Radium contamination of the banks of the river Laak as a consequence of the phosphate industry in Belgium

For over half a century, phosphate ores of marine origin, containing 226Ra, have been processed in Belgium to produce calcium phosphate for use in cattle food. As a result, the waste water containing 226Ra were discharged into two little rivers, one of which is the Laak. The purpose of this study was to chart the radium contamination of the river banks and some areas that are regularly flooded by the river. It was seen that enhanced concentrations of 226Ra do occur along the river banks, but that the contaminated area is mostly confined to a 10 m strip on both sides of the river, even in the flooding zones. At present, no dwellings are present on top of the contamination and no crops for direct human consumption are grown there, so there is no immediate threat to the population.     

Contamination of settling ponds and rivers as a result of discharge of radium-bearing waters from Polish coal mines

Saline waters from underground coal mines in Poland often contain natural radioactive isotopes, mainly 226Ra from the uranium decay series and 228Ra from the thorium series. Approximately 40% of the total amount of radium remains underground as radioactive deposits, but 225 MBq of 226Ra and 400 MBq of 228Ra are released daily into the rivers along with the other mine effluents from all Polish coal mines. Technical measures such as inducing the precipitation of radium in gobs, decreasing the amount of meteoric inflow water into underground workings, etc. have been undertaken in several coal mines, and as a result of these measures, the total amount of radium released to the surface waters has diminished by about 60% during the last 5-6 years. Mine water can have a severe impact on the natural environment, mainly due to its salinity. However, associated high levels of radium concentration in river waters, bottom sediments and vegetation have also been observed. Sometimes radium concentrations in rivers exceed 0.7 kBq/m3, which is the permitted level for waste waters under Polish law. The extensive investigations described here were carried out for all coal mines and on this basis the total radium balance in the effluents has been calculated. Measurements in the vicinity of mine settling ponds and in rivers have given us an opportunity to study radium behaviour in river waters and to assess the degree of contamination. Solid waste materials with enhanced natural radioactivity have been produced in huge amounts in the power and coal industries in Poland. As a result of the combustion of coal in power plants, low-radioactive waste materials are produced, with 226Ra concentration seldom exceeding a few hundreds of Bq/kg. A different situation is observed in coal mines, where, as a result of precipitation of radium from radium-bearing waters, highly radioactive deposits are formed. Sometimes the radioactivity of such materials is extremely high; precipitates from coal mines may have radium concentrations of 400,000 Bq/kg--equivalent to 3% uranium ore. Usually, such deposition takes place underground, but sometimes co-precipitation of radium with barium takes place on the surface, in settling ponds and in rivers. Therefore management of solid waste with technologically enhanced natural radioactivity (TENR) is a very important subject.     

Irrigation canals as tools for climate change adaptation and fish biodiversity management in Southern France

This paper is based on the interdisciplinary research conducted in the south of France that analyses the different economic, social and environmental roles played by agricultural irrigation canals. We argue that beyond their productive role, which is to supply farmers with water, they fulfil other environmental services and play an important role in the context of future climate change to face challenges of adaptation. We point up several ecosystem services provided by such canals, e.g. replenishing the groundwater table, the development of riparian vegetation and wet areas in the Mediterranean zone, tools for regulating flooding and drought, the bases for new cultural approaches to nature. Moreover, they play an important role in the maintenance of an ichthyological biodiversity that is indispensable for the persistence of natural ecosystem. Functioning as an ecological corridor, they display interesting capacities as refuges for certain fish species under stress. Indeed, they can potentially connect upstream and downstream zones over a continuum of more than 300 km and thus covering very contrasted climatic zones (alpine versus Mediterranean). For now, most of these services remain largely unknown and underestimated. However, they serve as assets for territorial development since they combine economic, ecological and social factors whose remodelling is becoming increasingly necessary in the face of climate change.     

