共查询到20条相似文献,搜索用时 15 毫秒
1.
Chang Wang Ling Wang Ying Wang Yong Liang Jie Zhang 《Environmental Earth Sciences》2012,65(6):1643-1649
To offer an insight into the toxicity of nanomaterials (NM) on the growth of bacteria, Escherichia coli (E. coli), Bacillus subtilis (B. subtilis) and Agrobacterium tumefaciens (A. tumefaciens) were exposed to nano-Au, nano-Ag, nano-Fe and fullerene (C60) in this study. As an effective bactericide, nano-Ag induced high toxicity on these three bacteria; C60 could inhibit their growth; however, B. subtilis and E. coli could recover as exposure time extended. Nano-Au and nano-Fe had hardly any effect on three bacteria. A. tumefaciens showed the lowest resistance and slowest growth rate during exposure. Images obtained by scanning electron microscope (SEM)
revealed that nano-Ag could cause damage to the cell structure of three bacteria at 1 μg/mL. Slight damage on E. coli was found when exposed to C60, whereas no obvious physical damage was found after exposure to nano-Au or nano-Fe. It is assumed that surface activities
of NM might be responsible for the different toxic effects on these bacteria. 相似文献
2.
3.
Ramona L. Walls 《Estuaries and Coasts》2010,33(4):902-918
Japanese knotweed s.l. (Fallopia spp.) is a highly invasive clonal plant, best known from roadside and riparian habitats. Its expansion into beaches on Long
Island, NY, USA, represents a major habitat shift. I surveyed populations from beaches and wetlands and conducted a common
garden experiment to test for variation in drought tolerance and phenotype among populations and habitats. All populations
were composed mostly of first- and later-generation hybrids. I found significant variation among populations in growth, lamina
size, specific leaf area (SLA), and biomass allocation, in both the field and the common garden. Lamina size, growth, and
root-to-shoot responded plastically to drought treatment. Wetland populations tolerated drought as well as beach populations.
Differentiation in SLA between habitats suggests that some selection for beach genotypes may have occurred. It appears that
both hybridization and phenotypic plasticity are contributing to the expansion of Fallopia spp. into novel habitat. 相似文献
4.
Scott Zengel Steven C. Pennings Brian Silliman Clay Montague Jennifer Weaver Donald R. Deis Michelle O. Krasnec Nicolle Rutherford Zachary Nixon 《Estuaries and Coasts》2016,39(4):1154-1163
The Deepwater Horizon oil spill was the largest marine oil spill in US waters to date and one of the largest worldwide. Impacts of this spill on salt marsh vegetation have been well documented, although impacts on marsh macroinvertebrates have received less attention. To examine impacts of the oil spill on an important marsh invertebrate and ecosystem engineer, we conducted a meta-analysis on fiddler crabs (Uca spp.) using published sources and newly available Natural Resources Damage Assessment (NRDA) and Gulf of Mexico Research Initiative (GoMRI) data. Fiddler crabs influence marsh ecosystem structure and function through their burrowing and feeding activities and are key prey for a number of marsh and estuarine predators. We tested the hypothesis that the spill affected fiddler crab burrow density (crab abundance), burrow diameter (crab size), and crab species composition. Averaged across multiple studies, sites, and years, our synthesis revealed a negative effect of oiling on all three metrics. Burrow densities were reduced by 39 % in oiled sites, with impacts and incomplete recovery observed over 2010–2014. Burrow diameters were reduced from 2010 to 2011, but appeared to have recovered by 2012. Fiddler crab species composition was altered through at least 2013 and only returned to reference conditions where marsh vegetation recovered, via restoration planting in one case. Given the spatial and temporal extent of data analyzed, this synthesis provides compelling evidence that the Deepwater Horizon spill suppressed populations of fiddler crabs in oiled marshes, likely affecting other ecosystem attributes, including marsh productivity, marsh soil characteristics, and associated predators. 相似文献
5.
