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1.
Dissolved and particulate Mn and Fe in the nearshore waters were determined at 27 stations along the west coast of Taiwan during 19-23 November 2004. The latitudinal distributions of Mn and Fe were very similar; however, the concentration in the dissolved phase was lower, whereas that in the particulate phase was higher in the northern regime. The higher percentage of Fe than Mn that was associated with particles resulted in a two-order of magnitude higher particle-water partition coefficient for Fe, Kd(Fe), than that for Mn, Kd(Mn). The removal fluxes of Mn and Fe could be estimated by multiplying the particulate 234Th removal flux with the Mn/234Th and Fe/234Th ratios in suspended particles, which ranged from 0.1 to 3.8 mmol m−2 d−1 for Mn, and from 3.4 to 194.5 mmol m−2 d−1 for Fe. Residence times ranged from 1 to 20 days for Mn and Fe were estimated in the nearshore.  相似文献   

2.
In the joint estuary of the Odiel and Tinto rivers (SW Spain), the invasive Spartina densiflora Brongn. and the native Spartina maritima (Curtis) Fernald are growing over sediments with extreme concentrations of heavy metals. The contents of As, Cu, Fe, Mn, Pb and Zn were determined in sediments, rhizosediments and different tissues of both species, from Odiel and Tinto marshes. S. densiflora showed a higher capability to retain metals around their roots and to control the uptake or transport of metals, mediated by a higher formation of plaques of Fe/Mn (hydro) oxides on the roots. At the Tinto marsh, there were no differences between the metal concentrations of the sediment and those of the rhizosediment, a fact that could be explained by the extremely high concentrations of metals which can pass over a threshold value, altering the properties of root cells and preventing roots from acting as a ‘barrier’ to the uptake or transport of metals.  相似文献   

3.
Hafnium and Nd isotopes are increasingly used as paleoceanographic proxies. Comparing the “mantle–crust array” and the “seawater array” in plots of εHf vs. εNd, it has been observed that for a given εNd value the corresponding εHf value is higher for seawater than it is for terrestrial rocks. While this difference had initially been explained by significant hydrothermal input of mantle Hf into seawater, the currently favoured explanation is incongruent weathering of continental rocks producing radiogenic riverine Hf input.We here address this topic from the perspective of the behaviour of these two elements in seawater and in ferromanganese (Fe–Mn) crusts. We distinguish between a “truly dissolved” and a “dissolved” Hf and Nd pool, the latter being comprised of truly dissolved and colloid-bound (“colloidal”) Hf and Nd. While there exists a hydrothermal pathway for colloid-bound dissolved mantle Hf into the oceans, there is, in marked contrast to Nd, no important riverine pathway for colloidal or truly dissolved continental Hf. Owing to their respective chemical speciation in seawater, there exists truly dissolved Nd in the ocean, while the amount of truly dissolved Hf is insignificant.Neodymium is in exchange equilibrium between local seawater and both, the hydrous Fe and Mn oxides hydrogenetic Fe–Mn crusts are composed of. Due to continuous ad- and desorption there is continuous isotopic re-equilibration and the isotopic composition of Nd in a Fe–Mn crust reflects that of truly dissolved Nd in local ambient seawater. In contrast, Hf is only associated with the hydrous Fe oxides on which it forms surface precipitates that do not exchange with seawater. Due to this lack of isotopic re-equilibration, the isotopic composition of Hf in a Fe–Mn crust is the average of that of all the Hf scavenged during the lifetime of the hydrous Fe oxide particles. Since the Hf-bearing hydrous Fe oxides in a Fe–Mn crust do not form from local ambient seawater at the crust's growth site but are advected as colloids or fine particles, their Hf isotopic composition depends on the origin and migration pathway of these colloids. Hence, while Nd isotopes in Fe–Mn crusts provide reliable information on truly dissolved Nd in local ambient seawater, Hf isotopes rather indicate the origin and pathway of hydrous Fe oxide colloids, and might differ from truly dissolved Hf in local ambient seawater. This may explain the occasional decoupling of Nd and Hf isotopes in Fe–Mn crusts and supports the notion of a significant hydrothermal mantle signal of Hf in seawater.  相似文献   