A study of radium bioaccumulation in freshwater mussels, Velesunio angasi, in the Magela Creek catchment, Northern Territory, Australia

Freshwater mussels, Velesunio angasi, along Magela Creek in Australia’s Northern Territory were examined to study radionuclide activities in mussel flesh and to investigate whether the Ranger Uranium mine is contributing to the radium loads in mussels downstream of the mine. Radium loads in mussels of the same age were highest in Bowerbird Billabong, located 20 km upstream of the mine site. Variations in the ratio of [Ra]:[Ca] in filtered water at the sampling sites accounted for the variations found in mussel radium loads with natural increases in calcium (Ca) in surface waters in a downstream gradient along the Magela Creek catchment gradually reducing radium uptake in mussels. At Mudginberri Billabong, 12 km downstream of the mine, concentration factors for radium have not significantly changed over the past 25 years since the mine commenced operations and this, coupled with a gradual decrease of the ²²⁸Ra/²²⁶Ra activity ratios observed along the catchment, indicates that the ²²⁶Ra accumulated in mussels is of natural rather than mine origin. The ²²⁸Th/²²⁸Ra ratio has been used to model radium uptake and a radium biological half-life in mussels of approximately 13 years has been determined. The long biological half-life and the low Ca concentrations in the water account for the high radium concentration factor of 30,000-60,000 measured in mussels from the Magela Creek catchment.     

Hierarchical priority setting for restoration in a watershed in NE Spain, based on assessments of soil erosion and ecosystem services

Maintaining and enhancing ecosystem services through the restoration of degraded ecosystems have become an important biodiversity conservation strategy. Deciding where to restore ecosystems for the attainment of multiple services is a key issue for future planning, management, and human well-being. Most restoration projects usually entail a small number of actions in a local area and do not consider the potential benefits of planning restoration at broad regional scales. We developed a hierarchical priority setting approach to evaluate the performance of restoration measures in a semiarid basin in NE Spain (the Martín River Basin, 2,112 km²). Our analysis utilized a combination of erosion (a key driver of degradation in this Mediterranean region) and six spatially explicit ecosystem services data layers (five of these maps plotted surrogates for soil retention and accumulation, water supply and regulation, and carbon storage, and one plotted a cultural service, ecotourism). Hierarchical maps were generated using a geographic information system that combined areas important for providing a bundle of ecosystem services, as state variables, with erosion maps, as the disturbance or regulatory variable. This was performed for multiple scales, thereby identifying the most adequate scale of analysis and establishing a spatial hierarchy of restoration actions based on the combination of the evaluation of erosion rates and the provision of ecosystem services. Our approach provides managers with a straightforward method for determining the spatial distribution of values for a set of ecosystem services in relation to ecological degradation thresholds and for allocating efforts and resources for restoration projects in complex landscapes.     

Abnormal high natural radium concentration in surface waters

Unexpected high 228Ra concentrations, up to 2 Bq 1(-1), were found in waters of a coastal lagoon close to a monazite sand separation plant. Due to their use as process waters in this plant, the initial supposition was a contamination related to its operation. However, it was concluded that these abnormal radium concentrations had a natural origin, springs at the lagoon head area with high 228Ra and 226Ra concentrations. The strong relationship among radium and light rare-earth elements (LREEs), the observed 228Ra/226Ra activity ratio and the rare-earth element pattern in the spring waters suggested that monazite is the main source of nuclides for water, indicating the disturbance of monazite chemical stability by the combined effects of low pH and high salinity. Both factors combined allow relatively low mobility of thorium, but, on the other hand, a relatively high mobility of radium and LREEs.     

Isotope tracing of submarine groundwater discharge offshore Ubatuba, Brazil: results of the IAEA-UNESCO SGD project