The compressibility at room temperature and the thermal expansion at room pressure of two disordered crystals (space group
C2/c) obtained by annealing a natural omphacite sample (space group P2/n) of composition close to Jd56Di44 and Jd55Di45, respectively, have been studied by single-crystal X-ray diffraction. Using a Birch–Murnaghan equation of state truncated
at the third order [BM3-EoS], we have obtained the following coefficients: V
0 = 421.04(7) Å3, K
T0 = 119(2) GPa, K′ = 5.7(6). A parameterized form of the BM3 EoS was used to determine the axial moduli of a, b and c. The anisotropy scheme is β
c
≤ β
a
≤ β
b
, with an anisotropy ratio 1.05:1.00:1.07. A fitting of the lattice variation as a function of temperature, allowing for linear
dependency of the thermal expansion coefficient on the temperature, yielded αV(1bar,303K) = 2.64(2) × 10−5 K−1 and an axial thermal expansion anisotropy of α
b
≫ α
a
> α
c
. Comparison of our results with available data on compressibility and thermal expansion shows that while a reasonable ideal
behaviour can be proposed for the compressibility of clinopyroxenes in the jadeite–diopside binary join [K
T0 as a function of Jd molar %: K
T0 = 106(1) GPa + 0.28(2) × Jd(mol%)], the available data have not sufficient quality to extract the behaviour of thermal expansion for the same binary join in
terms of composition. 相似文献
6.
C. A. Timotheo C. M. LauerJr. 《International Journal of Environmental Science and Technology》2018,15(3):659-664
Vegetable tannins are complex polyphenols, which occur widely in nature. Traditionally, natural tannins have been used for tanning leather. In Brazil, the main tannin-based products are obtained from Acacia mearnsii, which is a leguminous tree native to Southeastern of Australia, and the first seeds were brought to Brazil in 1928. The main cultivation of acacia was established in Rio Grande do Sul state due to the possibility of raw material for charcoal, adhesives to fuel and for tanning leather. The leather tanning processes based on plant tannins are thought to be less harmful than chromium-based tanning, and it has been used as a sustainable alternative. However, there is scarce information about the environmental impact of the leather tanning processes, with most studies reporting inhibitory effects against microorganisms at high doses and stimulatory and positive health effects at low concentrations. The aim of this study was to evaluate the toxicity of tannin preparations extracted from A. mearnsii in Saccharomyces cerevisiae. Vegetable tannin toxicity in yeast was tested using two tannin treatments in different concentrations. In general, the results showed toxicity of vegetable in yeast, BY4741 and gsh1Δ strains. 相似文献
7.
L. N. Berdnikov O. V. Vozyakova A. Yu. Kniazev V. V. Kravtsov A. K. Dambis S. V. Zhuiko 《Astronomy Reports》2012,56(4):290-304
We have obtained 26 372 CCD frames in the B, V, and I
c
filters for 81 RR Lyrae stars in 2008–2010, using the 76-cm telescope of the South African Astronomical Observatory and the
40-cm telescope of the Cerro Armazones Observatory, North Catholic University (Chile) using an SBIG ST-10XME CCD camera. For
12 of these RR Lyrae stars, we also obtained 337 brightness measurements in the B and V bands in 2000–2001 using the 60-cm telescope of the High Altitude Mt. Maidanak Observatory (Republic of Uzbekistan). We present
tables of observations, light curves, and improved light-curve elements for all these RR Lyrae stars. The Blazhko effect was
detected for SU Hor. 相似文献
8.
Alejandro?D.?Canepuccia Maria?S.?Fanjul Eugenia?Fanjul Florencia?Botto Oscar?O.?Iribarne Consejo Nacional de Investigaciones Científicas y Técnicas Departamento de Biología Universidad Nacional de Mar del Plata Mar del Plata Argentina 《Estuaries and Coasts》2008,31(5):920-930
The role of positive and indirect interactions is often crucial in communities with intense abiotic stress such as salt marshes.
The burrowing crab, Neohelice (=Chasmagnathus) granulata, is the dominant benthic macroinvertebrate of southwest Atlantic marshes (southern Brazil to Northern Argentinean Patagonia),
having strong direct and indirect effects on marsh soil and, in consequence, on marsh vegetation and primary consumers. In
this work, we investigate if this crab indirectly modifies habitat use by the granivorous rodents, Akodon azarae and Oligoryzomys flavescens, by increasing nutrient availability and thus enhancing seed production by the marsh plant Spartina densiflora. The study was conducted at the Mar Chiquita Coastal Lagoon, Argentina (37°32′ S). Rodent frequencies in S. densiflora were positively correlated with crab densities throughout the low and middle marsh. Additionally, the highest quality of
S. densiflora and inflorescence density was recorded at the highest crab densities. Experimental manipulation of crab densities shows that
N. granulata indirectly enhances the performance of S. densiflora (e.g., decreased fiber content and C/N ratios) and increases density of seeds. Moreover, N. granulata also facilitates S. densiflora seed availability to rodents by concentrating them in sediment mound at their burrows entrances. Experimental rodent exclusions
showed that rodent species used S. densiflora seeds, a variable positively related to crab burrow density. Thus, our results show that N. granulata drives the granivorous rodent distribution and the intensity of seeds–rodent interaction trough facilitative and indirect
interactions in marsh community. 相似文献
11.
