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1.
Saltmarsh sparrows (Ammospiza caudacuta) and seaside sparrows (A. maritima) are species of conservation concern primarily due to global sea-level rise and habitat degradation. Environmental mercury (Hg) contamination may present additional threats to their reproductive success and survival. To assess site-specific total mercury (THg) exposure and identify environmental correlates of THg detection, we sampled blood from adult male saltmarsh and seaside sparrows at 27 sites between Maine and Virginia, USA. The mean THg concentration (±1 SD) throughout the entire sampling range was 0.531 ± 0.287 µg/g wet weight (ww) for saltmarsh sparrows and 0.442 ± 0.316 µg/g ww for seaside sparrows. Individual THg concentrations ranged from 0.135–1.420 µg/g ww for saltmarsh sparrows and 0.153–1.530 µg/g ww for seaside sparrows. Model averaging from a suite of linear mixed models showed that saltmarsh sparrows averaged 20.1% higher blood THg concentrations than seaside sparrows, potentially due to differences in diet or foraging behavior. We found no evidence for a relationship between sparrow THg concentrations and land cover surrounding sampled marshes or average precipitation-based Hg deposition. Overall, our results suggest considerable, unexplained variation in tidal marsh sparrow blood THg concentrations over their co-occurring breeding ranges. 相似文献
2.
Nelson’s and saltmarsh sparrows ( Ammodramus nelsoni and A. caudacutus) have recently been recognized as separate species, and because of their limited distributions and the susceptibility of
their wetland habitats to climate change, these two new species are of conservation concern. Both species are known to bioaccumulate
mercury at breeding sites in New England, USA where their ranges overlap, with the saltmarsh sparrow reported to have twice
the concentration of blood total mercury. In this study we sampled both species on their shared wintering grounds, and documented
that mercury exposure is lower than that reported for the breeding range, with saltmarsh sparrow blood mercury 2.6 times higher
than in Nelson’s sparrow. Feather mercury, which is incorporated on the breeding grounds, confirmed that saltmarsh sparrows
had incorporated 2.3 times more mercury than Nelson’s sparrows during the previous breeding season. A comparison of stable
isotopes of nitrogen and carbon suggests that the higher exposure of saltmarsh sparrows may be not due to feeding at a higher
trophic level, as previously hypothesized, but rather could be related to a difference in the carbon source at the base of
each species’ food chain. This study, along with recently published data from both species on additional breeding and wintering
grounds, provides a more complete picture of relative mercury exposure. Saltmarsh sparrows are exposed to mercury levels that
warrant concern, with the highest exposure being during the breeding season. Areas set aside for the long-term conservation
of this species should be carefully assessed for mercury bioaccumulation. 相似文献
3.
We examined factors influencing mercury concentrations in 90 fledgling Forster’s terns ( Sterna forsteri) and evaluated whether mercury influenced postfledging survival in San Francisco Bay, California. Mercury concentrations
(±SE) in chicks 21–29 days old (just before fledging) were 0.33 ± 0.01 μg g −1 ww for blood and 6.44 ± 0.28 μg g −1 fw for breast feathers. Colony site had an overriding influence on fledgling contamination, however hatching date and age
also affected blood, but not feather, mercury concentrations. Blood mercury concentrations decreased by 28% during the 50-day
hatching period and increased with chick age by 30% during the last week prior to fledging. Using radio-telemetry, we calculated
that cumulative survival during the 35-day postfledging time period was 0.81 ± 0.09 (SE). Postfledging survival rates increased
with size-adjusted mass, and cumulative survival probability was 61% lower for terns with the lowest, compared to the highest,
observed masses. Conversely, survival was not influenced by blood mercury concentration, time since fledging, sex, or hatch
date. Mercury concentrations in breast feathers of fledglings found dead at nesting colonies also were no different than those
in live chicks. Our results indicate that colony site, hatching date, and age influenced mercury concentrations in fledgling
Forster’s terns, but that mercury did not influence postfledging survival. 相似文献
4.