Results of groundwater and seawater analyses for radioactive ((3)H, (222)Rn, (223)Ra, (224)Ra, (226)Ra, and (228)Ra) and stable (D and (18)O) isotopes are presented together with in situ spatial mapping and time series (222)Rn measurements in seawater, direct seepage measurements using manual and automated seepage meters, pore water investigations using different tracers and piezometric techniques, and geoelectric surveys probing the coast. This study represents first time that such a new complex arsenal of radioactive and non-radioactive tracer techniques and geophysical methods have been used for simultaneous submarine groundwater discharge (SGD) investigations. Large fluctuations of SGD fluxes were observed at sites situated only a few meters apart (from 0cmd(-1) to 360cmd(-1); the unit represents cm(3)/cm(2)/day), as well as during a few hours (from 0cmd(-1) to 110cmd(-1)), strongly depending on the tidal fluctuations. The average SGD flux estimated from continuous (222)Rn measurements is 17+/-10cmd(-1). Integrated coastal SGD flux estimated for the Ubatuba coast using radium isotopes is about 7x10(3)m(3)d(-1) per km of the coast. The isotopic composition (deltaD and delta(18)O) of submarine waters was characterised by significant variability and heavy isotope enrichment, indicating that the contribution of groundwater in submarine waters varied from a small percentage to 20%. However, this contribution with increasing offshore distance became negligible. Automated seepage meters and time series measurements of (222)Rn activity concentration showed a negative correlation between the SGD rates and tidal stage. This is likely caused by sea level changes as tidal effects induce variations of hydraulic gradients. The geoelectric probing and piezometric measurements contributed to better understanding of the spatial distribution of different water masses present along the coast. The radium isotope data showed scattered distributions with offshore distance, which imply that seawater in a complex coast with many small bays and islands was influenced by local currents and groundwater/seawater mixing. This has also been confirmed by a relatively short residence time of 1-2 weeks for water within 25km offshore, as obtained by short-lived radium isotopes. The irregular distribution of SGD seen at Ubatuba is a characteristic of fractured rock aquifers, fed by coastal groundwater and recirculated seawater with small admixtures of groundwater, which is of potential environmental concern and has implications on the management of freshwater resources in the region.     

Migration and biological effect of natural heavy radionuclides on plants

A complex radioecological study of technogenic landscapes of southern Yakutia showed that the main factor responsible for their contamination with uranium and radium is radionuclide dispersal by air with products of rock weathering. Coefficients of biological absorption by plants decrease with an increase in the contamination level, which is explained by the fact that strongly fixed forms of uranium and radium prevail in the contaminated areas. In addition, the root barrier plays an important role. Radiation load is mainly determined by background gamma-radiation. The contribution of internal irradiation accounted for by incorporated radionuclides does not exceed 16% and decreases with an increase in the level of soil contamination. Manchurian alder seeds produced under conditions of enhanced background radiation are more viable than those from the control area. It is shown that seed generations of plants growing under conditions of chronic irradiation are highly resistant to the radiation factor.     

Availability of radium isotopes and heavy metals from scales and tailings of Polish hard coal mining

Radium and heavy metal contaminated tailings and scales resulting from Polish hard coal mining were investigated for their mobilisation potential by using leaching methods. The main focus is set on a three-step extraction procedure proposed by BCR (Bureau Communautaire de Référence, now Standards Measurements and Testing Programme) of the European Union, which was used for investigating the availability of radium isotopes. In addition, the results of a Polish extraction procedure for the heavy metals' water solubility are presented for rough comparison. After a special treatment, the BCR-reagents were measured by gamma-spectrometry to define their radium activity concentrations; the heavy metal content in the water soluble fractions was determined by ICP-AES. The samples were collected at two different sites influenced by the discharge of pit water from hard coal mining. The tailings were taken from a former tailing pond, which now is no longer in use, but the settled material is still present. At another abandoned and meanwhile flooded tailing pond, the scales were scraped from the inside of a discharge tube. The results obtained show that there is different leaching behaviour between the radium isotopes. The tailings being characterised by surface adsorbed radium provide up to 25% of the initial (226)Ra content, (228)Ra is altogether leached up to 15%. The scales comprise stable radiobaryte (Ba[Ra]SO(4)) and can be considered as being unable to provide radium isotopes, since no trace of radium dissolution was observed. The leaching behaviour of heavy metals is similar to that of radium. Mn, Ni and Zn are dissolved by water from the tailings; the scales do not provide any.     

