Cadmium sorption by sodium and thiourea-modified zeolite-rich tuffs

In the present investigation, two zeolite-rich tuffs from Guaymas and El Cajon(State of Sonora), which were conditioned with a sodium chloride solution and subsequently modified with a thiourea solution, were chosen to evaluate the removal of Cd from aqueous systems. The zeolitic materials were characterized by scanning electron microscopy and X-ray diffraction. The surface area was also determined. The experiments were performed in a batch system, and the influences of p H, contact time between phases, and the concentration of Cd in the solution on the adsorption by sodium or thiourea-modified zeolite-rich tuff were investigated. It was found that the efficiency of Cd ion removal from aqueous solutions is influenced by the p H of the aqueous systems. The Cd adsorption kinetic data were well fitted to a pseudo-second-order model in all cases. The Langmuir and Langmuir–Freundlich isotherms adequately described the Cd sorption behavior by the zeolite from El Cajon pretreated with Na Cl and the zeolite from Guaymas modified with thiourea, respectively.     

Stable oligonucleotide-functionalized gold nanosensors for environmental biocontaminant monitoring

The global propagation of environmental biocontaminants such as antibiotic resistant pathogens and their antibiotic resistance genes(ARGs) is a public health concern that highlights the need for improved monitoring strategies. Here, we demonstrate the environmental stability and applicability of an oligonucleotide-functionalized gold nanosensor. The mec A ARG was targeted as model biocontaminant due to its presence in clinically-relevant pathogens and to its emergence as an environmental contaminant.mec A-specific nanosensors were tested for antibiotic resistance gene(ARG) detection in ARG-spiked effluent from four wastewater treatment plants(WWTPs). The mec A-specific nanosensors showed stability in environmental conditions and in high ionic strength([MgCl_2] 50 m M), and high selectivity against mismatched targets. Spectrophotometric detection was reproducible with an LOD of 70 pM(≈ 4 × 10~7 genes/μL), even in the presence of interferences associated with non-target genomic DNA and complex WWTP effluent. This contribution supports the environmental applicability of a new line of cost-effective, field-deployable tools needed for wide-scale biocontaminant monitoring.     

Was endothermy in amniotes induced by an early stop in growth during ontogeny?

Endothermy and its evolution are still an unresolved issue. Here, we present a model which transforms an ectothermic amniote (ancestor) into a derived amniote (descendant) showing many characteristics seen in extant endothermic birds and mammals. Consistent with the fossil record within the ancestral lineages of birds and mammals, the model assumes that mutations in genes which get active during ontogeny and affect body growth resulted in a reduced asymptotic body size and an early growth stop of the descendant. We show that such a postulated early growth stop in the descendant simultaneously increases the growth rate and metabolic rate, and also changes six life history traits (offspring mass, annual clutch/litter mass, number of offspring per year, age and mass at which sexual maturity is reached, age at which the individual is fully grown) of the descendant compared to a similar-sized ancestor. All these changes coincide with known differences between recent ectothermic and endothermic amniotes. We also elaborate many other differences and similarities in biological characteristics supporting the early growth stop. An early stop in growth during ontogeny thus could have played a key role in the evolution of endothermy within the reptilia and therapsids. It generated variability in characteristics of ancestral ectotherms, which was subject to natural selection in the past and resulted in many adaptations linked to endothermy in today’s birds and mammals.     

Developing a standard for psychosocial risk management: PAS 1010

The nature of work has changed dramatically due to globalisation, migration, technological advances and the emergence of the knowledge-based economy. These changes have been accompanied by the increased prevalence of new and emerging types of risk to workers’ health and safety, such as psychosocial risks. This paper reviews the key regulatory and voluntary standards on occupational health and safety of relevance to the management of psychosocial risks in the workplace that are applicable to the European Union member states. The review indicates that regulatory standards set the minimum level of protection for workers and voluntary standards may further enable organisations to go beyond their legal obligations. However, the review also highlights that the terms ‘stress’ and ‘psychosocial risks’ are not mentioned explicitly in most pieces of legislation leading to lack of clarity on the terminology used. While voluntary standards seek to address this, very few provide specific guidance on the process of psychosocial risk management to enable organisations to manage psychosocial risks successfully. On the basis of the review, the case for the development of a voluntary standard for psychosocial risk management is presented. The paper further discusses the recent development of such a standard and its implications at the European level.     

Defining Nutrient and Biochemical Oxygen Demand Baselines for Tropical Rivers and Streams in São Paulo State (Brazil): A Comparison Between Reference and Impacted Sites

Determining reference concentrations in rivers and streams is an important tool for environmental management. Reference conditions for eutrophication-related water variables are unavailable for Brazilian freshwaters. We aimed to establish reference baselines for São Paulo State tropical rivers and streams for total phosphorus (TP) and nitrogen (TN), nitrogen-ammonia (NH₄ ⁺) and Biochemical Oxygen Demand (BOD) through the best professional judgment and the trisection methods. Data from 319 sites monitored by the São Paulo State Environmental Company (2005 to 2009) and from the 22 Water Resources Management Units in São Paulo State were assessed (N = 27,131). We verified that data from different management units dominated by similar land cover could be analyzed together (Analysis of Variance, P = 0.504). Cumulative frequency diagrams showed that industrialized management units were characterized by the worst water quality (e.g. average TP of 0.51 mg/L), followed by agricultural watersheds. TN and NH₄ ⁺ were associated with urban percentages and population density (Spearman Rank Correlation Test, P < 0.05). Best professional judgment and trisection (median of lower third of all sites) methods for determining reference concentrations showed agreement: 0.03 &; 0.04 mg/L (TP), 0.31 &; 0.34 mg/L (TN), 0.06 &; 0.10 mg-N/L (NH₄ ⁺) and 2 &; 2 mg/L (BOD), respectively. Our reference concentrations were similar to TP and TN reference values proposed for temperate water bodies. These baselines can help with water management in São Paulo State, as well as providing some of the first such information for tropical ecosystems.     

