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991.
992.
At specific locations within the Baltic Sea, thermoclines and haloclines can create rapid spatial and temporal changes in
temperature (T) and salinity (S) exceeding 10°C and 9 psu with seasonal ranges in temperature exceeding 20°C. These wide ranges in abiotic factors affect
the distribution and abundance of Baltic Sea copepods via species-specific, physiological-based impacts on vital rates. In
this laboratory study, we characterized the influence of T and S on aspects of reproductive success and naupliar survival of a southwestern Baltic population of Temora longicornis (Copepoda: Calanoida). First, using ad libitum feeding conditions, we measured egg production (EP, no. of eggs female−1 day−1) at 12 different temperatures between 2.5 and 24°C, observing the highest mean EP at 16.9°C (12 eggs female−1 day−1). Next, the effect of S on EP and hatching success (HS, %) was quantified at 12°C for cohorts that had been acclimated to either 8, 14, 20 or 26 psu
and tested at each of five salinities (8, 14, 20, 26 and 32 psu). The mean EP was highest for (and maximum EP similar among)
14, 20 and 26 psu cohorts when tested at their acclimation salinity whereas EP was lower at other salinities. For adults reared
at 8 psu, a commonly encountered salinity in Baltic surface waters, EP was relatively low at all test salinities—a pattern
indicative of osmotic stress. When incubated at 12°C and 15 different salinities between 0 and 34 psu, HS increased asymptotically
with increasing S and was maximal (82.6–84.3%) between 24 and 26 psu. However, HS did depend upon the adult acclimation salinity. Finally,
the 48-h survival of nauplii hatched and reared at 14 psu at one of six different temperatures (10, 12, 14, 16, 18 and 20°C)
was measured after exposure to a novel salinity (either 7 or 20 psu). Upon exposure to 7 psu, 48-h naupliar mortality increased
with increasing temperature, ranging from 26.7% at 10°C to 63.2% at 20°C. In contrast, after exposure to 20 psu, mortality
was relatively low at all temperatures (1.7% at 10°C and ≤26.7% for all other temperatures). An intra-specific comparison
of EP for three different T. longicornis populations revealed markedly different temperature optima and clearly demonstrated the negative impact of brackish (Baltic)
salinities. Our results provide estimates of reproductive success and early survival of T. longicornis to the wide ranges of temperatures and salinities that will aid ongoing biophysical modeling examining climate impacts on
this species within the Baltic Sea. 相似文献
993.
Bryaninops, Gobiodon, Paragobiodon and Pleurosicya are the most abundant genera of coral-associated gobies. These genera are adapted to live among coral, while other small
reef gobies (e.g., the genus Eviota) show no obligate association with this living substrate. Thirteen coral-associated species and two Eviota species were sampled from different regions of the Red Sea, along with four populations/species of Gobiodon from the Indian and western Pacific Oceans. A molecular phylogenetic analysis was performed using partial sequences of 12S
rRNA, 16S rRNA and cytochrome b mitochondrial genes, 1,199 base pairs in total. Several clades were consistently resolved in neighbor joining-, maximum parsimony-,
maximum likelihood and Bayesian analyses. While each of the four genera Gobiodon, Paragobiodon, Bryaninops and Pleurosicya proved to be monophyletic, their relative position in the phylogeny did not support an emergence of coral-associated gobiids
as a monophyletic assemblage. Instead, two separate monophyletic sub-groups were discovered, the first comprising Gobiodon and Paragobiodon, and the second Bryaninops and Pleurosicya. Our molecular phylogenetic examinations also revealed one unassigned species of Gobiodon from the Maldives as a distinct species and confirmed three putative and yet unassigned species from the Red Sea. Moreover,
the uniformly black colored species of Gobiodon are not monophyletic but have evolved independently within two distinct species groups. Genetic distances were large in particular
within Pleurosicya and Eviota. Estimated divergence times suggest that coral-associated gobies have diversified in parallel to their preferred host corals.
In particular, divergence times of Gobiodon species closely match those estimated for their typical host coral genus Acropora. 相似文献
994.
We investigated the constraints on sulfide uptake by bacterial ectosymbionts on the marine peritrich ciliate Zoothamnium niveum by a combination of experimental and numerical methods. Protists with symbionts were collected on large blocks of mangrove-peat.