A study of radium uptake by the water-lily Nymphaea violacea (Lehm) from contaminated sediment

The rate and extent of radium-226 accumulation from sediment by the water-lily Nymphaea violacea (Lehm) were assessed. The plants were collected from Magela Creek, Northern Territory, Australia and grown in ²²⁶RaCl₂-labelled laboratory sediment over a period of 570 days. The nominal sediment activity of 5 Bq g⁻¹ dry weight was 100 times that of the naturally occurring concentration.In the roots and rhizomes, ²²⁶Ra accumulated on plant surfaces. This result was confirmed by autoradiographic studies which showed the presence of an iron-containing plaque on the surface of these tissues with which the radium was closely associated. Little radium reached the pith of the rhizomes and acropetal translocation was not detected. The average concentration ratio for growing rhizomes was 0·22. Assuming first order accumulation kinetics and likely incremental environmental concentrations, this Aboriginal dietary tissue could become dose-limiting within 50 years.The foliar accumulation of radium originating from the sediment was predominately due to contamination via the sediment-water-plant pathway. Differences in foliar radium concentrations in plants of different ages were due to differential biomass turnover rates. Plants with faster biomass turnover had higher average radium concentrations.     

The source of anomalous radioactivity in the springs bordering the Sea of Galilee, Israel

Situated within the Jordan Rift Valley, along the shores of Lake Kinneret (Sea of Galilee) which serves as the national water reservoir of Israel, are saline hot springs that are notable for their enrichment in radon and radium. Though the anomalous radioactivity has been known for almost half a century, the source of the radioactive anomalies has been a subject of conjecture. Radiometric analysis of a rock core drilled through Mt. Arbel, situated to the west of the lake, reveals that the oil shale sequence of the Senonian En Zetim and Ghareb formations is strikingly deficient in radium. Mt. Arbel has been cut by Rift Valley related faults that serve as conduits for ascending brines. The organic matter enriched sequence is encountered in the subsurface at elevations lower than the water level of the nearby radioactive enriched hot springs. It is thus concluded that hot ascending brines underlying the lake flush through the organic matter enriched sequence and remove a substantial percentage of 226Ra from the uranium enriched organic material, before draining to the outlets of the springs. Saline springs that are in contact with organic matter enriched sequence show excess of radium and radon, while fresh water springs in the same stratigraphic position show only excess of radon.     

Studies on the Leaching of Radium and the emanation of radon from fertilizer process sludge

Radium-226 present in rock phosphate is carried to CaCO₃, the main process waste sludge of the fertilizer industry. Disposal of the sludge in the environment enhances the radiation background in the area. Two states of adherence of radium in the sludge have been identified, one loosely bound and the other chemically exchanged. The loosely bound fraction accounts for nearly 40% of the total activity, as demonstrated by leaching studies. Laboratory experiments show that activity leach-out by infiltration of water through the sludge is low. Lateral seepage is found to cause extensive areal contamination due to dispersal of suspended solids in the vicinity of the disposal area. The rate of emanation of radon from the sludge is found to be high, a factor of 10 over the normal background emanation rate. The radiation field in the waste disposal area also shows enhancement, with levels 4–6 times higher than natural background.     

Pesticide levels and environmental risk in aquatic environments in China — A review

China is one of the largest producers and consumers of pesticides in the world today. Along with the widespread use of pesticides and industrialization, there is a growing concern for water quality. The present review aims to provide an overview of studies on pesticides in aquatic environments in China. The levels in the water, sediment and biota were scored according to a detailed environmental classification system based on ecotoxicological effect, which is therefore a useful tool for assessing the risk these compounds pose to the aquatic ecosystem. Our review reveals that the most studied areas in China are the most populated and the most developed economically and that the most frequently studied pesticides are DDT and HCH. We show maps of where studies have been conducted and show the ecotoxicological risk the pesticides pose in each of the matrices. Our review pinpoints the need for biota samples to assess the risk. A large fraction of the results from the studies are given an environmental classification of “very bad” based on levels in biota. In general, the risk is higher for DDT than HCH. A few food web studies have also been conducted, and we encourage further study of this important information from this region.The review reveals that many of the most important agricultural provinces (e.g., Henan, Hubei and Hunan) with the largest pesticide use have been the subject of few studies on the environmental levels of pesticides. We consider this to be a major knowledge gap for understanding the status of pesticide contamination and related risk in China. Furthermore, there is also a lack of studies in remote Chinese environments, which is also an important knowledge gap. The compounds analyzed and reported in the studies represent a serious bias because a great deal of attention is given to DDT and HCH, whereas the organophosphate insecticides dominating current use are less frequently investigated. For the future, we point to the need for an organized monitoring plan designed according to the knowledge gaps in terms of geographical distribution, compounds included, and risks.     

