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1.
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
2.
Leonard Boszke Artur Kowalski Witold Szczuciński Grzegorz Rachlewicz Stanisław Lorenc Jerzy Siepak 《Environmental Geology》2006,51(4):527-536
The 26 December 2004 tsunami covered significant portion of a coastal zone with a blanket of potentially contaminated sediments. In this report are presented results on mercury concentrations in sediments deposited by the tsunami in a coastal zone of Thailand. Since the total mercury concentrations are insufficient to assess mercury mobility and bioavailability in sediment, its fractionation was applied. Sediments were sampled within 50 days after the event and analyzed by sequential extraction method. The procedure of sequential extraction involved five subsequent stages performed with solutions of chloroform, deionized water, 0.5 M HCl, 0.2 M NaOH, and aqua regia. The mean concentration of total mercury in sediments was 119 ± 50 ng g−1 dry mass (range 66–230). The fractionation revealed that mercury is mainly bound to the least bioavailable sulphides 75 ± 6% (range 62–86), organomercury compounds 14 ± 7% (range 4–26), and humic matter 9 ± 7% (range 1–27). The lowest contributions bring fractions of water-soluble mercury 0.8 ± 1.0% (range 0.1–3.6) and acid soluble mercury 0.9 ± 0.5% (range 0.2–2.1). Although, the total mercury content is similar in a reference sample and in the tsunami sediments, the highly toxic organomercury fraction contribution is higher in the latter. The results were compared with chemical and sedimentological properties of the sediments but no significant correlations were obtained between them. 相似文献
3.
Phosphorus (P) is the limiting macronutrient for primary production in most lakes. Sediment characteristics are strongly correlated
to the internal P loading in lakes. This study investigated speciation of P, Fe, Al, and Ca in sediments of six sampling sites
with varying trophic status in Baiyangdian Lake of North China during the period of July 2008 and March 2009. The results
of sequential extraction experiments of the top sediments showed that total extractable P ranged approximately from 13 to
28 μmol g−1 for all sampling sites and the rank order of P-fractions was HCl–P > NaOH85–P > NaOH25–P > BD–P > NH4Cl–P. BD–P and BD–Fe had a consistent change with seasons. Their concentrations were both much higher in early spring and
mid-autumn. BD–Fe, Al extracted with NaOH at 25°C and 85°C affected corresponding P concentration in sediments, while high
concentration of extractable Ca from sediments showed no direct effects. According to the Kopáček et al. model of the molar
ratios of Al:Fe and [NaOH25–Al]:[NH4Cl–P + BD–P], there was potential P release from sediments twice a year for some hypereutrophic sites in early spring and
mid-autumn, especially in the former season. 相似文献
4.
Heavy metals in sediments of a large, turbid tropical lake affected by anthropogenic discharges 总被引:2,自引:0,他引:2
Bottom-water data and trace metal concentration of Cu, Cr, Ni, Pb, Co, Zn, and organic matter in surficial sediment samples
from 13 sampling stations of Lake Chapala in Mexico were studied. The lake is turbid with a great amount of flocculated sediments
as a result of wind mixing, sediment re-suspension, and Lerma River discharges. Al distribution pattern in sediments was used
as an indicator of the Lerma River discharges into Lake Chapala. The highest values of Cu (33.27 ppm), Cr (81.94 ppm), Pb
(99.8 ppm), and Zn (149.7 ppm) were detected in sediments near the lake outlet. The bioavailable metal fraction is low for
all metals except Pb, which shows 65–93% of the total metal concentration in bioavailable form. The minimum energy zone in
the lake was related to organic matter concentration and was located in the SE part of the lake. An analysis of the studied
parameters shows two zones: eastern zone (fluvio-deltaic) and central-western zone (lacustrine).
Received: 9 September 1998 · Accepted: 16 November 1998 相似文献
5.
