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1.
A systematic study of the granulometric properties and the occurrence and distribution of rare earth elements (REE) within
surface sediments from ten bays situated along the coast of Southeast China has facilitated a more rigorous understanding
of constraints on sediment provenance in the area. The results show that REE concentrations are similar within a single bay,
but vary considerably (133.58–251.77 mg/kg) among the bays. The chondrite-normalized distribution patterns show the typical
enrichment of light REEs (LREEs: La–Eu) relative to heavy REEs (HREEs: Gd–Lu), and an apparent depletion of Eu, which is diagnostic
of a terrigenous sediment source. Obvious enrichments of the middle REEs (MREEs: Sm–Ho) in the PAAS-normalized (Post-Archean
Australian Shale) distribution patterns of these bay sediments are similar to results reported from large rivers in China.
Comparing the REE composition of the bay sediments with those of adjoining fluvial sediments and with the bedrock of the surrounding
drainage basins, the latter are indicated as the dominant sediment source. The uniform REE distribution patterns, and MREE
enrichments, prove that the sediments are derived from the material transported by the streams and rivers that discharge into
the bays. 相似文献
2.
Behavior of heavy metals in sulfide mine tailings and bottom sediment (Salair,Kemerovo region,Russia) 总被引:2,自引:1,他引:1
The given work focused on solving the problem of environmental geochemistry related to investigation of element speciation,
their mobility, and migration in polluted areas. The purpose was to describe quantitatively migration, distribution, and redistribution
of heavy metals by the example of the old tailings (Talmovaya sands) of the Lead Zinc Concentration Plant (Salair, Kemerovo
region, Russia) and technogenic bottom sediments of the Malaya Talmovaya river. Contents of elements in the sulfide tailings
range in the following limits: Zn: 1,100–27,000 ppm, Cd: 1.3–240 ppm, Pb: 0.01–0.81 ppm, Cu: 220–960 ppm, As: 15–970 ppm,
Fe: 19,000–76,000 ppm, and Ba: 80,000–1,00,000 ppm. Element concentrations in the river sediment are proportional to the element
contents in the sulfide tailings. Element speciations in the sulfide tailings and technogenic bottom sediments were investigated
by the modified sequential extraction procedure. Chemical forms of heavy metals in pore water and surface water were calculated
by WATEQ4F software. Principles of heavy metal migration in the sulfide tailings and technogenic bottom deposits were established.
The obtained results about element species in the sulfide tailings and sediment explain the main principles of element migration
and redeposition. In the mine waste and technogenic bottom deposits, there is vertical substance transformation with formation
of geochemical barriers. 相似文献
3.
The redox stratification of bottom sediments in Kandalaksha Bay, White Sea, is characterized by elevated concentrations of
Mn (3–5%) and Fe (7.5%) in the uppermost layer, which is two orders of magnitude and one and a half times, respectively, higher
than the average concentrations of these elements in the Earth’s crust. The high concentrations of organic matter (Corg = 1–2%) in these sediments cannot maintain (because of its low reaction activity) the sulfate-reducing process (the concentration
of sulfide Fe is no higher than 0.6%). The clearest manifestation of diagenesis is the extremely high Mn2+ concentration in the silt water (>500 μM), which causes its flux into the bottom water, oxidation in contact with oxygen,
and the synthesis of MnO2 oxyhydroxide enriching the surface layer of the sediments. Such migrations are much less typical of Fe. Upon oxygen exhaustion
in the uppermost layer of the sediments, the synthesized oxyhydroxides (MnO2 and FeOOH) serve as oxidizers of organic matter during anaerobic diagenesis. The calculated diffusion-driven Mn flux from
the sediments (280 μmM/m2 day) and corresponding amount of forming Mn oxyhydrate as compared to opposite oxygen flux to sediments (1–10 mM/m2 day) indicates that >10% organic matter in the surface layer of the sediments can be oxidized with the participation of MnO2. The roles of other oxidizers of organic matter (FeOOH and SO42−) becomes discernible at deeper levels of the sediments. The detailed calculation of the balance of reducing processes testifies
to the higher consumption of organic matter during the diagenesis of surface sediments than it follows from the direct determination
of Corg. The most active diagenetic redox processes terminate at depths of 25–50 cm. Layers enriched in Mn at deeper levels are metastable
relicts of its surface accumulation and are prone to gradual dissemination 相似文献
4.