Simultaneous measurement of (226)Ra and (228)Ra in natural water by liquid scintillation counting

Several types of bottled drinking water originating from three different areas in Egypt are studied through measurement of radium activity, assessment of related annual dose for adults and finally to define the role of water quality on radium levels. The mean levels of (226)Ra activity range from 0.44 to 0.92 Bq/L and the mean levels of (228)Ra from 0.30 to 0.78 Bq/L, with related (226)Ra/(228)Ra ratios ranging from 2.61 to 0.56. Water types originating from the Eastern Nile Delta area are characterized by low (226)Ra levels and relatively high (228)Ra activity, presumably due to the muddy agricultural nature of this area, which is subject to water from several surface resources for irrigation. In general, the mean activity levels for both (226)Ra and (228)Ra are within those in drinking water in several other countries and the annual ingested dose is comparable with the typical range reported by UNSCEAR. Also, the effect of TDS, pH, calcium, bicarbonate, sulphate and chloride ion concentrations on radium levels is studied and discussed.     

Estimating the dynamics of groundwater input into the coastal zone via continuous radon-222 measurements

Submarine groundwater discharge (SGD) into the coastal zone has received increased attention in the last few years as it is now recognized that this process represents an important pathway for material transport. Assessing these material fluxes is difficult, as there is no simple means to gauge the water flux. To meet this challenge, we have explored the use of a continuous radon monitor to measure radon concentrations in coastal zone waters over time periods from hours to days. Changes in the radon inventories over time can be converted to fluxes after one makes allowances for tidal effects, losses to the atmosphere, and mixing with offshore waters. If one assumes that advective flow of radon-enriched groundwater (pore waters) represent the main input of 222Rn in the coastal zone, the calculated radon fluxes may be converted to water fluxes by dividing by the estimated or measured 222Rn pore water activity. We have also used short-lived radium isotopes (223Ra and 224Ra) to assess mixing between near-shore and offshore waters in the manner pioneered by. During an experiment in the coastal Gulf of Mexico, we showed that the mixing loss derived from the 223Ra gradient agreed very favorably to the estimated range based on the calculated radon fluxes. This allowed an independent constraint on the mixing loss of radon-an important parameter in the mass balance approach. Groundwater discharge was also estimated independently by the radium isotopic approach and was within a factor of two of that determined by the continuous radon measurements and an automated seepage meter deployed at the same site.     

大型水生植物对骆马湖氮磷元素及磷酸酶活性的影响

在骆马湖中选择有大型水生植物生长区域及无草对照区,测定主要水质指标,采集沉积物柱状样,分层测定沉积物氮磷元素含量及磷酸酶活性,探讨大型水生植物对骆马湖生态系统中氮磷元素及磷酸酶活性影响特征,结果表明：（1）大型水生植物生长区上覆水透明度明显高于对照(CK),是对照(CK)19倍;但有草区凯氏氮(KN)、可溶性氮(DN)含量低于对照(CK),方差分析表明二者差异极显著(〖WTBX〗p〖WTBZ〗≤001);（2）大型水生植物生长能降低磷酸酶的活性,有草区不同深度沉积物酸（碱）磷酸酶活性总体小于对照(CK),但沉积物表层磷酸酶活性最强;（3）有草区不同深度沉积物TP含量低于对照(CK),但有草区表层沉积物凯氏氮(KN)含量高于对照(CK ).     

