Boron is a naturally occurring mineral in shale and coal beds formed in marine environments, as found in the Uinta Basin. Mining activity and the application of excess irrigation water on agricultural lands in the Pariette watershed lead to mobilization of B via surface run off. Water quality monitoring records from 2006- 2009 reported violations of Utah B standard for irrigation water 43-100% of the time, for water flowing through the Pariette Wetlands. This study aims to determine B distribution in abiotic (water, sediments) and biotic samples (macroinvertebrates, aquatic vegetation, fish, bird eggs), and to establish correlations between B concentrations in the samples.
Abiotic samples had average B concentrations of 2.87 ± 0.8 mg L-1 in water and 51.65 mg kg-1 in sediments. The concentrations exceeded established lowest-observable-adverse-effect levels (LOAELs) for aquatic plants and sensitive invertebrates like crustaceans. The total average B concentration in benthic macroinvertebrates (28.45 ± 12.04 mg kg-1) was higher than B concentrations in their habitat (sediment and water). Benthic macroinvertebrate (BMI) biodiversity was low in all four wetland units with increased populations of pollution tolerant taxa like Chironomidae (midges). Reduced numbers of freshwater BMIs such as Ephemeroptera (mayflies), Plecoptera (stoneflies) or Trichoptera (caddisflies) indicate environmental stress and impaired conditions. Submerged plants (Potamageton (pondweed) and Chara (stonewort)) had higher total average B concentrations than emergent plants (Typha domingensis and Typha latifolia (cattails), Scirpus acutus (bulrush), and Phragmites austalis (common reed)), and higher B concentrations than the water, suggesting B bioconcentration. The B content in waterfowl and fish food sources were not high enough to impact adult birds or freshwater fish tolerant of poor water quality. Simple linear statistical correlations between B in biotic samples (bird eggs, fish) and their habitats and food sources were poor to non-existent; however, positive correlations and high p–values established using Mantel test coefficients suggest possible pathways for exposure to B via ingestion. We concluded that even though B bioconcentrates in aquatic vegetation it is not biomagnifing in aquatic food-chain components we investigated in the Pariette Wetlands. In addition to continued water monitoring, we recommend using submerged vegetation and macroinvertebrates to alert site managers to adverse effects of B on wetland fish and bird eggs
