiego
)( x *d
10 20 30 40 50 60 70 80 Solar Zenith Angle (degrees) Figure 1. Daily noontime erythemally weighted (McKinlay and Diffey 1987) UV irradiance recorded at Palmer Station, Antarctica, and at San Diego, California. Time is expressed as solar zenith angles and is shown from winter to summer solstice to allow comparison of these sites at different latitudes. The impact of the "ozone hole" at Palmer Station caused higher erythemally weighted irradiances than seen in San Diego. (p.W/cm2 denotes microwatts per square centimeter.) of the latitude dependence and range in time from winter to summer solstice of 1993. The absolute maximum erythemally weighted value in our dataset was recorded at Palmer Station in 1990 when antarctic ozone depletion lasted unusally long. As indicated in table 2, however, on 26 October 1993, Palmer Station recorded the highest DNA-weighted irradiance of our dataset. The erythemally weighted and UV-B irradiances for this date nearly tied the dataset maxima and exceeded the irradiances measured in San Diego at summer solstice. The 26 October maxima occurred when the solar zenith angle was 52°—an angle 10° lower in the sky than the solar zenith angles of the previously recorded maxima. Preliminary total ozone mapping spectrometer (Meteor 3, McPeters personal communication) ozone values of 161 Dobson units (DU) were reported for this day over Palmer Station. The data discussed here and all other data recorded by the NSF UV Monitoring Network are available for all qualified researchers. The data are divided into three classes. Level 1 data are in their original, uncorrected binary form, and level 2
data have been referenced to beginning-of-sea son calibration constants. These two classes are available only to NSF-sponsored researchers. Level 3 data are referenced to both beginningand end-of-season calibration constants. These data are distributed on CD-ROM and are available to any researcher, subject to availability. The information available on CD-ROM is illustrated in figure 2. For more information, please contact C.R. Booth at Biospherical Instruments Inc., 5340 Riley Street, San Diego, CA 92110 [Fax: (619) 686-1887 or Internet: [email protected] ]. We thank a variety of contributors to this effort including Sue Weller, John Gress, Susana Diaz, David Norton, Dan Endres, and David Neuschuler.
References Booth, C.R., T.B. Lucas, T. Mestechkina, J. Tusson, DA. Neuschuler, and J. H. Morrow. 1992. NSF Polar Pro-
grams UV Spectro radiometer Network 1991-1992 Operations Report. San Deigo: Biospherical Instruments, Inc.
Booth, C.R., T.B. Lucas, J.H. Morrow, C.S. Weiler, and P.A. Penhale. 1993. The United States National Science Foundation's polar network for monitoring ultraviolet radiation. In C.S. Weiler and P.A. Penhale (Eds), Ultraviolet radiation in Antarctica: Measurements and biological effects (Antarctic Research Series, Vol. 62). Washing-
ton, D.C.: American Geophysical Union. Booth, C.R., T.B. Lucas, J. Yeh, and D.A. Neuschuler. 1990. Antarctic ultraviolet spectroradio meter monitoring program. In W.D. Komhyr (Ed.), Climate Monitoring and Diagnostics Laboratory no. 18. Summary report 1989. Boulder: U.S. Department of Commerce. Booth, C.R., and S. Madronich. 1993. Radiation amplication factors— Improved formulation accounts for large increases in ultraviolet radiation associated with antarctic ozone depletion. In C.S. Weiler and P.A. Penhale (Eds), Ultraviolet radiation in Antarctica: Measurements and biological effects (Antarctic Research Series, Vol. 62).
Washington, D.C.: American Geophysical Union. Booth, C.R., C.S. Weiler, and P.A. Penhale. 1988. Collection and distribution of data from the United States Antarctic Program's UV monitoring network. In C.S. Weiler (Ed.), Workshop on ultraviolet radiation and biological research in Antarctica (NSF publication 88-108). Washington, D.C.: Government Printing Office. Cullen, J.C., P.J. Neale, and M.P. Lesser. 1992. Biological weighting function for the inhibition of phytoplankton photosynthesis by ultraviolet radiation. Science, 258, 646-650. Lubin, D., and J.E. Frederick. 1989. Ultraviolet moni toring program at Palmer Station, spring 1988. Antarctic Journal of the U.S., 24(5), 172-174. Lubin, D. and J.E. Frederick. 1990a. Column ozone measurements at Palmer Station, Antarctica: Variations during the austral springs of 1988 and 1989. Journal of Geophysical Research, 95(D9), 13883-13889. Lubin, D. and J.E. Frederick. 1990b. Observations of ozone and cloud properties from NSF ultravioletmonitor measurements at PalmerStation, tarcruyure . usia avaiiaoie on voiumes 1 tnrough 4 of published CD-ROMs. Note that voltica.AntarcticJournal of the U.S., 25(5), 241-242. ume 4 is still in the preliminary stages of development, and the dates could change Lubin, D., and J.E. Frederick. 1991. The ultraviolet upon final production. On special request, data acquired before publishing volume 1 radiation environment of the Antarctic Peninsula: may also be obtained. Contact the authors for more information.