Marcin Frankowski Anetta Zioła-Frankowska Artur Kowalski Jerzy Siepak 《Environmental Earth Sciences》2010,60(6):1165-1178
The study presents the results of Cu, Pb, Zn, Mn and Fe determination in the samples of bottom sediments collected from the
Oder and Warta rivers. The sequential extraction of metals in the samples of bottom sediments was performed after introducing
the modification of the extraction scheme suggested by Tessier et al. (Anal Chem 51(7):844–851, 1979). The extraction times
of particular stages were optimised. The fifth stage was altered by introducing the new methods of performing extraction.
The samples of bottom sediments submitted the following granulometric analyses: dry, wet and wet with (HMP) dispersing reagent.
Seven granulometric fractions with the following grain sizes were isolated: >2.0, 2.0–1.0, 1.0–0.5, 0.5–0.25, 0.25–0.1, 0.1–0.063
and <0.063 mm. The sequential extraction of particular granulometric fractions was performed. The concentration of metals
variability was analysed depending on the method of sample preparation for the chemical analysis, granulometric fraction of
sediments subjected to the analysis, extraction conditions and the site of samples collection. The lack of linearity between
the metal concentration and the size of granulometric fraction was observed. The highest concentrations of metals were observed
in fractions >2.0, 2.0–1.0 and 0.1–0.063 and <0.063 mm while the lowest concentrations occurred in fractions 1.0–0.5, 0.5–0.25,
and 0.25–0.1 mm. The atomic absorption spectrometry with flame atomisation (F-AAS) was used for the determination of the investigated
elements. 相似文献
5.
Geological and seismic profiling data (more than 25000 km of seismic profiles and about 1000 sediment sampling stations) collected
during the last 30 yr by research vessels of the Shirshov Institute of Oceanology, Russian Academy of Sciences are summarized.
Seismic records are directly correlated with sediment cores. The distribution map (scale 1 : 500000) of Quaternary lithofacial
complexes corresponding to certain stages of the Baltic Sea evolution is compiled. The following four complexes are distinguished
(from the base to the top): (I) moraine, with maximum thicknesses 60 and 170 m in valleys and ridges respectively: (II) varved
clay of periglacial basins and from the Baltic Ice Lake (BIL), up to 25 m thick in depressions; (III) lacustrinemarine homogeneous
clay with a thickness up to 4–8 m in depressions; (IV) marine sediments (mud, aleurite, coarse-grained deposits) accumulated
in environments with intense bottom currents activity (thickness 2–4 m in the Gotland Basin, 4–6 m in the Gdansk Basin, and
10–20 m in fans and prodeltas). The Quaternary sequence is cut through by inherited valleys, where the thickest Holocene sediments
are noted. Today, these valleys serve as routes of sediment transport to slope bases and central parts of basins. Outblows
of deep gas (through faults and fractures) and diagenetic gas (from sediments) to the bottom surface also occur in the valleys.
Sedimentation rates are higher in the Gdansk Basin (up to 100–120 cm/ka). Thick sand, aleurite, and mud bodies are accumulated
here (about 15–20 m in the Visla River prodelta). The sedimentation rate is slower in the Gotland Basin (up to 50–60 cm/ka),
where thin (2–4 m) sections of more fine-grained mud occur 相似文献
6.
