Different factors determine 137Cs concentration factors of freshwater fish and aquatic organisms in lake and river ecosystems

Comparison between the Baltic Sea and Irish Sea level of Cs-137 contamination on benthic, demersal and pelagic fish species

The Irish Sea and the Baltic Sea are nowadays still the two most Cs-137 contaminated Seas worldwide. However, the origins of this contaminations are completely different. While the Baltic Sea was unintentionally contaminated due to global fallout after the accident in the Chernobyl nuclear powerplant in 1986, the Irish sea was intentionally used for low level liquid radioactive waste discharges from the Sellafield nuclear reprocessing facility (called Windscale until 1981) between the 1950s and 1990s. Nowadays, more than 30 years later, it is still possible to detect these contaminations in fish, water and sediments of both seas. Since fish are an important part of the human diet, monitoring Cs-137 levels in fish is essential for assessing the potential radiation exposure to humans. In 2019 and 2020 two surveys were dedicated to study the current levels of radioactive contamination in fish species from both Seas. During both surveys, fish samples were collected and analysed by gamma spectrometry later on. The results show that the average Cs-137 activity in benthic, demersal and pelagic fish species from the Baltic Sea are 2.7, 4.6 and 4.2, respectively, times higher than the corresponding values of the Irish Sea. Based on this and two other comparisons, it is concluded that the Baltic Sea is the most contaminated with Cs-137.

Contrasting radiocesium transfer in the river and lake food webs: Importance of trophic level and food source

Radiocesium (¹³⁷Cs) contamination of the freshwater ecosystems adjacent to the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan has persisted long after the accident that occurred at the facility in March 2011. It is necessary to elucidate the dynamics of ¹³⁷Cs in various aquatic ecosystems to predict ¹³⁷Cs concentrations in fish and manage freshwater fisheries in the vicinity of FDNPP. To these ends, we applied stable isotope analysis to evaluate changes in ¹³⁷Cs levels through trophic positions and the relative importance of the ¹³⁷Cs sources at the trophic bases of two rivers and two lakes in Fukushima. The δ¹⁵N analyses disclosed that ¹³⁷Cs decreases from primary producers to fish consumers in the river food web and ¹³⁷Cs increases among fish consumers with increasing trophic position in the lake food web. The δ¹³C analysis revealed that autochthonous ¹³⁷Cs contributed to fish contamination. The periphyton-dependent and zooplankton-dependent fish had comparatively higher ¹³⁷Cs concentrations in the rivers and lakes, respectively. Cesium-137 supply from the pelagic food web was observed to contribute to greater ¹³⁷Cs levels in the fish consumers inhabiting the lakes. The results of this study show that stable isotope analysis may help clarify ¹³⁷Cs dynamics in freshwater food webs and identify the important ¹³⁷Cs sources in the food web. Identifying important ¹³⁷Cs sources and trophic transfers depending on the ecosystem help guide regulatory and management frameworks to establish profitability of the food fish stocks there and maintain food security.

Impact of long-term operation of nuclear power plants on the marine ecosystem of Daya Bay

Based on the monitoring data of Daya Bay in 2011-2017, the impact of long-term operation of nuclear power plants (NPPs) on the marine ecosystem was accessed. ¹³⁷Cs and ⁹⁰Sr in seawater and sediment of Daya Bay decreased with time. The environmental half-lives of ¹³⁷Cs and ⁹⁰Sr in seawater, ¹³⁷Cs in sediment were 7.1 a, 11.7 a and 13.9 a, respectively. The total dose rates of the marine organisms ranged from 230.5 to 853.9 nGy/h, lower than the ERICA screening benchmark (10 μGy/h). ²¹⁰Po, ²²⁶Ra and ²³²Th were the main dose contributors. ¹³⁷Cs and ⁹⁰Sr contributed to ~0.01 %-~0.06 % of the total radiation. ¹³⁷Cs contributed to <0.6 ‰ of the committed effective dose for humans. There were almost no radiation effects on the marine ecosystem of Daya Bay from NPPs before 2017. In the future, there will be no radiation risk for the long-term discharge of low-level radioactive waste to Daya Bay.