Transport of terrestrial organic carbon to the oceans by rivers: re-estimating flux- and burial rates 总被引:5,自引:0,他引:5
This study re-estimates one important component in the global carbon cycle: the modern global fluviatile organic carbon discharge-
and burial rates. According to these results, approximately 430×1012 g of terrestrial organic carbon are transported to the ocean in modern times. This amount is higher than the latest estimates
but takes into account new data from Oceania not previously considered in global flux studies. However, only the minor amount
of 10% or approximately 43×1012 gC year–1 is most likely buried in marine sediments. This amount is similar to the burial of marine organic carbon in the coastal ocean
(55×1012 gC year–1). Adding both estimates gives approximately 100×1012 gC year–1, which is the value calculated by Berner (1982) for "terrestrial" deltaic-shelf sediments. However, the results in this study
suggest that on a global scale the organic carbon content in coastal ocean sediments is not solely of terrestrial origin but
a mixture of nearly equal amounts of marine and terrestrial organic carbon. The major part of the terrestrial organic carbon
that enters the ocean by rivers (approximately 400×1012 gC year–1) seems to be either (a) remineralised in the ocean, whereas the mechanism by which the terrestrial organic carbon is oxidised
in the ocean are unknown; or (b) is dispersed throughout the oceans and accumulates in pelagic sediments.
Received: 9 November 1998 / Accepted: 25 May 1999 相似文献
6.
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
7.
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
8.
This paper examines the surface sediments collected from Dongping Lake in China for speciation and distribution of toxic heavy metals (Cu, Pb, Ni, Cd) in different grain size fractions, and for the factors that need to be considered in potential hazard of metals to the environment. Four grain size fractions (<63, 63–78, 78–163 and 163–280 μm), divided in wet condition, and bulk samples less than 280 μm in diameter were analyzed for their distribution, density and appearance. A three-stage extraction procedure following the BCR protocol was used to chemically fractionate metals into “acid soluble”, “reducible”, “oxidizable” and “residual” fractions. Correlation analysis was used to analyze the datasets. The results showed that <63 μm grain size part constitutes the major proportion of the sediments, but its density is the smallest among the four grain size fractions. In general, the metal content curve against grain size presents “S” distribution, and the highest concentrations do not exist in <63 μm grain size. Appearance observation indicates that the adsorbed substance increases gradually along with the decreasing grain size. The dominant speciation of elements and the extent of pollution are responsible for the metal distribution in different grain size sediments. While studying bioavailability and mobilization of metals, it is advisable to take metal speciation, grain size distribution and density into consideration. 相似文献
9.
Bo Peng Xiaoya Tang Changxun Yu Changyin Tan Chunyan Yin Guang Yang Qian Liu Kesu Yang Xianglin Tu 《Environmental Earth Sciences》2011,64(5):1455-1473
This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan
province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and
Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The results show that trace
metals Cd, Bi, Sn, Sc, Cr, Mn, Co, Ni, Cu, Zn, Sb, Pb and Tl are enriched in the sediments. Among these metals, Cd, Bi and
Sn are extremely highly enriched (EF values >40), metals Zn, Sn, Sb and Pb significantly highly (5 < EF < 20), and metals
Sc, Cr, Mn, Co, Ni, Cu and Tl moderately highly (2 < EF < 5) enriched in the river sediments. All these metals, however, are
moderately enriched in the lake sediments. Geochemical results of trace metals Th, Sc, Co, Cr, Zr, Hf and La, and Pb isotopes
suggest that metals in the river sediments are of multi-sources, including both natural and anthropogenic sources. Metals
of the natural sources might be contributed mostly from weathering of the Indosinian granites (GR) and Palaeozoic sandstones
(PL), and metals of anthropogenic sources were contributed from Pb–Zn ore deposits distributed in upper river areas. Metals
in the lake sediments consist of the anthropogenic proportions, which were contributed from automobile exhausts and coal dusts.
