Historical record of mercury contamination in sediments from the Babeni Reservoir in the Olt River,Romania

Background, aim and scope

Mercury (Hg) is a ubiquitous and hazardous contaminant in the aquatic environment showing a strong biomagnification effect along the food chain. The most common transfer path of Hg to humans is contaminated fish consumption. In severely exposed humans, Hg poisoning may lead to damage in the central nervous system. Thus, it is important to examine current and past contamination levels of Hg in aquatic milieu. The Olt River is the largest Romanian tributary of the Danube River. The use of Hg as an electrode in a chlor-alkali plant contributed to the contamination of the aquatic environment in the Rm Valcea region. The purpose of this study was to compare the current state of Hg contamination with the past contamination using a historical record obtained from a dated sediment core from one of the Olt River reservoirs (Babeni) located downstream from the chlor-alkali plant. To our knowledge, no published data on Hg contamination in this region are available. The Babeni Reservoir was selected for this study because it is situated downstream from the chlor-alkali plant, whilst the other reservoirs only retain the pollutants coming from the upstream part of the watershed. Preliminary analyses (unpublished) showed high Hg concentrations in the surface sediment of the Babeni Reservoir. One core was taken in the upstream Valcea Reservoir to provide a local background level of Hg concentrations in sediments.

Results and discussion

Sediment texture was uniform in the cores from both reservoirs. Laminated sediment structure, without any obvious discontinuities, was observed. Hg concentrations in the sediment core from the Valcea Reservoir were low and constant (0.01–0.08 mg/kg). In Babeni Reservoir sediments, Hg concentrations were very high in the deeper core section (up to 45 mg/kg in the longest core) and decreased to lower concentrations toward the top of the cores (1.3–2.4 mg/kg). This decrease probably reflects technological progress in control of emissions from the Hg-cell-based chlor-alkali industry. Two strong peaks could be distinguished in older sediments. The mean rate of sedimentation (5.9 cm/year) was calculated from the depth of the ¹³⁷Cs Chernobyl peak. This was in good agreement with the sedimentation rate estimated at this site from a bathymetric study. Assuming a constant sedimentation rate, the two Hg peaks would reflect two contamination events in 1987 and 1991, respectively. However, it is also possible that the two peaks belong to the same contamination event in 1987 but were separated by a sediment layer richer in sand and silt. This layer had a low Hg concentration, which can be interpreted as a mass deposition event related to a major flood bringing Hg-free sediments.

Conclusions

Whilst the chlor-alkali plant partly switched to a cleaner technology in 1999, no obvious decrease of Hg concentrations was observed in recent decade. Results from the sediment core reflected the historical trend of Hg release from the chlor-alkali plant, revealed important contamination episodes and confirmed a legacy of contamination of Hg in recent sediments even if the concentrations of Hg decreased toward the surface due to a more efficient emission control.

Recommendations and perspectives

Although the Hg concentrations in Babeni Reservoir sediments were extremely high in the late eighties and they remain one order of magnitude higher in the surface sediments than in sediments from the upstream reservoir, little is known about the transfer of Hg to the biota and human population. Our initial measurements indicate the presence of monomethyl-Hg (MMHg) in pore water, but further studies are necessary to evaluate fluxes of MMHg at the sediment–water interface. Samples of fish and hair from various groups of the local population were recently collected to evaluate the potential hazard of Hg contamination to human health in the Rm Valcea region.

     

Spatial and temporal variability of atmospheric mercury concentrations emitted from a coal-fired power plant in Mexico

Atmospheric mercury in the environment as a result of the consumption of fossil fuels, such as coal used in electricity generation, has gained increased attention worldwide because of its toxicity, atmospheric persistence, and bioaccumulation. Determining or predicting the concentration of this pollutant in ambient air is essential for determining sensitive areas requiring health protection. This study investigated the spatiotemporal variability of gaseous elemental mercury (GEM) concentrations and its dry deposition surrounding the Presidente Plutarco Elías Calles (CETEPEC) coal-fired power plant, located on Mexico’s Pacific coast. The CALPUFF dispersion model was applied on the basis of the daily consumption of coal during 2013 for each generating unit in the power plant and considering the local scale. The established 300-ng/m³ annual average risk factor considered by the U.S. Department of Health and Human Services (U.S. DHHS) and Integrated Risk Information System (IRIS) must not be exceeded to meet satisfactory air quality levels. An area of 65 × 60 km was evaluated, and the results show that the risk level for mercury vapor was not exceeded because the annual average concentration was 2.8 ng/m³. Although the predicted risk level was not exceeded, continuous monitoring studies of GEM and of particulates in the atmosphere, soil, and water may be necessary to identify the concentration of this pollutant, specifically that resulting from coal-fired power plants operated in environmental areas of interest in Mexico. The dry mercury deposition was low in the study area; according to the CALPUFF model, the annual average was 1.40E?2 ng/m²/sec. These results represent a starting point for Mexico’s government to implement the Minamata Convention on Mercury, which Mexico signed in 2013.

