Figure 3
Metal (Sr, Ba, Mg, Mn, Ca) to calcium ratios and metal concentrations (mg/kg) in the soft tissue of freshwater mussels compared to the values in the water for control (red circle) and samples in the high dose (squares) and low dose (triangles) tanks collected both early (~ 4 weeks [green square and blue triangle) and late (~ 8 weeks following a second dose [yellow square and green triangle]). The color represents the dose of produced water with the highest dose (1:20) represented by yellow, the moderate dose 1:40 (green), and the low dose (1:80) by blue. Metal/Ca ratios in the soft tissue of mussels collected from dosed tanks generally increased relative to the control tanks for both Sr, and Ba (A, C). However, other metal/Ca ratios such as Mg or Mn (E, G) did not show a clear relationship. For example, Mn/Ca ratios in the soft tissue were highest in the control tank mussels. Mn/Catissue displayed a slight negative trend with dose and exposure time. Mg concentrations in the soft tissue appear to be related to concentration in the water without apparent influence from ratios with calcium, but similar to both Sr and Ba, the relationship may not be as strong at the extreme concentrations observed in the highest dose of produced water.