Factors affecting 137Cs radioactivity and water-to-body concentration ratios of fish in river and pond environments near the Fukushima Dai-ichi Nuclear Power Plant

To elucidate ¹³⁷Cs contamination levels and mechanisms of fish inhabiting river and pond environments near the Fukushima Dai-ichi Nuclear Power Plant, ¹³⁷Cs activity concentrations in fish (15 species, n = 164) and water collected from Maeda River (3.3-8.9 km from the plant) and Shimofukazawa Pond (2.9 km) in 2017 were analyzed. Also, an 8-week rearing experiment using Japanese dace Pseudaspius hakonensis fed on non-contaminated pellets and the pond water (mean ¹³⁷Cs concentration of 2.0 Bq/L) was conducted to evaluate ¹³⁷Cs accumulation from water to fish. The ¹³⁷Cs concentrations in Japanese dace, the only species collected throughout five sampling sites from estuarine to upstream areas in Maeda River, were found to be correlated with ambient air dose rates and fish size, exhibiting large variations (16.5-2.6×10³ Bq/kg-wet). By contrast, dissolved ¹³⁷Cs in river waters increased from the upper to lower course (0.025-0.28 Bq/L), which caused large variations of the water-to-body concentration ratio (CR) in Japanese dace (60.0-35700 L/kg-wet). These CRs (geometric mean of 3670 L/kg-wet) were much higher than the steady-state CR of reared fish (9.7 L/kg-wet), indicating that river fish uptake ¹³⁷Cs mainly from prey items from aquatic and riparian zones, rather than from water. Statistically significant negative correlations between K⁺ concentrations in water and river fish CRs were detected, resulting in the decreasing trend of CRs from upstream to estuarine areas. These results suggest that the large heterogeneity of air dose rates, K⁺ concentration, and estuarine processes in brackish water habitats, in association with the feeding habit and size effect in fish, can engender wide variation of ¹³⁷Cs concentrations and CRs of river fish along a river course. In contrast, ¹³⁷Cs concentrations in pond fish (4.3-14.6 kBq/kg-wet) were higher than in river fish. The CRs of pond fish were constantly high but the range was smaller (1010-3440 L/kg-wet) with larger values in fish of higher trophic levels. These findings suggest that biomagnification within a pond was inferred as the main cause of ¹³⁷Cs contamination of pond fish.

Contrasting seasonality of 137Cs concentrations in two stream animals that share a trophic niche

Understanding the seasonality of ¹³⁷Cs concentrations in aquatic animals is crucial for reviving local inland fisheries. The seasonality of ¹³⁷Cs concentrations in animals is expected to vary, even if focal species consume similarly contaminated foods because the ¹³⁷Cs excretion rate is species-specific, and ¹³⁷Cs uptake by foraging autochthonous food resources also vary among seasons. Here, we conducted a seasonal monitoring survey of dissolved ¹³⁷Cs concentrations as an indicator of the contamination level of food resources and measured ¹³⁷Cs concentrations in two carnivorous aquatic animals (Palaemon paucidens and Rhinogobius sp.) that share a trophic niche in a stream connected to a dam reservoir. The dissolved ¹³⁷Cs concentration had clear seasonality-high in summer and low in winter. The ¹³⁷Cs concentrations in the animals revealed a different seasonal pattern-it peaked in October in P. paucidens and peaked in February in Rhinogobius. Overall, the ¹³⁷Cs concentration was relatively higher in P. paucidens than in Rhinogobius, suggesting that P. paucidens has a lower excretion rate than Rhinogobius. Consequently, the seasonality of the ¹³⁷Cs concentration in P. paucidens showed temporal changes similar to those of the dissolved ¹³⁷Cs concentration, which were likely affected by ¹³⁷Cs uptake through foraging, whereas that in Rhinogobius was controlled by ¹³⁷Cs excretion. This study shows that the seasonality of ¹³⁷Cs concentration can differ between sympatric animals that share a trophic niche. Accumulating knowledge and comparing the seasonality of ¹³⁷Cs concentrations in fisheries species based on the balance between uptake and excretion will be valuable to determine the appropriate seasons to obtain less-contaminated products.