4.
The two marine algae, Chaetomorpha brychagona and Enteromorpha crinita are found abundantly on the iron ore tailings of Tolo Harbour, Hong Kong, with a rather high level of various metals. Tissue analysis of the algae revealed that the contents of heavy metals (Fe, Mn, Pb and Zn) were higher than in the population collected from the two uncontaminated sites far away from the tailings. It was suggested that the algae were able to adapt to such a harsh environment with a comparatively high level of trace elements and the lack of basic nutrients. However, further studies are needed before any conclusion can be drawn. The delicate situation of the land-locked sea, Tolo Harbour, where the tailings and future heavy industrial site are situated, should not be overlooked.  相似文献   

5.
Surface waters collected along the salinity gradient of the Hudson River estuary in four cruises between 1995 and 1997 were size-fractionated into particulate (>0.45 μm), ‘dissolved' (<0.45 μm), colloidal (10 kDa, 0.45 μm) and low molecular weight (<10 kDa) phases. Dissolved Cd concentrations (range: 0.11–1.19 nM) in surface waters of the estuary appear to have decreased fourfold (from an average of 2.36 to 0.61 nM) over a 23-year period, since the initial analysis of samples collected in the 1970s by Klinkhammer and Bender [Estuar. Coastal Shelf Sci. 12 (1981) 629–643]. This interannual decline reflects improvement in sewage treatment and the elimination of industrial Cd sources to the Hudson River estuary. In contrast, dissolved Mn levels (range: 0.033–1.46 μM) have remained relatively constant over the same period of time, suggesting that anthropogenic sources have very limited impact on Mn concentrations in the estuary. The concentrations of both Cd and Mn appeared to strongly depend on the season and/or river discharge. The highest concentrations were detected under low freshwater discharge, implying that limited hydraulic flushing allows a build-up of metals in the water column. Although the decline in Cd levels within the estuary reflects a reduction in the magnitude of anthropogenic inputs, mass balance estimates indicated that current sources of Cd to the estuary include sewage discharges (in the lower estuary around Manhattan) and diagenetic remobilization from industrial Cd deposited in sediments nearly 2 decades ago (in the upper estuary near Foundry Cove). Moreover, under low river discharge, the sources considered in our model (sewage, riverine input, atmospheric deposition, and benthic fluxes) could account for no more than 60% of the Cd exported from the lower estuary to the ocean. This suggests that undefined sources such as ground water and inputs from other watersheds (e.g., Long Island Sound and Newark Bay) may potentially influence the water quality of the New York Harbor. The size-fractionated metal concentrations indicated that most of the traditionally defined ‘dissolved' Cd and Mn consisted of <10 kDa molecular weight species. High molecular weight colloidal species of Mn accounted for about 50% of the dissolved fraction at the riverine end-member and <5% at intermediate and high salinities. Colloidal Cd accounted for <6% of the dissolved phase throughout the estuary. Unlike the non-conservative excess (relative to ideal dilution of river water and seawater) of dissolved Mn observed along the estuary, high molecular weight colloidal Mn appeared to be removed at the head of the estuary. The small contribution of colloidal Cd and Mn to the ‘dissolved' phase suggests that remobilization from suspended particulate phases and/or from sediments occurs through the formation of small molecular weight species.  相似文献   

6.
The effects of depuration, size and sex on the concentrations of Mn, Ni, Cu, Zn and Cd were determined for gonadal and somatic tissues of Mytilus edulis from Yaquina Bay, Oregon. After depuration, Mn levels decreased significantly in both tissues while Cu and Ni concentrations increased in somatic tissues. The latter finding may have been associated with a stress response manifested by the appearance of new byssal threads and attachment to the vessel. Larger, and presumably older, mussels contained higher concentrations of Ni, Cu and Cd in their somatic tissues while smaller animals had greater somatic levels of Mn. There were no significant differences in gonad concentrations between the two size groups. Manganese and Zn levels were greater in the gonads of female mussels and Cd was more concentrated in the somatic tissues of females.  相似文献   

