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981.
A series of experiments investigated the potential role of microbial mats in nutrition of the early settlement stages of Penaeus semisulcatus. From 3 days post-metamorphosis, the microbial mat supported high growth and survival rates in postlarvae, equivalent to
that supported by a control diet of Artemia nauplii and mussel. Examination of gut contents indicated that benthic postlarvae feed indiscriminately on the microbial
mat. However, when postlarvae were fed separated size-fractions of the microbial mat, only the fraction containing a high
concentration of infauna (mainly nematodes) was able to support the same growth as intact microbial mat. This appears to be
due to the low nitrogen content (0.4–0.9 mmol g−1) of the various size-fractions, compared to that of infauna (4.0 mmol g−1). The stable isotope composition of the dietary size-fractions and postlarval shrimp tissue supports the hypothesis that
the shrimp assimilated C and N primarily from the associated infauna. This may be due to selective feeding that is not apparent
from stomach contents, due to rapid digestion of fauna soft tissues, or to differential assimilation of infaunal prey relative
to other microbial mat components. The results demonstrate that microbial mats may support survival and growth in early-stage
penaeid shrimp postlarvae on intertidal mud flats. 相似文献
982.
The discovery of ordered mesoporous materials in 1992 by Mobil Oil Corporation scientists has opened great opportunities for new applications in many emerging fields such as heterogeneous catalysis, biocatalysis, energy conversion, biosensors, photocatalytic devices and environmental technologies. Porous materials are grouped by the International Union of Pure and Applied Chemistry (IUPAC) into three classes according to their pore diameter: microporous (<?2 nm), mesoporous (2–50 nm) and macroporous (>?50 nm). One of the most versatile methods for the preparation of those materials is the soft template approach which combines the sol–gel process with molecular self-assembly. While the micelles formed by ionic or nonionic surfactants, as well as amphiphilic polymers, have been extensively used as templates, the supramolecular assemblies formed between cyclodextrins and block copolymers have been less investigated, despite their large chemical and structural diversity. This review article focuses mainly on nanostructured porous inorganic materials derived from cyclodextrins or cyclodextrin-based assemblies. More than 100 references are described and discussed, in which we look both at their synthesis and characterization, as well as their applications in the emerging fields of heterogeneous catalysis and photocatalysis. A special attention is paid to the evaluation of the critical parameters that need to be controlled for improving their (photo) catalytic performances. 相似文献
983.
Arsenic,antimony, and other trace element contamination in a mine tailings affected area and uptake by tolerant plant species 总被引:1,自引:0,他引:1
Anawar HM Freitas MC Canha N Santa Regina I 《Environmental geochemistry and health》2011,33(4):353-362
The study was conducted to characterize mineralogical and elemental composition of mine tailings in order to evaluate the environmental hazards, and identify the metal accumulation potential of native plant species from São Domingos mine, one of the long-term activity mines of the Iberian Pyrite Belt dating back to pre-Roman times. The mine tailings including soils and different plant species from São Domingos were analyzed for determination of tailings characteristics and chemical element contents in tailings and plants. The large amounts of mining wastes are causing significant adverse environment impacts due to acid mine drainage production and mobilization of potentially toxic metals and metalloids in residential areas, agricultural fields, downstreams, and rivers. The typical mineralogical composition is as follows: quartz, micas, K-feldspar, olivine-group minerals, magnetite, goethite, hematite, jarosite, and sulfides. The mine tailings were highly contaminated by As, Ag, Cr, Hg, Sn, Sb, Fe, and Zn; and among them, As and Sb, main contaminants, attained the highest concentrations except Fe. Arsenic has exhibited very good correlations with Au, Fe, Sb, Se, and W; and Sb with As, Au, Fe, Se, Sn, and W in tailings. Among the all plant species, the higher concentrations of all the metals were noted in Erica andevalensis, Erica australis, Echium plantagium, and Lavandula luisierra. Considering the tolerant behavior and abundant growth, the plant species Erica australis, Erica andevalensis, Lavandula luisierra, Daphne gnidium, Rumex induratus, Ulex eriocladus, Juncus, and Genista hirsutus are of major importance for the rehabilitation and recovery of degraded São Domingos mining area. 相似文献
984.
Paz-Alberto AM Sigua GC Baui BG Prudente JA 《Environmental science and pollution research international》2007,14(7):498-504
Background, Aims and Scope The global problem concerning contamination of the environment as a consequence of human activities is increasing. Most of
the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment
makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive
and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation.
Phytoremediation is an alternative method that uses plants to clean up a contaminated area. The objectives of this study were:
(1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass, cogongrass
and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass
species as potential phytoremediators in terms of Pb accumulation by plants.