Linking biophysical models and public preferences for ecosystem service assessments: a case study for the Southern Rocky Mountains

Through extensive research, ecosystem services have been mapped using both survey-based and biophysical approaches, but comparative mapping of public values and those quantified using models has been lacking. In this paper, we mapped hot and cold spots for perceived and modeled ecosystem services by synthesizing results from a social-values mapping study of residents living near the Pike–San Isabel National Forest (PSI), located in the Southern Rocky Mountains, with corresponding biophysically modeled ecosystem services. Social-value maps for the PSI were developed using the Social Values for Ecosystem Services tool, providing statistically modeled continuous value surfaces for 12 value types, including aesthetic, biodiversity, and life-sustaining values. Biophysically modeled maps of carbon sequestration and storage, scenic viewsheds, sediment regulation, and water yield were generated using the Artificial Intelligence for Ecosystem Services tool. Hotspots for both perceived and modeled services were disproportionately located within the PSI’s wilderness areas. Additionally, we used regression analysis to evaluate spatial relationships between perceived biodiversity and cultural ecosystem services and corresponding biophysical model outputs. Our goal was to determine whether publicly valued locations for aesthetic, biodiversity, and life-sustaining values relate meaningfully to results from corresponding biophysical ecosystem service models. We found weak relationships between perceived and biophysically modeled services, indicating that public perception of ecosystem service provisioning regions is limited. We believe that biophysical and social approaches to ecosystem service mapping can serve as methodological complements that can advance ecosystem services-based resource management, benefitting resource managers by showing potential locations of synergy or conflict between areas supplying ecosystem services and those valued by the public.     

Radioactivity in the environment around past radium and uranium mining sites of Portugal

Measurements of ambient radiation doses and determination of radionuclide concentrations in mining waste and soils were performed in 60 areas of former radium and uranium mining. In several places, mining waste and low-grade uranium ore left on the surface contain radioactivity above regional background. Most of the former mining sites present no enhanced radionuclide concentrations. However, in the mining facilities where the radioactive ore was chemically extracted, mill tailings contain materials with elevated levels of radioactivity, up to 200 times the levels in unaffected soils of the region. Mud from neutralization ponds used to treat acid mine waters contains also elevated radionuclide concentrations. Furthermore, depending on the type of waste, the radioelement composition varies. Environmental rehabilitation measures shall take these differences into account in order to prevent in the long term the radioactive contamination of agriculture soils and water resources, and to ensure adequate radiological protection to the public and to the environment.     

Occurrence of Kepone in white-footed mice (Peromyscus leucopus noveboracensis) on Jamestown Island,Virginia

Significant quantities of Kepone (chloredecone) were found in the livers of white-footed mice captured on Jamestown Island, Virginia, in the James River. Levels of Kepone were significantly greater than found in the livers of mice of the same species from inland populations captured on the Ecological Study Area of the College of William and Mary, Williamsburg, Virginia, adjacent to a tributary of the James River but at a distance of approximately 4.8 km from the river. These data are the first indicating Kepone contamination of small mammals in a terrestrial ecosystem.     

基于淹水特征的分时段湿地生态系统管理——以南洞庭湖万子湖为例

利用2013年遥感影像和地形图制作地势图,将万子湖湿地洲滩分为27 m以下、27~28、28~29、29~30、30 m以上共5级地势阶梯。利用1983~2013年万子湖逐日平均水位数据分析不同地势阶梯洲滩在春汛期、洪水期、退水期、枯水期等4个时段的淹水特征,结合生物特性和人为干扰分析,确定万子湖湿地生态系统管理的边界范围和策略。研究表明:4个时段中的生态系统管理边界分别为29、31、29、28 m地势阶梯分界线,3个重点时段和管理区域为:春汛期,管理目标是产卵亲鱼保护,28 m以下洲滩是重点管理区域;退水期,管理目标是保障鱼类洄游,28 m以下洲滩和湖槽洄游通道是重点管理区域;枯水期,管理目标是洲滩上鱼类产卵场、幼鱼索饵场和越冬候鸟栖息地的恢复与保护,28 m以下洲滩是重点管理区域。而生态系统管理重点则是去除过度人为干扰(包括洲滩过度开发、过度捕捞),恢复湿地生态系统整体性功能,应坚决停止重点区域内滩涂水面的养殖承包、引淤抬洲、洲滩植树等系列干扰性活动。