Adaptation to osmotic stress provides protection against ammonium nitrate in Pelophylax perezi embryos

The negative effects of pollution on amphibians are especially high when animals are additionally stressed by other environmental factors such as water salinity. However, the stress provoked by salinity may vary among populations because of adaptation processes. We tested the combined effect of a common fertilizer, ammonium nitrate (0-90.3 mg N-NO₃NH₄/L), and water salinity (0-2‰) on embryos of two Pelophylax perezi populations from ponds with different salinity concentrations. Embryos exposed to the fertilizer were up to 17% smaller than controls. Survival rates of embryos exposed to a single stressor were always below 10%. The exposure to both stressors concurrently increased mortality rate (>95%) of embryos from freshwater. Since the fertilizer was lethal only when individuals were stressed by the salinity, it did not cause lethal effects on embryos naturally adapted to saline environments. Our results underscore the importance of testing multiple stressors when analyzing amphibian sensitivity to environmental pollution.     

Environmental pollution by antibiotics and by antibiotic resistance determinants

Antibiotics are among the most successful drugs used for human therapy. However, since they can challenge microbial populations, they must be considered as important pollutants as well. Besides being used for human therapy, antibiotics are extensively used for animal farming and for agricultural purposes. Residues from human environments and from farms may contain antibiotics and antibiotic resistance genes that can contaminate natural environments. The clearest consequence of antibiotic release in natural environments is the selection of resistant bacteria. The same resistance genes found at clinical settings are currently disseminated among pristine ecosystems without any record of antibiotic contamination. Nevertheless, the effect of antibiotics on the biosphere is wider than this and can impact the structure and activity of environmental microbiota. Along the article, we review the impact that pollution by antibiotics or by antibiotic resistance genes may have for both human health and for the evolution of environmental microbial populations.     

不同来源的海州香薷和野胡萝卜的铜抗性及铜积累差异

以来自矿区(铜绿山和赤马山铜矿)和非矿区(红安、武汉严西湖)的海州香薷和野胡萝卜种群为对象,通过土培实验,研究了2种植物的铜抗性及铜吸收积累差异.结果显示,来自矿区的海州香薷和野胡萝卜种群的铜抗性都明显高于非矿区种群,但2种植物种群的铜吸收积累特征明显不同:海州香薷植物吸收的Cu主要集中在根中,但矿区种群吸收积累的铜量明显低于非矿区种群;而野胡萝卜吸收的Cu主要集中在地上部分(地上部分的Cu富集量是根的1.5倍),但积累的铜量在矿区和非矿区种群间没有明显的差异.因此,来自矿区的海州香薷可能进化为铜避性对策,而野胡萝卜的铜抗性与其吸收积累的总量没有明显的关系,但有很好的向地上运输能力.     

Marine macroalgal community structure, metal content and reproductive function near an acid mine drainage outflow

Marine macroalgal communities were examined near the outflow of acid mine drainage (AMD) from the Britannia Mine, British Columbia, Canada. No marine algae were present within 100 m of the mouth of Britannia Creek, which carries the AMD into the marine environment. At greater distances (300-700 m) from this Creek, mean summer cover of filamentous green algae, mostly Enteromorpha intestinalis, was >60%, which was significantly higher than at nearby reference stations. At still greater distances (600-1000 m) from Britannia Creek, Fucus gardneri dominated algal communities that were similar to those at reference stations. No consistent differences were detected in mean plant length, mean per cent cover or mean oocyte production between F. gardneri near Britannia Creek and those at reference stations. Cu body burden in F. gardneri near Britannia Creek was five to 17 times higher than in reference plants.     

Evidence of population genetic effects in Peromyscus melanophrys chronically exposed to mine tailings in Morelos, Mexico

Effects of environmental chemical pollution can be observed at all levels of biological organization. At the population level, genetic structure and diversity may be affected by exposure to metal contamination. This study was conducted in Huautla, Morelos, Mexico in a mining district where the main contaminants are lead and arsenic. Peromyscus melanophrys is a small mammal species that inhabits Huautla mine tailings and has been considered as a sentinel species. Metal bioaccumulation levels were examined by inductively coupled plasma mass spectrometry and genetic analyses were performed using eight microsatellite loci in 100 P. melanophrys individuals from 3 mine tailings and 2 control sites. The effect of metal bioaccumulation levels on genetic parameters (population and individual genetic diversity, genetic structure) was analyzed. We found a tissue concentration gradient for each metal and for the bioaccumulation index. The highest values of genetic differentiation (Fst and Rst) and the lowest number of migrants per generation (Nm) were registered among the exposed populations. Genetic distance analyses showed that the most polluted population was the most genetically distant among the five populations examined. Moreover, a negative and significant relationship was detected between genetic diversity (expected heterozygosity and internal relatedness) and each metal concentration and for the bioaccumulation index in P. melanophrys. This study highlights that metal stress is a major factor affecting the distribution and genetic diversity levels of P. melanophrys populations living inside mine tailings. We suggest the use of genetic population changes at micro-geographical scales as a population level biomarker.     