Implications: The obtained concentrations of mercury from a bigger coal-fired plant in Mexico, through the application of the CALPUFF dispersion model by the mercury emissions, are below the level recommended according to the US Department of Health and Human Services and Integrated Risk Information System. These results provide evidence of important progress in the planning and installation to the future of monitoring mercury stations in the area of interest.     

Mercury human exposure through fish consumption in a reservoir contaminated by a chlor-alkali plant: Babeni reservoir (Romania)

Purpose  

Chlor-alkali plants are one of the most important point sources of mercury to aquatic environment. The problem of Hg contamination has been studied in a region, Rm Valcea (Romania), impacted by the wastewater discharge of a chlor-alkali plant. The purpose of the present study is to evaluate the current status of mercury pollution in the Babeni reservoir (Olt River) and the exposure of local population via fish consumption to mercury originating from the chlor-alkali plant.     

Nurse Plant and Floral Biology of a Rare Night-Blooming Cereus, Peniocereus striatus (Brandegee) F. Buxbaum

The Sonoran night-blooming cereus ( Peniocereus striatus ) is a rare cactus found in the Sonoran Desert. Its survival is dependent on maintenance of its habitat and its ability to recruit. This study evaluates the role of nurse plants in P. striatus survival and the floral and pollination ecology controlling recruitment. A strong association was detected between P. striatus and its nurse plants, which include Olneya tesota and Larrea tridentata . Because of the harvesting of Olneya tesota and Prosopis velutina for charcoal over a 20,000 square km area of its range, this night-blooming cereus is vulnerable to rapid habitat degradation in both Sonora (Mexico) and adjacent Arizona (U.S.A.). The temporal and local scarcity of sphingid moths available for pollination caused by pesticides and small flower numbers, appear to produce low recruitment rates. These two important threats to the biotic associates of this cactus have increased its natural rarity. This can only be alleviated through international cooperation.     

Forest Fragmentation and Bird Extinctions: San Antonio Eighty Years Later

We report on the extent of bird extinctions at San Antonio, a fragmented cloud forest site in the western Andes of Colombia, for which surveys dating back to 1911 and 1959 an available. In 1911, 128 forest bird species were present in San Antonio. Twenty-four species had disappeared by 1959, and since then 16 more species have gone locally extinct, for a total of 40 species or 31% of the original avifauna. We analyzed patterns of extinction in relation to geographic distribution and foraging guilds. We found that in this montane assemblage, being at the limits of the altitudinal distribution was the main correlate of extinction; 37% of the extinct species were at the upper limit of their altiudinal distribution. We also found that the most vulnerable guilds were the understory insectivores and the large canopy frugivores. Our study illustrates the extent of bird extinctions that are currently undocumented in the highly fragmented forests of the northern Andes, where the absence of baseline information on the fauna of unaltered forests is a limiting factor for the development of conservation and management plans. We stress the need to establish data bases and long-term monitoring projects for the Andean fauna.     

<Emphasis Type="Italic">Alexandrium catenella</Emphasis> (Dinophyceae), a toxic ribotype expanding in the NW Mediterranean Sea

The presence of the paralytic shellfish poisoning (PSP) dinoflagellate Alexandrium catenella in the north western (NW) Mediterranean Sea has been known since 1983. From this date on, the species has spread along the Spanish and Italian coastlines. Information concerning A. catenella isolates in the NW Mediterranean Sea was gained through phylogenetic studies. Twenty established toxic cultures of A. catenella taken from various NW Mediterranean Sea locations were analysed by nucleotide sequencing of the 5.8S rDNA and internal transcribed spacer regions. These rDNA ribosomal markers resulted useful in delineating the phylogenetic position of this species in the genus Alexandrium as well as in determining relationships between A. catenella isolates from different geographic areas. The phylogenetic position of the Mediterranean A. catenella ribotype, when compared to the “Alexandrium tamarense/catenella/fundyense species complex”, fits this species complex well. All the Mediterranean A. catenella isolates were constituted by only one genetic ribotype. By comparing the isolate sequences with those of other geographic areas, it revealed that the Mediterranean A. catenella ribotype was closely related to the A. catenella from Japan, Western Pacific Ocean. It was also evident that in temperate Japanese waters, a genetic variability was detected within A. catenella isolates; in fact, all strains resulted divergent showing as many as 15 mutational steps. The possibility that A. catenella has been recently introduced into the Mediterranean basin from temperate Asian areas is discussed.     