As is less toxic than Hg, Cd, Pb, Se, Zn, and Cu. The As clarke for clays and shales is 10 ppm. Our samples of bottom sediments from Kurshskii Bay were determined to contain from 15 to 26 ppm As and up to 34 ppm As in the vicinity of the Neman River mouth. Elevated As concentrations (50–114 ppm) were detected in four columns of subsurface bottom sediments (at depths of 10–65 cm) from the Vistula Lagoon. Elevated As concentrations (50–180 ppm) were also found in a few surface samples of sand from the Gdansk Deep near oil platform D-6. These sediments are either partly contaminated with anthropogenic As or contain Fe sulfides and glauconite, which can concentrate As and contain its elevated concentrations. The As concentration in columns of bottom sediments from the Gulf of Finland were at the natural background level (throughout the columns) typical of the area (9–34 ppm). We repeatedly detected very high As concentrations (up to 227 ppm As) in pelitic ooze from Bornholm Deep, in the vicinity of the sunken vessel with chemical weapons. The sources of elevated As concentrations in the Baltic Sea are the following: (1) chemical weapon (CW) material buried in the floor of the Baltic Sea; (2) As-bearing pesticides, agricultural mineral fertilizers, and burned coal and other fuels; (3) kerogen-bearing Ordovician rocks exposed on the bottom; and (4) As-rich Fe sulfides brought to the area together with construction sand and gravel. This mixture was used in paper production and for the construction of hydraulic engineering facilities in the Vistula Lagoon in the early 20th century and later caused the so-called lagoon disease. 相似文献
7.
The concentrations of N, P and Fe in surface sediments and interstitial and overlying (bottom and surface) waters of the
Ashtamudi estuary located in the southwest coast of India are reported along with the various chemical species of N (NO2–N, NO3–N, NH3–N and total N) and P (organic P, inorganic P and total P) in interstitial and overlying waters and discussed in terms of
the physico-chemical environment of the system. The interstitial water exhibits higher salinity values compared to bottom
and surface waters, indicating the coupled effects of salt-wedge phenomena and gravitational convection of more saline-denser
marine water downward through surface sediments. N, P and Fe as well as their chemical forms are enriched in the interstitial
water compared to bottom and surface waters. However, the dissolved oxygen (DO) shows an opposite trend. The marked enrichment
of NH3–N in the interstitial water and its marginal presence in bottom and surface waters, together with the substantial decrease
in the DO concentrations of bottom water and consequent increase in the concentrations of NO2–N and NO3–N in interstitial and bottom waters, points to the nitrification process operating in the sediment-water interface of the
Ashtamudi estuary. The enrichment of total N, P and Fe in the interstitial water compared to the overlying counterparts and
the positive correlation of sediment N, P and Fe with mud contents as well as organic carbon indicate that these elements
are liberated during the early diagenetic decomposition of organic matter trapped in estuarine muds.
Received: 5 Oktober 1998 · Accepted: 9 February 1999 相似文献
8.
U-Pb (SHRIMP-II) isotopic dating has been conducted for zircons of the ash sediments of the Ust’-Suifun Suite, which was the
final stage of Late Cenozoic explosive volcanism in Southwest Primorskii krai. These pyroclastic units are widespread within
sediments that fill in Cenozoic depressions including large coalfields. The concordant dates (23.7–24.6 Ma) are in line with
the results of the K-Ar determinations for volcanic tephra (23.6–27.1 Ma) and correspond to the beginning of the active phase
of spreading and taphrogenesis in the neighboring Trench of the Sea of Japan. These processes started as early as the Eocene
and are reflected in the continental vicinity with the formation of riftogenic depressions and the occurrence of a peculiar
gas volcanism. 相似文献
9.
