Effect of pH and redox potential on heavy metal chemistry in sediment-water systems affecting toxic metal bioavailability

Book · Thu Jan 01 04:00:00 EST 1976

OSTI ID:5324508

Gambrell, R P; Khalid, R A; Collard, V R; Reddy, C N; Patrick, Jr, W H

The pH and oxidation-reduction (redox) potential of surface waters and sediments are important to the regulatory processes affecting the solubility of heavy metals and their distribution among various geochemical forms. Changes in pH or redox potential of a sediment water system can result in chemical transformations of metals between geochemical forms affecting their availability to aquatic and benthic organisms. These parameters may also influence the uptake of heavy metals by plants grown on dredged materials applied to land. A moderately low pH and reducing redox potential environment generally favor the relatively bioavailable soluble and exchangeable chemical forms of metals. Sparingly soluble metal oxides and hydroxides predominate at higher pH and oxidation levels. Important regulatory mechanisms affecting the chemistry of heavy metals include precipitation as insoluble sulfides under highly reduced conditions, formation of discrete metal oxides of low solubility or adsorption to colloidal hydrous oxides in aerobic, neutral or alkaline environments, and complexation with soluble and insoluble organic matter at all levels of pH and redox potential. Conversely, complexation with insoluble organics is an important sink for many metals. Redox potential influences both of these processes by quantitatively and qualitatively affecting the organic compounds present. Reduced environments favor slower degradation of organics and the formation of structurally complex, large molecular weight molecules which are more effective in binding metals. This report deals with the influence of pH, redox potential, and sediment properties on the chemistry of selected metals in sediment-water systems. Also, data indicating the influence of pH and redox potential on heavy metal uptake by plants grown on sediment material will be discussed.

• OSTI ID: 5324508
• Country of Publication: United States
• Language: English

Related Subjects

520200* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
560303 -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AQUATIC ORGANISMS
BIOGEOCHEMISTRY
BIOLOGICAL AVAILABILITY
CHEMISTRY
ELEMENTS
GEOCHEMISTRY
METALS
MOLECULAR WEIGHT
ORGANIC MATTER
PH VALUE
PLANTS
REDOX POTENTIAL
SEDIMENTS
SOLUBILITY
SURFACE WATERS
UPTAKE
WATER CHEMISTRY