Photosynthesis/respiration ratios in aquatic microcosms under arsenic stress

Conference · Sat Jan 01 00:00:00 EST 1977

OSTI ID:7303024

Giddings, Jeffrey; Eddlemon, Gerald K.

The ratio of net photosynthesis (P) to total ecosystem respiration (R) usually declines when an aquatic ecosystem is subjected to various types of stress. P/R ratios were measured in 12 80-liter microcosms containing water, sediment, and entire biotic communities (dominated by Elodea sp.) from a shallow pond. P and R were estimated from changes in dissolved oxygen concentrations during the day and night, respectively. After 10 weeks, the microcosms were stressed by the addition of sodium arsenate at concentrations of 0, 0.066, 11.5, and 143 ppM (as arsenic). P/R ranged from 1.0 to 1.4 in all microcosms before arsenate was added. Under stress, both P and R declined in the 11.5 and 143 ppM microcosms, with negative net photosynthesis (i.e., decreases in dissolved oxygen during the day) observed on several occasions. P/R in these microcosms fell to zero or below, returning to 1.0 after three weeks. P/R remained above 1.0 in the 0.066 ppM and control microcosms. The P/R response could be used for screening suspected hazardous substances in microcosms, as well as for monitoring natural ecosystems.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7303024
• Report Number(s): CONF-770654-1
• Resource Relation: Conference: 40. annual meeting of the American Society of Limnology and Oceanography, East Lansing, MI, USA, 20 Jun 1977
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
ARSENIC
BIOLOGICAL EFFECTS
MICROORGANISMS
PHOTOSYNTHESIS
RESPIRATION
AQUATIC ECOSYSTEMS
CHEMICAL REACTIONS
ECOSYSTEMS
ELEMENTS
PHOTOCHEMICAL REACTIONS
SEMIMETALS
SYNTHESIS
520100* - Environment
Aquatic- Basic Studies- (-1989)
550500 - Metabolism