One potential drawback of compost-based passive bioreactors, which is a promising biotechnology for acid mine drainage (AMD)
treatment, is the transport of dissolved organic matter (DOM)-metal complexes in surface waters. To address this problem, the objective
of this study was to assess the maximum capacity of organic substrates to release soluble DOM-metal complexes in treated water.
The reactivities of DOM in maple wood chips and sawdust, composted poultry manure, and leaf compost were quantified toward
Cd2+, Ni2+, Fe2+, and Cu2+ using fluorescence quenching. The DOM showed the highest reactivity toward Fe, but a limited number
of available sites for sorption, whereas DOM-Cd complexes exhibited the lowest fluorescence quenching. Overall, the DOM from a
mixture of wastes formed higher concentrations of DOM-metal complexes relative to sole substrates. Among DOM-metal complexes,
the concentrations of DOM-Ni complexes were the highest. After reaching steady-state, low concentrations of DOM-metal complexes
were released in treated water, which is in agreement with theoretical predictions based on geochemical modeling. Therefore, in addition
to physicochemical characterization, fluorescence quenching technique is recommended for the substrate selection of bioreactors. 相似文献
Most small-colony termites live confined within a single piece of wood on which they feed and do not possess permanent workers: Tasks are done by developmentally flexible immatures (pseudergates). By contrast, large-colony termites possess a specialized (true) worker caste and forage outside their nest for food. To shed light on possible transitional steps between these contrasting patterns of social organization, we studied an atypical Rhinotermitidae, Prorhinotermes inopinatus. In this species, despite the absence of a true worker caste, soldiers, pseudergates, and neotenic reproductives may leave the nest and explore their surroundings. Although evidence presented in this study indicates that termites recognize unknown areas, there is no directional recruitment toward them. The discovery of a food source, i.e., a piece of wood, is followed by the establishment of a long-lasting trail between the nest and the food source. A large fraction of the colony, including neotenic reproductives, ultimately migrates into the piece of wood. Our results thus demonstrate that multiple features of external foraging behavior can evolve independently of the existence of a true worker caste in termites. We suggest that large colonies with true workers, like those of most Rhinotermitidae, may easily have evolved from a Prorhinotermes-like pattern if submitted to increasing selective pressures for worker efficiency in a stable environment. 相似文献
The presence of the frontal gland is well established in termite soldiers of Rhinotermitidae, Serritermitidae, and Termitidae. It is one of their main defensive adaptations or even an exclusive weapon. The gland was also occasionally reported in alate imagoes, but never in the worker caste. Here, we report the first observation of a frontal gland in workers of several Neotropical and one African species of Apicotermitinae. The ultrastructure of Aparatermes cingulatus and Anoplotermes nr. subterraneus is described in detail. In these two species, the gland is well-developed, functional and consists of class 1 secretory cells. The presence of envelope cells, wrapping the gland, is an unusual feature, as well as the presence of several zonulae adherens, connecting neighbouring glandular cells. The frontal gland of workers is homologous to this organ in soldiers and imagoes, as evidenced by the same position in the head and its connection to the same muscle. However, the defensive role of the frontal gland in workers remains to be confirmed. 相似文献
Individual specialisation is widespread and can affect a population’s ecological and evolutionary dynamics. Whether intra-specific
niche differences can influence reproductive investment was examined in a marine mammal, the southern elephant seal (Mirounga leonina), whose females were known to forage in two different areas during the austral winter. The study was conducted at Kerguelen
Islands (49°21′S, 70°18′E), southern Indian Ocean, in late winter–early spring 2006. Pups were used as proxies of their mothers’
biology and combined information on their weaning mass (a proxy of females’ foraging success and short-term fitness) together
with their blood δ13C value (a proxy of female foraging zone). First, the use of isotopic signature of pups was validated to study the female
foraging ecology during their pre-breeding trip by demonstrating that δ13C and δ15N values of pups and their mothers were positively and linearly correlated. Then, blood samples were taken from a large number
of newly-weaned pups, which were also weighed, to provide information at the population level. Estimated δ13C values of female seals encompassed a large range of values (from −23.7 to −19.1‰) with an unimodal frequency distribution,
suggesting no contrasted foraging areas within the population. No significant relationship was found between pup weaning mass
and their carbon signature, indicating no link between female foraging areas and maternal foraging success and investment.