Radiocesium-bearing microparticles cause a large variation in 137Cs activity concentration in the aquatic insect Stenopsyche marmorata (Tricoptera: Stenopsychidae) in the Ota River, Fukushima, Japan

After the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Plant accident in Japan, freshwater ecosystems near the site remained contaminated by radiocesium (RCs). Clarifying RCs concentrations in aquatic insects is crucial because fishes consume these insects that transfer RCs into freshwater ecosystems. As aquatic insects are usually measured for radioactivity in bulk samples of several tens of insects, variation in RCs concentration among individuals is not captured. In this study, we investigated the variability in 137Cs activity concentration in individual aquatic insects in detritivorous caddisfly (Stenopsyche marmorata) and carnivorous dobsonfly (Protohermes grandis) larvae from the Ota River, Fukushima. Caddisfly larvae showed sporadically higher radioactivity in 4 of the 46 caddisfly larvae, whereas no such outliers were observed in 45 dobsonfly larvae. Autoradiography and scanning electron microscopy analyses confirmed that these caddisfly larvae samples contained radiocesium-bearing microparticles (CsMPs), which are insoluble Cs-bearing silicate glass particles. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Although CsMP distribution and uptake by organisms in freshwater ecosystems is relatively unknown, our study demonstrates that CsMPs can be taken up by aquatic insects.

Pre- and post-accident environmental transfer of radionuclides in Japan: lessons learned in the IAEA MODARIA II programme

An international review of radioecological data derived after the accident at the Fukushima Daiichi nuclear power plant was an important component of activities in working group 4 of the IAEA Models and data for radiological impact assessment, phase II (MODARIA II) programme. Japanese and international scientists reviewed radioecological data in the terrestrial and aquatic environments in Japan reported both before and after the accident. The environmental transfer processes considered included: (a) interception and retention radionuclides by plants, (b) loss of radionuclides from plant and systemic transport of radionuclides in plants (translocation), (c) behaviour of radiocaesium in soil, (d) uptake of radionuclides from soil by agricultural crops and wild plants, (e) transfer of radionuclides from feedstuffs to domestic and wild animals, (f) behaviour of radiocaesium in forest trees and forest systems, (g) behaviour of radiocaesium in freshwater systems, coastal areas and in the ocean, (h) transport of radiocaesium from catchments through rivers, streams and lakes to the ocean, (i) uptake of radiocaesium by aquatic organisms, and (j) modification of radionuclide concentrations in food products during food processing and culinary preparation. These data were compared with relevant global data within IAEA TECDOC-1927 'Environmental transfer of radionuclides in Japan following the accident at the Fukushima Daiichi Nuclear Power Plant'. This paper summarises the outcomes of the data collation and analysis within MODARIA II work group 4 and compares the Japan-specific data with existing radioecological knowledge acquired from past and contemporary radioecological studies. The key radioecological lessons learned are outlined and discussed.

Monitoring of radioactive cesium in wild boars captured inside the difficult-to-return zone in Fukushima Prefecture over a 5-year period

Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, tissue samples from wild boar (Sus scrofa) outside the evacuation zone (difficult-to-return zone, DRZ) tended to show high activity concentrations of cesium-137 (¹³⁷Cs). Understanding the ¹³⁷Cs dynamics of wild boar populations inside the DRZ is necessary because they affect ¹³⁷Cs dynamics and wild boar management in areas outside the DRZ. Since few detailed, long-term studies have been conducted inside the DRZ, we measured ¹³⁷Cs activity concentrations in 221 wild boar muscle samples obtained from wild boar caught inside the DRZ and surrounding areas over a 5-year period. Our results showed that the ¹³⁷Cs activity concentration in wild boar from inside the DRZ were higher than those in wild boar outside this zone. No significant difference was observed between muscle and soil ¹³⁷Cs levels, but significant correlations were observed between muscle ¹³⁷Cs activity concentrations and body length and body weight in the low-activity-concentration season, but not between all seasons and the high-activity-concentration seasons. It is considered that the size effects observed during the low-activity-concentration season may be due to factors related to metabolism and changes in food habit. This is the first long-term survey of ¹³⁷Cs in wild boar inside the DRZ.

