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1.
Sediments from stormdrain catchments and outlets in Wellington city and sediment traps from Wellington Harbour were sampled
for trace metal content. Samples were analysed for total metal content using XRF and ICP-MS. High values of Pb and Zn were
found in stormdrain catchments and outlets, decreasing to elevated background rock levels in the harbour. Maximum values were
recorded in an inner city stormdrain catchment, with levels of Pb (4605 ppm), Cu (2981 ppm) and Zn (3572 ppm) all higher than
the biological probable effects levels (PEL). Concentrations of As, Cr, Cu, Pb, Ni and Zn concentrations in all harbour sediment
trap samples were below the PEL. The mean values for each harbour sediment trap sample can be used as an accurate historical
baseline in future studies. Stormdrain samples with high trace metal levels were close to industrial and construction sites.
The proximity of these outlets to recreational areas should be of concern to local authorities.
Received: 28 August 1997 · Accepted: 15 December 1997 相似文献
2.
Eighteen sediment samples and six water-column samples were collected in a small (6 km2), coastal embayment (Port Jefferson Harbor, New York) to define a high-resolution spatial distribution of metals and to elucidate sources of contaminants to the harbor. Sediment metal (Ag, Cu, Fe, Ni, Pb, V, and Zn) concentrations varied widely, reflecting differences in sediment grain size, with higher metal concentrations located in the fine-grained inner harbor sediments. Calculated enrichment factors for these sediments show that Ag, Pb, Cu, and Zn are elevated relative to both crustal abundances and their respective abundances in sediments in central Long Island Sound. Metal concentrations were 1.2 to 10 fold greater in water from the inner harbor compared to water from Long Island Sound collected outside the mouth of the harbor. Spatial variations in trace metals in surface waters within the bay parallel the spatial variations of trace metals in sediments within the harbor. Elevated water-column metal concentrations appear to be partially derived from a combination of diagenetic remobilization from contaminated sediments (e.g., Ag) and anthropogenic sources (e.g., Cu and Zn) within the southern portions of the harbor. Although the National Status and Trends Program had reported previously that sediment metal concentrations in Port Jefferson Harbor were low, the results of this study show sediment metals have high spatial variability and are enriched in the inner harbor sediments at levels comparable to more urbanized western north shore Long Island harbors. 相似文献
3.
Sediments from San Antonio Bay, the northwest Gulf of Mexico, and the Mississippi River Delta were acid leached and analyzed
for Fe, Mn, Pb, Zn, Cd, Cu and Ni by atomic absorption spectrophotometry. In order to account for differences in sediment
clay, carbonate, and organic matter content, metal concentrations were normalized to Fe. Significant linear correlations of
metals to Fe were obtained for unpolluted sediments and deviations from these “natural” statistical populations were found
for areas thought to have metal input caused by man.
San Antonio Bay sediments show little evidence of metal pollution despite 70 years of shell dredging in the bay. However,
the San Antonio-Guadalupe River system, the bay's prime sediment source, has 10% to 50% higher than natural levels of Pb,
Cd and Cu.
Sediments from a 1500 km2 area of the Mississippi River Delta have Pb and Cd concentrations 10% to 100% higher than expected levels. The vertical distribution
of Pb and Cd in these sediments suggests that inputs have occurred during the past 30 to 40 years. We find no indication of
metal pollution in other areas of the Delta or along the continental shelf of the northwest Gulf of Mexico. 相似文献
4.
