Planktonic larval duration of one hundred species of Pacific and Atlantic damselfishes (Pomacentridae)

The plankton larval duration for 100 species of Pacific and Atlantic damselfishes was estimated from daily growth increments on the otolith of juvenile fish collected at various localities between July 1987 and September 1988. For newly-settled fishes, larval duration was determined by counting the entire number of increments present on the otolith, while for older juveniles estimates were made by counting the number of increments between the center of the otolith and a mark corresponding to settlement. We document the development of otolith formation during the period when eggs are incubated on the reef and show that daily increments are only accreted after larvae hatch and enter the planktonic phase. The planktonic larval duration for damselfish is shorter and less variable, both between and within species, compared to other groups of reef fishes such as wrasses and surgeonfishes. Larval duration ranged from 12 to 39 d. Average duration between species ranged from 13.1 to 35.2 d. The time spent in the plankton was not significantly correlated with geographic distribution when evaluated among species, however, genera with confined regional distribution have a shorter mean larval life than do widely distributed genera. Size at settlement was positively correlated with time spent in the plankton among species, but a significant correlation between these variables was only evident within one of ten species. The low variance in planktonic larval duration within species indicates that most damselfish are unable to delay metamorphosis following competency. This inability to postpone settlement limits the potential for dispersal, especially when dispersal time between suitable habitats is greater than about 30 d.     

Interpolation performance of a spatio-temporal model with spatially varying coefficients: application to PM<Subscript>10</Subscript> concentrations in Rio de Janeiro

In this work we present a Bayesian analysis in linear regression models with spatially varying coefficients for modeling and inference in spatio-temporal processes. This kind of model is particularly appealing in situations where the effect of one or more explanatory processes on the response present substantial spatial heterogeneity. We describe for this model how to make inference about the regression coefficients and response processes under two scenarios: when the explanatory processes are known throughout the study region, and when they are known only at the sampling locations. Using a simulation experiment we investigate how parameter inference and interpolation performance are affected by some features of the data and prior distribution that is used. The proposed methodology is used to model the dataset on PM₁₀ levels in the metropolitan region of Rio de Janeiro presented in Paez and Gamerman (2003).     

Ambient toxicity due to chlorpyrifos and diazinon in a central California coastal watershed

The Salinas River watershed along the central coast of California, U.S.A., supports rapidly growing urban areas and intensive agricultural operations. The river drains to an estuarine National Wildlife Refuge and a National Marine Sanctuary. The occurrence, spatial patterns, sources and causesof aquatic toxicity in the watershed were investigated by sampling four sites in the main river and four sites in representative tributaries during 15 surveys between September1998 and January 2000. In 96 hr toxicity tests, significant Ceriodaphnia dubia mortality was observed in 11% of the mainriver samples, 87% of the samples from a channel draining anurban/agricultural watershed, 13% of the samples fromchannels conveying agricultural tile drain runoff, and in 100% of the samples from a channel conveying agricultural surface furrow runoff. In six of nine toxicity identificationevaluations (TIEs), the organophosphate pesticides diazinon and/or chlorpyrifos were implicated as causes of observed toxicity, and these compounds were the most probable causes oftoxicity in two of the other three TIEs. Every sample collectedin the watershed that exhibited greater than 50% C. dubia mortality (n = 31) had sufficient diazinon and/or chlorpyrifos concentrations to account for the observed effects.Results are interpreted with respect to potential effects on other ecologically important species.     

Sustainability of agricultural and wild cereals to aerotechnogenic exposure

In recent decades, the problem of the constantly increasin level of anthropogenic load on the environment is becoming more and more acute. Some of the most dangerous pollutants entering the environment from industrial emissions are heavy metals. These pollutants are not susceptible to biodegradation over time, which leads to their accumulation in the environment in dangerous concentrations. The purpose of this work is to study the sustainability of cultivated and wild plants of the Poaceae family to aerotechnogenic pollution in the soil. The content of heavy metals in couch grass (Elytrigia repens (L.) Nevski), meadow bluegrass (Poa pratensis L.) and soft wheat (Triticum aestivum) plants grown in the impact zone of Novocherkassk Power Station has been analyzed. Contamination of cultivated and wild cereals with Pb, Zn, Ni and Cd has been established. It has been shown that the accumulation of heavy metals is individual for each plant species. An average and close correlation have been established between the total HM content and the content of their mobile forms in the soil and their content in plants. For the plants studied, the translocation factor (TF) and the distribution coefficient (DC) of HM have been calculated. The TF is formed by the ratio of the concentration of an element in the root plant dry weight to the content of its mobile compounds in the soil. The DC value makes it possible to estimate the capacity of the aboveground parts of plants to absorb and accumulate elements under soil pollution conditions and is determined as the ratio of the metal content in the aboveground biomass to its concentration in the roots. TF and DC values have shown a significant accumulation of elements by plants from the soil, as well as their translocation from the root system to the aboveground part. It has been revealed that even within the same Poaceae family, cultural species are more sensitive to man-made pollution than wild-growing ones.