Contamination of fish populations with methylmercury is common in the region of the Laurentian Great Lakes as a result of
atmospheric deposition and methylation of inorganic mercury. Using fish mercury monitoring data from natural resource agencies
and information on tissue concentrations injurious to fish, we conducted a screening-level risk assessment of mercury to sexually
mature female walleye ( Sander vitreus), northern pike ( Esox lucius), smallmouth bass ( Micropterus dolomieu), and largemouth bass ( Micropterus salmoides) in the Great Lakes and in interior lakes, impoundments, and rivers of the Great Lakes region. The assessment included more
than 43,000 measurements of mercury in fish from more than 2000 locations. Sexually mature female fish that exceeded threshold-effect
tissue concentrations of 0.20 μg g −1 wet weight in the whole body occurred at 8% (largemouth bass) to 43% (walleye) of sites. Fish at 3% to 18% of sites were
at risk of injury and exceeded 0.30 μg g −1 where an alteration in reproduction or survival is predicted to occur. Most fish at increased risk were from interior lakes
and impoundments. In the Great Lakes, no sites had sexually mature fish that exceeded threshold-effect concentrations. Results
of this screening-level assessment indicate that fish at a substantive number of locations within the Great Lakes region are
potentially at risk from methylmercury contamination and would benefit from reduction in mercury concentrations. 相似文献
6.
In order to assess the toxicity of heavy metals on the early development of Meretrix meretrix, the effects of mercury (Hg), cadmium (Cd) and lead (Pb) on embryogenesis, survival, growth and metamorphosis of larvae were
investigated. The EC 50 for embryogenesis was 5.4 μg l −1 for Hg, 1014 μg l −1 for Cd and 297 μg l −1 for Pb, respectively. The 96 h LC 50 for D-shaped larvae was 14.0 μg l −1 for Hg, 68 μg l −1 for Cd and 353 μg l −1 for Pb, respectively. Growth was significantly retarded at 18.5 μg l −1 (0.1 μM) for Hg, 104 μg l −1 (1 μM) for Cd and 197 μg l −1 (1 μM) for Pb, respectively. The EC 50 for metamorphosis, similar to 48 h LC 50, was higher than 96 h LC 50. Our results indicate that the early development of M. meretrix is highly sensitive to heavy metals and can be used as a test organism for ecotoxicology bioassays in temperate and subtropical
regions. 相似文献
7.
The development of suitable biomarker-based microbioassays with model species with ecological relevance would help increase
the cost-efficiency of routine environmental monitoring and chemical toxicity testing. The anti-inflammatory drug diclofenac
has been widely reported in the environment but ecotoxicological data are scarce. The aim of this work is to assess the acute
and chronic sublethal toxicity of diclofenac in relevant taxa of aquatic and riparian ecosystems (the fish Danio rerio and the fern Polystichum setiferum). Reliable biomarkers of cell viability (mitochondrial activity), plant physiology (chlorophyll), growth (DNA content) or
oxidative damage (lipid peroxidation) were assessed as sensitive endpoints of toxicity. DNA quantification shows that diclofenac
induces acute lethal phytotoxicity at 24 and 48 h (LOECs 30 and 0.3 μg l −1, respectively). Hormetic effects in mitochondrial activity in spores of Polystichum setiferum mask lethality, and adverse effects are only observed at 48 h (LOEC 0.3 μg l −1). In chronic exposure (1 week) LOEC for DNA is 0.03 μg l −1. Mitochondrial activity shows a strong hormetic stimulation of the surviving spore population (LOEC 0.3 μg l −1). Little changes are observed in chlorophyll autofluorescence (LOEC 0.3 μg l −1). A very short exposure (90 min) of zebrafish embryos induces a reduction of lipid peroxidation at 0.03 μg l −1. Environmental concentrations of diclofenac can be deleterious for the development of significant populations of sensitive
individuals in aquatic and riparian ecosystems. 相似文献
8.