ANTARCTIC JOURNAL - REVIEW 1994 258
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The roles of ozone and cloud cover. Journal of Applied Meteorology, 30(4), 478-493. Lubin, D., J.E. Frederick, C.R. Booth, T.B. Lucas, and D.A. Neuschuler. 1989. Measurements of enhanced springtime ultraviolet radiation at Palmer Station, Antarctica, Geophysical Research Letters, 16(8), 783-785. Lubin, D., B.G. Mitchell, J.E. Frederick, A.D. Alberts, C.R. Booth, T.B. Lucas, and D.A. Neuschuler. 1992. A contribution toward understanding the biospherical significance of Antarctic ozone depletion. Journal of Geophysical Research, 97(8), 7817-7828. Madronich, S. 1993. UV radiation in the natural and perturbed atomosphere. In M. Tevini (Ed.), UV-B radiation and ozone depletion: Effects on humans, animals, plants, microorganisms, and materi als. Boca Raton, Florida: Lewis Publishers.
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Effects of solar ultraviolet radiation on antarctic phytoplankton during springtime ozone depletion VIRGINIA E. V1LLAFAIE, E. WALTER HELBLING, and OSMUND HOLM-I-IANSEN, Polar Research Program, Scripps Institution of
Livio
Oceanography, University of California at San Diego, La Jolla, California 92093-0202 SALA, Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia, Chubut, Argentina
n recent years, much attention has been given to the forI mation of the seasonal ozone "hole" over Antarctica, with the concomitant increase in ultraviolet-B [UV-B, 280-320nanometer (nm)] radiation levels (see Weiler and Penhale 1994). The enhanced UV-B radiation can be very damaging to biological systems and has been shown to cause a significant decrease in rates of primary production (Smith et al. 1992; Holm-Hansen, Helbling, and Lubin 1993). In this paper, we are concerned with describing the impact of "normal" ultraviolet radiation (UVR), as well as enhanced UV-B radiation, on natural assemblages of phytoplankton as well as on just the nanoplankton fraction [cells less than 20 micrometers (sm)] and the microplankton fraction (cells >20 tm). Our studies also included estimation of the impact of UVR as influenced by the taxonomic composition of the phytoplankton and the mitigating effect of cellular UV-absorbing compounds. All studies were carried out at Palmer Station (64.7 0 S 64.1 0 W) on Anvers Island from early October to the end of December 1993. This period provided excellent opportunities to document the impact of enhanced UV-B radiation on phytoplankton because the ozone hole was very well developed over Palmer Station in the month of October;
column ozone concentrations ranged from 140 to 220 Dobson units (DU). During the period of study, incident solar radiation was monitored continuously (and recorded every minute) using a spectroradiometer (model PUV-510; Biospherical Instruments, Inc.) with sensors for photosynthetically available radiation (PAR, 400-700 nm), and four UV wavelengths (305, 320, 340, and 380 nm). Phytoplankton samples were taken at a coastal site at 1-meter depth with a 5-liter Go-Flo bottle and were used for chlorophyll-a (chl-a) analysis, determination of absorption spectra (250-750 nm) of the particulate fraction, floristic analysis, and carbon-14 ( 14c) incorporation. Chl-a analyses were performed by fluorometric techniques (Holm-Hansen et al. 1965; Holm-Hansen and Riemann 1978). The chl-a of the nanoplankton fraction was obtained by prefiltering the sample through a nylon mesh fabric (Nitex®) with a mesh opening of 20 rim; the filtrate was treated in the same way as for total chl-a concentrations. For absorption spectra analysis, a variable amount of seawater (between 5 and 9 liters) was filtered through a Whatman GF/F filter (47-millimeter). The pigments were extracted in 10 milliliters of absolute methanol, and the extract was used
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