The blocks were placed in a flow cell with flow adjusted to in situ velocity. The water motion around the colonies was then
characterized by particle tracking velocimetry. This shows that the feather-shaped colony of Z. niveum generates a unidirectional flow of seawater through the colony with no recirculation. The source of the feeding current was
the free-flowing water although the size of the colonies suggests that they live partly submerged in the diffusive boundary
layer. We showed that the filtered volume allows Z. niveum to assimilate sufficient sulfide to sustain the symbiosis at a few micromoles per liter in ambient concentration. Numerical
modeling shows that sulfide oxidizing bacteria on the surfaces of Z. niveum can sustain 100-times higher sulfide uptake than bacteria on flat surfaces, such as microbial mats. The study demonstrates
that the filter feeding zooids of Z. niveum are preadapted to be prime habitats for sulfide oxidizing bacteria due to Z. niveum’s habitat preference and due to the feeding current. Z. niveum is capable of exploiting low concentrations of sulfide in near norm-oxic seawater. This links its otherwise dissimilar habitats
and makes it functionally similar to invertebrates with thiotrophic symbionts in filtering organs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
995.
Risk to humans of consuming metals in anchovy (<Emphasis Type="Italic">Coilia</Emphasis> sp.) from the Yangtze River Delta 总被引:1,自引:0,他引:1
Fengyan Liu Jiachun Ge Xin Hu Teng Fei Yuehua Li Yuan Jiang Zhiqiang Xu Shuyan Ding John P. Giesy 《Environmental geochemistry and health》2009,31(6):727-740
Concentrations of metals were determined in four species of anchovy (Coilia sp.) from the Yangtze River, Taihu Lake, and Hongze Lake in Jiangsu Province, China. Concentrations of Cr in anchovy fish
muscle ranged from 2.6 × 10−2 to 5.0 mg/kg ww, and Coilia nasus taihuensis in Jiaoshan, Taihu Lake contained the highest concentrations of Cr, which was almost 111-fold higher than the mean value
at other locations. Concentrations of Pb ranged from 1.5 × 10−2 to 1.3 × 10−1 mg/kg ww. Comparisons of concentrations of lead (Pb) among the four species indicated that anadromous species contained higher
concentrations of Pb than did freshwater species. However, concentrations of Pb in C. nasus from the Nanjing and Haimen locations in the Yangtze River were not significant higher than those of two freshwater species:
C. nasus taihuensis from Taihu Lake and C. brachygnathus from Hongze Lake (Duncan’s test, α = 0.05). While concentrations of Cd and Zn ranged from 7.0 × 10−4 to 3.6 × 10−3 mg/kg ww and 3.4 to 4.8 mg/kg ww, respectively, there were no significant differences in concentrations among the eight locations.
The only concentration of the metals studied that exceeded the Chinese National Standard was Cr in Coilia from Jiaoshan, Taihu Lake, which was 2.5-fold higher than the standard. These results indicate that people who consume the
genus Coilia are not at risk due to concentrations of metals, except Cr in C. nasus taihuensis from Jiaoshan in Taihu Lake. Concentrations of all of the metals studied except for Cr were similar to or less than those
of metals in most other areas in the world. 相似文献
996.
Comparative study of the fate and mobility of metals discharged in mining and urban effluents using sequential extractions on suspended solids 总被引:1,自引:0,他引:1
Christian Gagnon Patrice Turcotte Bernard Vigneault 《Environmental geochemistry and health》2009,31(6):657-671
The fate, bioavailability and environmental impacts of metals discharged in municipal and mining wastewater discharge will
depend to a large extent on chemical speciation and distribution. Previous studies on metal bioaccumulation have shown that
total metal concentrations are not a good predictor of bioavailability in the dispersion plumes of municipal effluents. The
objective of this study was to determine the solid phase speciation of metals in surface waters receiving urban and mining
effluents in order to assess their fate and relative mobility in the receiving environment. Suspended particulate matter was
sampled using sediment traps at several sites downstream of effluent outfall plumes as well as at reference upstream sites.
Particulate metal in operationally defined fractions—exchangeable/carbonates, reducible, oxidisable and residual—were determined
in suspended particulate matter with a series of selective chemical extractions. Metal enrichment in suspended particles was
generally observed in both mining and urban effluent discharges. When compared to its receiving environment, the mining effluent
appeared to release more particulate metals (Cu, Fe, Zn) in the most reactive fractions (i.e. exchangeable/carbonates + reducible
forms, 23–43%), while other released metals, such as Cd and Mn, were predominantly in the least reactive forms (i.e., oxidisable + residual,
73–97%). In contrast, the reactivity of all particulate metals, with the exception of Mn, from the urban effluent was much
higher, with up to 65, 42, 30 and 43% for Cd, Cu, Fe and Zn, respectively, in the two most reactive fractions. As expected
in effluent dispersion plumes, parameters such as the organic carbon, Fe oxide and carbonate contents have specific effects
on the partitioning of several trace metals, particularly Cd, Cu and Zn. Our results indicated that the relative distributions
of metals among geochemical fractions varied in the effluent receiving waters where organic carbon and Fe oxides appeared
as the most important parameters. This could therefore decrease the exposure for aquatic organisms that are exposed to those
contaminated sediments as well as the risk to human health. 相似文献
997.
