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211.
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
212.
Simon W. Townsend Markus Zöttl Marta B. Manser 《Behavioral ecology and sociobiology》2011,65(10):1927-1934
Socio-demographic factors, such as group size and their effect on predation vulnerability, have, in addition to intrinsic
factors, dominated as explanations when attempting to understand animal vigilance behaviour. It is generally assumed that
animals evaluate these external factors visually; however, many socially foraging species adopt a foraging technique that
directly compromises the visual system. In these instances, such species may instead rely more on the acoustical medium to
assess their relative risk and guide their subsequent anti-predator behaviour. We addressed this question in the socially
foraging meerkat (Suricata suricatta). Meerkats forage with their head down, but at the same time frequently produce close calls (‘Foraging’ close calls). Close
calls are also produced just after an individual has briefly scanned the surrounding environment for predators (‘Guarding’
close calls). Here, we firstly show that these Guarding and Foraging close call variants are in fact acoustically distinct
and secondly subjects are less vigilant (in terms of frequency and time) when exposed to Guarding close call playbacks than
when they hear Foraging close calls. We argue that this is the first evidence for socially foraging animals using the information
encoded within calls, the main adaptive function of which is unrelated to immediate predator encounters, to coordinate their
vigilance behaviour. In addition, these results provide new insights into the potential cognitive mechanisms underlying anti-predator
behaviour and suggest meerkats may be capable of signalling to group members the ‘absence’ of predatory threat. If we are
to fully understand the complexities underlying the coordination of animal anti-predator behaviour, we encourage future studies
to take these additional auditory and cognitive dimensions into account. 相似文献
213.
José S. Antunes do Carmo Mechteld ten Voorde Maria G. Neves 《Journal of Coastal Conservation》2011,15(4):531-546
Surfing has becoming more and more attractive in the past few decades, constituting nowadays an important source of revenue
for many countries with extensive coastlines. For this purpose and also for environmental reasons, the conventional ways of
protecting a coastline appear to entail some disadvantages. An innovative and interesting way of improving surfing capacities
and contributing to protect a local coastal zone is by means of multifunctional artificial reefs. A multifunctional artificial
reef (MFAR) is a submerged structure that serves several purposes; in particular, it may enhance the surfing possibilities
and the environmental value of the local area. This structure has some promising new aspects, too: first, it provides an unimpaired
visual amenity; second, it offers tourist and economic benefits by improving the surfing conditions; third, it can enhance
the environmental value of the area where it is built, and fourth, if designed properly, the down drift erosion can be minimal.
An appropriate reef design in terms of ‘surfability’, i.e. the possibility to surf a wave, for the Leirosa beach, located
to the south of Figueira da Foz, midway along Portugal’s West Atlantic coast, has been investigated. In order to achieve the
best design several steps were conducted. First, the performance of the Boussinesq-type COULWAVE model is tested with experimental
data. Next, this numerical model is used to define the best values for three design parameters: reef angle; geometry of the
reef (without or with a platform), and horizontal dimensions for the appropriate geometry. A preliminary design was achieved
step by step, making use of the theory and of the state of the art of multifunctional reefs. This reef geometry is used in
the numerical study. In terms of ‘surfability’ and for the conditions of the local coastline of Leirosa, the following values
were found for the main parameters: a reef angle of 66°; a structure height of 3.20 m; a reef geometry composed of a delta
without a platform; a reef submergence of 1.50 m, and a structure seaward slope of 1:10. 相似文献
214.
We review a range of lack-of-fit tests suitable for assessing the appropriateness of the mean function in dose-response models.
The review encompasses both well-known tests and new tests based on recent developments in statistics, which we have extended
to the dose-response case. We argue that the classical methods are inadequate in certain situations, where the new tests may
be applied. Power comparisons are carried out by means of extensive simulation studies, covering both designs with and without
replicates at small and large sample sizes. Three datasets from dose-response applications illustrate differences and similarities
between the tests. The results suggest that the new tests perform better and exhibit a wider applicability. 相似文献
215.
Male fitness is often determined by the ability of the male to gain access to multiple mates, although in species that exhibit
sexual cannibalism, males might increase their likelihood of being cannibalized with each encounter. This risk should create
selection for males who are able to perceive potential risks associated with mating encounters. We studied male Schizocosa ocreata wolf spiders to determine whether they use female chemotactile cues (silk, excreta) as indicators of potential risks and
how these cues affected subsequent male courtship behaviors. Female treatments included satiated females vs. starved females,
as well as a treatment where females had recently cannibalized a male S. ocreata. We performed experiments to assess (1) if males use female chemotactile cues to determine potential risks associated with
differing female feeding treatments and alter courtship investment, and 2) how male experience with female chemotactile cues
affected courtship investment in subsequent female encounters. At first encounter, males do not vary courtship investment
(number of bouts, duration, and vigor) with different female feeding treatments. However, male behaviors during subsequent
encounters with female chemotactile cues varied in complex ways, depending on female feeding treatment and male first encounter
experience. These data suggest that male experience impacts perception of female chemical cues and offers the male opportunity
to avoid sexual cannibalism in high-risk situations. 相似文献
216.
