Ultraviolet radiation and bio-optics in Crater Lake, Oregon

Hargreaves, Bruce R.; Girdner, Scott F.; Buktenica, Mark W.; Collier, Robert W.; Urbach, Ena; Larson, Gary L.

doi:10.1007/978-1-4020-5824-0_7

Cited by 13 publications

(19 citation statements)

References 65 publications

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“…6). Past measurements of total organic carbon (TOC) at Crater Lake suggest a background value of about 0.1 g C m -3 , dominated by dissolved organic carbon (DOC) (Urbach et al, 2001;Hargreaves et al, 2007). This magnitude of DOC is at least a factor of five lower than open ocean values (compared to values found in the Bermuda Atlantic and the Hawaiian Ocean time series).…”

Section: Colored Dissolved Materials and Dommentioning

confidence: 96%

Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR

Boss

Collier

Larson³

et al. 2007

Hydrobiologia

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Section: Colored Dissolved Materials and Dommentioning

confidence: 96%

Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR

Boss

Collier

Larson³

et al. 2007

Hydrobiologia

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“…Bioassays suggest that primary production is limited by nitrogen and iron (see Groeger, 2007). Hargreaves et al (2007) also hypothesized that increasing UV-B radiation over this same period might inhibit the phytoplankton, as correlated with a drop in Chl-a, which may also impact primary productivity. Temporal changes in species composition, density, and biomass of the phytoplankton assemblages were not clearly linked with those of the zooplankton assemblage (see McIntire et al, 2007).…”

Section: Biological Componentsmentioning

confidence: 97%

“…Data collected near a intra-caldera wall stream after a rain storm emphasized the common observation of the dramatic increases in lithogenous particulate matter carried into the lake by these events. Hargreaves et al (2007) discussed the impact of these events on the pelagic water column as the lithogenous particles settle through the water column over a time scale of days to weeks. Continuing with an extensive review of the optical properties of Crater Lake, Hargreaves et al (2007) focused on the long-wavelength ultraviolet radiation (UVR) by making use of downwelling spectral irradiance profiles and upwelling radiance collected by a variety of radiometers and photometers.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…Hargreaves et al (2007) discussed the impact of these events on the pelagic water column as the lithogenous particles settle through the water column over a time scale of days to weeks. Continuing with an extensive review of the optical properties of Crater Lake, Hargreaves et al (2007) focused on the long-wavelength ultraviolet radiation (UVR) by making use of downwelling spectral irradiance profiles and upwelling radiance collected by a variety of radiometers and photometers. These apparent optical properties (AOP) were dependent on the IOP of the water and the properties of the incident downwelling and upwelling light fields.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…These apparent optical properties (AOP) were dependent on the IOP of the water and the properties of the incident downwelling and upwelling light fields. Hargreaves et al (2007) derived a series of ''proxies'' for the attenuation of UV radiation based on other bio-optical measurements, including the particle attenuation coefficient measurements by the beam transmissometer, the chlorophyll fluorescence, attenuation measurements by a photometer in the ''blue'' spectral range, and Secchi disk depths -which offered a long time series of UVR attenuation estimates. The authors observed a correlation between the atmospheric column inventory of ozone and the standing stock phytoplankton in the lake and discussed the hypothesis that UV-B irradiance, as controlled by stratospheric ozone variations, had an inhibitory effect on the plankton.…”

Section: Optical Propertiesmentioning

confidence: 99%

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Long-term limnological research and monitoring at Crater Lake, Oregon

Larson¹,

Collier

Buktenica

2007

Hydrobiologia

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Crater Lake is located in the caldera of Mount Mazama in Crater Lake National Park, Oregon. The lake has a surface area of about 53 km 2 at an elevation of 1882 m and a maximum depth of 594 m. Limited studies of this ultraoligotrophic lake conducted between 1896 and 1981, lead to a 10-year limnological study to evaluate any potential degradation of water quality. No long-term variations in water quality were observed that could be attributed to anthropogenic activity. Building on the success of this study, a permanent limnological program has been established with a long-term monitoring program to insure a reliable data base for use in the future.Of equal importance, this program serves as a research platform to develop and communicate to the public a better understanding of the coupled biological, physical, and geochemical processes in the lake and its surrounding environment. This special volume represents our current state of knowledge of the status of this pristine ecosystem including its special optical properties, algal nutrient limitations, pelagic bacteria, and models of the inter-relationships of thermal properties, nutrients, phytoplankton, deep-water mixing, and water budgets.

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Thermal, chemical, and optical properties of Crater Lake, Oregon

Larson¹,

Hoffman²,

McIntire

et al. 2007

Hydrobiologia

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Crater Lake covers the floor of the Mount Mazama caldera that formed 7700 years ago. The lake has a surface area of 53 km 2 and a maximum depth of 594 m. There is no outlet stream and surface inflow is limited to small streams and springs. Owing to its great volume and heat, the lake is not covered by snow and ice in winter unlike other lakes in the Cascade Range.The lake is isothermal in winter except for a slight increase in temperature in the deep lake from hyperadiabatic processes and inflow of hydrothermal fluids. During winter and spring the water column mixes to a depth of about 200-250 m from wind energy and convection. Circulation of the deep lake occurs periodically in winter and spring when cold, near-surface waters sink to the lake bottom; a process that results in the upwelling of nutrients, especially nitrate-N, into the upper strata of the lake. Thermal stratification occurs in late summer and fall. The maximum thickness of the epilimnion is about 20 m and the metalimnion extends to a depth of about 100 m. Thus, most of the lake volume is a cold hypolimnion. The year-round near-bottom temperature is about 3.5°C. Overall, hydrothermal fluids define and temporally maintain the basic water quality characteristics of the lake (e.g., pH, alkalinity and conductivity). Total phosphorus and orthophosphate-P concentrations are fairly uniform throughout the water column, where as total Kjeldahl-N and ammonia-N are highest in concentration in the upper lake. Concentrations of nitrate-N increase with depth below 200 m. No long-term changes in water quality have been detected. Secchi disk (20-cm) clarity varied seasonally and annually, but was typically highest in June and lowest in August. During the current study, August Secchi disk clarity readings averaged about 30 m. The maximum individual clarity reading was 41.5 m in

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Ultraviolet radiation and bio-optics in Crater Lake, Oregon

Cited by 13 publications

References 65 publications

Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR

Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR

Long-term limnological research and monitoring at Crater Lake, Oregon

Thermal, chemical, and optical properties of Crater Lake, Oregon

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