title: Evaluation of factors influencing accumulation of stable Sr and Cs in lake and coastal fish.
abstract: As a result of nuclear accidents and weapons tests, the radionuclides Cs-137 and Sr-90 are common contaminants in aquatic ecosystems. Concentration ratios (CR) based on concentrations of stable Cs and Sr in biota and media are used for the estimation of transfer of their radioisotopes for radiation dose calculations in environmental and human safety assessments. Available element-specific CRs vary by over an order of magnitude for similar organisms, thus affecting the dose estimates proportionally. The variation could be reduced if they were based on a better understanding of the influence of the underlying data and how that affects accumulation and potential biomagnification of stable Cs and Sr in aquatic organisms. For fish, relationships have been identified between water concentrations of K and CR of Cs-137, and between water concentrations of Ca and CR of Sr-90. This has not been confirmed for stable Cs and Sr in European waters. In this study, we analysed an existing dataset for stable Cs and Sr, as well as K and Ca, in four Swedish lakes and three Baltic Sea coastal areas, in order to understand the behaviour of these elements and their radioisotopes in these ecosystems. We found significant seasonal variations in the water concentrations of Cs, Sr, K and Ca, and in electrical conductivity (EC), especially in the lakes. CR values based on measurements taken at single or few time points may, therefore, be inaccurate or introduce unnecessarily large variation into risk assessments. Instead, we recommend incorporating information about the underlying variation in water concentrations into the CR calculations, for example by using the variation of the mean. The inverse relationships between fish CR(Cs)-[K]water and fish CR(Sr)-[Ca]water, confirmed that stable Cs and Sr follow the same trends as their radioisotopes. Thus, they can be used as proxies when radioisotope data are lacking. EC was also strongly correlated with K and Ca concentrations in the water and could potentially be used as a quick and cost-effective method to estimate water chemistry to obtain less variable CR. We also recommend some simple improvements to data collection that would greatly enhance our ability to understand Cs and Sr uptake by fish.
authors.affiliation: Department of Ecology, Environment and Plant Sciences, (DEEP), Stockholm University, 10691 Stockholm, Sweden. Electronic address: lena.ecology@gmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Konovalenko
authors.affiliation: Department of Ecology, Environment and Plant Sciences, (DEEP), Stockholm University, 10691 Stockholm, Sweden. Electronic address: clare.bradshaw@su.se.
authors.forename: C
authors.initials: C
authors.lastname: Bradshaw
authors.affiliation: Swedish Nuclear Fuel and Waste Management Co, (SKB), Box 250, 10124 Stockholm, Sweden. Electronic address: Eva.Andersson@skb.se.
authors.forename: E
authors.initials: E
authors.lastname: Andersson
authors.affiliation: Department of Environmental Science and Analytical Chemistry, (ACES), Stockholm University, 10691 Stockholm, Sweden. Electronic address: dennis.lindqvist@aces.su.se.
authors.forename: D
authors.initials: D
authors.lastname: Lindqvist
authors.affiliation: Swedish Nuclear Fuel and Waste Management Co, (SKB), Box 250, 10124 Stockholm, Sweden. Electronic address: ulrik.kautsky@skb.se.
authors.forename: U
authors.initials: U
authors.lastname: Kautsky
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002588:Cesium Radioisotopes / Q000032:analysis* / Q000378:metabolism; D004553:Electric Conductivity; D005399:Fishes / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D060106:Lakes / Q000032:analysis; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D009792:Oceans and Seas; D011188:Potassium / Q000032:analysis; D011834:Radiation Monitoring; D012623:Seawater / Q000032:analysis; D013326:Strontium Radioisotopes / Q000032:analysis* / Q000378:metabolism; D013548:Sweden; D014875:Water Pollutants, Radioactive / Q000032:analysis* / Q000378:metabolism
chemical_list: D002588:Cesium Radioisotopes; D013326:Strontium Radioisotopes; D014875:Water Pollutants, Radioactive; D011188:Potassium; D002118:Calcium
keywords: Bioaccumulation; Biomagnification; Caesium; Concentration ratio; Fish; Strontium