Vertical accretion rates and heavy metal chronologies in wetland sediments of the Tijuana Estuary 总被引:3,自引:0,他引:3
This study represents the first report on sediment accretion rates using137Cs dating for a southern California salt marsh. Vertical accretion rates ranged from 0.7 to 1.2 cm yr−1, which is at the high end of sediment accretion values for coastal wetlands. This has lead to increases in elevation within the estuary from 18 to 35 cm over the last 35 years. Depth profiles of metal concentrations were converted to time-based profiles using vertical accretion rates. Chronologies for most cores indicate a consistent peak in sediment lead (Pb) concentrations in the early to mid 1980s, corresponding to the historic decline in Pb use, which was completed in the U.S. by the early 1980s, but not begun in Mexico until 1991. Sediment Pb levels ranged from about 6–56 μg g−1. Other metals did not show any consistent trends in sediment chronology, except for a single core from a mid-marsh site (east-mid 2), which showed a 2–3-fold increase in levels of Cu, Ni, and Zn during the past two decades. Sediment levels of copper (Cu), nickel (Ni), and zinc (Zn) ranged from 6–34 μg g−1, 11–27 μg g−1, and 42–122 μg g−1, respectively. Despite rapid industrial development of the watershed, a comparison of the sediment metal concentrations in the Tijuana Estuary to other anthropogenically-impacted estuaries in the United States and Europe, shows that metal levels in sediments of the north arm of the estuary are relatively low. 相似文献
5.
Sediment metal profiles were carefully examined for their distribution, chemical fractions, and mobility in three major marine-estuarine
transects in the world’s largest mangrove (Sundarban) ecosystem because anthropogenic influences had been very often noticed.
The level of pollutants was determined by CF and PLI. Metal contents in the freshly deposited sediment of Hugli transect were
relatively high (Pb, Fe, Zn, Mn, Ni, and Co) in comparison to Matla and Saptamukhi due to lithogenic contribution from large
catchments area (8 × 105 km2). Principal component analysis and correlation coefficient revealed that the concentrations of metals were mainly governed
by the variability of the sediment properties. Sediment was subjected to sequential chemical extractions to delineate metal
fractions, namely exchangeable, carbonate, Fe–Mn oxide, organic, and residual. This indicated a valuable insight into the
geochemical mode of the metal retention and their environmental behavior. Single extraction did not help significantly to
explain the metal profiling. 相似文献
6.
Between 1991 and 2000, Boston Harbor, a bay–estuary in the northeast USA, experienced a decrease in loadings of total nitrogen
(TN), total phosphorus (TP), and particulate organic carbon (PC) of between ∼80% and ∼90%. The average concentrations of TN
and TP in the harbor water column were decreased in linear proportion to the loadings. The changes to the chlorophyll-a (chl-a), PC, and bottom water DO concentrations were curvilinear relative to the loadings, with larger changes at low than high
loadings. For TN and TP, the starts of the decreases in concentrations coincided with the starts of the decreases in loadings.
For the three variables that showed curvilinear responses, the starts of the changes lagged by 2 to 3 years the starts of
the decreases in TN loadings. Total suspended solid concentrations and water clarity in the harbor were unchanged. The study
shows that for systems such as Boston Harbor, decreases in nutrient loadings will have quite different effects depending on
the base loadings to the system. 相似文献
7.
This study investigated physico-chemical characteristics of the water column and chemistry of suspended particulate material
(SPM) under quiescent, high-wind and high-wind/heavy-rainfall conditions in Homebush Bay, a highly contaminated embayment
of Port Jackson (Australia) to distinguish source and possible adverse effects to benthic and pelagic animals. Mean concentrations
in surficial sediment were <1, 14, 181, 141, 37, 290 and 685 μg g−1 for Cd, Co, Cr, Cu, Ni, Pb and Zn, respectively. Sediment chemistry indicated these metals had multiple sources, i.e. the
estuary, stormwater and industry. Mean total suspended solids (TSS) were 7, 17 and 20 mg L−1 during quiescent, high-rainfall and heavy rainfall/high wind conditions, respectively, whereas SPM Cd, Co, Cr, Cu, Ni, Pb
and Zn concentrations varied between 13–25, 166–259, 127–198, 38–82, 236–305 and 605–865 μg g−1, respectively under these conditions. TSS and total water metal concentrations were lowest during quiescent conditions. High
TSS and metal loads in surface water characterised high-rainfall events. Wind-induced resuspension contributed the greatest
mass of SPM and metals to the water column. Benthic animals may be adversely affected by Pb and Zn in sediment. Total water
Cu and Zn concentrations may pose a risk to filter-feeding animals in the water column due to resuspension of contaminated
sediment. 相似文献
8.