Mental health and media links based on five essential elements to promote psychosocial support for victims: the case of the earthquake in Chile in 2010

This paper reviews the role of news with respect to the mental health of a population exposed to a disaster. It is based on the five essential elements of psychosocial care presented by Stevan E. Hobfoll et al. (2007) that can be introduced after a potentially traumatic event: promoting a sense of safety, calming, self and collective efficacy, connectedness, and hope. This study developed a method to relate these elements to television coverage and applied it to the stories (n=1,169) aired by the main networks in Chile in the 72 hours after an 8.8 magnitude earthquake struck on 27 February 2010. Of the five elements, promoting a sense of safety occurred most often (82.72 per cent), whereas the others were barely present (less than 10 per cent). The study argues that these elements can increase the possibility of framing the news, given that the audience watching can also be affected by a disaster.     

Essential and non-essential heavy metals in skin and muscle tissues of franciscana dolphins (Pontoporia blainvillei) from the southern Argentina coast

Franciscana dolphin, Pontoporia blainvillei, is a small and ‘vulnerable’ cetacean, which exhibits coastal marine habits according to the IUCN (2008). The aim of this work was to determine the presence of essential (Zn and Cu) and non-essential (Cd, Pb, Cr and Ni) heavy metals in skin (n=33) and muscle (n=36) tissues of franciscana dolphins from southern Buenos Aires, establishing the influence of biological parameters on the accumulation of these pollutants. Histological standardised methods were used to determine both age and sexual maturity of the dolphins. Heavy metal concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Zn was 8-fold higher than Ni in the skin. Zn was significantly affected by the age of the specimens and might be influenced by the state of body condition. Ni showed a behaviour pattern similar to that of non-essential heavy metals. The relationship between Ni and Zn concentration determined in skin and muscle might provide a tool for studying the general condition of endangered marine mammal species such as franciscana dolphins.     

GIS-based modeling of the geographic distribution of Quercus emoryi Torr. (Fagaceae) in México and identification of significant environmental factors influencing the species’ distribution

The greatest concentration of oak species in the world is believed to be found in Mexico. These species are potentially useful for reforestation because of their capacity to adapt to diverse environments. Knowledge of their geographic distribution and of species–environment relations is essential for decision-making in the management and conservation of natural resources. The objectives of this study were to develop a model of the distribution of Quercus emoryi Torr. in Mexico, using geographic information systems and data layers of climatic and other variables, and to determine the variables that significantly influence the distribution of the species. The study consisted of the following steps: (A) selection of the target species from a botanical scientific collection, (B) characterization of the collecting sites using images with values or categories of the variables, (C) model building with the overlay of images that meet the habitat conditions determined from the characterization of sites, (D) model validation with independent data in order to determine the precision of the model, (E) model calibration through adjustment of the intervals of some variables, and (F) sensitivity analysis using precision and concordance non-parametric statistics applied to pairs of images. Results show that the intervals of the variables that best describe the species’ habitat are the following: altitude from 1650 to 2750 amsl, slope from 0 to 66°; average minimum temperature of January from −12 to −3 °C; mean temperature of June from 11 to 25 °C; mean annual precipitation from 218 to 1225 mm; soil units: lithosol, eutric cambisol, haplic phaeozem, chromic luvisol, rendzina, luvic xerosol, mollic planosol, pellic vertisol, eutric regosol; type of vegetation: oak forest, oak–pine forest, pine forest, pine–oak forest, juniperus forest, low open forest, natural grassland and chaparral. The resulting model of the geographic distribution of Quercus emoryi in Mexico had the following values for non-parametric statistics of precision and agreement: Kappa index of 0.613 and 0.788, overall accuracy of 0.806 and 0.894, sensitivity of 0.650 and 0.825, specificity of 0.963, positive predictive value of 0.945 and 0.957 and negative predictive value of 0.733 and 0.846. Results indicate that the variable average minimum temperature of January, with a maximum value of −3 °C, is an important factor in limiting the species’ distribution.     

Polymer types ingested by northern fulmars (Fulmarus glacialis) and southern hemisphere relatives

Environmental Science and Pollution Research - Although ingestion of plastic by tubenosed seabirds has been documented regularly, identification of the polymer composition of these plastics has...