7.
We present major and trace element data for olivines and rapidly quenched groundmass material separated from eight samples of basaltic rock. From these data apparent olivine/liquid distribution coefficients (D) for the elements Mg, Mn, Ni, Co, Cr, Sc, Na, Sm, and Ca have been calculated. Petrographic and electron microprobe studies indicate that olivines in most of these samples are but slightly zoned and groundmass glasses are essentially uniform in composition; these data suggest that the co-existing olivine-groundmass pairs are in equilibrium. In addition, olivine crystallization temperatures were calculated using experimental calibrations of lnD vs.1/T for the elements Mg, Fe, Mn, Ni, and Co. A high degree of concordancy for the resulting temperatures, based on five different elements for most samples, also suggests that olivine-groundmass equilibrium was obtained. We conclude that the apparent olivine/liquidD's derived from this study are representative of equilibriumD's, but emphasize that variations in temperature, and possibly bulk composition, strongly affect suchD's in natural magmas.  相似文献   

8.
The concentrations of 25 major, minor and trace elements have been determined in four clasts, a metal-rich inclusion and two dark metal-poor inclusions from the Abee enstatite chondrite. The clasts are heterogeneous, displaying 2-fold enrichments or depletions in some elements. The data suggest that there are two generations of metal, one with low, the other with high concentrations of refractory siderophiles. The other elemental patterns can be understood in terms of variations in the abundance of major minerals. We infer that Sc and Mn are located largely in the niningerite ((Fe,Mg)S), V in the troilite (FeS) and rare earth elements in the oldhamite (CaS).Heterogeneities among the clasts are probably primary, resulting from the accretion-agglomeration process, although shock processes in a regolithic setting remain a possibility provided that they were followed by a period of metamorphism sufficient to erase petrologic evidence.In the dark inclusions the concentrations of the rare earths, Eu excepted, are 4 × higher than mean EH levels; this infers enhanced amounts of CaS. The dark inclusions are low in siderophiles, Sc, Mn, K, Na and Al, implying low amounts of metal, niningerite and feldspar. The origin of the dark inclusions is unclear; they do not appear to be the result of a simple, single-stage process.  相似文献   

9.
Estuarine environments are particularly vulnerable to human impacts. In this study, trace elements in Ruppia megacarpa, Halophila ovalis, sediment and porewater were analysed to assess the potential contamination of the Leschenault Estuary, Western Australia, from a primarily agricultural drain. Sediment concentrations of Cd, Cu, Mn, and Ni and were highest nearest the drain while Al, As, Cr, Fe and Zn and were highest further from the drain. H. ovalis showed greater accumulation of Fe, Al, and As than R. megacarpa. Concentrations of Fe, Al, As, and Ni were generally higher in below-ground plant parts than above, suggesting uptake of these trace elements via the sediment-route pathway. This study suggested that the drain was a source of Cu and Mn, with these elements entering the estuary through water inflows. As and Fe, were highest furthest from the drain suggesting input of trace elements from sources other than the drain under study.  相似文献   

10.
The fundamental mode Love and Rayleigh waves generated by ten earthquakes and recorded across the Tibet Plateau, at QUE, LAH, NDI, NIL, KBL, SHL, CHG, SNG and HKG are analysed. Love- and Rayleigh-wave attenuation coefficients are obtained at time periods of 5–120 s using the spectral amplitudes of these waves for 23 different paths. Love wave attenuation coefficient varies from 0.0021 km?1, at a period of 10 s, to 0.0002 km?1 at a period of 90 s, attaining two maxima at time periods of 10 and 115 s, and two minima at time periods of 25 and 90 s. The Rayleigh-wave attenuation coefficient also shows a similar trend. The very low value for the dissipation factor, Qβ, obtained in this study suggests high dissipation across the Tibetan paths. Backus-Gilbert inversion theory is applied to these surface wave attenuation data to obtain average Qβ?1 models for the crust and uppermost mantle beneath the Tibetan Plateau. Independent inversion of Love- and Rayleigh-wave attenuation data shows very high attenuation at a depth of ～50–120 km (Qβ ? 10). The simultaneous inversion of the Love and Rayleigh wave data yields a model which includes alternating regions of high and low Qβ?1 values. This model also shows a zone of high attenuating material at a depth of ～40–120 km. The very high inferred attenuation at a depth of ～40–120 km supports the hypothesis that the Tibetan Plateau was formed by horizontal compression, and that thickening occurred after the collision of the Indian and Eurasian plates.  相似文献   