Thus, heavy-metal contamination for the river sediments is attributed to the exploitation and utilization (e.g., mining, smelting,
and refining) of Pb–Zn ore mineral resources in the upper river areas, and this for the lake sediments was caused by automobile
exhausts and coal combustion. Metals Bi, Cd, Pb, Sn and Sb have anthropogenic proportion of higher than 90%, with natural
contribution less than 10%. Metals Mn and Zn consist of anthropogenic proportion of 60–85%, with natural proportion higher
than 15%. Metals Sc, Cr, Co, Cu, Tl, Th, U and Ta have anthropogenic proportion of 30–70%, with natural contribution higher
than 30%. Metals Ba, V and Mo might be contributed mostly from natural process. 相似文献
10.
Rare earth elements in the sedimentary cycle: A summary 总被引:2,自引:0,他引:2
David Z. Piper 《Chemical Geology》1974,14(4):285-304
The relative and absolute concentrations of rare earth elements (REE) in authigenic and biogenic phases of deep-sea sediments are quite different. Competition between these phases for REE has resulted in fractionation from the parent material, the latter consisting predominantly of terrigenous material, but with a contribution from marine volcanism. The strongest feature of this fractionation is a depletion of Ce, relative to La, in CaCO3, opalline silica, phillipsite, phosphorite, barite, and montmorillonitic clays; and a Ce enrichment in Fe/Mn nodules. The distribution of REE in different masses of seawater strongly reflects their fractionation in sediments. Whereas the relative concentration of REE in rivers resembles that of shale, their removal from seawater by authigenic and biogenic phases results in: (1) a decrease of their total concentration; (2) a depletion of Ce; and (3) an enrichment of heavy REE relative to light REE. The order of fractionation for water masses in the Atlantic Ocean is:Antarctic intermediate water > North Atlantic deep water > Antarctic bottom water> shelf water > river water ~ shale.The shale-normalized pattern for the sum of REE in the authigenic and biogenic phases of pelagic sediment and in seawater resembles that of an admixture of shale and basalt corresponding presumably to the realtive inputs from continents and marine volcanism respectively. The estimated rate of accumulation of each REE in the sediment, however, is approximately 12 times the estimated rate of input of REE from these two sources. 相似文献
11.
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
12.
Geochemical Characteristics of Amino Acids in Sediments of Lake Taihu, A Large, Shallow, Eutrophic Freshwater Lake of China 总被引:1,自引:0,他引:1
Xin Yao Guangwei Zhu Linlin Cai Mengyuan Zhu Linlin Zhao Guang Gao Boqiang Qin 《Aquatic Geochemistry》2012,18(3):263-280
To examine the biogeochemistry of amino acids (AAs) in the sediment of Lake Taihu, surface sediments (0–3 cm) and deeper sediments
(18–21 cm) were collected at 21 sites from different ecotype zones of the lake. AAs were extracted from the sediments, and
the total hydrolyzable amino acids (THAA) were determined by high-performance liquid chromatography instrument. The THAA contents
in Taihu sediment were much lower than that in marine sediments, ranging from 6.84 to 38.24 μmol g−1 in surface sediments and from 2.91 to 18.75 μmol g−1 in deeper sediments in Taihu, respectively. AAs were a major fraction of the organic matter (OM) and organic nitrogen in
Taihu sediments. The AAs on average contributed 8.2% of organic carbon (OC) and 25.0% of total nitrogen (TN) from surface
sediments, and 5.9% of OC and 20.5% of TN in deeper sediments, respectively. AA composition provided very useful information
about the degradation of OM. Glycine (Gly) and lysine (Lys) were the predominant forms of AAs in the sediments, irrespective
of lake regions, followed by alanine, glutamic acid, serine (Ser), and aspartic acid (Asp). The high concentrations of Gly,
Lys, and Ser suggested that these forms of AAs were relatively refractory during OM degradation in sediments. The relationship
between the Asp/Gly ratio and Ser + Thr [mol%] indicated that OM in surface sediment was relatively fresher than that in deeper
sediments. The AAs-based degradation index (DI) gave a similar conclusion. The composition and DI of AAs in surface sediments
are markedly different across different zones in Taihu. The percentages of AAs to organic carbon (AA-C%) and total nitrogen
(AA-N%) were higher in phytoplankton-dominated zones than those in macrophyte-dominated zones. These results suggest that
DI could provide useful information about the degradation of OM in shallow lakes such as Taihu. 相似文献
13.