     

The toxic effect of CuO of different dispersion degrees on the structure and ultrastructure of spring barley cells (Hordeum sativum distichum)

Environmental Geochemistry and Health - Nowadays, nanotechnology is one of the most dynamically developing and most promising technologies. However, the safety issues of using metal nanoparticles,...     

Cadmium,zinc and total mercury levels in the tissues of several fish species from La Plata river estuary,Argentina

A survey of the concentrations of heavy metals — cadmium, zinc and total mercury — in the tissues of fifteen fish species from Samborombón Bay, La Plata river estuary, in Argentina, has been carried out. Liver appeared to be the main organ accumulating cadmium and zinc, while both liver and muscle showed a similar ability for accumulating mercury. The bioaccumulation process was verified for the three metals analyzed, even though low concentrations have been determined. The biomagnification process of the metals studied was not verified in this environment. The highest metal concentrations were recorded in Mugil liza, and particulate matter and sediments — which are closely related to its trophic and ecological habits — seemed to be the main source of metals for this species. Both Micropogonias furnieri and Mugil liza were recognized as possible indicator species for future monitoring programmes for heavy metals in Samborombón Bay. Considering the present results, this area of La Plata river estuary is characterized as a non-polluted environment.Scientific Researcher from the National Council for Scientific and Technological Researches (CONICET), of Argentina     

The use of agricultural substrates to improve methane yield in anaerobic co-digestion with pig slurry: Effect of substrate type and inclusion level

Anaerobic co-digestion of pig slurry with four agricultural substrates (tomato, pepper, persimmon and peach) was investigated. Each agricultural substrate was tested in co-digestion with pig slurry at four inclusion levels: 0%, 15%, 30% and 50%. Inclusion levels consisted in the replacement of the volatile solids (VS) from the pig slurry with the VS from the agricultural substrate. The effect of substrate type and inclusion level on the biochemical methane potential (BMP) was evaluated in a batch assay performed at 35 °C for 100 days. Agricultural substrate’s chemical composition was also analyzed and related with BMP. Additionally, Bacteria and Archaea domains together with the four main methanogenic archaeal orders were quantified using quantitative real-time TaqMan polymerase chain reaction (qPCR) at the end of the experiment to determine the influence of agricultural substrate on sludge’s microbial composition. Results showed that vegetable substrates (pepper and tomato) had higher lipid and protein content and lower carbohydrates than fruit substrates (persimmon and peach). Among substrates, vegetable substrates showed higher BMP than fruit substrates. Higher BMP values were obtained with increasing addition of agricultural substrate. The replacement of 50% of VS from pig slurry by tomato and pepper increased BMP in 41% and 44%, respectively compared with pig slurry only. Lower increments in BMP were achieved with lower inclusion levels. Results from qPCR showed that total bacteria and total archaea gene concentrations were similar in all combinations tested. Methanomicrobiales gene concentrations dominated over the rest of individual archaeal orders.     

Reduction of NO by CO using Pd-CeTb and Pd-CeZr catalysts supported on SiO2 and La2O3-Al2O3

The catalytic activity of Pd catalysts supported on Ce_0.73Tb_0.27O_x/SiO₂, Ce_0.6Zr_0.4O_x/SiO₂, Ce_0.73Tb_0.27O_x/La₂O₃-Al₂O₃ and Ce_0.6Zr_0.4O_x/La₂O₃-Al₂O₃ was studied using the reduction of NO by CO. The catalysts were characterized by X-ray fluorescence, surface area, X-ray diffraction, temperature-programmed reduction, CO chemisorption and oxygen storage capacity. Temperature-programmed reduction results indicated that Tb or Zr incorporation improves the reducibility and oxygen storage capacity. CO chemisorption data suggested the presence of large PdO particles due to the low CO/Pd ratio. No significant differences were obtained in light off temperatures (T_{Light off}) for all Pd catalysts and the most active was 1.5%Pd/Ce_0.6Zr_0.4O_x/SiO₂.