Remobilisation of radiocaesium from bottom sediments to water column in reservoirs in Fukushima, Japan

Reservoir sediments generally act as a sink for radionuclides derived from nuclear accidents, but under anaerobic conditions, several radionuclides remobilise in bioavailable form from sediments to water columns, which may contribute to the long-term contamination of aquatic products. This study systematically investigated the ¹³⁷Cs activities of sediment-pore water, providing a direct evidence of the remobilisation of bioavailable ¹³⁷Cs from sediments in two highly contaminated reservoirs affected by the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. We observed that the dissolved ¹³⁷Cs activity concentration of pore water (3.0-65.8 Bq L^-1) was one to two orders of magnitude higher than that of reservoir water. Moreover, the distribution coefficient (K_d) values for the ¹³⁷Cs of sediment-pore water (2.6-14 × 10³ L kg^-1) decreased with depth. The K_d values were significantly and negatively correlated with the concentration of the major ¹³⁷Cs competing cation NH₄⁺. Our results strongly indicate a competitive ion exchange process between ¹³⁷Cs and NH₄⁺ via a highly selective interaction with the frayed edge sites of phyllosilicate minerals, which is the major reason for the variability of K_d values of sediment-pore water, even in the Fukushima case. Additionally, the sediment accumulation rates were relatively high, and the annual depositional rate of exchangeable ¹³⁷Cs prevailed over the annual diffusive flux of ¹³⁷Cs from the sediment to the overlying water. This finding indicates that even after 10 years since the FDNPP accident, the bioavailable ¹³⁷Cs is still continuously supplied from the catchment covered by mountainous forests, and reservoir sediments are a long-term important source of bioavailable ¹³⁷Cs in the riverine system. Our findings provide important parameter values for mid- and long-term assessments of the radiation impact of radionuclide discharges to freshwater environments.

Investigating the Influence of Column Depth on the Treatment of Textile Wastewater Using Natural Zeolite

Textile industry production processes generate one of the most highly polluted wastewaters in the world. Unfortunately, the field is also challenged by the availability of relatively cheap and highly effective technologies for wastewater purification. The application of natural zeolite as a depth filter offers an alternative and potential approach for textile wastewater treatment. The performance of a depth filter treatment system can be deeply affected by the column depth and the characteristics of the wastewater to be treated. Regrettably, the information on the potential of these filter materials for the purification of textile wastewater is still scarce. Therefore, this study investigated the potential applicability of natural zeolite in terms of column depth for the treatment of textile wastewater. From the analysis results, it was observed that the filtration efficiencies were relatively low (6.1 to 13.7%) for some parameters such as total dissolved solids, electrical conductivity, chemical oxygen demand, and sodium chloride when the wastewater samples were subjected to the 0.5 m column depth. Relatively high efficiency of 82 and 93.8% was observed from color and total suspended solids, respectively, when the wastewater samples were subjected to the 0.5 m column depth. Generally, the 0.75 m column depth achieved removal efficiencies ranging from 52.3% to 97.5%, whereas the 1 m column depth achieved removal efficiencies ranging from 86.9% to 99.4%. The highest removal efficiency was achieved with a combination of total suspended solids and 1 m column depth (99.4%). In summary, the treatment approach was observed to be highly effective for the removal of total suspended solids, with a 93.8% removal efficiency when the wastewater was subjected to the 0.5 m column depth, 97.5% for 0.75 m column depth, and 99.4% for 1 m column depth. Moreover, up to 218.233 mg of color per g of the filter material was captured. The results derived in this study provide useful information towards the potential applicability of natural zeolite in the textile wastewater treatment field.

Untangling radiocesium dynamics of forest-stream ecosystems: A review of Fukushima studies in the decade after the accident

Forest-stream ecosystems are widespread and biodiverse terrestrial landscapes with physical and social connections to downstream human activities. After radiocesium is introduced into these ecosystems, various material flows cause its accumulation or dispersal. We review studies conducted in the decade after the Fukushima nuclear accident to clarify the mechanisms of radiocesium transfer within ecosystems and to downstream areas through biological, hydrological, and geomorphological processes. After its introduction, radiocesium is heavily deposited in the organic soil layer, leading to persistent circulation due to biological activities in soils. Some radiocesium in soils, litter, and organisms is transported to stream ecosystems, forming contamination spots in depositional habitats. While reservoir dams function as effective traps, radiocesium leaching from sediments is a continual phenomenon causing re-contamination downstream. Integration of data regarding radiocesium dynamics and contamination sites, as proposed here, is essential for contamination management in societies depending on nuclear power to address the climate crisis.