Finally, blood δ13C and δ15N values gave new insights into southern elephant seal ecology, suggesting that females mainly foraged north of the Polar
Front where they preyed upon myctophid fish in late winter. 相似文献
The emperor and Adélie penguins are the only two species of penguins that co-occur at high-Antarctic latitudes. We first measured
and compared their isotopic niches on the same year in Adélie Land in spring, when the two species co-exist. Emperor and Adélie
penguins segregated by their blood isotopic signatures, with adult δ13C values (−24.5 ± 0.2 and −25.4 ± 0.2‰, respectively) suggesting that emperor penguins foraged in more neritic waters than
Adélie penguins in spring. At that time, difference in their δ15N values (4.1‰, 12.0 ± 0.4 vs. 7.9 ± 0.1‰) encompassed more than one trophic level, indicating that emperor penguins preyed
mainly upon fish (and squids), while Adélie penguins fed exclusively on euphausiids. Second, we compared the food of breeding
adults and chicks. The isotopic signatures of adults and chicks of emperor penguins were not statistically different, but
δ15N value of Adélie penguin chicks was higher than that of adults (10.2 ± 0.8 vs. 9.0 ± 0.2‰). The difference showed that adult
Adélie penguins captured higher trophic level prey, i.e. higher-quality food, for their chicks. Third, the isotopic signatures
of Adélie penguins breeding in Adélie Land showed that adults fed on Antarctic krill in oceanic waters in spring and shifted
to neritic waters in summer where they preyed upon ice krill for themselves and upon fish and euphausiids for their chicks.
A comparison of isotopic niches revealed large overlaps in both blood δ13C and δ15N values within the community of Antarctic seabirds and pinnipeds. The continuum in δ15N values nevertheless encompassed more than one trophic level (5.2‰) from Adélie penguin and crabeater seal to the Weddell
seal. Such a broad continuum emphasizes the fact that all Antarctic seabirds and marine mammals feed on varying proportions
of a few crustacean (euphausiids) and fish (Antarctic silverfish) species that dominate the intermediate trophic levels of
the pelagic neritic and oceanic ecosystems. 相似文献
BOD5 dates back to 1912 when the Royal Commission decided to use the mean residence time of water in the rivers of England, 5 days, as a standard to measure the biochemical oxygen demand. Initially designed to protect the quality of river waters from extensive sewage discharge, the use of BOD5 has been quickly extended to waste water treatment plants (WWTPs) to monitor their efficiency on a daily basis. The measurement has been automatized but remains a tedious, time- and resource-consuming analysis. We have cross-validated a surrogate BOD5 method on two sites in France and in the USA with a total of 109 samples. This method uses a fluorescent redox indicator on a 96-well microplate to measure microbial catabolic activity for a large number of samples simultaneously. Three statistical tests were used to compare surrogate and reference methods and showed robust equivalence. 相似文献
Health risks associated with inhalation of fine particulate matter of 2.5 µm in diameter or smaller depend on their atmospheric levels and physicochemical properties. The relationships between chemical compositions and genotoxic activities of particles emitted by mineral industries, traffic and urban sources during summer and winter in the region of Provence-Alpes-Côte d'Azur (France) were investigated.
The fine particles were separated in respect to water-soluble (13 minerals and metals) and organic-extractable (16 polycyclic aromatic hydrocarbons) components that were quantified. The chromosome damaging properties of the hydrophilic and lipophilic extracts were assessed using the centromeric micronucleus assay on a human lung fibroblast cell line.
The composition of the fine particulate matter was variable and depended upon the sources and seasons. Both the hydrophilic and lipophilic extracts induced chromosome damage: (1) in hydrophilic extracts, Ca and Zn affected chromosome losses induction; (2) acenapthylene affected chromosome damage (breakages and losses) induction and naphthalene affected chromosome damage and losses induction in lipophilic extracts without metabolic activation; and (3) benzo[a]pyrene affected chromosome losses induction in lipophilic extracts with metabolic activation. Fine particulate matter arising from coal-fired power station, road traffic, and other urban sources were the most efficient to induce chromosome breakage. 相似文献