Methods The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg kg−1 (37.5 kg ha−1) and 150 mg kg−1 (75 kg ha−1) of Pb, respectively. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments
using an atomic absorption spectrophotometer. This study was laid out following a 3 × 2 factorial experiment in a completely
randomized design.
Results On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39
Mg ha−1). Carabaograss had the lowest herbage mass production of 4.12 Mg ha−1 and 5.72 Mg ha−1 from soils added with 75 and 150 mg Pb kg−1, respectively. Vetivergrass also had the highest percent plant survival which meant it best tolerated the Pb contamination
in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 ± 2.81 mg kg−1). This was followed by cogongrass (2.34 ± 0.52 mg kg−1) and carabaograss with a mean Pb level of 0.49 ± 0.56 mg kg−1. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150
mg kg−1) to the soil.
Discussion Vetivergrass yielded the highest biomass; it also has the greatest amount of Pb absorbed (roots + shoots). This can be attributed
to the highly extensive root system of vetivergrass with the presence of an enormous amount of root hairs. Extensive root
system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The efficiency
of plants as phytoremediators could be correlated with the plants’ total biomass. This implies that the higher the biomass,
the greater the Pb uptake. Plants characteristically exhibit remarkable capacity to absorb what they need and exclude what
they do not need. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport
of the metals from root to shoots. Combination of high metal accumulation and high biomass production results in the most
metal removal from the soil.
Conclusions The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil.
It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also
potential phytoremediators since they can absorb small amount of Pb in soils, although cogongrass is more tolerant to Pb-contaminated
soil compared with carabaograss. The important implication of our findings is that vetivergrass can be used for phytoextraction
on sites contaminated with high levels of heavy metals; particularly Pb.
Recommendations and Perspectives High levels of Pb in localized areas are still a concern especially in urban areas with high levels of traffic, near Pb smelters,
battery plants, or industrial facilities that burn fuel ending up in water and soils. The grasses used in the study, and particularly
vetivergrass, can be used to phytoremediate urban soil with various contaminations by planting these grasses in lawns and
public parks.
ESS-Submission Editor: Dr. Willie Peijnenburg (wjgm.peijnenburg@rivm.nl) 相似文献
985.
The ascidian Styela clava, native to the north-west Pacific, is an invasive species affecting New Zealand’s marine ecosystems, biodiversity and aquaculture
operations. To provide detailed information on the reproductive biology of S. clava in New Zealand for post-border biosecurity management, long-term seasonal patterns of gametogenesis were determined from
May 2006 to May 2008 in Auckland’s Waitemata Harbour (36°49′20″S, 174°45′85″E). Of particular interest was whether the critical
15°C threshold spawning temperature for reproduction observed in the Northern Hemisphere applied here to the first Southern
Hemisphere study. S. clava gametogenesis followed a regular seasonal cycle with ripe gametes appearing as early as September and persisting to June;
this time frame corresponds to the period when sea surface temperatures in the region first reach 15°C and with spawning occurring
mainly during late summer to early autumn. From photoperiod manipulation, it was determined that spawning occurred at approximately
18:20. The extended reproductive period and a short generation time in the Waitemata Harbour provides a lengthy opportunity
for S. clava to spread. Findings are discussed in relation to S. clava’s post-border management. 相似文献
986.
Positive plant–animal interactions are important in community ecology, but relatively little attention has been paid to their
effect on the production of mangroves, dominant halophytic trees in tropical coastal marshes. Here, the role of fiddler crab
(Uca spp.) burrowing on the growth and production of the white mangrove, Laguncularia racemosa (<2 years old), was examined in a restored marsh in Tampa Bay, Florida (27°41.65 N, 82°30.34 W) with manipulative experiments
from June 2006 to May 2007. Fiddler crab burrowing significantly increased mangrove height by 27%, trunk diameter by 25%,
and leaf production by 15%, compared to mangroves in crab exclusion enclosures. Additionally, the exclusion of fiddler crabs
significantly increased interstitial water salinity from 32.4 to 44.2, and decreased the oxidation–reduction potential of
the low organic sediments, but did not affect soil pH or sulfide concentration. Mangrove height, trunk diameter, and leaf
production along a transect that varied in crab burrow density were positively associated with the number of crab burrows.
Further, the density of sympatric Spartina alterniflora shoots was positively correlated with crab burrow density along the transect. As in temperate marshes, fiddler crabs can
have significant ecological effects on mangrove communities, serving as ecological engineers by modulating the amount of resources
available to marsh plants, and by altering the physical, chemical, and biological state of these soft sediment communities.
In restored coastal systems that typically have very poor sediment quality, techniques such as soil amendment could be used
to facilitate a more natural interaction between crabs and mangroves in ecosystem development. 相似文献
987.