Galerucella placida Baly (Coleoptera: Chrysomelidae) is a potential biocontrol agent of the rice-field weed Polygonum orientale L. (Polygonaceae). The volatile organic compound (VOC) profiles from undamaged and mechanically damaged plants, and from plants 12- and 36-h following continuous feeding of female G. placida adults and 2nd instar larvae were identified and quantified by GC–MS and GC-FID analyses. Twenty-four and 21 compounds were identified in volatiles of undamaged and insect feeding plants, respectively; whereas 22 compounds were detected in volatiles of mechanically damaged plants. Decanal and 1-dodecanol were unique to undamaged plants, and linalool was detected in volatiles of undamaged and mechanically damaged plants, but not in volatiles of insect damaged plants. However, the beetles are not attracted by none of these volatile components, when tested individually in Y-shaped glass tube olfactometer bioassays. In all plants, methyl jasmonate was predominant. 1-Undecanol was the least amount in undamaged plants, and plants 12-h after feeding by G. placida adults and larvae; whereas 1-tridecanol was the least abundant in plants 36-h after feeding by G. placida adults and larvae, and mechanically damaged plants. The beetles showed significant preference to the whole volatile blends from plants 12-h after feeding by larvae and plants 36-h after feeding by either larvae or adults compared to those of undamaged plants. Further, G. placida responded to individual synthetic compounds, 3-hexanol, 1-octen-3-ol, nonanal, and geraniol at 7, 1.38, 3.75 and 4.5 µg/25 µL CH2Cl2, respectively, and provide a basis for attraction of the potential biocontrol agent in the field. 相似文献
217.
Lenka Okenicová Mária Žemberyová Simona Procházková 《Environmental Chemistry Letters》2016,14(1):67-77
Some trace metals are highly toxic for the environment. There is therefore a need for reliable methods for the determination of metals at trace levels. To this end, new sample pretreatment methods such as separation, preconcentration and speciation prior to the determination of metal ions have developed rapidly. Biosorption has become a major tool for solid-phase extraction methods. This review covers selected biosorbents such as algae, bacteria, filamentous fungi and yeasts, as new sorbents used in the solid-phase extraction of metal ions from various water sample matrices. A survey of the literature over 2004-2014 shows possible applications of selected new sorbents available for use in trace metal analysis in waters using solidphase extraction. We highlight the preconcentration of the toxic elements prior to their determination by atomic spectrometry. 相似文献
218.
Hydroxyl-enriched materials are promising boron adsorbents. However, the use of these materials is hampered by issues of separation, recovery, and selectivity, notably due to the presence of interfering ions. Therefore, we synthesized here a cheap magnetic nanopowder, which was further functionalized with polyvinyl alcohol and glycidol to produce boron-selective adsorbents. We studied their selectivity and removal efficiency using batch and fixed-bed systems. Sorption was studied at both concentrated and trace amounts of boron. Results show that nanopowders have 5.3–6.5 nm pore sizes and 145–203 m2/g surface areas, using Brunauer–Emmett–Teller analysis. Polyvinyl alcohol-functionalized particles removed 93 % of boron at 5 mg/L at pH 7 in 30 min, whereas only 68 % of boron was removed by glycidol-functionalized particles. However, at higher boron concentration, of 50 mg/L, glycidol-functionalized particles showed higher adsorption affinity of 68.9 mg/g. We conclude that internal hydroxyl groups of polyvinyl alcohol-functionalized particles are less accessible at higher boron concentration. This is the first report on magnesium ferrites for boron recovery. The spent adsorbents were separated easily from the aqueous media by an external magnet and repeatedly used. Overall, our findings demonstrated that the hydroxyl-enriched magnetic nanopowders are a better alternative to the existing boron adsorbents regarding magnetic separation, reusability, and selectivity. 相似文献
219.
Yuankai ZHANG Hongchen WANG Lu QI Guohua LIU Zhijiang HE Songzhu JIANG 《Frontiers of Environmental Science & Engineering》2016,10(2):319-326
In wastewater treatment plants (WWTPs), a secondary settler acts as a clarifier, sludge thickener, and sludge storage tank during peak flows and therefore plays an important role in the performance of the activated sludge process. Sludge thickening occurs in the lower portions of secondary clarifiers during their operation. In this study, by detecting the hindered zone from the complete thickening process of activated sludge, a simple model for the sludge thickening velocity, u s = aX b (a = 0.9925SSVI 3.5, b = 3.541ln(SSVI 3.5)+12.973), describing the potential and performance of activated sludge thickening in the hindered zone was developed. However, sludge thickening in the compression zone was not studied because sludge in the compression zone showed limited thickening. This empirical model was developed using batch settling data obtained from four WWTPs and validated using measured data from a fifth WWTP to better study sludge thickening. To explore different sludge settling and thickening mechanisms, the curves of sludge thickening and sludge settling were compared. Finally, it was found that several factors including temperature, stirring, initial depth, and polymer conditioning can lead to highly concentrated return sludge and biomass in a biologic reactor. 相似文献
220.
Boxiong SHEN Jianhong CHEN Ji CAI 《Frontiers of Environmental Science & Engineering》2016,10(2):236-243
This study described the use of clay impregnated by KI in gas phase elemental mercury (Hgo) removal in flue gas. The effects of KI loading, temperature, O2, SO2 and H2O on Hgo removal were investigated using a fixed bed reactor. The Hgo removal efficiency of KI-clay with 3% KI loading could maintain at a high level (approximately 80 %) after 3 h. The KI-clay demonstrated to be a potential adsorbent for Hgo removal when compared with activated carbon based adsorbent. O2 was found to be an important factor in improving the Hgo removal. O2 was demonstrated to assist the transfer of KI to I2 on the surface of KI-clay, which could react with Hgo directly. NO and SO2 could slightly improve Hgo removal, while H2O inhibited it greatly. The results indicated that after adsorption, most of the mercury escaped from the surface again. Some of the mercury may have been oxidized as it left the surface. The results demonstrated that the chemical reaction primarily occurred between KI and mercury on the surface of the KI-clay. 相似文献