Jorge M. Navarro Waleska Labraña Oscar R. Chaparro Barbara Cisternas Alejandro Ortíz 《Estuaries and Coasts》2016,39(4):1133-1141
Frequent blooms of the dinoflagellate Alexandrium catenella in southern Chile encouraged undertaking the present study which uses the oyster Ostrea chilensis as a model for evaluating the feeding, growth, lipid storage and mortality responses to diets containing paralytic shellfish poisoning (PSP) produced by A. catenella. Medium-term (30 days) physiological responses of two groups of juvenile oysters were measured every 10 days. Five replicates were exposed to diets containing A. catenella and other five replicates were fed with a diet containing the non-toxic algae Isochrysis galbana. Diets were continuously supplied at a concentration of 2 mg L?1, in which the feeding and metabolic activity was measured, and the scope for growth calculated. Lipids storage, actual growth and mortality were also measured every 10 days. The results showed that the toxic diet has dramatic negative effects on feeding and metabolism of the juvenile individuals of O. chilensis, with high reduction of the lipid storage and growth. Mortality was also increased in individuals fed with the contaminated diet. This study supports the conclusion that the toxic dinoflagellate A. catenella restricts the energy acquisition in the juvenile O. chilensis, an important fishery and aquaculture resource in southern Chile. 相似文献
12.
Marianne Holmer Núria Marbà Morgane Lamote Carlos M. Duarte 《Estuaries and Coasts》2009,32(3):456-466
Species of the macroalgae Caulerpa sp. are increasingly being observed in meadows of the endemic Mediterranean seagrass Posidonia oceanica, and in particular Caulerpa taxifolia, has been considered as an invasive species leading to seagrass decline. Studies have so far failed to reveal the underlying
mechanisms of the success of the macroalgae, and here, we examine how biogeochemical changes of the environment associated
to indigenous (Caulerpa prolifera) and non-indigenous (Caulerpa racemosa and C. taxifolia) species affect the habitat of P. oceanica. Two of the species (C. prolifera and C. racemosa) affect the sediment biogeochemical conditions by increasing organic matter pools, microbial activity, and sulfide pools
of the sediments, and limited effects were found for C. taxifolia. Biomass of the macroalgae contributed to the extent of impacts, and high sulfide invasion into the seagrasses and regression
of the meadow were pronounced at the location with the highest Caulerpa biomass. This suggests that Caulerpa invasion contributes to seagrass decline probably because Caulerpa thrives better than the seagrasses in the modified environment. 相似文献
13.
M. Seifipour M. Emadi-Baygi B. Saffar Sh. Abolmaali 《International Journal of Environmental Science and Technology》2017,14(3):481-486
Cadmium and other heavy metals lead to environmental danger, and these heavy metals are a great threat to human and other animal’s health. Investigation of the relationship between survival of E. coli and metallothionein smtA gene expression against cadmium ion is the goal of this research. Survival of recombinant bacteria containing smtA gene was analyzed against various concentrations of cadmium chloride salt using optical density (OD). At the resistive range, recombinant bacteria were subjected to different treatments. At the logarithmic phase of bacterial growth, sampling, RNA extraction and cDNA synthesis were performed and smtA gene expression was then analyzed by real-time PCR using designed primers for smtA gene and Amp resistance (as the calibrator gene). Relative gene expression was calculated using the ??Ct method. The resistive range against cadmium chloride was 0.5–0.7 mM (minimum inhibitory concentration (MIC = 0.5 mM)). Survival and gene expression analysis showed that in induced bacteria, smtA expression was increased significantly that in turn conferred resistance to cadmium chloride prominently. There was a direct relationship between increased smtA gene expression and survival of the recombinant bacteria. Therefore, our result may help to confront to cadmium metal environmental pollution using overexpression of smtA gene expression in recombinant bacteria. 相似文献
14.
David R. Legates 《GeoJournal》2007,70(1):15-19
An Inconvenient Truth (AIT) has earned Al Gore an Oscar and a share of the 2007 Nobel Peace Prize and has been widely acclaimed by the mass media.