An integrative assessment of a watershed impacted by abandoned mined land discharges

The Ely Creek watershed in Lee County, VA, USA, contains an abundance of abandoned mined land areas with acid mine drainage (AMD) that contaminate the majority of the creek and its confluence into Stone Creek. Acidic pH measurements ranged from 2.73 to 5.2 at several stations throughout the watershed. Sediments had high concentrations of iron (approximately 10,000 mg kg-1), aluminum (approximately 1,500 mg kg-1), magnesium (approximately 400 mg kg-1) and manganese (approximately 150 mg kg-1), and habitat was partially to non-supporting at half of the stations due to sedimentation. Benthic macroinvertebrate surveys at six of 20 stations sampled in the watershed yielded no macroinvertebrates, while eight others had total abundances of only one to nine organisms. Four reference stations contained > or = 100 organisms and at least 13 different taxa. Asian clam in situ toxicity testing supported field survey results. Laboratory, 10-day survival/impairment sediments tests with Daphnia magna and Chironomus tentans and 48-h water column bioassays with Ceriodaphnia dubia indicated environmental stress to a lesser degree. Ten parameters that were directly influenced by AMD through physical, chemical, ecological and toxicological endpoints were assimilated into an ecotoxicological rating (ETR) to form a score of 0-100 points for the 20 sampling stations, and the lower the score the greater the AMD stress. Twelve of the 15 sampling stations influenced by AMD received an ETR score of 13.75-57.5, which were categorized as severely stressed (i.e. comprised the < 60 percentile category) and worthy of the highest priority for future ecological restoration activities in the watershed.     

磁黄铁矿氧化机理及酸性矿山废水防治的研究进展

磁黄铁矿是矿山尾矿堆中最为常见且分布很广的一种硫化铁矿物.由于硫化物矿物氧化后不仅产生酸性废水,还会释放出大量可溶的、生物可利用形态的微量金属,并且酸性环境会进一步增强这些有毒金属的移动性,因此是造成矿山周围水体环境污染的罪魁祸首.为了阻止或降低磁黄铁矿的自然风化反应速度从而达到源头治理酸性矿山废水的目的,首先必须研究它在各种条件下的氧化机理、氧化产物和氧化速度.对近年来国外在磁黄铁矿晶体结构、反应活性以及酸性矿山废水的产生与防治等方面的研究进行了综述.     

Corrosion control when using passively treated abandoned mine drainage as alternative makeup water for cooling systems

Passively treated abandoned mine drainage (AMD) is a promising alternative to fresh water as power plant cooling water system makeup water in mining regions where such water is abundant. Passive treatment and reuse of AMD can avoid the contamination of surface water caused by discharge of abandoned mine water, which typically is acidic and contains high concentrations of metals, especially iron. The purpose of this study was to evaluate the feasibility of reusing passively treated AMD in cooling systems with respect to corrosion control through laboratory experiments and pilot-scale field testing. The results showed that, with the addition of the inhibitor mixture orthophosphate and tolyltriazole, mild steel and copper corrosion rates were reduced to acceptable levels (< 0.127 mm/y and < 0.0076 mm/y, respectively). Aluminum had pitting corrosion problems in every condition tested, while cupronickel showed that, even in the absence of any inhibitor and in the presence of the biocide monochloramine, its corrosion rate was still very low (0.018 mm/y).     

Ecotoxicity revealed in parasite communities of Sigmodon hispidus in terrestrial environments contaminated with petrochemicals

Several studies have documented contaminant-induced alterations in host-parasite relationships of vertebrate hosts in aquatic environments, suggesting this functional relationship may be useful for monitoring community-level effects of stressors in terrestrial systems. We hypothesized that gastrointestinal helminth communities of hispid cotton rat (Sigmodon hispidus) hosts would be sensitive to exposure to complex mixtures of petrochemicals in soils of tallgrass prairie habitats contaminated with oil refinery wastes. Parasite communities were surveyed (1993-95) on three contaminated and two reference sites on an oil refinery complex in Oklahoma. Abundance of Schizotaenia sigmodontis infections was two-fold higher in hosts from reference than contaminated sites. Strongyloides sigmodontis exhibited pronounced seasonal differences in prevalence and abundance in host populations from reference sites, with much higher seasonal variation compared to hosts from contaminated sites. Other helminth species, including Schizotaenia sigmodontis, Protospirura muris, Longistriata adunca, also exhibited seasonal fluctuations in abundance. Differences in species richness and composition were also observed, with hosts from the reference sites consistently supporting a higher mean number of species compared to those from contaminated sites. Differences in community structure indicate that host-parasite relationships can provide another useful method for monitoring community-level impacts of contamination in a terrestrial system.     