The influence of dissolved organic carbon (DOC), in the form of Suwannee River fulvic acid (SRFA), on uranium (U) toxicity
to the unicellular eukaryote, Euglena gracilis (Z strain), was investigated at pH 6. In a background medium without SRFA, exposure of E. gracilis to 57 μg L −1 U resulted in a 50% reduction in growth (IC 50). The addition of 20 mg L −1 DOC (as SRFA), reduced U toxicity 4 to 5-fold (IC 50 increased to 254 μg L −1 U). This reduction in toxicity was also evident at more sensitive effect levels with a 10% reduction in growth (IC 10) occurring at 5 μg L −1 U in the background medium and at 17 μg L −1 U in the SRFA medium, respectively. This amelioration of toxicity with the addition of SRFA was linked to a decrease in the
bioavailability of U, with geochemical speciation modelling predicting 84% of U would be complexed by SRFA. The decrease in
bioavailability of U in the presence of SRFA was also evident from the 11–14 fold reduction in the cellular concentration
of U compared to that of E. gracilis in the background medium. Stepwise multiple linear regression analyses indicated that UO 2
2+ alone explained 51% of the variation in measured U toxicity to E. gracilis. Preliminary U exposures to E. gracilis in the presence of a reactive oxygen species probe, suggest exposure to ≥60 μg L −1 U may induce oxidative stress, but this endpoint was not considered to be a sensitive biological indicator. 相似文献
9.
Selenium effects in nature are mediated by the relatively large bioconcentration of aqueous Se by primary producers and smaller,
yet critical, dietary transfers to primary consumers. These basal processes are then propagated through food webs to higher
trophic levels. Here we quantified the movement of dissolved Se (as selenite) to periphyton, and used the resultant periphyton
as a food source for conducting full life-cycle dietary Se exposures to the mayfly Centroptilum triangulifer. Periphyton bioconcentrated Se ~2,200-fold from solution in a log-linear fashion over dissolved Se concentrations ranging
from 1.1 to 23.1 μg L −1. We examined the influence of two feeding ration levels ( 1x and 2x) on trophic transfer, tissue Se concentrations, maternal transfer, and functional endpoints of mayfly performance. Mayflies
fed a lesser ration ( 1x) displayed greater trophic transfer factors (mean TTF, 2.8 ± 0.4) than mayflies fed 2x rations (mean TTF, 1.1 ± 0.3). In 1x exposures, mayflies exhibited significant ( p < 0.05) reductions in survivorship and total body mass at dietary [Se] ≥ 11.9 μg g −1, reduced total fecundity at ≥4.2 μg g −1, and delayed development at ≥27.2 μg g −1. Mayflies fed a greater ration ( 2x) displayed reduced tissue Se concentrations (apparently via growth dilution) relative to 1x mayflies, with no significant effects on performance. These results suggest that the influence of Se on mayfly performance
in nature may be tied to food resource availability and quality. Furthermore, nutritional status is an important consideration
when applying laboratory derived estimates of toxicity to risk assessments for wild populations. 相似文献
10.
Acute toxic effects and mechanisms of two typical endocrine disrupting chemicals, nonylphenols (NPs) and bisphenol A (BPA),
to the embryonic development of the abalone Haliotis diversicolor supertexta, were investigated by the two-stage embryo toxicity test. The 12-h median effective concentrations (EC 50) of NPs and BPA to the trochophore development were 1016.22 and 30.72 μg L −1, respectively, and the respective 96-h EC 50 values based on the completion of metamorphosis (another experimental endpoint) were reduced to 11.65 and 1.02 μg L −1. Longer exposure time and magnified exposure concentrations in the benthic diatom, that serves as both food source and settlement
substrate during the metamorphosis, via bioaccumulation, led to the higher sensitivity of metamorphosis to target EDCs compared
with the trochophore development. The hazard concentrations for 5% of the species (HC 5) could be employed as the safety thresholds for the embryonic development of the abalone. The 12-h HC 5 values of NPs and BPA were 318.68 and 13.93 μg L −1, respectively, and the respective 96-h HC 5 values were 0.99 and 0.18 μg L −1, which were at environmentally relevant levels. Results of proteomic responses revealed that NPs and BPA altered various
functional proteins in the abalone larvae with slight differences between each chemical and affected various physiological
functions, such as energy and substance metabolism, cell signalling, formation of cytoskeleton and cilium, immune and stress
responses at the same time, leading to the failure of metamorphosis. 相似文献
11.
Wetlands play a major role in the export of methylmercury (MeHg) to a watershed. The large contribution of wetlands to watersheds
in northern Wisconsin, coupled with the acidic environment of this area, makes these habitats especially vulnerable to mercury
(Hg) accumulation by biota. The purpose of this study was to compare Hg accumulation between northern Wisconsin wetlands and
southern Wisconsin wetlands using the swamp sparrow ( Melospiza georgiana) as a representative species. The swamp sparrow was selected as a representative passerine species in which to examine Hg
in these habitats, because during their breeding season, they feed at a higher trophic level than many of their counterparts.
