Relationship of land use and elevated ionic strength in Appalachian watersheds

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Abstract-Increased ionic concentrations are associated with the impairment of benthic invertebrate assemblages. However, the causal nature of that relationship must be demonstrated so that it can be used to derive a benchmark for conductivity. The available evidence is organized in terms of six characteristics of causation: co-occurrence, preceding causation, interaction, alteration, sufficiency, and time order. The inferential approach is to weight the lines of evidence using a consistent scoring system, weigh the evidence for each causal characteristic, and then assess the body of evidence. Through this assessment, the authors found that a mixture containing the ions Ca þ , Mg þ , HCO À 3 , and SO À 4 , as measured by conductivity, is a common cause of extirpation of aquatic macroinvertebrates in Appalachia where surface coal mining is prevalent. The mixture of ions is implicated as the cause rather than any individual constituent of the mixture. The authors also expect that ionic concentrations sufficient to cause extirpations would occur with a similar salt mixture containing predominately HCO À 3 , SO 2À 4 , Ca 2þ , and Mg 2þ in other regions with naturally low conductivity. This case demonstrates the utility of the method for determining whether relationships identified in the field are causal. Environ. Toxicol.

Section: Preceding Causationmentioning

confidence: 86%

Section: Preceding Causationmentioning

confidence: 99%

Section: Preceding Causationmentioning

confidence: 99%

Section: Preceding Causationmentioning

confidence: 99%

Section: Preceding Causationmentioning

confidence: 99%

See 3 more Smart Citations

Assessing causation of the extirpation of stream macroinvertebrates by a mixture of ions

Cormier¹,

Suter²,

Zheng³

et al. 2012

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A method for assessing causation of field exposure–response relationships

Cormier

Suter

2013

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Abstract-Because associations between agents and environmental effects are not necessarily causal, it is necessary to assess causation before using such relationships in environmental management. The authors adapted epidemiological methods to assess general causal hypotheses. General causation establishes that an agent is capable of causing an effect. The method uses all relevant and good-quality evidence in a weight-of-evidence system. The system is credible due to its explicit a priori criteria. The evidence is organized in terms of six characteristics of causation: co-occurrence, preceding causation, interaction, alteration, sufficiency, and time order. The causal assessment proceeds through six steps that generate, organize, and score evidence to determine whether causation is adequately supported by the body of evidence. Environ. Toxicol. Chem. 2013;32:272-276. # 2012 SETAC

Surface coal mining influences on macroinvertebrate assemblages in streams of the Canadian Rocky Mountains

Kuchapski

Rasmussen²

2015

To determine the region-specific impacts of surface coal mines on macroinvertebrate community health, chemical and physical stream characteristics and macroinvertebrate family and community metrics were measured in surface coal mine-affected and reference streams in the Canadian Rocky Mountains. Water chemistry was significantly altered in mine-affected streams, which had elevated conductivity, alkalinity, and selenium and ion concentrations compared with reference conditions. Multivariate redundancy analysis (RDA) indicated alterations in macroinvertebrate communities downstream of mine sites. In RDA ordination, Ephemeroptera family densities, family richness, Ephemeroptera, Plecoptera, Trichoptera (EPT) richness, and % Ephemeroptera declined, whereas densities of Capniidae stoneflies increased along environmental gradients defined by variables associated with mine influence including waterborne Se concentration, alkalinity, substrate embeddedness, and interstitial material size. Shifts in macroinvertebrate assemblages may have been the result of multiple region-specific stressors related to mining influences including selenium toxicity, ionic toxicity, or stream substrate modifications.