Mercury species accumulation and trophic transfer in biological systems using the Almadén mining district (Ciudad Real,Spain) as a case of study

The impact of mercury (Hg) pollution in the terrestrial environments and the terrestrial food chains including the impact on human food consumption is still greatly under-investigated. In particular, studies including Hg speciation and detoxification strategies in terrestrial animals are almost non-existing, but these are key information with important implications for human beings. Therefore, in this work, we report on Hg species (inorganic mercury, iHg, and monomethylmercury, MeHg) distribution among terrestrial animal tissues obtained from a real-world Hg exposure scenario (Almadén mining district, Spain). Thus, we studied Hg species (iHg and MeHg) and total selenium (Se) content in liver and kidney of red deer (Cervus elaphus; n?=?41) and wild boar (Sus scrofa; n?=?16). Similar mercury species distribution was found for both red deer and wild boar. Major differences were found between tissues; thus, in kidney, iHg was clearly the predominant species (more than 81 %), while in liver, the species distribution was less homogeneous with a percentage of MeHg up to 46 % in some cases. Therefore, Hg accumulation and MeHg transfer were evident in terrestrial ecosystems. The interaction between total Se and Hg species has been evaluated by tissue and by animal species. Similar relationships were found in kidney for both Hg species in red deer and wild boar. However, in liver, there were differences between animals. The possible underlying mechanisms are discussed.     

Spatiotemporal Associations of Reservoir Nutrient Characteristics and the Invasive,Harmful Alga Prymnesium parvum in West Texas

Golden alga (Prymnesium parvum) is a harmful alga that has caused ecological and economic harm in freshwater and marine systems worldwide. In inland systems of North America, toxic blooms have nearly eliminated fish populations in some systems. Modifying nutrient profiles through alterations to land or water use may be a viable alternative for golden alga control in reservoirs. The main objective of this study was to improve our understanding of the nutrient dynamics that influence golden alga bloom formation and toxicity in west Texas reservoirs. We examined eight sites in the Upper Colorado River basin, Texas: three impacted reservoirs that have experienced repeated golden alga blooms; two reference reservoirs where golden alga is present but nontoxic; and three confluence sites downstream of the impacted and reference sites. Total, inorganic, and organic nitrogen and phosphorus and their ratios were quantified monthly along with golden alga abundance and ichthyotoxicity between December 2010 and July 2011. Blooms persisted for several months at the impacted sites, which were characterized by high organic nitrogen and low inorganic nitrogen. At impacted sites, abundance was positively associated with inorganic phosphorus and bloom termination coincided with increases in inorganic nitrogen and decreases in inorganic phosphorus in late spring. Management of both inorganic and organic forms of nutrients may create conditions in reservoirs unfavorable to golden alga.     

Diversity of bacterial isolates during full scale rotary drum composting

Bacterial diversity of full scale rotary drum composter from biodegradable organic waste samples were analyzed through two different approaches, i.e., Culture dependent and independent techniques. Culture-dependent enumerations for indigenous population of bacterial isolates mainly total heterotrophic bacteria (Bacillus species, Pseudomonas species and Enterobacter species), Fecal Coliforms, Fecal Streptococci, Escherichia coli, Salmonella species and Shigella species showed reduction during the composting period. On the other hand, Culture-independent method using PCR amplification of specific 16S rRNA sequences identified the presence of Acinetobacter species, Actinobacteria species, Bacillus species, Clostridium species, Hydrogenophaga species, Butyrivibrio species, Pedobacter species, Empedobactor species and Flavobacterium species by sequences clustering in the phylogenetic tree. Furthermore, correlating physico-chemical analysis of samples with bacterial diversity revealed the bacterial communities have undergone changes, possibly linked to the variations in temperature and availability of new metabolic substrates while decomposing organics at different stages of composting.     

Removal of congo red and basic violet 1 by chir pine (Pinus roxburghii) sawdust,a saw mill waste: batch and column studies

The efficiency of chir pine sawdust (CPS) for adsorptive removal of the dyes, congo red (CR) and basic violet 1 (BV), from aqueous solution was evaluated using batch and column studies. The equilibrium was attained in 60 min for CR and 45 min for BV. The adsorption of BV obeyed the Langmuir isotherm model while the Freundlich isotherm fitted the equilibrium data of CR adsorption. The Langmuir monolayer adsorption capacities (Q_o) of CPS for BV and CR were 11.3 and 5.8 g kg^?1, respectively. The kinetic data for CR were best fitted to the Lagergren pseudo-first-order model and for BV to the pseudo-second-order model. The intra-particle diffusion was found to be the rate-controlling step for CR adsorption, while the adsorption kinetics of BV were controlled by both intra-particle and liquid-film diffusion. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic in nature. The adsorption activation energy (E_a) for CR (124 kJ mol^?1) implied chemical adsorption while that for BV (5.4 kJ mol^?1) indicated physical adsorption. An increase in the Thomas model constant (K_Th) with increasing flow indicated that for both dyes the mass transport resistance decreased during adsorption. Thus, CPS may be an efficient low-cost adsorbent for decolorization of dye-containing wastewaters.     