During the breeding seasons of 2007 and 2008, blood samples were collected from swamp sparrows inhabiting wetlands in both
northern and southern Wisconsin and analyzed for total Hg. The mean concentration of total Hg in swamp sparrows from northern
wetlands was 0.135 ± 0.064 μg/ml while the mean concentration of total Hg in swamp sparrows from southern wetlands was 0.187 ± 0.106 μg/ml.
Results revealed no significant difference ( P = 0.17) between Hg accumulation in swamp sparrows from less-acidic wetlands in southern Wisconsin and Hg in swamp sparrows
from acidic wetlands in northern Wisconsin. The results are contrary to those observed in other species such as common loon,
tree swallow and river otter where higher accumulation has been observed in individuals from acidic habitats. Reasons for
the lack of this accumulation pattern in swamp sparrows are unclear and warrant further study. 相似文献
12.
Lethal and sublethal toxicity of Nickel (Ni) to three marine copepods Tigriopus japonicus, Apocyclops borneoensis and Acartia pacifica was investigated . The 48-h LC50 values were 17.70, 13.05 and 2.36 mg l −1 Ni, respectively. A. pacifica was found to be the most sensitive to Ni in acute exposure tests. In order to assess sublethal effects of Ni on copepod reproduction,
the test organisms were exposed to four nominal Ni concentrations 0, 10, 100, 1000 μg l −1 Ni. The results indicated that offspring production of T. japonicus and A. borneoensis was significantly reduced after exposure to 10 μg l −1 Ni. Whereas egg production and egg hatching success of A. pacifica were significantly reduced at 100 and 10 μg l −1 Ni, respectively. Exposure of copepods to the highest Ni concentration caused a severely reduced nauplii production from
T. japonicus, A. borneoensis and A. pacifica by 87.8, 56.9 and 65.8%, respectively, and a significantly reduced egg production of A. pacifica by 74.4%. These results show that Ni excess in the coastal environment can have detrimental effects on reproduction of copepods. 相似文献
13.
Hyperaccumulators are important in the phytoremediation of cadmium (Cd)-contaminated soil. In this study, Cd accumulation
and the interactions between Cd and four other trace elements (Fe, Mn, Cu, and Zn) in Lonicera japonica Thunb . were investigated. As a result of exposure to soil containing 50 mg kg −1 Cd, stem and shoot Cd concentrations reached 344.49 ± 0.71 and 286.12 ± 9.38 μg g −1 DW respectively, without showing symptoms of visible damage to the plants. This suggests that L. japonica has a strong tolerance to Cd. It is proposed that trace metal elements are involved in the Cd-detoxification mechanisms shown
by hyperaccumulators. There is a synergistic interaction in accumulation and translocation between Cd and Fe and a significantly
negative correlation between Cd and Cu or Zn concentrations in L. japonica plant tissues. The imbalanced trace element concentrations influences detoxification processes to Cd, therefore, L. japonica could be considered as a new Cd-hyperaccumulator model to investigate the metal tolerance strategies of plants. 相似文献
14.
Relative cytotoxicity and genotoxicity of a widely used antibiotic, trimethoprim (TRIMP) was evaluated under in vitro conditions
using rainbow trout gonad-2 (RTG-2) and Chinese hamster ovary-K1 (CHO-K1) cells. Whilst cytotoxicity was determined using
neutral red retention (NRR) assay, the genotoxicity was determined using single cell gel electrophoresis or the Comet assay
and cytokinesis-block micronucleus (CBMN) assay. For NRR assay, concentration-dependent cytotoxic effect was observed for
both the cell lines (estimated EC 50 values: 671.82 ± 21.78 and 611.6 ± 20.4 μg ml −1 for RTG-2 and CHO-K1 cells, respectively). There was no statistically significant difference between the two cell lines for
this assay. For the Comet assay, standard 6 h exposure to TRIMP did not show any positive response for any of the cell types
used. However, 48 h exposure to RTG-2 cells showed a concentration-dependent induction of DNA damage ( r = 0.86). The highest concentration of TRIMP used (i.e. 100 μg ml −1) showed relatively higher DNA damage, compared to ethyl methane sulfonate (EMS; 1 μg ml −1 or 8 mM), a reference genotoxic agent, used concurrently. In contrast, 24 h exposure time for CHO-K1 cells did not show any
concentration-dependent increase for this assay. For MN assay, a significant correlation was found between the MN induction
and TRIMP concentration for both the cell lines (RTG-2: r = 0.68; CHO-K1: r = 0.79), although only the highest concentration used showed a significant increase for binucleated (BN) cell with micronuclei
(BNMN). The study suggests that whilst the cells of different origin could exhibit similar cytotoxicity, they could display
differential genotoxic effects. Furthermore, genotoxic effects of TRIMP are primarily exposure period dependent phenomena
and, in addition to inhibiting the action of dihydrofolate reductase, oxidative stress could also contribute for the observed
toxic effects, fish cells in general being more sensitive for genotoxic effects. 相似文献
15.