Scale-dependent patterns of variability of a grazing parrotfish (<Emphasis Type="Italic">Leptoscarus vaigiensis</Emphasis>) in a tropical seagrass-dominated seascape

Although herbivorous fish form critical linkages between primary producers and higher trophic levels, the major factors regulating their spatial structure in seagrass systems remain poorly understood. The present study examined the parrotfish Leptoscarus vaigiensis in seagrass meadows of a tropical embayment in the western Indian Ocean. Stomach content analysis and direct field observations showed that L. vaigiensis is an efficient grazer, feeding almost exclusively on seagrass leaves. Seagrass shoot density was highly correlated to all density variables (total, juvenile and subadult) and juvenile biomass of L. vaigiensis, while subadult biomass was predicted by distance to neighbouring coral habitat. Moreover, density and biomass of predatory fish (piscivores) were predicted by seagrass canopy height and the distribution patterns of predators followed those of L. vaigiensis. Hence, factors at local (seagrass structural complexity and feeding mode) and landscape scale levels (seascape context and distribution of piscivores) likely mutually structure herbivorous fish communities. The findings underscore the importance of incorporating multiple scale-dependent factors when managing coastal seagrass ecosystems and their associated key species.     

Magnetic orientation by hatchling loggerhead sea turtles (Caretta caretta) from the Gulf of Mexico

Loggerhead sea turtle hatchlings emerge from nests on either the east or west coast of the South Florida peninsula and then migrate offshore in opposite directions. Under laboratory conditions, magnetic cues induce east coast hatchlings to swim in directions that promote their transport by oceanic surface currents, such as the North Atlantic gyre. However, the surface currents used by west coast hatchlings are unknown. We examined the responses of west (Sarasota) hatchlings to magnetic cues in the Gulf of Mexico, the Florida Straits, and the Gulf Stream to determine their (1) likely migratory routes (2) orientation where currents lead into the Atlantic Ocean, and (3) orientation adjacent to Florida’s east coast. The results suggest that migration inside Gulf waters may be circuitous, that the turtles respond appropriately to enter Atlantic waters, and that orientation along Florida’s east coast probably promotes transport by the Gulf Stream into the North Atlantic gyre.     

Somatic and population growth responses of Ceriodaphnia dubia and Daphnia pulex (Cladocera) to changes in food (Chlorella vulgaris) level and temperature

We quantified the combined effects of three food levels (0.01 x 10(6), 0.1 x 10(6) and 1.0 x 10(6) cells ml(-1)) and three temperature levels (15, 20 and 25 degrees C) on the somatic and the clonal population growth of two cladocerans Ceriodaphnia dubia and Daphnia pulex for 24 to 42 days. The somatic growth data showed that both the cladoceran species began to increase their body size within 3 days and remained stable beyond a week. Food density had a significant effect on the body size of C. dubia while for D. pulex, food level and temperature as well as their interaction had significant effect on the body size. The population growth of both the cladoceran species was affected by temperature. At 15 degrees C, C. dubia showed little growth at the highest food density, while at low food level, there was some increase in the population abundances, especially after a long lag phase of about 2 weeks. At 15 degrees C and under the lowest tested food level, the population of D. pulex did not increase beyond the inoculation density. Optimal population growth of D. pulex was observed at intermediate temperature and at 1.0 x 10(6) cells ml(-1) of food level while for C. dubia 25 degrees C and the highest food level yielded highest growth. At low food level and low temperature, the rate of population increase (r) of C. dubia was much lower than that of D. pulex at comparable conditions. On the hand, at higher food levels and temperature regimes, the r of D. pulex was much higher than that of C.dubia. Regardless of the food levels and temperature, the r of C. dubia varied from 0.03 to 0.07 while that of D. pulex varied from 0.01 to 0.08 day(1).     

Removal of arsenate from water by adsorbents: a comparative case study

Laboratory and field filtration experiments were conducted to study the effectiveness of As(V) removal for five types of adsorbent media. The media included activated alumina (AA), modified activated alumina (MAA), granular ferric hydroxide (GFH), granular ferric oxide (GFO), and granular titanium dioxide (TiO?). In laboratory batch and column experiments, the synthetic challenge water was used to evaluate the effectiveness for five adsorbents. The results of the batch experiments showed that the As(V) adsorption decreased as follows at pH 6.5: TiO? > GFO > GFH > MAA > AA. At pH 8.5, however, As(V) removal decreased in the following order: GFO = TiO? > GFH > MAA > AA. In column experiments, at pH 6.5, the adsorbed As(V) for adsorbents followed the order: TiO? > GFO > GFH, whereas at pH 8.5 the order became: GFO = TiO? > GFH when the challenge water containing 50 μg/L of As(V) was used. Field filtration experiments were carried out in parallel at a wellhead in New Jersey. Before the effluent arsenic concentration increased to 10 μg/L, approximately 58,000 and 41,500 bed volumes of groundwater containing an average of 47 μg/L of As(V) were treated by the filter system packed with GFO and TiO?, respectively. The As(V) adsorption decreased in the following sequence: GFO > TiO? > GFH > MAA > AA. Filtration results demonstrated that GFO and TiO? adsorbents could be used as media in small community filtration systems for As(V) removal.