WP241 (RAB-1118-414517) GSI Criterion Development for Chloroethane - Predicted vs Measured Values.
Start time: 8:00 AM
Rabe, B¹, VanDellen, E², Susan, J³, ¹ Environmental Resources Management, Inc., Holland, MI, USA² Alticor, Inc., Ada, MI, USA³ Fishbeck, Thompson, Carr & Huber, Grand Rapids, MI, USA
As part of a RCRA Corrective Action remediation project involving the historical presence of chloroethane in groundwater venting to surface water, an environmentally acceptable limit for chloroethane needed to be established. With the lack of any established GSI criteria for chloroethane, the project team developed a method of estimating the toxicity from existing chloroethane molecules containing two, three, four, five, or six chlorine atoms. This method predicted an acute toxicity value of 249 mg/L. Needing additional support for regulatory acceptance, a Tier II Final Acute Value for chloroethane was generated using the waterflea (Daphnia magna) and fathead minnow. The results of the testing generated an acute LC50 of 322 mg/L for the waterflea and 266 mg/L for the fathead minnow. The results of the modeling method were found to be very similar to the actual Tier II values obtained from laboratory data.

WP242 (INO-1117-794551) Contamination of Arsenic in Groundwater from Lower Mekong Basin.
Start time: 8:00 AM
Inoue, S¹, Agusa, T¹, Minh, T², Tu, N³, Tuyen, B³, Chamnan, C⁴, Tana, T⁵, Iwata, H¹, Tababe, S¹, ¹ Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime, Japan² Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan³ Nong Lam University, Ho Chi Minh, Vietnam⁴ Department of Fisheries, Ministry of Agriculture, Forestry and Fisheries, Phnom Penh, Cambodia⁵ Cabinet of the Council of Minister, Phnom Penh, Cambodia
The present study reports the levels and possible toxic effects of Arsenic (As) and 20 other trace elements in the ground water collected from the lower Mekong River Basin in Vietnam (September 2003 and May 2004) and Cambodia (September 2004). Concentrations of Arsenic were considerably higher in Cambodia (<0.1 to 1,930 g/L) than in the adjacent Vietnam (<0.1 to 411 g/L). The levels of As in Cambodia were comparable to the world′s well known Arsenic polluted regions, such as Bangladesh and West Bengal in India. While only 16% of the As values in Vietnam exceeded the WHO guidelines in drinking water, 57% of the samples from Cambodia had concentrations more than the guideline values. In addition, concentrations over the WHO drinking water guideline were found for Manganese (Mn) and Barium (Ba) in the samples from both the countries. In Cambodia the percentage of the samples which had Mn above the guideline values is 33% and in Vietnam 34% of the samples exceeded the limit. The corresponding values for Cambodia and Vietnam are 10 and 6.3%. Our results clearly indicated that groundwater in the lower Mekong Basin in Cambodia and Vietnam was contaminated with As, Mn and Ba. From our findings, it can be concluded that the inhabitants of Lower Mekong River Basin are presently exposed to a high chronic risk of As, Mn and Ba toxicity by the consumption of contaminated ground water in their every day life.