However, significant errors exist in the film, owing to alarmism and exaggeration. As this forum does not provide for a detailed
examination of these errors, this paper will focus only on the portrayal of the hydrologic cycle by AIT—precipitation and
floods, soil moisture and droughts, and storminess. AIT argues that precipitation and intense rainfalls, floods, droughts,
and the total number, intensity, and duration of tropical cyclones have all increased due exclusively to anthropogenically-driven
climate change; indeed, AIT paints a picture of near scientific certainty with an overwhelming bias toward catastrophe scenarios.
A closer look at the science, however, reveals that the data do not support these claims and that the scientific community
is divided as to what the impact of anthropogenic climate change on the hydrologic cycle will be. Thus, the film gives a false
impression of both the current state of climate change and that ‘the science is settled’.
相似文献
David R. LegatesEmail: |
15.
Rhizedra lutosa (Hübner) (Lepidoptera: Noctuidae), native to Europe, was first found in North America in 1988 in southern New Jersey. The
insect is reported to cause serious damage toPhragmites australis in the Netherlands, but it now appears to be relatively unimportant throughout central Europe. We are investigating this
insect as part of an effort to characterize existing natural enemies ofP. australis in North America toward a goal of biological control of this invasive plant. We trapped adults ofR. lutosa with blacklights in Rhode Island, Massachusetts, Connecticut, New York, Delaware, and Maryland; we also found it in Ohio
and Pennsylvania.R. lutosa larvae feed in stems and rhizomes ofP. australis growing in dry sites. Based uponR. lutosa damage surveys andP. australis biomass measurements, we have determined that this insect does cause a reduction of plant growth in some sites, however,
because of low moth densities, this effect is small. Despite spreading rapidly,R. lutosa densities do not appear to be increasing at sites we have investigated, and this insect does not currently appear to have
much of an impact uponP. australis in North America. 相似文献
16.
In this study the effects of polybrominated diphenyl ether compounds (PBDEs), BDE-47 and BDE-99 on carassius aurats were discussed. The reproductive capacity viability and proliferation percent decreased with increasing BDE-47and BDE-99 concentrations (p<0.05), presenting a dose-dependent manner. Physiological biomarkers such as cholesterol (CHL), acetylcholinesterase (AChE), ethoxyresorufin-O-deethylase (EROD) and vitamin were studied to reveal the toxicological effects of BDE-47 and BDE-99 exposure. CHL levels generally decrease with increasing BDE-47 exposure. However, there were no significant differences between the samples and the control. As to BDE-99, the CHL level decreased as compared with the control level when the BDE-99 concentrations reached 20 μg/L (p<0.05). The degree of inhibition of the AChE increased with the increase of DE-47and BDE-99 concentrations. The EROD activity during 72 hours' exposure significantly increased to 20 μg/L for BDE-47 (p<0.05), however, EROD activity was not significantly different at different concentrations of BDE-99 (p<0.05). Carassius aurats hepatocytes reacted to the BDE-47 exposure with increasing EROD activities in the dose dependent manner. Although at lower concentrations, the induced effects of BDE-47 and BDE-99 were not significantly different, though BDE-47 showed strong induced effects on the EROD activity with increasing concentrations in carassius aurats hepatocytes. In contrast, BDE-99 did not influence EROD activity consistently. The VA level of carassius aurats was significantly different from that of the controls for BDE-99 (p<0.001), as far as the VA level was significantly lower of carassius aurats than the controls for BDE-47 (p<0.001). CHL, AChE, EROD, and VA levels in carassius aurats were differently affected by BDE-47 and BDE-99 exposures, therefore, they would be good indicators for exposure. 相似文献
17.
M. Rocío Fernández San Juan Carolina B. Albornoz Karen Larsen Roberto Najle 《Environmental Earth Sciences》2018,77(11):404
Contamination with heavy metals in surface and groundwater is a threat to human health and ecosystems. Due to this, the need arises to remediate water polluted through ecological and profitable technologies, such as phytoremediation. The objective of the work was to evaluate the concentration of lead (Pb) and zinc (Zn) in the floating macrophytes Limnobium laevigatum and Ludwigia peploides, after being exposed to contaminated water experimentally. In this way to be able to determine if these plants have mechanisms that allow them to accumulate the metals in the roots and to perform the translocation of these to different vegetative organs, L. laevigatum and L. peploides were placed in solutions contaminated with Pb ([Pb]?=?5 mg/l) and Zn ([Zn]?=?20 mg/l). The concentrations of metals in water, root and leaf samples were evaluated as a function of time (0, 1, 2 and 4 days). The determination of the metals was performed by the atomic absorption spectrophotometry technique. After 4 days of exposure to Pb and Zn, the plants showed high metal removal efficiencies of water, more to 70% in all cases. Pb was accumulated fundamentally by roots, while Zn was accumulated more in the leaves. In addition, the bioconcentration and translocation factors for each metal were calculated. 相似文献
18.
