Photosynthesis/respiration ratios in aquatic microcosms under arsenic stress

Conference · Sat Jan 01 04:00:00 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
• Country of Publication: United States
• Language: English

Related Subjects

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