L. Zühlsdorff V. Spieß C. Hübscher H. Villinger A. Rosenberger 《International Journal of Earth Sciences》2000,88(4):655-667
A high-resolution seismic survey was carried out at the accretionary prism on the continental slope off Vancouver Island,
Canada. Two GI-Gun data sets with different source frequency ranges of 50–150 and 100–500 Hz were combined with 4 kHz narrow-beam
echosounding data (Parasound). The data allow spatial correlation between a gas hydrate bottom simulating reflector (BSR)
and distinct areas of high near-sea-floor reflectivity. An integrated interpretation of the multi-frequency data set provides
insight into the regional distribution of tectonically induced fluid migration and gas hydrate formation in the vicinity of
ODP Leg 146 Sites 889 and 890. The BSR at the base of the gas hydrate stability field is observed within accreted and deformed
sediments, but appears to be absent within bedded slope basin deposits. It is suggested that these basin deposits inhibit
vertical fluid flow and prevent the formation of a BSR, whereas the hydraulic conductivity of the accreted sediments is sufficiently
high to allow for pervasive gas migration. An elevation of the BSR beneath the flanks of a topographic high is interpreted
as an indicator for local upflow of warm fluids along permeable pathways within outcropping accreted sediments. Parasound
data reveal discontinuous zones of high reflectivity at or directly beneath the sea floor, which may indicate local cementation
of surface sediments. In combination with GI-Gun data, the occurrence of these reflective areas can be related to the location
of slope sedimentary basins acting as hydraulic seals. It is proposed that the seals sometimes fail along faults extending
beneath the BSR, leading to focused upflow of methane-bearing fluid and the formation of carbonate pavements at the sea floor.
Received: 9 November 1998 / Accepted: 6 April 1999 相似文献
10.
Trace element concentrations in shallow marine sediments of the Buyat-Ratototok district of North Sulawesi, Indonesia, are
affected by submarine disposal of industrial gold mine tailings and unregulated dumping of tailings and wastewater from small-scale
gold mining using mercury amalgamation. Industrial mine tailings contained 590–690 ppm arsenic, 490–580 ppm antimony, and
0.8–5.8 ppm mercury. Tailings-affected sediment As and Sb concentrations were 20–30 times higher than in muddy sediments not
contaminated with tailings, and 50–60 times higher than pre-mining average. Highest mercury concentrations were observed in
sediments affected by small-scale mining using mercury amalgamation (5–29 ppm). Concentrations of most other trace elements
were comparable in sediments affected by both types of mining and were slightly higher than regional averages for sediments
collected before the onset of industrial mining. Elevated concentrations of both As and Sb in approximately equal proportions
suggest tailings dispersal of at least 3.5 km. Mercury released from artisanal gold mining dispersed up to 4 km from river
mouths. Slight increases in concentrations of non-mercury trace elements in areas affected by artisanal mining over pre-industrial
mining concentrations were probably caused by increased rates of erosion.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
11.
Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia) 总被引:1,自引:0,他引:1
Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric
composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the
analyzed metals (Cd: 0.06–0.12 mg kg−1, Pb: 28.5–67.3 mg kg−1, Zn: 17.0-65.4 mg kg−1, Cu: 21.1–51.9 mg kg−1, Ni: 27.8–40.2 mg kg−1) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in
the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform.
Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and
carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below
the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate,
while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained
results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building
of the nautical marina) investigated area belonged to unpolluted areas. 相似文献
12.
Carlton D. Hunt David G. Borkman P. Scott Libby Richard Lacouture Jefferson T. Turner Michael J. Mickelson 《Estuaries and Coasts》2010,33(2):448-470
The Massachusetts Water Resources Authority (MWRA) conducts a comprehensive multidisciplinary monitoring program in Massachusetts
Bay, Cape Cod Bay, and Boston Harbor to assess the environmental effects of a relocated secondary-treated effluent outfall.
