St. Helens Chronicle. The St. Helens woman has been missing for two weeks. Her boyfriend, currently in the Lane County jail for other offenses, is now considered a person of interest. Police are currently searching for St. Helens woman, Cheryl Hart, who has been missing for nearly two weeks.
First, there are typically two varieties, or species, of arsenic in water: arsenic 3 and arsenic 5.. This is significant because arsenic 3 is very difficult to remove from water and must be changed or oxidized to arsenic 5 before it can be removed.
icity and transport properties of arsenic strongly depend on their chemical form. The forms of arsenic occur with valance states of â3, 0, 3, and 5. Most arsenic exists as arsenite (AsO3 3, As(III)) and arsenate (AsO3 4, As(V)) in water [3], and As(III) is more toxic than As(V). Meanwhile, selenium is a natural trace element, known to be an essential nutrient for animals and humans. Selenium contamination in drinking water is currently of concern because of the narrow range between selenium deï¬ciency and toxicity to humans [4,5]. Selenium is introduced into water from various sources including agricultural activities, fossil fuel combustion, and other industrial efï¬uents [6]. Selenium exists in valance state of â2, 0, 4, and 6 and has several organic forms [7]. Because higher valance forms of selenium are more water soluble, selenite (SeO2 3, Se(IV)) and selenate (SeO 2 4, Se(VI)) are the predominant forms found in water, and Se(IV) is more toxic than Se(VI) [5,8]. The United States Environmen-tal Protection Agency has established the maximum