This paper aims to determine the correlation between Cd, Cu and Pb concentration in the sediment and in five aquatic plants
sampled during wet, normal and dry seasons. Analyses of the sediment showed that concentrations of exchangeable Cd and Cd
after acid reduction were higher during the wet season (October) than on other sampling dates with mean values of 0.18 and
0.29 μg g−1, respectively. The concentration of Cu in the organic oxidation phase was higher in the normal season (January) than on other
sampling dates with a mean value of 11.1 μg g−1. The concentrations of exchangeable Pb and that in the residual phase were higher during the wet season than on other sampling
dates with mean values of 1.05 and 9.18 μg g−1, respectively. Cd and Pb concentrations in the leaves, stems and roots varied between sampling dates with a reduced concentration
during dry season (July) and the highest metal concentrations (Cd and Pb) during wet season. There were positive correlations
between Cd and Cu concentrations in the plant tissues (leaves, stems and roots) of most aquatic plants in the acid reduction
fraction. Conversely, there was no positive correlation between Pb concentration in the plant tissues of all aquatic plants
and the acid reduction fraction of the sediment. 相似文献
9.
Nitrogen losses through sediment denitrification in Boston Harbor and Massachusetts Bay 总被引:1,自引:0,他引:1
Barbara L. Nowicki John R. Kelly Edwin Requintina Donna van Keuren 《Estuaries and Coasts》1997,20(3):626-639
Sediment denitrification is a microbial process that converts dissolved inorganic nitrogen in sediment porewaters to N2 gas, which is subsequently lost to the atmosphere. In coastal waters, it represents a potentially important loss pathway for fixed nitrogen which might otherwise be available to primary producers. Currently, data are lacking to adequately assess the role of denitrification in reducing or remediating the effects of large anthropogenic nitrogen loads to the coastal zone. This study describes the results of 88 individual measurements of denitrification (as a direct flux of N2 gas) in sediment cores taken over a 3-yr period (1991–1994) from six stations in Boston Harbor, nine stations in Massachusetts Bay, and two stations in Cape Cod Bay. The dataset is unique in its extensive spatial and temporal coverage and includes the first direct measurements of denitrification for North Atlantic shelf sediments. Results showed that rates of denitrification were significantly higher in Boston Harbor (mean=54, range<5–206 μmol N2 m?2 h?1) than in Massachusetts Bay (mean=23, range<5–64 μmol N2 m?2 h?1). Highest rates occurred in areas with organic-rich sediments in the harbor, with slower rates observed for low-organic sandy sediments in the harbor and at shallow shelf stations in the bay. Lowest rates were found at the deepest shelf stations, located in Stellwagen Basin in Massachusetts Bay. Observed rates were correlated with temperature, sediment carbon content, and benthic macrofaunal activity. Seasonally, highest denitrification rates occurred in the summer in Boston Harbor and in the spring and fall in Massachusetts Bay, coincident with peak phytoplankton blooms in the overlying water column. Despite the fact that sediment denitrification rates were high relative to rates reported for other East Coast estuaries, denitrification losses accounted for only 8% of the annual total nitrogen load to Boston Harbor, a consequence perhaps, of the short water-residence times (2–10 d) of the harbor. 相似文献
10.
Asmae Mhamdi Alaoui Mohamed Choura Mohamed Maanan Bendahhou Zourarah Marc Robin Maria Freitas Conceição César Andrade Mehdi Khalid Christian Carruesco 《Environmental Earth Sciences》2010,61(2):275-286
The metal content in surface sediments (0–2 cm, 26 samples), in a sediment core (120, 1 cm slices), taken from Moulay Bousselham
(Morocco) was investigated. Concentrations of Al, Fe, Mn, Pb, Zn, Cu, Ni, Cr, Cd, As, and Hg were evaluated in surface and
cored sediments of Moulay Bousselham lagoon. Significantly high concentrations in μg g−1 dw of Pb (31.7–6.2), Zn (758.9–167), Cu (310.7–22), Ni (96–10.5), Cr (113–18.9), Cd (0.84–0.02), As (1–0.1), and Hg (0.61–0.02)
were found in sediment samples from Moulay Bousselham lagoon. Calculated enrichment factors [EFMe = (Me/Al)sample/(Me/Al)background], using Al as a normalizer, and correlation matrices showed that metal pollution in Merja Zerga of Moulay Bousselham lagoon
was the product of anthropogenic sources, while the metal content in Merja Kehla was of natural origins. The results suggest
that a major change in the sedimentary regime of the lagoon, associated with internal trapping and re-distribution of heavy
metal, has been occurring in the past few decades. The cause would appear to be the construction of a Nador Canal at the lagoon.