11.
The oyster Crassostrea rhizophorae is a bivalve abundant in Venezuelan estuaries and consumed by local populations. No known values have been reported on trace metals in oysters from the central Venezuelan coast. We report the concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn in the soft parts of C. rhizophorae, which were collected bimonthly between March 2008 and March 2009, at two sampling areas from the Central Venezuelan Coast: Buche estuary and Mochima estuary. Our results show that for each metal there is a similar temporal variation pattern. The concentrations of the heavy metals reported in this work are useful as reliable baselines and can be used for comparison in future environment studies. Concentrations in C. rhizophorae from the Buche estuary can be interpreted to be high on a global scale for Cd, Cu, Ni and Mn, indicating atypically raised bioavailabilities.  相似文献   

12.
Phase and group velocities and Q of mantle Love and Rayleigh waves from the 1963 Kurile Islands earthquake (Mw = 8.5) were determined over 37 great circle paths by a time variable filtering technique, in a period range 100–500 s for the fundamental modes and 100–275 s for the first higher modes. The preliminary reference Earth model (PREM) explains reasonably well the average dispersion results for the fundamental Love and Rayleigh waves. There exists a small, but significant inconsistency between the observation and the model for the first higher Love and Rayleigh waves. The Q structure of PREM is inconsistent with the observation for the fundamental Love waves, but explains other observations reasonably well. The dispersion of each mode shows a clear azimuthal dependence from which the four azimuthal windows were established. The phase and group velocity measurements for each window were, in general, shown to be mutually consistent. The azimuthal variations are largest for the first higher Rayleigh waves, indicating strong lateral heterogeneity in the structure of the low velocity zone. The first of the four windows is characterized by the largest fraction of Precambrian shields and the second window by the largest fraction of normal oceans. A comparison of these two windows may give some insight into deep lateral heterogeneity between continents and oceans. The observed phase and group velocities of the first window are systematically higher than those of the second window for the fundamental Love and Rayleigh waves at periods up to 400 s, and for the first higher Love and Rayleigh waves up to 175 s. Their differences are greatest for the first higher Rayleigh waves and least for the fundamental Rayleigh waves. Although the fundamental Rayleigh waves show the least velocity differences, their persistence up to a period of longer than 300 s is in striking contrast with some of the pure path phase velocities derived earlier for continents and oceans. A set of models for continents and oceans. PEM-C and PEM-O are not consistent with our observation. The third azimuthal window is characterized by trench-marginal seas and the fourth window by mountainous areas, typically the Asian high plateaus from northern China to the Middle East through Tibet. A comparison of these two windows gives some information about deep structural differences between subduction zones and continental collision zones, both belonging to plate convergence zones. For the fundamental and the first higher Love waves, the phase and group velocities for the third window are markedly low, whereas those for the fourth window are somewhat comparable to those for the second window. Slow Rayleigh waves are evident for two windows, with the fourth window apparently being the slowest for the fundamental Rayleigh above 200 s and for the first higher Rayleigh. For the fundamental Rayleigh waves, the third window is very slow below 200 s, but becomes progressively fast as the period increases and tends to be the fastest window around 400 s, suggesting a deep seated high velocity anomaly beneath trench-marginal seas. The dispersion characteristics of the fourth window indicate a thick high velocity lid with an extensive low velocity zone beneath it. The shield-like lithosphere, coupled with an extensive low velocity zone, may be a characteristic feature of continental collision zones. The particle motion of the fundamental Love waves was found not to be purely transverse to a great-circle connecting the epicenter to a station. The departure from the purely transverse motion is systematic among different periods, different G arrivals (G2, G3,…) and different stations, which may be interpreted as being due to lateral refraction.  相似文献   