Small mammal populations at hazardous waste disposal sites near Houston, Texas, USA

Small mammals were trapped, tagged and recaptured in 0.45 ha plots at six hazardous industrial waste disposal sites to determine if populations, body mass and age structures were different from paired control site plots. Low numbers of six species of small mammals were captured on industrial waste sites or control sites. Only populations of hispid cotton rats at industrial waste sites and control sites were large enough for comparisons. Overall population numbers, age structure, and body mass of adult male and female cotton rats were similar at industrial waste sites and control sites. Populations of small mammals (particularly hispid cotton rats) may not suffice as indicators of environments with hazardous industrial waste contamination.     

Quantitative–spatial assessment of soil contamination in S. Francisco de Assis due to mining activity of the Panasqueira mine (Portugal)

Through the years, mining and beneficiation processes produces large amounts of As-rich mine wastes laid up in huge tailings and open-air impoundments (Barroca Grande and Rio tailings) that are the main source of pollution in the surrounding area once they are exposed to the weathering conditions leading to the formation of AMD and consequently to the contamination of the surrounding environments, in particularly soils. In order to investigate the environmental contamination impact on S. Francisco de Assis (village located between the two major impoundments and tailings) agricultural soils, a geochemical survey was undertaken to assess toxic metals associations, related levels and their spatial distribution, and to identify the possible contamination sources. According to the calculated contamination factor, As and Zn have a very high contamination factor giving rise to 65.4 % of samples with a moderate to high pollution degree; 34.6 % have been classified as nil to very low pollution degree. The contamination factor spatial distribution put in evidence the fact that As, Cd, Cu, Pb, and Zn soils contents, downstream Barroca Grande tailing, are increased when compared with the local Bk soils. The mechanical dispersion, due to erosion, is the main contamination source. The chemical extraction demonstrates that the trace metals distribution and accumulation in S. Francisco de Assis soils is related to sulfides, but also to amorphous or poorly crystalline iron oxide phases. The partitioning study allowed understanding the local chemical elements mobility and precipitation processes, giving rise to the contamination dispersion model of the study area. The wind and hydrological factors are responsible for the chemical elements transport mechanisms, the water being the main transporter medium and soils as one of the possible retention media.     

Synthesising acid mine drainage to maintain and exploit indigenous mining micro-algae and microbial assemblies for biotreatment investigations

The stringent regulations for discharging acid mine drainage (AMD) has led to increased attention on traditional or emerging treatment technologies to establish efficient and sustainable management for mine effluents. To assess new technologies, laboratory investigations on AMD treatment are necessary requiring a consistent supply of AMD with a stable composition, thus limiting environmental variability and uncertainty during controlled experiments. Additionally, biotreatment systems using live cells, particularly micro-algae, require appropriate nutrient availability. Synthetic AMD (Syn-AMD) meets these requirements. However, to date, most of the reported Syn-AMDs are composed of only a few selected heavy metals without considering the complexity of actual AMD. In this study, AMD was synthesised based on the typical AMD characteristics from a copper mine where biotreatment is being considered using indigenous AMD algal-microbes. Major cations (Ca, Na, Cu, Zn, Mg, Mn and Ni), trace metals (Al, Fe, Ag, Na, Co, Mo, Pb and Cr), essential nutrients (N, P and C) and high SO₄ were incorporated into the Syn-AMD. This paper presents the preparation of chemically complex Syn-AMD and the challenges associated with combining metal salts of varying solubility that is not restricted to one particular mine site. The general approach reported and the particular reagents used can produce alternative Syn-AMD with varying compositions. The successful growth of indigenous AMD algal-microbes in the Syn-AMD demonstrated its applicability as appropriate generic media for cultivation and maintenance of mining microorganisms for future biotreatment studies.     

Zinc acclimation and its effect on the zinc tolerance of Raphidocelis subcapitata and Chlorella vulgaris in laboratory experiments.

