MP19 Remediation
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(BEN-1117-735920) Suitability of the capping substrate, AquaBlok, as an alternative sediment.

Bentivegna, C¹, Ferrara, K¹, ¹ Seton hall University, South Orange, NJ, USA

ABSTRACT- This experiment evaluated a new sediment capping substrate called AquaBlok. The substrate is designed to be deposited on top of toxic sediments and to form a barrier between the sediment and aquatic life in the water above. AquaBlok is made up of bentonite clay and polymers that surround a gravel core. The question addressed was the extent to which a common benthic macroinvertebrate could utilize AquaBlok as an alternative substrate for sediment. Chironomids (Chironomus riparius), an aquatic insect larvae, was used as the test organism. The experiment consisted of six treatments: one negative control (sand only) one positive control (sand plus 1 M Cd) and four others consisting of AquaBlok with varying percentages of organic matter incorporated into it- 0, 0.1, 0.5 and 2.0 %. Two types of organic matter were tested, corn cob and peat moss. There were five replicates per treatment with ten 5-6 day old larvae added to each replicate. Chironomids were fed and their water changed daily by static renewal. On day ten, chironomids from each replicate were removed, counted to determine % survival and dried overnight at 60 °C to determine combined dry weight, an indicator of growth. Water quality tests were also conducted. Each day, temperature and dissolved oxygen were recorded, and on days one and nine, pH, alkalinity and water hardness were also tested. Data indicated that chironomids grew better in sand than unammended Aquablok. Adding organic matter improved growth in AquaBlok but also tended to reduced dissolved oxygen. Total hardness was also reduced indicating that AquaBlok might adsorb heavy metals in contaminated environments and make them less bioavailable.

Key words: chironomid, sediment capping, AquaBlok, remediation