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Aluminium speciation in surface waters from a Welsh upland area
1Colloid and Interface Group, Department of Chemical Engineering-UCS, Singleton Park, Swansea SA2 8PP, UK.
Environmental Pollution (Barking, Essex : 1987)
|January 1, 1988
Summary
This study quantifies aluminium species in acidified surface waters, revealing significant adsorbed aluminium during storm events. Findings indicate saturation with gibbsite during dry weather but undersaturation during storms.
Area of Science:
- Environmental Chemistry
- Geochemistry
- Water Quality Analysis
Background:
- Acidified catchments pose risks due to aluminium mobilisation.
- Understanding aluminium speciation is crucial for assessing water quality.
- Previous studies lacked comprehensive quantification of adsorbed aluminium species.
Purpose of the Study:
- To determine the complete aluminium speciation in surface waters of an acidified catchment.
- To quantify adsorbed aluminium (Al(ad)) for the first time.
- To investigate aluminium behaviour during dry weather and storm episodes.
Main Methods:
- Surface water samples were collected during dry and storm conditions.
- Aluminium speciation was analysed, including monomeric aluminium.
- Adsorbed aluminium (Al(ad)) was calculated using filtration to separate suspended solids.
Main Results:
- Significant adsorbed aluminium (Al(ad) > 40 µg/L) was observed with high suspended solids (> 20 mg/L) during storm episodes.
- Dry weather samples showed saturation with respect to gibbsite (pAl(3+) vs. pH slope ≈ 2.5).
- Storm episode samples exhibited undersaturation with respect to gibbsite (near zero slope).
Conclusions:
- Adsorbed aluminium is a significant fraction during storm events in acidified catchments.
- Gibbsite solubility controls aluminium in dry weather, while storm events alter mobilisation mechanisms.
- Further research into aluminium mobilisation mechanisms during high flow events is warranted.