Through 2007, 8.7 years of baseline data and 7.3 years of postdiversion data (16 total years), including species level estimates
of phytoplankton and zooplankton abundance, have been collected. MWRA’s monitoring program and other studies make this region
one of the most thoroughly studied and well-described marine systems in the world. The data show that the diversion of MWRA
effluent from the harbor to the bay has decreased nutrients concentrations and improved water quality in the harbor (e.g.,
higher dissolved oxygen, lower chlorophyll). The diversion also resulted in an increase in dissolved inorganic nutrients (especially
ammonium) in the vicinity of the bay outfall, but no obvious impacts such as increased biomass or decreased bottom water dissolved
oxygen have been observed. Regional changes in phytoplankton and zooplankton unrelated to the diversion have been seen, and
it is clear that the bays are closely connected both physically and ecologically with the greater Gulf of Maine. Direct responses
to modifications of the nutrient field within a 10 × 10-km area centered near the midpoint of the 2-km long outfall diffuser
in Massachusetts Bay (a.k.a. the nearfield) have not been seen in the plankton community. However, plankton variability in
the bays has been linked to large regional to hemispheric scale (NAO) processes. 相似文献
13.
The regularities of distribution of radionuclides and reare-earth elements in bottom sediments of Siberian lakes 总被引:1,自引:0,他引:1
V.D. Strakhovenko B.L. Shcherbov I.N. Malikova Yu.S. Vosel' 《Russian Geology and Geophysics》2010,51(11):1167-1178
Geochemical studies of the ecosystems of 184 Siberian lakes in three largest zones of northern Asia (humid, arid, and semiarid) and in mountainous area were carried out. The contents of natural radionuclides, radiocesium, and rare-earth elements in conjugate components of the systems and the types of the main sources of the bottom sediment material have been determined.Dating of the bottom sediments was made by the activity of radioisotopes 137Cs and 210Pb, which permitted estimation of the sedimentation rates in lakes in different regions of Siberia: 0.35 cm/year in the south and 0.25–0.3 cm/year in the north.Six main ions have been determined in the waters of the studied lakes: Ca2+, Mg2+, Na+, HCO3?, SO42?, and Cl?. The distribution of natural radionuclides in the stratified sections of bottom sediments of Siberian lakes evidences the stable sedimentation and characterizes their contents in the soils of water-catchment areas, which can be considered background contents there. Sediments enriched in organic matter have higher concentrations of U and lower ones of Th and K. The Th/K ratio in the studied bottom sediments is the same as in the soils. The Th/U ratios are somewhat lower than those in the soils because U is accumulated by chemogenic and organic components. The overall 137Cs pollution of bottom sediments of Siberian lakes is close to the global background (40 mCi /km2 in 2000), but in the Altai Territory and Buryatia and Altai Republics it is twice higher. The uneven areal and temporal distribution of residual radiocesium is observed not only in the lacustrine sediments but also in the lake water areas. The REE patterns of bottom sediments of different mineral types are similar to those of continental crust and clays of the Russian Platform, though organogenic and carbonate sediments have higher absolute REE contents than terrigenous ones. Pelitic fraction is the main REE concentrator in the bottom sediments. 相似文献
14.
T. A. Myskova R. I. Mil’kevich P. A. L’vov 《Stratigraphy and Geological Correlation》2012,20(2):166-178
During our study we obtained the first age datings of detrital zircons from metasandstones of the Ladoga Group (North Ladoga
Region, Russia) with the U-Pb isotopic method using the SHRIMP-II ion microprobe. The data obtained made it possible to clarify
the lower age limit of sedimentation and to obtain additional age data for evaluating the chemical composition and an age
of source areas. This work presents the results of isotopic-geochemical (Sm-Nd) and geochemical studies of metasediments.