13.
In this work the surface temperature anomaly (dTG) and sunspot number (Rz) time series in the period 1880–2000 are studied with wavelet multi-resolution analysis. We found a very low correlation of 0.11 between dTG and Rz in the 11-yr-solar cycle band. A higher correlation of 0.66 is found in the ～22-yr-band with zero lag correlation coefficient between dTG and Rz. Furthermore, the long-term trend is markedly different between dTG and Rz. This might occurs because of the long-term warming on the last century, which is attributed mainly to anthropogenic effects.  相似文献   

14.
Water samples collected at the 21°N hydrothermal site on the East Pacific Rise crest, including Deep-Tow and hydrocast samples collected in 1977 and three hot vent water samples collected recently with the submersible “Alvin”, contain significant additions of3He,4He, and Mn. Although the vent water collections were at least 50-fold diluted with ambient seawater, they are up to 53 times enriched in3He and 7.4 times enriched in4He relative to saturated seawater, with concentrations of total dissolvable manganese (TDM) up to 310 μg/kg.3He and4He covary in the vent samples, with3He/4He about 8 times the atmospheric ratio, reflecting a mantle helium source. In contrast to the helium isotopes the Mn/3He ratio in the vent samples is variable, ranging from 4.3 × 104 up to 1.0 × 105 g/cm3. Profiles of3He/4He and TDM in the water column at 21°N show a sharp maximum ofδ(3He) = 47%and TDM= 0.69 μg/kg, much higher than the average values of 34% and 0.2 μg/kg for the deep water in this region. This spike in3He and Mn occurs at 2400 m depth, 200 m above the level of the 21°N vents, and 100 m higher than any local bathymetry, evidence for upward transport of the hydrothermal discharge via rising plumes of hot vent water. Two of the 21°N Deep-Tow samples associated with small (?0.010°C) temperature anomalies hadδ(3He) = 38%and TDM= 0.28 and 0.58 μg/kg, also slightly elevated relative to background. The Deep-Tow and hydrocast samples have lower Mn/3He ratios than average vent samples due to Mn removal by scavenging. Comparison of vent samples and water column measurements at 21°N indicate that the pure vent water could be detected using3He and Mn even when diluted ～105 times with seawater, confirming that these two tracers are extremely sensitive indicators of submarine hydrothermal activity.  相似文献   

15.
The amphipod crustacean Talitrus saltator is an established, easily accessible, biomonitor of trace metal bioavailabilities in coastal waters. We have carried out a geographically widespread collection of T. saltator from European shores, stretching from the north-west Atlantic through the Baltic to the Mediterranean. A primary aim of the work was to establish a database of accumulated trace metal concentrations (Cd, Cr, Cu, Fe, Mn and Zn) in this biomonitor. Statistical analysis has shown significant geographical differences in the bioavailabilities of all the metals, the most distinct being copper, iron and manganese. It has proved possible to identify unusually high accumulated concentrations of Cd, Cr, Cu, Fe, Mn and Zn in this biomonitor, indicative of high metal bioavailability at a particular site. These may serve as reference points for future biomonitoring programmes seeking to identify metal contamination in coastal waters.  相似文献   

16.
Metal loads were determined from water samples collected under different streamflow conditions (baseflow and storm events) in a rural catchment (NW Spain) during 4 years. A study at annual, seasonal and storm‐event scales was carried out. In all analysed scales, the export order was Fe > Al > Mn > Zn > Cu. A high inter‐annual, seasonal and storm‐event scale variability of metal load was observed. The total metal loads in stream were higher during baseflow conditions than during storm events, which only represented 4% of the duration of the study period and 25% of streamflow. During storm events, both Al and Fe loads accounted 45% of the total load of the study period, whereas Mn, Cu and Zn loads represented 42%, 33% and 24%, respectively. This highlights the role of high flows on metal export. Only four big events exported around 30% of load of each metal transported in events. At all time scales, a prevalence of export of particulate metals over dissolved metals was observed, more pronounced for Al, Fe and Mn than for Cu and Zn. The export of metals in the Corbeira catchment is influenced by runoff and, to a lesser extent, by the rainfall amount. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