Skulrat Pichaiyut Charoen Nakason Suwaluk Wisunthorn 《Journal of Polymers and the Environment》2018,26(7):2855-2866
This work aimed to prepare biodegradable thermoplastic elastomers based on NR/LLDPE/TPS ternary simple blends to achieve some exclusive properties, i.e., good biodegradability in terms of water absorption and weight loss after burial, together with reasonable mechanical and thermal properties. A comparative study on biodegradability and other related properties of NR/LLDPE binary and NR/LLDPE/TPS ternary blends was performed. It was found that increasing the TPS proportion decreased storage modulus and complex viscosity. In addition, the size of dispersed TPS domains in the NR/LLDPE co-continuous matrix increased with TPS proportion, while the mechanical properties in terms of 100% moduli, tensile strength, elongation at break, and hardness decreased. This might be attributed to decreased interfacial adhesion with increasing size of TPS domains. Furthermore, increasing the TPS loading in the blend reduced the temperatures for 5 or 50% mass loss (T5 or T50) and the degradation temperature (T d ). However, the biodegradability improved, in terms of increased water absorption and weight loss after burial in soil, with the loading level of TPS. 相似文献
988.
A. Vignesh Arun. S. Siddarth B. Ramesh Babu 《Journal of Material Cycles and Waste Management》2017,19(1):155-162
This contribution reports a novel and cost efficient strategy for nickel ion removal from metal finishing effluents by electro-dissolution of scrap aluminium and iron sacrificial anodes. Electro-coagulation of effluent was carried out at 30 mA/cm2 current density for 60 min. The nickel ion concentration of electroplating effluent was analysed by Atomic Absorption Spectroscopy. SEM images of iron and aluminium scrap anodes were critically analysed. Parameters such as heavy metal removal, anode dissolution rate with respect to heavy metal removal, reaction kinetics and cost estimation have been elaborately studied. Electro-coagulation at 30 mA/cm2 for 60 min using iron and aluminium scrap anodes resulted in 95.9 and 94.1 % nickel ion reduction, respectively, with 0.0094 and 0.0053 g/ppm dissolution rates. The energy consumption for scrap aluminium and iron anodes was 0.0547 kWh/L. Loose internal bonding and spongy surface morphology of used metal scrap render high porosity and active surface area, enhancing reaction rate. Low cost and ready availability of waste scrap makes the process of electro-coagulation economically viable. Thus, the findings from this contribution point decisively at the superiority of waste metal scrap-based anodes for economic and environmentally sustainable heavy metal ion removal from metal finishing effluent. 相似文献
989.
Jesús Cambrollé Juan Manuel Mancilla-Leytón Sara Muñoz-Vallés Beatriz Morenza-Barrera Manuel Enrique Figueroa 《Journal of Coastal Conservation》2018,22(6):1201-1207
Human pressure has been exponentially growing during recent decades in coastal areas, which have led to drastic losses of biodiversity in coastal ecosystems. The current conservation status of many coastal plant species is directly related to a lack of environmental criteria in the urban planning of coastal areas over recent decades. This study aimed to evaluate the evolution, over the last 9 years, of the conservation status of various populations of the endangered plant Glaucium flavum, exploring the extent to which human pressure and different management strategies practiced in the coastal areas where the populations are established have affected the conservation status of the species. The populations analysed have evolved in a different manner over the last 9 years, as have their threat factors, and a relationship was evident between their conservation status and the evolution of these different threat factors. Our results indicate that an appropriate planning of local management actions, such as the installation of walkways or the successful eradication of invasive species, may be determinant factors for successful conservation of the coastal vegetation. The presence of species that are sensitive to slight changes in the ecosystem, and the main factors that govern the plant performance of these species, must be given full consideration in decision-making processes of coastal planning and management. 相似文献
990.
We performed male attraction experiments and staged courtship sequences to test for non-random mating with respect to social
behavioral phenotype in the comb-footed spider, Anelosimus studiosus. While asocial behavior is the dominant phenotype in all A. studiosus populations examined to date, a social phenotype approaches a frequency of 15% in colder environments. We collected test
subjects from higher latitude polymorphic populations and scored all individuals as to their behavioral phenotype prior to
their use in these trials. Males of both phenotypes differentially approached and courted social females over asocial females
and no-spider controls. By offering males different numbers of females of one type vs. the other in subsequent trials, we
determined that the difference in attractiveness between the two phenotypes social/asocial is 1.5/1. Both the web produced
by a female and a female that has been removed from its web attract males. We suggest that the male attracting pheromone is
present on females and is also attached to silk threads. Staged encounters completed between males and females of the respective
phenotypes demonstrated that courting males suffer significantly less pre-copulatory sexual cannibalism with social females
than with asocial ones, and thus, female social tendency is phenotypically linked to sexual aggression. We propose that the
male preference for social females is adaptive because of the observed asymmetry in courtship success. 相似文献