High LREE concentrations, a high La/Sc ratio and a low Cr/h ratio, and the presence of a distinct Eu-minimum (Eu/Eu* = 0.54–0.72)
indicate a significant role of acidic terrigenous material in source areas. In addition, the data of the isotope analysis
of detrital zircons show that sediments of the Ladoga Group accumulated from the destruction of Proterozoic rocks (1.9–2.0
Ga; a proportion in sediments is 60–70%) and, to a lesser extent, Archean rocks (2.54–2.74 and 2.9–3.01 Ga; the proportion
in sediments is 30–40%). One of the Archean source areas could be granite-gneisses of the Pitkyaranta-Koirinoya dome structure
with the U-Pb zircon age of 2659 ± 15 Ma. We have established the lower age limit of sedimentation as 1.9 Ga within the measurement
error. The Sm-Nd model ages obtained (2.5–2.6 Ga for sediments of the Ladoga Group and over 3.4 Ga for granite-gneisses of
the dome structure) suggest a significant contribution of ancient crustal source area into source rocks. Our age data agree
well with those for svecofennides of Finland. 相似文献
15.
A large pool of nitrogen in the sediment pore fluid of a eutrophic lake in Iowa, USA, was mapped in this study. Previously,
the lake had supported fishing and boating, but today it no longer supports its designated uses as a recreational water body.
In the top 5 cm of the lake bottom, the pore water nitrogen ranges between 3.1 and 1,250 μg/cm3 of sediments, with an average of 160.3 μg/cm3. Vertically, nitrate concentrations were measured as 153 μg/cm3 at 0–10 cm, 162 μg/cm3 at 10–20 cm, and 32 μg/cm3 at 20–30 cm. Nitrate mass distribution was quantified as 3.67 × 103 kg (65%) in the bottom sediments, 172 kg (3%) in suspended particulates, and 1.83 × 103 kg (32%) in the dissolved phase. Soil runoff nutrients arrive at the lake from the heavily fertilized lands in the watershed.
Upon sedimentation, a large mass of nitrogen desorbs from mineral particles to the relatively immobile pore fluid. Under favorable
conditions, this nitrogen diffuses back into the water column, thereby dramatically limiting the lake’s capability to process
incoming nutrients from farmlands. Consequently, a condition of oxygen deficiency disrupts the post-season biological activities
in the lake. 相似文献
16.
Zhangdong Jin Hangxin Cheng Li Chen Xiangdong Li Guangwei Zhu Guangmin Zhuang Na Qian 《中国地球化学学报》2010,29(1):33-41
To assess the contamination trends and potential bio-availability of sediment-bound heavy metals, concentrations of heavy
metals in acid-leaching fraction and in bulk sediments from the two typical bays (the Meiliang Bay and Xuhu Bay) of the Taihu
Lake, East China, were studied. Pb and Zn showed elevated concentrations in the sediments from both areas, although sedimentation
history and degree of pollution are different between the two bays. In the Meiliang Bay, both Pb and Zn pollutions started
in the late 1970’s, the same time as the beginning of eutrophication of the lake, while the in the Xuhu Bay the metal contamination
started since recent 10 years. The concentrations of acid-leachable Pb in the sediments from the Meiliang Bay are correlated
with the historical eutrophication process. Before the eutrophication and heavy metal pollution, the chemical properties of
the lake sediments were the same as the source compositions of the Xiashu loess. Both Pb and Zn in the sediments mainly occur
in leachable forms by nitric or hydrochloric acid, whilst most of Cu is in residual fraction. The results indicate that both
Pb and Zn may have higher mobility and bioavailability in water and biology than Cu. 相似文献
17.
S. A. War P. Nongkynrih D. T. Khathing P. S. Iongwai L. M. Dkhar 《Environmental Earth Sciences》2012,65(6):1695-1703
Primordial radionuclides in sand sediments that are often used as constructing materials are one of the sources of radiation
hazard in dwellings. Activity concentrations of the primordial radionuclides of 40K, 226Ra and 232Th have been measured in sand sediments collected from streams and streamlets lying within and around the uranium mineralization
deposit blocks of Kylleng-Pyndensohiong, Mawthabah Areas of West Khasi Hills District, Meghalaya, India. The technique of
gamma-ray spectroscopy using a NaI(Tl) detector with a PC-based multi channel analyser was applied for determination of the
activity concentrations. The activity of the sand sediments obtained in this study ranges from 95.3 to 1,088.8 Bq kg−1 for 40K; 38.3 to 784.1 Bq kg−1 for 226Ra and 78.0 to 316.1 Bq kg−1 for 232Th. Sand sediments from two sampling locations lying within the mineralization zone show highest concentrations of these radionuclides.