Accumulation of nitrogen and changes in assimilation pigments of lichens transplanted in an agricultural area

The results of a survey aimed at testing the hypothesis that the lichen Evernia prunastri, when transplanted in an agricultural area with high atmospheric NH₃ concentrations, would respond to NH₃ air pollution accumulating nitrogen in its thalli and showing changes in the concentration of assimilation pigments are presented. The results confirmed the hypothesis and showed that all lichen transplants accumulated nitrogen, suggesting that besides the release of atmospheric ammonia by animal stockfarms, the use of N-based fertilizers and the deposition of N-rich dust also may contribute to the high nitrogen availability to lichens in the study area. The result indicated that in the study area both the critical level of NH₃ and the critical load of N for lichens are exceeded and physiological damage is to be expected in sensitive species. The results of assimilation pigments in E. prunastri, with a decrease in the concentration of chlorophylls a and b and carotenoids, as well as chlorophyll degradation to phaeophytin, confirmed this hypothesis. However, owing to the limited data set and pending further studies, these conclusions should be considered as limited to the study area.     

Distribution and availability of trace elements in municipal solid waste composts

Trace element contamination is one of the main problems linked to the quality of compost, especially when it is produced from urban wastes, which can lead to high levels of some potentially toxic elements such as Cu, Pb or Zn. In this work, the distribution and bioavailability of five elements (Cu, Zn, Pb, Cr and Ni) were studied in five Spanish composts obtained from different feedstocks (municipal solid waste, garden trimmings, sewage sludge and mixed manure). The five composts showed high total concentrations of these elements, which in some cases limited their commercialization due to legal imperatives. First, a physical fractionation of the composts was performed, and the five elements were determined in each size fraction. Their availability was assessed by several methods of extraction (water, CaCl(2)-DTPA, the PBET extract, the TCLP extract, and sodium pyrophosphate), and their chemical distribution was assessed using the BCR sequential extraction procedure. The results showed that the finer fractions were enriched with the elements studied, and that Cu, Pb and Zn were the most potentially problematic ones, due to both their high total concentrations and availability. The partition into the BCR fractions was different for each element, but the differences between composts were scarce. Pb was evenly distributed among the four fractions defined in the BCR (soluble, oxidizable, reducible and residual); Cu was mainly found in the oxidizable fraction, linked to organic matter, and Zn was mainly associated to the reducible fraction (iron oxides), while Ni and Cr were mainly present almost exclusively in the residual fraction. It was not possible to establish a univocal relation between trace elements availability and their BCR fractionation. Given the differences existing for the availability and distribution of these elements, which not always were related to their total concentrations, we think that legal limits should consider availability, in order to achieve a more realistic assessment of the risks linked to compost use.     

Reduction of pollutants in pulp paper mill effluent treated by PCP-degrading bacterial strains

Two PCP-degrading bacterial strains, Bacillus cereus (ITRC-S6) and Serratia marcescens (ITRC-S7) were used for the treatment of pulp and paper mill effluent at conditions; 1.0% glucose and 0.5% peptone at 30 +/- 1 degrees C at 120 rpm for 168 h of incubation. These two bacterial strains effectively reduced colour (45-52%), lignin (30-42%), BOD (40-70%), COD (50-60%), total phenol (32-40%) and PCP (85-90%) within 168 h of incubation. However, the highest reduction in colour (62%), lignin (54%), BOD (70%), COD (90%), total phenol (90%) and PCP (100%) was recorded by mixed culture treatment. The bacterial mechanism for the degradation of pulp and paper mill effluent may be explained by an increase in the cells biomass using added co-substrates resulting liberation of significant amount of chloride due to bacterial dechlorination of chlorolignins and chlorophenols this showed reduction in colour, lignin and toxicity in the effluent. Further, GC-MS analysis of ethyl acetate-extractable compounds from treated pulp paper mill effluent reinforces the bacterium capability for the degradation of lignin and pentachlorophenol, as many aromatic compounds such as 2-chlorophenol, 2, 4, 6-trichlorophenol and tetrachlorohydroquinone, 6-chlorohydroxyquinol and tetrachlorohydroquinone detected which were not present in the untreated effluent.     

Water quality improvement through macrophytes—a review

Increasing urbanization, industrialization and over population is leading to the degradation of the environment. The main hazardous contents of the water pollution are heavy metals etc. Water bodies are the main targets for disposing the pollutants directly or indirectly. They are again at the receiving end as the storm water, residential and commercial waste is disposed into it. The prevailing purification technologies used to remove the contaminants are too costly and sometimes non-eco friendly also. Therefore, the research is oriented towards low cost and eco friendly technology for water purification, which will be beneficial for community. The present paper is a comprehensive review of approximately 38 literature sources. The paper discusses the potential of different aquatic plants (macrophytes) in purifying water and wastewater. Experimental work was developed to test the hypothesis that nutrient enrichment enhances metal tolerance of relative macrophyte.