Natalia Borrelli M. Osterrieth A. Romanelli M. F. Alvarez J. L. Cionchi H. Massone 《Environmental Earth Sciences》2012,65(2):469-480
Although phytoliths constitute part of the wetland suspended load, there are few studies focused on the quantification of
them in the biogenic silica (BSi) pool. So, the aim of this paper is both to determine BSi content (diatoms and phytoliths)
and its relationship with dissolved silica in surface waters, and the influence of soil and groundwater Si biogeochemistry
in Los Padres wetland (Buenos Aires Province, Argentina). In the basin of the Los Padres wetland, dissolved silica (DSi) concentration
is near 840 ± 232 μmol/L and 211.83 ± 275.92 μmol/L in groundwaters and surface waters, respectively. BSi represents an 5.6–22.1%
of the total suspension material, and 8–34% of the total mineralogical components of the wetland bottom sediments. DSi and
BSi vary seasonally, with highest BSi content (diatoms specifically) during the spring–summer in correlation to the lowest
DSi concentration. DSi (660–917.5 μmol/L) and phytolith (3.35–5.84%) concentrations in the inflow stream are higher than in
the wetland and its outflow stream (19.1–113 μmol/L; 0.45–3.2%, respectively), probably due to the high phytolith content
in soils, the high silica concentration in the soil solution, and the groundwater inflow. Diatom content (5–16.8%) in the
wetland and its outflow stream is higher than in the inflow stream (0.45–1.97%), controlling DSi in this system. The understanding
of the groundwater–surface water interaction in an area is a significant element for determining the different components
and the role that they play on the local biogeochemical cycle of Si. 相似文献
14.
A. A. Makhnach B. G. Pokrovsky O. V. Murashko O. L. Petrov 《Lithology and Mineral Resources》2020,55(1):24-35
The behavior of stable carbon and oxygen isotopes in carbonates during the deposition and diagenesis of sediments in the bioproductive Upper Famennian Pripyat Trough (southern Belarus) is discussed. Limestones and clayey limestones (Corg 0.92 ± 0.11%) are characterized by very low δ13C values (–9.6 ± 0.3‰). Parental sediments of these rocks were deposited in the shallow-water zone during slow downwarping episodes of the seafloor. Lithification of the sediments took place in oxidative conditions of the diagenesis zone. Organic matter was actively oxidized by free oxygen. Carbon dioxide with isotopically light organic carbon formed in this process was used during the crystallization of diagenetic carbonates that are visually indiscernible from the sedimentational variety. Marls, clayey marls, and carbonate-bearing clays (Corg 6.02 ± 0.80%) are characterized by δ13C values as high as –3.5 ± 0.6‰. In combustible shales (Corg >10%), δ13C value is ‒1.2 ± 0.6‰). The clayey rocks mark the episodes of sedimentation in relatively deep-water conditions that appear during the uncompensated sagging of the basin floor. The diagenetic zone with free oxygen was significantly decreased or absent at all. Here, oxygen of marine sulfates was the main or single oxidizer of organic matter (sulfate reduction). The sulfate oxygen is a weaker oxidizing agent than free oxygen. Therefore, much more organic matter was retained and fossilized in clayey rocks than in carbonate rocks. Organic carbon released during the sulfate reduction and mobilized later for the diagenetic carbonate formation was insufficient for the significant decrease of δ13C values relative to the marine carbonate standard. Isotopic composition of carbonate oxygen in the studied rocks is invariable and does not depend on the content of clay and organic matter. In these rocks, δ18O values are at the level (approximately –5‰) shown for the Famennian in the Global Chemostratigraphic Chart. This fact is consistent with the supposition that oxygen isotope composition of atmospheric precipitates, which influenced the rock formation via continental flow, is close to that of sea water in low latitudes where the territory of Belarus was located in the Late Devonian. 相似文献
15.