Long-term prediction of [Formula: see text]Cs in Lake Onuma on Mt. Akagi after the Fukushima accident using fractional diffusion model

The Fukushima Daiichi Nuclear Power Plant accident also contaminates lakes in Japan. Especially in closed lakes, there is a problem of prolonged low-level [Formula: see text]Cs contamination because the activity concentration of [Formula: see text]Cs declines sharply immediately after the accident, but then begins to decrease slowly. In this paper, we derived a long-term prediction formula based on the fractional diffusion model (FDM) for the temporal variation in [Formula: see text]Cs activity concentrations of the water in Lake Onuma on Mt. Akagi, one of the closed lakes, and of pond smelt (Hypomesus nipponensis), a typical fish species inhabiting in the lake. The formula reproduced well the measured [Formula: see text]Cs activity concentration of the lake water and pond smelt for 5.4 years after the accident. Next, we performed long-term prediction for 10,000 days using this formula and compared it with the prediction results of the two-component decay function model (TDM), which is the most common model. The results suggest that the FDM prediction will lead to a longer period of contamination with low-level [Formula: see text]Cs than the TDM prediction.

Distribution and transfer of naturally occurring radionuclides and 137Cs in the freshwater system of the Plitvice Lakes, Croatia, and related dose assessment to wildlife by ERICA Tool

The aim of this study was to investigate the natural radioactivity of Plitvice Lakes, under the assumption that due to its status as a National Park, the area can be considered an example of a natural freshwater system. Also, considering the transfer parameter data as the largest source of uncertainty in radiological risk assessments, the impact of site-specific data on dose rate assessment, as opposed to currently available data, was investigated. The study included gamma and alpha spectrometric measurements of ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Ra, and ⁴⁰K in water, sediment, and fish samples, as well as ¹³⁷Cs due to the coinciding of the study with the Fukushima accident. The content of naturally occurring radionuclides significantly varied in sediments of different Lakes, probably as a reflection of the different underlying geology of the area. Also, the ²¹⁰Pb distribution in sediments indicated an up to 312 Bq kg^-1 of the allochthonous contribution of this radionuclide at the beginning of the Lake's watercourse, which probably entered into the lake system by the major inlet river with its steady decrease along downstream lakes. Low ⁴⁰K activity concentrations (27.5 ± 20.1 mBq L^-1) in the Lake's waters might be one of the causes of increased ¹³⁷Cs activity concentrations in fish samples (1.5 ± 0.4 Bq kg^-1), which was found to be an order of magnitude higher than average values for different fish species from other Croatian freshwater systems (0.2 ± 0.1 Bq kg^-1). A temporary increase of ¹³⁷Cs activity concentrations was measured in water samples collected immediately after the Fukushima accident. Calculated site-specific sediment/water distribution coefficients and fish/water concentration ratios for radium and caesium were on average lower than generic ones found in the literature. Background dose rate assessments performed by the ERICA Tool indicated a profound impact of different input data on assessment results with water activity concentrations resulting in significantly higher dose rates (0.1-67 μGy h^-1) in comparison to sediment activity concentrations (0.03-9 μGy h^-1). An incremental dose rate due to ¹³⁷Cs was found to be in the range of < 0.001-0.023 μGy h^-1 which, in comparison to background dose rates, can be considered negligible.

Seasonal dynamics of the activities of dissolved 137Cs and the 137Cs of fish in a shallow, hypereutrophic lake: Links to bottom-water oxygen concentrations

