Graduation Year

Spring 2012

Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts

Department

Environmental Analysis

Reader 1

Char Miller

Reader 2

Charles J. Taylor

Terms of Use & License Information

Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2011 Thuy M. Ly

Abstract

Although arsenic is naturally present in the environment, 99% of human exposure to arsenic is through ingestion. Throughout history, arsenic is known as “the king of poisons”; it is mutagenic, carcinogenic, and teratogenic. Even in smaller concentrations, it accumulates in the body and takes decades before any physical symptoms of arsenic poisoning shows. According to the World Health Organization (WHO), the safe concentration of arsenic in drinking water is 10 µg/L. However, this limit is often times ignored until it is decades too late and people begin showing symptoms of having been poisoned.

This is the current situation for Vietnam, whose legal arsenic concentration limit is 50 µg/L, five times higher than the WHO guidelines. Groundwater in Vietnam was already naturally high in arsenic due to arsenic-rich soils releasing arsenic into groundwater. Then, in the past half century, with the use of arsenic-laden herbicides dispersed during the Vietnam War and subsequent industrial developments, the levels of bio-available arsenicals has dangerously spiked. With the proliferation of government-subsidized shallow tube-wells in the past two decades, shallow groundwater has become the primary source for drinking and irrigation water in Vietnam. This is a frightening trend, because this groundwater has arsenic concentrations up to 3050 µg/L, primarily in the +3 and +5 oxidation states, the most readily available oxidation states for bioaccumulation.

This thesis argues that measures must be taken immediately to remedy the high concentration of arsenic in groundwater, which in Vietnam is the primary and, in some cases, the sole source of water for domestic consumption and agricultural production. Although there are numerous technologies available for treating arsenic in groundwater, not all of them are suited for Vietnam. By analyzing the historical, cultural, economic, and political parameters of Vietnam, several optimal treatments of groundwater for drinking water emerged as most recommended, a classification that is based on their local suitability, social acceptability, financial feasibility, and governmental support. Further research on irrigation water treatment is proposed due to the need for sustainable crop production, the safe ingestion of rice and vegetables, and the continued growth of Vietnam’s economy, which is heavily dependent on agriculture.

Comments

Senior thesis submitted in December 2011.