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141.
M. Pérez-Rama E. Torres C. Suárez C. Herrero J. Abalde 《Journal of environmental management》2010,91(10):2045-2050
The present work reports the use of living cells of the marine microalga Tetraselmis suecica for the biosorption of cadmium ions. For a better understanding of the biosorption characteristics, three fractions of removed cadmium (total, bioadsorbed and intracellular) were measured in the cells after 24 and 72 h of exposure to different initial cadmium concentrations (0.6–45 mg L?1). Both the Langmuir and Freundlich models were suitable for describing the sorption of cadmium ions by this microalga. The maximum sorption capacity was estimated to be 40.22 mg Cd g?1 after 72 h using the Langmuir sorption model. In the lower cadmium concentrations, metal removed intracellularly was higher than that removed on the microalgal cell surface. Therefore, the intracellular fraction contributed more to the total removed cadmium than the fraction bioadsorbed to the cellular surface. The results showed that the cadmium removal capacity using living biomass could be much more effective than with non-living biomass due to the intracellular bioaccumulation. According to the microorganism selected and its tolerance to the toxic effect of the metal, the cadmium content in the intracellular fraction can become very significant, just like it happened with Tetraselmis. 相似文献
142.
Pedro Lorite Xulio Maside Olivia Sanllorente María I. Torres Georges Periquet Teresa Palomeque 《Die Naturwissenschaften》2012,99(12):1007-1020
To date, only three types of full-length mariner elements have been described in ants, each one in a different genus of the Myrmicinae subfamily: Sinvmar was isolated from various Solenopsis species, Myrmar from Myrmica ruginodis, and Mboumar from Messor bouvieri. In this study, we report the coexistence of three mariner elements (Tnigmar-Si, Tnigmar-Mr, and Tnigmar-Mb) in the genome of a single species, Tapinoma nigerrimum (subfamily Dolichoderinae). Molecular evolutionary analyses of the nucleotide sequence data revealed a general agreement between the evolutionary history of most the elements and the ant species that harbour them, and suggest that they are at the vertical inactivation stage of the so-called Mariner Life Cycle. In contrast, significantly reduced levels of synonymous divergence between Mboumar and Tnigmar-Mb and between Myrmar and Botmar (a mariner element isolated from Bombus terrestris), relative to those observed between their hosts, suggest that these elements arrived to the species that host them by horizontal transfer, long after the species?? split. The horizontal transfer events for the two pairs of elements could be roughly dated within the last 2 million years and about 14 million years, respectively. As would be expected under this scenario, the coding sequences of the youngest elements, Tnigmar-Mb and Mboumar, are intact and, thus, potentially functional. Each mariner element has a different chromosomal distribution pattern according to their stage within the Mariner Life Cycle. Finally, a new defective transposable element (Azteca) has also been found inserted into the Tnigmar-Mr sequences showing that the ant genomes have been invaded by at least four different types of mariner elements. 相似文献
143.
This paper presents an attempt to model the water balance in the metropolitan center landfill (MCL) in Salvador, Brazil. Aspects such as the municipal solid waste (MSW) initial water content, mass loss due to decomposition, MSW liquid expelling due to compression and those related to weather conditions, such as the amount of rainfall and evaporation are considered. Superficial flow and infiltration were modeled considering the waste and the hydraulic characteristics (permeability and soil-water retention curves) of the cover layer and simplified uni-dimensional empirical models. In order to validate the modeling procedure, data from one cell at the landfill were used. Monthly waste entry, volume of collected leachate and leachate level inside the cell were monitored. Water balance equations and the compressibility of the MSW were used to calculate the amount of leachate stored in the cell and the corresponding leachate level. Measured and calculated values of the leachate level inside the cell were similar and the model was able to capture the main trends of the water balance behavior during the cell operational period. 相似文献
144.
Atmospheric polycyclic aromatic hydrocarbons in remote European and Atlantic sites located above the boundary mixing layer 总被引:1,自引:1,他引:0
Barend Leendert Van Drooge Pilar Fernández Joan O. Grimalt Evzen Stuchlík Carlos J. Torres García Emilio Cuevas 《Environmental science and pollution research international》2010,17(6):1207-1216
Background, aim and scope
Ambient air concentrations of polycyclic aromatic hydrocarbons (PAH) were determined at five elevated mountain sites on the European continent and the Atlantic Ocean. All sites can be considered remote background areas since they are situated above the timberline and they lack local emission sources of these compounds. 相似文献145.
Roselinde Torres 《Conservation biology》2011,25(5):1060-1061
146.
Arturo Balderas Torres Douglas C. MacMillan Margaret Skutsch Jon C. Lovett 《Regional Environmental Change》2013,13(3):661-680
Adequate demand for, and recognition of, forest carbon services is critical to success of market mechanisms for forestry-based conservation and climate change mitigation. National and voluntary carbon-offsetting schemes are emerging as alternatives to international compliance markets. We developed a choice experiment to explore determinants of local forest carbon-offset valuation. A total of 963 citizens from Guadalajara in Mexico were asked to consider a purchase of voluntary offsets from the neighbouring Biosphere Reserve of La Primavera and from two alternative more distant locations: La Michilía in the state of Durango and El Cielo in Tamaulipas. Surveys were applied in market stall sessions and online using two different sampling methods: the snowball technique and via a market research company. The local La Primavera site attracted higher participation and valuation than the more distant sites. However, groups particularly interested in climate change mitigation or cost may accept cost-efficient options in the distant sites. Mean implicit carbon prices obtained ranged from $6.79 to $15.67/tCO2eq depending on the surveying methodology and profile of respondents. Survey application mode can significantly affect outcome of the experiment. Values from the market stall sessions were higher than those from the snowball and market research samples obtained online; this may be linked to greater cooperation associated with personal interaction and collective action. In agreement with the literature, we found that valuation of forest carbon offsets is associated with cognitive, ethical, behavioural, geographical and economic factors. 相似文献
147.