The radiological hazards of the sand sediments were calculated using various models given in the literature. The radium equivalent
activity was found to be higher than the accepted standard criterion value of 370 Bq kg−1 and the values of external and internal hazard indices were also found to be higher than unity in these two sampling locations.
Besides these two sampling locations, a sampling location lying at a nearby distance from the mineralization zone also exhibits
hazard indices values greater than unity. 相似文献
18.
We measured the amount of arsenic, chromium, copper, lead, nickel, vanadium, and zinc accumulated over a five-year period
from 1997 to 2002 in surface sediments of seven salt marshes along the New Brunswick coast of the Bay of Fundy, Canada. Study
sites extended from outer to inner Bay, spanning a gradient in tidal range (6–12 m) and mean sediment deposition rate (0.27–1.76
cm yr−1). In each study site, metal concentrations were measured in low and high marsh areas. Concentrations of chromium, nickel,
and zinc appear to be within their natural range, while arsenic, lead, and vanadium are enriched in some sites. Calculated
sediment metal loadings rates showed variability among marsh sites that closely followed sediment deposition patterns, suggesting
sediment deposition rate is the driving factor of short-term metal accumulation in Fundy marshes. The value of salt marshes
as a sink for metals may be enhanced by high sedimentation rates. 相似文献
19.
D. Ciszewski 《Environmental Geology》1997,29(1-2):50-57
The influence of sources of effluents on pollution of bottom sediments of the small Chechło River (23 km long, mean discharge
1.5 m3 s–1) in southern Poland was examined through analysis of heavy metals distribution in transverse and longitudinal cross sections.
Underground waters from a Pb–Zn mine cause very high concentrations of Zn, Cd, and Pb in both fractions investigated (<1 mm
and <0.063 mm) of sediments in the active channel zone, whereas sedimentation of huge amounts of suspended matter discharged
from oil refinery cause concentrations of heavy metals in fine fractions rather uniform in cross sections. In the lowest reach,
with relatively reduced contamination, the highest concentration both in fine and coarse fractions occurs close to the river
banks and in the deepest points of the channel. The lowest concentrations have been found at the points of strongest reworking
and accumulation of sandy material in the riverbed.
Received: 25 April 1995 · Accepted: 11 September 1995 相似文献
20.
Origin of diamond and its indicator-minerals found in the Cretaceous, Paleogene, and Quaternary sediments in the southern
sector of the East European Platform has remained a debatable issue over the past period of approximately 40 years. It was
assumed that the Cretaceous diamond in the Volch’e placer and Central deposit confined to the Voronezh anteclise was derived
from the Uralian sources, whereas the Paleogene diamond was derived from the South Ukrainian sources. Analysis of paleogeographic
maps of new generation (scales 1: 200000–1: 500000) and new data on samples (50 samples 0.5–20 t each) examined by scientists
from the Geological Research Institute of Voronezh State University with the participation of authors of the present communication
support the hypothesis of local origin of diamonds and localization of their provenance in the sedimentary cover of the Voronezh
anteclise. This inference pertains to high-pressure minerals detected in pre-Quaternary sediments. Diamond grains and indicator-minerals
hosted in the Quaternary postglacial sediments of the Voronezh anteclise were likely derived from the Don glacial apron in
the early Pleistocene (gQI
ds) from northern areas of the platform (southeastern Finland, Karelia, Kola Peninsula, and Zimnii Bereg area of the Arkhangel’sk
region). Such grains are unsuitable for prospecting purposes. Lithofacies investigations made it possible to outline two areas
in the Lipetsk and Voronezh regions that likely accommodate productive diatremes. 相似文献