P. J. Henderson I. McMartin G. E. Hall J. B. Percival D. A. Walker 《Environmental Geology》1998,34(1):39-58
Trace element geochemistry of humus (<0.425 mm) and till (<0.002 mm) collected in the Flin Flon-Snow Lake area, northern
Manitoba and Saskatchewan, provides a regional context for assessing smelter contamination in the environment. The area includes
a Cu-Zn smelter known to discharge As, Cd, Cu, Fe, Hg, Pb, and Zn. In this study, sequential extraction analyses, scanning
electron microscopy and x-ray diffraction analyses were used on a suite of samples to determine: (1) the chemical and physical
characteristics of heavy metals in surficial sediments related to distance from the smelter, (2) criteria for assessing the
relative contribution of these metals from natural and anthropogenic sources, and (3) the potential of these metals for remobilization
in the environment.
Humus geochemistry reflects the anthropogenic and natural component of heavy metal concentrations. Smelter-related elements
show anomalously high values adjacent to the smelter, decreasing with distance until background values are reached at 70–104 km,
depending on the element. In humus, Zn is associated primarily with labile phases; Hg with non-labile phases. Adjacent to
the smelter, high proportions and concentrations of Zn and Hg in non-labile phases, indicative of smelter-derived particulates,
are confirmed by SEM examination. The particles occur as spheres, irregular grains, and with organics. With increasing distance
from the smelter, the geochemical response to bedrock composition is more obvious than the anthropogenic input.
Till geochemistry reflects the natural variation imposed by bedrock composition. At highly contaminated sites (<3 km from
the smelter), increased percentages of smelter-related elements in labile phases suggests heavy metals are leached from humus
to the underlying sediment.
Received: 5 November 1996 · Accepted: 31 March 1997 相似文献
16.
M. Chatterjee J. Canário S. K. Sarkar V. Branco A. K. Bhattacharya K. K. Satpathy 《Environmental Geology》2009,57(5):1125-1134
Mercury concentrations (HgT) in fine-grained fraction (<63 μm) of core sediments of the Hugli–Matla–Bidyadhari estuarine complex, India were analyzed.
Results revealed a wide range of spatial variations (<4–93 ng g−1 dry weight) with a definite enhancement level at the lower stretch of the estuarine complex infested with mangrove plants,
which might act as a sink to HgT. An elevated concentration of Hg was encountered in surface/subsurface layer of the core in majority of the cases resulting
from physical, biogenic and postdepositional diagenetic processes that remobilized and resuspended the metal from deeper sediments.
A strong positive correlation was observed between the Hg and clay fraction content of the sediments, while the correlations
of Hg with Al, Fe and Mn were poor. Based on the index of geoaccumulation (I
geo) and effects range-low (ER-L) value, it is considered that the sediments are less polluted and thus there is less chance
of ecotoxicological risk to organisms living in sediments. 相似文献
17.
L. L. Demina 《Doklady Earth Sciences》2011,439(1):981-985
A quantitative estimate has been made for the contribution of biological processes to accumulation and transformation of the
trace elements in the marginal biofilter of the ocean. It has been demonstrated that the proportion of phytoplankton having
the largest biomass reaches 96–99% of the total mass of trace elements accumulated by biota. The mass of trace elements taken
up by bivalved mollusks is tens to hundreds of times less than this, while that by macrophytes is an order of magnitude less
than the latter. A dynamic parameter of the biogenic migration, namely the duration of the biological cycle of phytoplankton,
has been calculated; this value does not exceed 2–3 days for Zn, Ni, Cu, Cd, Pb, Co, Fe, and Mn. First the trace metal balance
in the whole body of mussels Mytilus spp. between the soft tissues and shells was calculated based on their weight proportion (0.1 and 0.9, correspondingly).
As a result it was revealed that carbonate shells serve a great reservoir of Mn, Fe, Co, Ni, Cu and As and biomineralization
is an important process in their bioaccumulation. The suggested new approach can be applied when making environmental and
geochemical estimates of biotic self-purification of water bodies and when using shells as mineral supplements. 相似文献
18.