148.
The importance of salinity experienced during embryonic development and initial larval biomass on larval growth was studied
in the South American estuarine crab Chasmagnathus granulata. Ovigerous females were maintained at three salinities (15, 20, and 32‰) from egg laying to hatching of zoea l. Larvae from
all treatments were reared under constant conditions of photoperiod (12∶12), temperature (18°C), and salinity (first instar
at 20‰, subsequent instars at 32‰). Biomass was measured as dry weight, carbon, and nitrogen content per individual at egg
laying, hatching of zoea l, premoult zoea l, and zoea 4, and in 8-day-old megalopa. From hatching to premoult zoea 4, biomass
was higher for larvae from prehatching salinities of 15 and 32‰. There was a significant positive correlation between biomass
at hatching and at premoult zoea l and zoea 4. Accumulated biomass during zoeal stages tended to be higher for larvae from
broods with higher biomass at hatching, although this trend was not always significant. Zoea 4 either directly metamorphosed
to megalopa or moulted to zoea 5, following, respectively, a short or long developmental pathway. The proportion of zoea 4
that followed the long pathway was negatively correlated with biomass of zoeal stages. Biomass at hatching was correlated
with biomass of megalopae developed through the short pathway, although it was not correlated with the accumulated biomass
at this stage. Megalopae developed through the long pathway (i.e. metamorphosed from zoeae 5) had higher biomass than those
from the short pathway. The present results suggest that prehatching salinity and initial egg and larval biomass can be very
important for larval growth.
Published online: 9 August 2002 相似文献
149.
Age and growth of Electrona antarctica (Pisces: Myctophidae), the dominant mesopelagic fish of the Southern Ocean 总被引:1,自引:0,他引:1
Numerically and in biomass, the lanternfish Electrona antarctica is the dominant fish in the vast pelagic region of the Southern Ocean bounded on the north by the Antarctic Convergence and
in the south by the Antarctic continental shelf. It is an important krill predator, and in turn is important in the diets
of flighted and swimming seabirds. Further, it is the southernmost and coldest-dwelling representative of the globally distributed
fish family Myctophidae. The present study was undertaken to estimate the species' growth rate and average life span, to incorporate
the information in a basic energy budget, and to compare the growth of E. antarctica with more northerly confamilials. Fishes were aged using primary growth increments that were resolved on sagittal otoliths
using three sequential techniques: thin-section grinding and polishing, etching, and scanning electron microscopy (SEM). Based
on increment width (0.8 to 1.2 μm), continuity, and previous studies on confamilials, the microincrements were assumed to
be deposited on a daily basis. Montages of SEM photomicrographs were constructed for each sagitta to allow the daily rings
to be counted over the entire life span of 31 individuals representing the entire size range of the species. Results suggest
a larval stage of 30 to 47 d and a maximum life span of 3.5 yr, with females growing faster than males in the last 1.5 yr
of life and reaching a larger maximum size. Construction of a simple energy budget using the best information available suggests
that a surplus of energy is available to support the observed growth rates (0.05 to 0.07 mm d−1). The results of the present study contrast markedly with previous estimates of an 8 to 11 yr maximum age for E. antarctica. These results provide important data addressing the ecology and population dynamics of the pelagic Antarctic ecosystem.
E. antarctica is the end-member species in the continuum of vertically migrating myctophids that extend from the equator to the polar circle.
Its growth rate is consonant with that of all other myctophid species examined using primary growth increments to determine
age. The present study, in conjunction with earlier studies, suggests that growth rates of mesopelagic species are far higher
than previously thought.
Received: 12 September 1997 / Accepted: 25 July 1998 相似文献
150.
The Earth’s greatest living space is found in the bathypelagic zone of the oceans (depths >1,000 m), yet little research has
been dedicated to these ecosystems. The micronekton of the bathypelagic zone in the eastern Gulf of Mexico (EGOM) was investigated
with the goal of comparing its community structure with that of the well-studied mesopelagic micronekton. Herein is described
a portion of that community, specifically species belonging to the orders Lophogastrida, Mysida, and Decapoda. A total of
46 species were collected, most of which have broad zoogeographic distributions. Seventeen of the species had not previously
been collected above 1,000 m in the same location despite over 20 years of sampling. Compared to the mesopelagic zone, the
bathypelagic community showed increased contributions to abundance and estimated biomass from the Oplophoridae and Eucopiidae,
with a simultaneous decrease in the importance of the Dendrobranchiata. In addition, the bathypelagic zone was distinguished
by a relatively high percentage of individuals that brood their eggs (77% vs. 15% in the mesopelagic zone). The results are
interpreted as evidence that the bathypelagic zone contains a distinct pelagic community, with a biology and ecology fundamentally
different from that of the mesopelagic zone. 相似文献