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<blockquote data-quote="Allen" data-source="post: 185227" data-attributes="member: 389">Both the selenium and mercury are coming out of either the Pierre or Niobrara shale which has outcrops in the area. This is also responsible for a lot of the arsenic although I don't remember offhand which formation contributes more to DL.&nbsp; The groundwater in eastern ND is often found in aquifers loaded with shale fragments (sand to gravel sized) that can be mobilized via denitrification. At least, that's my theory.&nbsp; The organic portions of the shale tend to hold a lot of trace elements like mercury and selenium, whereas the inorganic (pyrite) holds the most arsenic.&nbsp; Oxidizing the organic carbon or pyrite frees it up and lets it become more mobile.- - - Updated - - -FWIW, I think the ducks out near Kelly's Slough have had several studies done on them for mercury.</blockquote>

[QUOTE="Allen, post: 185227, member: 389"] Both the selenium and mercury are coming out of either the Pierre or Niobrara shale which has outcrops in the area. This is also responsible for a lot of the arsenic although I don't remember offhand which formation contributes more to DL. The groundwater in eastern ND is often found in aquifers loaded with shale fragments (sand to gravel sized) that can be mobilized via denitrification. At least, that's my theory. The organic portions of the shale tend to hold a lot of trace elements like mercury and selenium, whereas the inorganic (pyrite) holds the most arsenic. Oxidizing the organic carbon or pyrite frees it up and lets it become more mobile. [COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR] FWIW, I think the ducks out near Kelly's Slough have had several studies done on them for mercury. [/QUOTE]

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