Graham Bird Mark G. Macklin Paul A. Brewer Sorin Zaharia Dan Balteanu Basarab Driga Mihaela Serban 《Environmental geochemistry and health》2009,31(6):741-758
Groundwater, accessed using wells and municipal springs, represents the major source of potable water for the human population
outside of major urban areas in northwestern Romania, a region with a long history of metal mining and metallurgy. The magnitude
and spatial distribution of metal contamination in private-supply groundwater was investigated in four mining-affected river
catchments in Maramureş and Satu Mare Counties through the collection of 144 groundwater samples. Bedrock geology, pH and
Eh were found to be important controls on the solubility of metals in groundwater. Peak metal concentrations were found to
occur in the Lapuş catchment, where metal levels exceed Dutch target and intervention values in up to 49% and 14% of samples,
respectively. A 700 m wide corridor in the Lapuş catchment on either side of the main river channel was identified in which
peak Cd (31 μg l−1), Cu (50 μg l−1), Pb (50 μg l−1) and Zn (3,000 μg l−1) concentrations were found to occur. Given the generally similar bedrock geologies, lower metal levels in other catchments
are believed to reflect differences in the magnitude of metal loading to the local environment from both metal mining and
other industrial and municipal sources. Sampling of groundwater in northwestern Romania has indicated areas of potential concern
for human health, where heavy metal concentrations exceed accepted environmental quality guidelines. The presence of elevated
metal levels in groundwater also has implications for the implementation of the EU Water Framework Directive (WFD) and achieving
‘good’ status for groundwater in this part of the Danube River Basin District (RBD). 相似文献
998.
The concentration of uranium was determined in 944 samples from stream water by the inductively coupled plasma quadrupole
mass spectrometry (ICP-QMS) method and represented on a color-shaded contour map. Uranium concentrations in surface water
were determined to be between 0.007 μg/l and 43.7 μg/l with median of 0.33 μg/l. The regional distribution of uranium is influenced
primarily by lithological and anthropogenic factors. In Mecklenburg, northern Brandenburg, and eastern Schleswig-Holstein,
elevated uranium concentrations coincide with the extent of the last Weichselian ice sheet. The maximum concentrations are
observed in the surface waters of the old mining districts in the western part of the Ore Mountains and in eastern Thuringia.
Elevated concentrations are found in areas of agriculturally used loess soils. These concentrations correlate with the use
of phosphate fertilizers. There is a zone of elevated concentrations up to 10.0 μg U/l in the Keuper Sandstone area south
of the Thuringian Forest and from northwest of Stuttgart as far as Coburg. The distribution of elevated values in mineral
water shows a clear correlation with the elevated values in surface water and the geology of those locations. Bunter and Keuper
strata are the most important uranium source. 相似文献
999.
Mixtures can be divided into simple (chemicals with comparable properties—health risk assessments on the chemicals) and complex,
which can be further subdivided into defined (a reasonably distinct composition, created at a specific time and place despite
dissimilar components—risk assessments on the common source) and coincidental (chemicals without similar properties or constant
composition in time or space—risk assessments on the receptor). Interactions recognized are: independent action, dose addition
(additivity), and potentiation (synergy and antagonism). Unpredicted outcomes need recognition. New approaches in higher education
and multidisciplinary investigations are essential. The community of the Society for Environmental Geochemistry and Health
should help clarify points such as when transformations in mixtures may become important enough to alter the classification
and the risk assessment. The multidisciplinary community is also well placed to support the integration of nonchemical influences
into mixture analysis and to contribute to the investigation of cumulative and multiple exposures. 相似文献
1000.
Natural muds used as or in cosmetics may expose consumers to toxic metals and elements via absorption through the skin, inhalation
of the dried product, or ingestion (by children). Despite the extensive therapeutic and cosmetic use of the Dead Sea muds,
there apparently has been no assessment of the levels of such toxic elements as Pb, As, or Cd in the mud and mud-based products.
Inductively coupled plasma mass spectrometry analysis of eight toxic elements in samples collected from three black mud deposits
(Lisan Marl, Pleistocene age) on the eastern shore of the Dead Sea in Jordan revealed no special enrichment of toxic elements
in the mud. A similar analysis of 16 different commercial Dead Sea mud cosmetics, including packaged mud, likewise revealed
no toxic elements at elevated levels of concern. From a toxic element standpoint, the Dead Sea black muds and derivative products
appear to be safe for the consumer. Whatever the therapeutic benefits of the mud, our comparison of the elemental fingerprints
of the consumer products with those of the field samples revealed one disturbing aspect: Dead Sea black mud should not be
a significant component of such items as hand creams, body lotions, shampoo, and moisturizer. 相似文献