G. Han B. X. Cui X. X. Zhang K. R. Li 《International Journal of Environmental Science and Technology》2016,13(10):2383-2392
A pot experiment was conducted to monitor the dynamic response of photosynthesis of Amorpha fruticosa seedlings to different concentrations of petroleum-contaminated soils from April to September. The results showed that the photosynthetic rates, stomatal conductance and transpiration rate of seedlings significantly decreased in 5–20 g kg?1 petroleum-contaminated soil during the three given sampling period of July 31 (early), August 30 (mid-term) and September 29 (late). However, the intercellular CO2 concentration significantly increased in 10 g kg?1 contaminated soil, while declined in 20 g kg?1 contaminated soil during the early sampling period as well as in 20 g kg?1 contaminated soil during the late sampling period. The leaf relative water content of seedlings significantly increased in 20 g kg?1 contaminated soil during the early sampling period, while it dropped dramatically in 15–20 g kg?1 contaminated soil during the late sampling period. The contents of chlorophyll a, chlorophyll b and the total chlorophyll of seedlings showed a sharp decline during the three sampling periods in contaminated soil. Comprehensively, considering the negative effects of petroleum on the photosynthesis, growth performance and remediation effect on petroleum of A. fruticosa seedlings, this plant was tolerant of petroleum-contaminated soil and was potentially useful for the phytoremediation of petroleum-contaminated sites in northern Shaanxi, China. 相似文献
19.
Fatma Aloulou Monem Kallel Mohamed Dammak Boubaker Elleuch Alain Saliot 《Environmental Earth Sciences》2010,61(1):1-10
We investigated the mineral composition and trace element contents of dustfall with different deposited phases at the Minqin
Oasis, in China’s Hexi Corridor. The contents of elements such as Pb, Cd, Cu, As, Sb, Se, Rb, Cs, and Ba (believed to be of
anthropogenic origin) indicated that the significance of human impacts on dust emissions increased from 1970s to the early
2000s. However, variations in the content of elements including Sc, Mn, Na, Cr, V, Eu, Ce, Nb, Zr, La, and Ce (believed to
originate from natural processes such as physical and chemical weathering) show no obvious changes in the major potential
dust source areas (PSAs) in this region. In addition, analysis of the assemblage of trace elements in dustfall indicated that
the elements assumed to originate from anthropogenic and natural processes appear to be intertwined, leading to difficulties
and uncertainties in identifying the PSAs and evaluating the significance of human impacts on dust emissions. Comparisons
of the element contents of dustfall collected in Beijing and Minqin with similar data for Beijing show that under different
conditions some differences in ranges are permitted; the contents of most trace elements were similar even though the dustfall
in the two areas came from different sources. These results suggest that before attempting to identify major PSAs, researchers
should perform an integrated analysis that includes the mineral, elemental, geomorphological, vegetation cover, climatic conditions,
and other characteristics of the regions being studied. 相似文献
20.
The feeding behavior of three species of mussels, the native Ischadium recurvum and the invasives Mytella charruana and Perna viridis, was studied in an invaded ecosystem in Florida (USA). In situ feeding experiments using the biodeposition method were performed along a salinity gradient in four different locations along the St. Johns River. Water characteristics, such as salinity, temperature, dissolved oxygen, and seston loads, were recorded to identify relationships between these variables and the feeding behavior of the mussels. Feeding behavior of the species varied by study site. Clearance, filtration, organic ingestion, and absorption rates of I. recurvum were negatively affected by salinity. For the invasive mussel, M. charruana, rejection was positively related to salinity while total ingestion, organic ingestion, and absorption rates were positively related to the percentage of organic matter in the seston. For P. viridis, total and organic ingestion rates were negatively affected by salinity but positively affected by total particulate matter. Condition indices for P. viridis and M. charruana were 13.16?±?0.64 and 6.63?±?0.43, respectively, compared to 4.82?±?0.41 for the native species I. recurvum, indicating that these mussels are well adapted to the environmental conditions in the area. This study indicates that the three species have different preferred habitats because of their specific responses to water characteristics. Thus, the invasive mussels will not totally occupy the niche of the native mussel in Florida despite overlapping zones. These data may help identify potential invaded areas and understand the extent of the invasion. 相似文献