The effect of zinc acclimation of Raphidocelis subcapitata (syn. Selenastrum capricornutum) and Chlorella vulgaris on their sensitivity towards this metal was examined in a series of laboratory experiments. These two commonly used algal species were acclimated to 65 microg Zn/l and changes in zinc tolerance were monitored using standard growth inhibition tests. The chemically defined ISO medium was used as a control culture medium. Both species demonstrated a maximum increase in zinc tolerance of a factor of 3 after 100 days of acclimation. Shifts in the shape of the concentration-response curve due to acclimation were observed for R. subcapitata. Compared to non-acclimated algae, acclimated R. subcapitata exhibited higher growth rates in all zinc treatments as well as in the controls. This suggests that the use of ISO-medium results in sub-optimal growth due to zinc deficiency. These effects could not be demonstrated for C. vulgaris. The zinc tolerance of both species decreased significantly one week after returning the acclimated algae to control (ISO) medium. 72hEC50 values based on growth rate were two to four times higher than those calculated using biomass measurements. Algal toxicity test results, particularly if used for metal risk assessments, must not be conducted using nutrient deficient media.     

Impact of acid mine drainage on benthic communities in streams: the relative roles of substratum vs. aqueous effects

Restoration of streams impacted by acid mine drainage (AMD) focuses on improving water quality, however precipitates of metals on the substrata can remain and adversely affect the benthos. To examine the effects of AMD precipitates independently of aqueous effects, four substrata treatments, clean sandstone, clean limestone, AMD precipitate-coated sandstone and coated limestone, were placed in a circumneutral stream of high water quality for 4 weeks. Iron and Al were the most abundant metals on rocks with AMD precipitate. and significantly decreased after the exposure. Precipitate on the substrata did not significantly affect macroinvertebrate or periphyton density and species composition. In an additional experiment, percent survival of caged live caddisflies was significantly lower when exposed in situ for 5 days in an AMD affected stream than in a reference stream. Caddisfly whole-body concentrations of all combined metals and Fe alone were significantly higher in the AMD stream. Whole-body metal concentrations were higher in killed caddisflies than in live, indicating the importance of passive uptake. The results suggest the aqueous chemical environment of AMD had a greater affect on organisms than a coating of recent AMD precipitate on the substrata (ca. 0.5 mm thick), and treatment that improves water quality in AMD impacted streams has the potential to aid in recovery of the abiotic and biotic benthic environment.     

Testing the use of juvenile Salmo trutta L. as biomonitors of heavy metal pollution in freshwater

Individual specimens of Salmo trutta were captured, from four sampling sites in Galician rivers (NW Spain) affected by different types of contamination: diffuse urban waste, run-off from an unrestored dump at a copper mine and waste from a fish farm. The ages of the captured trouts were established and only those belonging to the 1+ age class were selected for study. The liver and kidney were removed from each fish and analysed to determine the tissue concentrations of Cu, Fe and Zn. The results obtained showed that: (i) the use of 1+ individuals allowed differentiation of contamination scenarios on the basis of the tissue concentrations of metal; (ii) the use of 1+ individuals allowed standardization of the time of exposure, which was sufficiently long for differential uptake to have taken place; (iii) liver tissue provided the best results as, less effort was required than for processing kidney tissue, and significant differences between sampling sites were detected because the intrapopulational variability in metal levels was lower than for kidney, and (iv) the levels of elements detected were not affected by basal tissue concentrations or residual concentrations due to past contamination, which older trouts may have been exposed to. In addition, the use of 1+ trout may provide better results in annual environmental sampling surveys.     

Arsenate tolerance in Silene paradoxa does not rely on phytochelatin-dependent sequestration

Arsenate tolerance, As accumulation and As-induced phytochelatin accumulation were compared in populations of Silene paradoxa, one from a mine site enriched in As, Cu and Zn, the other from an uncontaminated site. The mine population was significantly more arsenate-tolerant. Arsenate uptake and root-to-shoot transport were slightly but significantly higher in the non-mine plants. The difference in uptake was quantitatively insufficient to explain the difference in tolerance between the populations. As accumulation in the roots was similar in both populations, but the mine plants accumulated much less phytochelatins than the non-mine plants. The mean phytochelatin chain length, however, was higher in the mine population, possibly due to a constitutively lower cellular glutathione level. It is argued that the mine plants must possess an arsenic detoxification mechanism other than arsenate reduction and subsequent phytochelatin-based sequestration. This alternative mechanism might explain at least some part of the superior tolerance in the mine plants.     