17.
The fate and effects of the spill of Eleni V heavy fuel oil in May 1978 have been followed at two sites; one a heavily-polluted area subject to mechanical clean-up and one an undisturbed site where oil remains. At the first site the mechanized clean-up, and re-sorting of beach material by winter storms, has left the area visually clean of oil. However, near-shore and interstitial waters still contain high concentrations of Eleni V hydrocarbons 12 months after the spill. At the undisturbed site there has been very little change in the appearance and chemical composition of the oil during this period.  相似文献   

18.
Four sediment traps of radically different design were deployed in the Santa Barbara Basin for approximately 45 days. The measured fluxes ranged from 370 to 774 g m?2 yr?1 for the different designs. These values lie within flux measurements previously determined for the basin. Compared to the 25-year record (920 g m?2 yr?1), however, all fluxes determined in this experiment are somewhat low. Because this experiment was conducted during a general period of high storm activity and runoff, measurement of greater than average flux was expected. It is probable that the higher flux recorded by the sediments results from a significant input of detritus into the basin by near bottom transport.The chemical composition of trapped material was nearly identical in all four trap designs. The deep cone design, however, had a significantly lower Mn content. Since this trap was the only one in which reducing conditions were produced in the sample container, reduction and mobilization of manganese after collection is believed to have occurred.In spite of the very different designs tested, the factor of two agreement in flux determination and the compositional similarity of the material collected is encouraging for future attempts to directly measure the flux of particulates in the ocean.  相似文献   

19.
Bombay harbour is one of the major sinks, on the western peninsula of the Indian subcontinent, receiving anthropogenic pollutants including heavy metals, radionuclides and hydrocarbons in addition to sewage. To evaluate possible impacts of a few heavy metals on the harbour ecosystem, the distribution patterns of Zn, Mn, Cu, Fe, Co, Ni, Cd, Cr, Pb and Sr in water, sediment and two benthic species, the blood clam Anadara granosa and gobiid mudskipper Boleophthalmus boddaerti were studied over the period 1976–1980. The present levels of the ten elements in biotic and abiotic matrices were found to be far below those that are known to affect adversely the life and quality of benthic communities. Furthermore, the concentrations of these elements in various compartments neither revealed any systematic temporal or spatial fluctuations nor reflected the substantial incease in the total budget over the past 8–12 years. Also these levels were within the range reported in the nearshore and oceanic environs along the west coast. In view of this, the poor growth and high percentage mortality observed in the clam Anadara granosa fished from the Sewri clam bed compared to that of the stock harvested from the Trombay region in the harbour may well be due to anoxic conditions caused by organic pollutants present in the domestic sewage and industrial wastes released in the vicinity of the Sewri clam bed.  相似文献   

20.
《Marine pollution bulletin》2013,71(1-2):119-124
The influence of different concentrations (10–2000 μM) of heavy metals (Cu, Mn, Ni, Zn) was analysed in Atriplex halimus and Salicornia ramosissima germination pattern and seedling size. They are two halophyte species that grow in the Estuary of Huelva (Southwest Iberian Peninsula, Spain), one of the most heavy metal-polluted environments in the world.All of the metals tested affected the final germination percentage in A. halimus and only Ni reduced germination in S. ramosissima. The germination rate was unaffected in both species.The study of seedling development shows that S. ramosissima, an intertidal annual species, has a higher tolerance of metals than A. halimus, a bush that inhabits the upper part of the marshes.Taking into account the metal concentrations in the estuary and the effects of these on the seedling development of the species analysed, we conclude that metals might limit plant colonisation in some parts of the marshes.  相似文献   

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