Effects of cadmium on in vitro and in vivo cholinesterase (ChE) activities of brain and muscle tissues of Oreochromis niloticus fingerlings were evaluated, considering its potential use in biomonitoring tropical water pollution. Results show that in vitro
ChE activities were depressed significantly by millimolar concentration ranges of Cd 2+. The IC 50 values of Cd 2+ on in vitro ChE activity in brain and muscle tissues were 1.56 and 4.31 mM, respectively. Exposure of fish to environmentally
relevant concentrations of Cd 2+ (5–30 μg l −l) for 28 days evoked only a transient inhibition (21–34%) of in vivo ChE activities. Prior exposure and co-exposure of fish
to 15 μg l −1 of Cd 2+ enhanced the extent of inhibition of ChE levels induced by the organophosphorous insecticide chlorpyrifos. As high concentrations
of cadmium have the potential to depress ChE activities, monitoring of metal levels in water bodies with suspected high levels
of metal inputs is necessary to accurately interpret the fish ChE inhibition data in relation to insecticide contaminations. 相似文献
16.
The growth of three marine phytoplankton species Skeletonema costatum, Scrippsiella trochoidea and Chattonella marina and the response of the antioxidant defense system have been investigated on exposure to commercial cypermethrin for 96 h
and 32 days in a co-culture system. Growth of the three species was generally comparable over 96 h with an inoculation of
1:3:6.5 ( C. marina: S. trochoidea: S. costatum), with stimulation at 5 μg l −1 and inhibition under higher concentrations (50, 100 μg l −1). However, when inoculating at ratios of 1:1:1 during a 32 day test, S. costatum became the most sensitive species and was significantly inhibited in all test groups under the dual stresses of cypermethrin
and interspecies competition. The growth of C. marina was significantly inhibited at the concentrations higher than 5 μg l −1, while the growth of S. trochoidea was significantly promoted at low concentrations. Superoxide dismutase (SOD) activities significantly increased during 6–12 h
exposure periods in test treatments at low concentrations, and enhanced in the control as well due to interspecies competition.
The lipid peroxidation product malondialdehyde was enhanced at high concentrations, but did not increase in control and low
concentration cultures with high SOD activities, indicating that algal cells activated the antioxidant enzymes promptly to
protect the cells from lipid membrane damage. Results from this study suggested that cypermethrin pollution in maricultural
sea waters might lead to a shift in phytoplankton community structure from diatom to harmful dinoflagellate species, and thus
potentially stimulatory for harmful algal blooms. 相似文献
17.
Seedling development, accumulation and distribution of lead (Pb) in Iris lactea var. chinensis (Fisch.) Koidz. and I. tectorum Maxim. were studied using plants grown in sand culture and exposed to 0–10 mmol l −1 concentrations of Pb supplied as Pb(NO 3) 2 for 28 days. A significant reduction in dry weight (dw) of shoots and roots of I. lactea var. chinensis was observed at 6 and 10 mmol l −1, respectively, and a significant reduction in dw of shoots and roots of I. tectorum was observed at 6 mmol l −1. Concentration of Pb in the shoots and roots of I. lacteal var. chinensis exposed to 4 mmol l −1 Pb reached 1,109 μg g −1 and 2,408 μg g −1 dw, respectively. The index of tolerance (IT) of I. lactea var. chinensis among 0–8 mmol l −1 Pb treatments were not significantly different, while those of I. tectorum at 6 mmol l −1 Pb were significantly decreased. The results indicated that I. lactea var. chinensis was more tolerant to Pb than I. tectorum. Sub-cellular localization of Pb in root cells was evaluated using transmission electron microscopy (TEM) and Pb deposits
were found along the plasma membrane of some root tip cells of I. lactea var. chinensis treated at 10 mmol l −1 Pb. Deposits of Pd were also observed along the surface, in the root tip cell wall and in the cytoplasm of a few malformed
cells of I. tectorum exposed at 10 mmol l −1 Pb treatment. One possible mechanism to explain these observations may be that most cells can maintain normal activities
in the plant by sacrificing a small number of cells that accumulate a large amount Pb and show toxicity. Future studies should
be designed to test this hypothesis. 相似文献
18.