Multiple resistance of acetolactate synthase and protoporphyrinogen oxidase inhibitors in Euphorbia heterophylla biotypes

Resistance to acetolactate synthase (ALS)-inhibiting herbicides in Brazil has been documented for six species. The probability to select biotypes of Euphorbia heterophylla (EPPHL) with multiple resistance increases in the same order of magnitude as the use of other herbicides belonging to only one mechanism of action. The objectives of this work were to evaluate the distribution of resistant populations (R) in the states of the Parana and Santa Catarina; to determine the existence of populations of EPHHL with multiple resistance to ALS and PROTOX inhibitors, and to confirm the occurrence of cross resistance to compounds of these mechanisms of action. Seeds of EPHHL of areas with suspected resistance had been sampled in 97 places during 2003. In the greenhouse experiment samples of each population were sprayed with imazethapyr or fomesafen, at only one rate. To identify the resistant ones they were sprayed with different levels of the herbicides imazethapyr and fomesafen. Later they were sprayed with diverse herbicides of the same mechanisms of action to confirm the multiple/cross resistance. There is widespread distribution in the region of populations with resistance to ALS inhibitors. Some biotypes demonstrated resistance to herbicides from the two mechanisms of action. The resistance factor (FR), or the relation of resistance between R and susceptible biotypes, confirms the existence of two biotypes of EPHHL with cross resistance to several herbicides inhibitors of ALS and PROTOX.     

Riboflavin content of coelomocytes in earthworm (Dendrodrilus rubidus) field populations as a molecular biomarker of soil metal pollution

The effect of Pb + Zn on coelomocyte riboflavin content in the epigeic earthworm Dendrodrilus rubidus inhabiting three metalliferous soils and one reference soil was measured by flow cytometry and spectrofluorimetry. A reciprocal polluted↔unpolluted worm transfer experiment (4-week exposure) was also performed. High proportions of autofluorescent eleocytes were counted in worms from all localities, but intense riboflavin-derived autofluorescence was detectable only in reference worm eleocytes. Other findings were: (i) fluorophore(s) other than riboflavin is/are responsible for eleocyte autofluorescence in residents of metalliferous soils; (ii) riboflavin content was reduced in the eleocytes of worms transferred from unpolluted to metal-polluted soil; (iii) the riboflavin content of D. rubidus eleocytes is a promising biomarker of exposure; (iv) COII mitochondrial genotyping revealed that the reference population is genetically distinct from the three mine populations; (v) metal exposure rather than genotype is probably the main determinant of inter-population differences in eleocyte riboflavin status.     

Depauperate macroinvertebrates in a mine affected stream: clean water may be the key to recovery

Acid mine drainage (AMD) is frequently linked with changes in macroinvertebrate assemblages, but the relative contribution of water and sediment to toxicity is equivocal. We have shown that the macroinvertebrate fauna of Neubecks Ck, a mine impacted stream in New South Wales, Australia, was much poorer than in two reference streams. Multivariate RELATE analyses indicated that the patterns in the biological data were more strongly correlated with the concentrations of common metals in the surface water than the pore water of these streams. From this we hypothesised that the water was more toxic to the biota than the sediment and we tested this hypothesis with a sediment transplant experiment. Sediment from Neubecks Ck that was placed in reference streams retained high concentrations of metals throughout the experiment, yet supported a macroinvertebrate assemblage similar to that in the reference streams. Sediment from the reference streams that was placed in Neubecks Ck supported few, if any, animals. This indicates that water in Neubecks Ck is toxic to biota, but that sediment is able to support aquatic biota in clean water. Therefore, remediation should focus on improving water quality rather than sediment quality.     

Microbial communities in acid water environments of two mines, China

To understand the compositions and structures of microbial communities in different acid-aqueous environments, a PCR-based cloning approach was used. A total of five samples were collected from two mines in China. Two samples, named as G1 and G2, were acid mine drainage (AMD) samples and from Yunfu sulfide mine in Guangdong province, China. The rest of the three samples named as D1, DY and D3, were from three sites undertaking bioleaching in Yinshan lead-zinc mine in Jiangxi province, China. Phylogenetic analysis revealed that bacteria in the five samples fell into six putative divisions, which were α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Firmicutes, Actinobacteria and Nitrospira. Archaea was only detected in the three samples from Yinshan lead-zinc mine, which fell into two phylogenentic divisions, Thermoplsma and Ferroplasma. In addition, the results of principal component analysis (PCA) suggested that more similar the geochemical properties in samples were, more similar microbial community structures in samples were.