RESUMO
One of the most representative predator species in tropical ecosystems is caiman that can provide relevant information about the impact of mercury (Hg) associated with artisanal and small-scale gold mining. To evaluate the degree to which adverse effects are likely to occur in Caiman crocodilus, total Hg (THg) concentrations in different tissues and DNA damage in erythrocytes were determined. Samples of claws, scutes, and blood were taken from 65 specimens in sites impacted by upstream gold mining, and in a crocodile breeding center as control site, located in a floodplain in northern Colombia. In all the sites, the highest THg among tissues was in the following order: clawsâ¯>>â¯scutesâ¯>â¯blood. High concentrations of THg were found in the different tissues of the specimens captured in areas impacted by mining activities, with mean values in claws (1100â¯ng/gâ¯ww), caudal scutes (490â¯ng/gâ¯ww), and blood (65â¯ng/gâ¯ww), and statistically significant differences compared to those of the control site (pâ¯<â¯0.05). THg in scutes from impacted sites are 15-fold higher than in control, whereas for claws and blood are 8 times higher, and a high significant correlation with THg was found in all the tissues. The comet assay reveals significant differences in the DNA damage in the exposed reptiles compared to the controls (pâ¯<â¯0.01). In sum, C. crocodilus from La Mojana floodplain presents a high ecological risk given its genotypic susceptibility to Hg levels present in its habitat, which could possibly influence vital functions such as reproduction of the species and the ecological niche that it represents within the ecosystem.
Assuntos
Jacarés e Crocodilos/fisiologia , Monitoramento Ambiental , Mercúrio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Colômbia , Dano ao DNA , Ecossistema , Ouro , Mercúrio/análise , Mercúrio/toxicidade , Mineração , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
Phytoremediation has received increased attention over the recent decades, as an emerging and eco-friendly approach that utilizes the natural properties of plants to remediate contaminated water, soils or sediments. The current study provides information about a pilot-scale experiment designed to evaluate the potential of the anchored aquatic plant Limnocharis flava for phytoremediation of water contaminated with mercury (Hg), in a constructed wetland (CW) with horizontal subsurface flow (HSSF). Mine effluent used in this experiment was collected from a gold mining area located at the Alacran mine in Colombia (Hg: 0.11 ± 0.03 µg mL-1) and spiked with HgNO3 (1.50 ± 0.09 µg mL-1). Over a 30 day test period, the efficiency of the reduction in the heavy metal concentration in the wetlands, and the relative metal sorption by the L. flava, varied according to the exposure time. The continued rate of removal of Hg from the constructed wetland was 9 times higher than the control, demonstrating a better performance and nearly 90% reduction in Hg concentrations in the contaminated water in the presence of L. flava. The results in this present study show the great potential of the aquatic macrophyte L. flava for phytoremediation of Hg from gold mining effluents in constructed wetlands.
Assuntos
Alismataceae/química , Biodegradação Ambiental , Ouro/química , Mercúrio/metabolismo , Mineração , Poluentes do Solo/metabolismo , Poluentes Químicos da Água/metabolismo , Áreas Alagadas , Mercúrio/isolamento & purificação , Poluentes do Solo/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodosRESUMO
Artisanal and small-scale gold mining (ASGM) is the largest sector of demand for mercury (Hg), and therefore, one of the major sources of Hg pollution in the environment. This study was conducted in the Alacrán gold-mining site, one of the most important ASGM sites in Colombia, to identify native plant species growing in Hg-contaminated soils used for agricultural purposes, and to assess their potential as phytoremediation systems. Twenty-four native plant species were identified and analysed for total Hg (THg) in different tissues (roots, stems, and leaves) and in underlying soils. Accumulation factors (AF) in the shoots, translocation (TF) from roots to shoots, and bioconcentration (BCF) from soil-to-roots were determined. Different tissues from all plant species were classified in the order of decreasing accumulation of Hg as follows: roots > leaves > stems. THg concentrations in soil ranged from 230 to 6320 ng g(-1). TF values varied from 0.33 to 1.73, with high values in the lower Hg-contaminated soils. No correlation was found between soils with low concentrations of Hg and plant leaves, indicating that TF is not a very accurate indicator, since most of the Hg input to leaves at ASGM sites comes from the atmosphere. On the other hand, the BCF ranged from 0.28 to 0.99, with Jatropha curcas showing the highest value. Despite their low biomass production, several herbs and sub-shrubs are suitable for phytoremediation application in the field, due to their fast growth and high AF values in large and easily harvestable plant parts. Among these species, herbs such as Piper marginathum and Stecherus bifidus, and the sub-shrubs J. curcas and Capsicum annuum are promising native plants with the potential to be used in the phytoremediation of soils in tropical areas that are impacted by mining.