Background: Pharmacokinetics and tissue concentrations of amiodarone may vary considerably in end-stage heart failure, but may be crucial
for treatment efficiency and antiarrhythmic drug therapy.
Objective: This study was undertaken to determine plasma amiodarone and desethylamiodarone concentrations and to determine whether
they correlate with myocardial concentrations in explanted hearts from patients with end-stage heart failure.
Patients and methods: Eight patients with idiopathic dilated cardiomyopathy and normal coronary arteries were included in the present study. Myocardial
tissue samples (seven sites) and epicardial fat were taken from each explanted heart, and drug concentrations of amiodarone
and desethylamiodarone were determined. In addition, plasma drug levels were measured and compared with the myocardial amiodarone/desethylamiodarone
concentrations.
Results: The mean cumulative amiodarone dose was 91 g and the mean plasma concentrations of amiodarone and desethylamiodarone were
0.68 and 0.84 μg · ml −1, respectively. The tissue concentrations of amiodarone amounted to 13.2 and 28.3 μg · g −1, respectively, in the atria and to 13.0 and 40.8 μg · g −1, respectively, in the ventricles. The distribution of the drug and its metabolite were similar in the right and left ventricles.
There was a good correlation between myocardial concentration of amiodarone and desethylamiodarone and the cumulative ingested
dose of amiodarone. Tissue drug concentrations correlated only poorly with plasma amiodarone or desethylamiodarone levels.
The highest drug levels were measured in the epicardial fat tissue, where the ratio of amiodarone 105 μg · g −1 to desethylamiodarone 32 μg · g −1 was reversed (3.3 compared with 0.29 in the ventricles). Thus, amiodarone concentrations in epicardial fat were approximately
10 times higher than myocardial and 150 times higher than plasma levels.
Conclusions: Our data confirm the slow equilibrium of amiodarone and desethylamiodarone concentrations between plasma and myocardium.
Myocardial tissue concentrations of desethylamiodarone and, to a lesser degree, amiodarone correlate with the cumulative ingested
dose of amiodarone. Monitoring of the total cumulative dose may be more relevant clinically than monitoring plasma levels.
These results support the clinical practice of reducing the maintenance dose of amiodarone in patients who are on long-term
treatment.
Received: 12 July 1997 / Accepted in revised form: 25 September 1997 相似文献
19.
A media consisting of isatin-Schiff bases (isatin-3-thiosemicarbazone, isatin-3-semicarbazone, and isatin-3-phenylhydrazone)
was developed to maximize the production of antibiotics Hexaene H-85 and Azalomycine B by Streptomyces hygroscopicus. The media isatin-3-thiosemicarbazone resulted in the maximum antibiotics concentration of 372 μg cm −3 for Hexaene H-85 and 118 μg cm −3 for Azalomycine B. The impact of modified media on soil morphology also was investigated. 相似文献
20.
The antimicrobial activity of five novel SQ109 derivatives including SQ109 against bacteria, yeast and filamentous fungi is reported herein. Using broth microdilution techniques, compounds 2 and 3 were found to be active against most tested fungi and bacteria, with minimum inhibitory concentrations (MICs) ranging from
0.98 to 31 μg ml −1, except for Klebsiella pneumonia where the MIC was 250 μg ml −1. SQ109 and derivative 4 did not show any significant activity against most of the organisms used. However, their reduced derivatives 1 and 5 showed promising activity with MICs between 0.49 and 62.5 μg ml −1 against most of the microorganisms used. 相似文献
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