Ammonium release characteristics of the sediments from the shallow lakes in the middle and lower reaches of Yangtze River region,China 总被引:2,自引:0,他引:2
Juan Wang Shengrui Wang Xiangcan Jin Shuquan Zhu Fengchang Wu 《Environmental Geology》2008,55(1):37-45
Ammonium release from sediments has significant effects on the water quality in eutrophic lakes. In this study, the ammonium
release kinetics and adsorption–desorption processes were investigated in 13 sediments of 6 shallow lakes from the middle
and lower reaches of Yangtze River region, China. The results show that First Order Model best described the ammonium release
process, the maximal release capacity had a strong correlation with organic matter (OM), cationic exchange capacity (CEC),
total nitrogen (TN) and total phosphorus (TP). But it only had a weak correlation with Fe, Ca and Al. The ammonium release
capacity in more polluted sediments was higher than that in less polluted sediments. The average release rate within 0–5 min
was the highest among the experimental period, the amount released within 0–5 min accounted for approximately 50–70% of the
total release capacity. The ammonium release rate had a significant and positive correlation with OM. But it did not have
a strong correlation with TN, TP, Fe, Ca and Al. The ammonium potential release capacity (obtained when the water/sediment
ratio was about 2,500) had strong and positive relation with OM and maximal release capacity, and it may provide useful information
for the sediment release risk assessment. Henry Model best described the ammonium sorption isotherms, and ammonium adsorption–desorption
equilibrium concentration can be considered as the ammonium release threshold to assess the release risk in the sediments. 相似文献
19.
Study on effective species of heavy metals in lacustrine sediment core from Xijiu Lake,Taihu Lake catchment,China 总被引:2,自引:1,他引:1
Zhaobin Sun Yanhong Wu Shuchun Yao Enfeng Liu Fuchun Li 《Environmental Earth Sciences》2009,59(2):371-377
The BCR sequential extraction procedure is applied to probe into the speciation distribution of heavy metals (Cd, Cr, Zn,
Cu and Pb) in lake sediments of Core XJ2 in Xijiu Lake, Taihu Lake catchment, China. The results showed that the effective
species concentration of this five heavy metal elements increased obviously during the past century, the proportions of organic/sulphide
fractions of Zn, Cu and Pb decreased while the Fe–Mn oxide fractions increased, and the proportion of Fe–Mn oxide fractions
of Cd decreased while the exchangeable and carbonate fractions increased. The concentrations of exchangeable and carbonate
fractions of these five elements were increased in the past century, especially the proportions of these fractions of Cd,
Zn, Cu and Pb increased prominently. These changes could be attributed to the anthropogenic pollution. Since the changes of
the heavy metal concentrations were corresponding to the history of human activities, especially the industry development,
within the catchment. 相似文献
20.
Fine-grained floodplain sediments of the catastrophic 2002 flood deposited along the lower reaches of the Berounka and Vltava
Rivers, Czech Republic, were not highly contaminated with heavy metals and other toxic elements. This is due to the dominantly
mineral character of the sediments (Ctot in the range 3.97–5.01%, relatively low content of clay minerals), and due to the very high degree of contamination dilution
by eroded pre-industrial non-contaminated floodplain sediments. Despite this high degree of dilution, the influence of the
small Litavka River, draining the historical Pb–Zn–Ag Příbram ore region, is well visible. The Litavka River is one of important
sources of Pb and Zn contamination in the whole Berounka–Vltava–Labe river system. The 2002 flood sediments deposited in the
floodplain of the Berounka and Vltava Rivers show poor vertical chemical zoning, except for some components enriched in the
uppermost layer by precipitation from evaporated pore-water contained in the mud, i.e. secondary carbonate. The content of
Ccarb of the sediments (0.05–0.15%) is partly represented by this secondary carbonate, which is later leached by rainwater, and
partly by fragments of river mollusk shells. A majority of the heavy metals contained in sediments can be readily leached
by diluted acids, and to a much smaller degree by rainwater. 相似文献