Remobilization of radiocesium from anoxic sediments can be an important mechanism responsible for long-term contaminations of lakes. However, it is unclear whether such remobilization occurs in shallow lakes, where concentrations of dissolved oxygen in the hypolimnion (bottom DO) change temporally in response to meteorological conditions, and whether remobilized radiocesium influences the activity in fish. We examined the seasonal dynamics of the activities of dissolved ¹³⁷Cs and ¹³⁷Cs in fish (pond smelt and crucian carp) from Lake Kasumigaura, a shallow, hypereutrophic lake, five years after the Fukushima Daiichi Nuclear Power Plant accident. The activities of both dissolved ¹³⁷Cs and ¹³⁷Cs in fish declined during that time, but the declines showed a clear seasonal pattern that included a summer peak of ¹³⁷Cs activity. The activity of dissolved ¹³⁷Cs increased when the bottom DO concentration decreased, and a nonlinear causality test revealed significant causal forcing of dissolved ¹³⁷Cs activity by bottom DO. The fact that NH₄-N concentrations in bottom waters were higher in the summer suggested that remobilization of ¹³⁷Cs from sediments could result from highly selective ion-exchange with NH₄-N. Despite the shallow depth of Lake Kasumigaura, winds had little influence bottom DO concentrations or dissolved ¹³⁷Cs activities. The fact that seasonal means of ¹³⁷Cs activities in pond smelt and crucian carp were positively correlated with the seasonal means of dissolved ¹³⁷Cs activities suggested that remobilized ¹³⁷Cs may have influenced the seasonal dynamics of radiocesium in fish through food-chain transfer, but higher feeding rates in warm water could may have also contributed to the seasonal dynamics of ¹³⁷Cs activity in fish. Our findings suggest that in shallow lakes, intermittent but repeated hypoxic events may enhance remobilization of radiocesium from sediments, and remobilized radiocesium may contributed to long-term retention of radiocesium in aquatic organisms.

Environmental radiobiology of amphibians - knowledge gaps to be filled using cell lines

Amphibians are facing an unprecedented level of population declines worldwide. The causes run the gamut from habitat loss and succumbing to opportunistic pathogen infections to vulnerability to toxic pollutants and ultraviolet (UV)-B radiation exposure. Anthropogenic activities including Chernobyl and Fukushima nuclear disasters and radioactive waste leakage into the environment raise the background radiation levels. Their immediate and chronic effects on amphibian populations are still being studied. However, the literature on environmental radiation effects on amphibian health still requires a lot more work. Laboratory and field works need to be conducted hand in hand in order to make informative and conclusive analyses to distinguish bad from good and harm from risk or to argue for or against the linear no-threshold model in radioprotection programs. Amphibian cell lines can help seek answers to important questions pertaining environmental radiobiology and amphibian health wherever they can suitably and effectively. The purpose of this work is to show that amphibian cell lines can 'rescue' important knowledge gaps in the literature, especially in the low-dose radiation mechanisms. Presently, there are 142 amphibian cell lines developed from six urodelans and 17 anurans. Amphibian cell lines can help expand and enrich the limited literature on environmental radiation effects on amphibians. They can be used to study mechanisms of radiation actions and discover reliable biomarkers for low-dose exposure. They can be used in environmental radiation monitoring and radioprotection programs. They can be used to determine the effects of co-exposure of IR and other stressors in the environment on amphibian health. They represent an ethical choice for amphibian conservation efforts in the current global amphibian declines. Lessons learned from cellular data can be useful guides to gain a better picture of effects occurring at the amphibian population and ecosystem levels.

Data on 137Cs concentration factor of freshwater fish and aquatic organisms in lake and river ecosystems

This article provides the data which were analyzed in the research article "Different factors determine ¹³⁷Cs concentration factors of freshwater fish and aquatic organisms in lake and river ecosystems" (Y. Ishii, S. S. Matsuzaki, S. Hayashi, 2019) [1]. Radionuclide accumulation in aquatic organism is defined in terms of the concentration factor (CF), which is calculated as the radionuclide concentration in the organism (Bq kg^-1) divided by that in the surrounding water (Bq L^-1). Quantification of the radionuclide CF allows estimation of environmental radionuclide transfer and the potential risks of consuming fish contaminated with the radionuclide. We calculated the ¹³⁷Cs CF values for freshwater fish and aquatic organisms using the monitoring data of multiple sites in five rivers and three lakes of Fukushima in years 2013-2017 after the Fukushima Dai-ichi Nuclear Power Plant accident. The data also include the ¹³⁷Cs activity concentration of the water and water chemistry data (pH, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, electric conductivity, salinity, total organic carbon, suspended solid concentration, turbidity) at each sampling location associated with each CF value.