Probable effects concentrations (PEC) were often exceeded for heavy metals in the lagoon sediments, especially for Zn, Cu,
Ni, and Cr, and four stations, stations MZ-11, MZ-12, MZ-13, MZ-14, MZ-16, and MZ-17, had multiple metals at presumptively
toxic levels. These comparisons suggest that sediment metal levels in the river are clearly high and probably pose an environmental
risk at some stations. The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance
when contamination issues are at stake. Metal concentrations found in Moulay Bousselham lagoon were comparable to aquatic
systems classified as contaminated from other regions of the world. 相似文献
11.
Amino acid composition of suspended particles,sediment-trap material,and benthic sediment in the Potomac Estuary 总被引:1,自引:0,他引:1
Sediment trap deployments in estuaries provide a method for estimating the amount of organic material transported to the sediments from the euphotic zone. The amino acid composition of suspended particles, benthic sediment, and sediment-trap material collected at 2.4 m, 5.8 m, and 7.9 m depths in the Potomac Estuary was determined in stratified summer waters, and in well-mixed oxygenated waters (DO) in late fall. The total vertical flow, or flux, of material into the top traps ranged from 3 g m?2 d?1 in August to 4.9 g m?2 d?1 in October. The carbon and nitrogen fluxes increased in the deepest traps relative to the surface traps during both sampling periods, along with that of the total material flux (up to 47.3 g m?2 d?1 in the deepest trap), although the actual weight percent of organic carbon and organic nitrogen decreased with depth. Amino acid concentrations ranged from 129 mg g?1 in surface water particulate material to 22 mg g?1 in particulate material in 9-m-deep waters and in the benthic sediment. Amino acid concentrations from 2.4-mg-depth sediment traps averaged 104±29 mg g?1 in stratified waters and 164±81 mg g?1 in well-mixed waters. The deep trap samples averaed, 77.3±4.8 mg g?1 amino acids in summer waters and 37±16 mg g?1 in oxygenated fall waters. Amino acids comprised 13% to 39% of the organic carbon and 12% to 89% of the orgnaic nitrogen in these samples. Analysis of the flux results suggest that resuspension combined with lateral advection from adjacent slopes can account for up to 27% of the material in the deep traps when the estuary was well-mixed and unstratified. When the estuary was stratified in late summer, the amino acid carbon produced by primary productivity in the euphotic zone decreased by 85% (86% for total organic carbon) at the pycnocline at 6 m depth, leaving up to 15% of the vertical organic flux available for benthic sediment deposition. 相似文献
12.
Pyritization of trace metals in estuarine sediments and the controlling factors: a case in Jiaojiang Estuary of Zhejiang Province,China 总被引:1,自引:0,他引:1
Siyuan Ye Edward A. Laws Qiang Wu Shaojun Zhong Xigui Ding Guangming Zhao Shaojun Gong 《Environmental Earth Sciences》2010,61(5):973-982
Three undisturbed sediment samples were collected from the intertidal zone of the Jiaojiang Estuary of Zhejiang Province,
China. The sediments were found to contain remarkably low concentrations of organic carbon (<0.6%) and acid volatile sulfide
(AVS) (<30 μmol g−1). The availability of these two substrates likely constrained sulfate reduction and pyritization of several trace metals,
respectively. This was especially true at one station where AVS concentrations in the upper 20 cm averaged less than 0.05 μmol g−1. Although the depth dependence of the degree of trace metal pyritization was generally consistent with expectations based
on redox conditions, depth profiles of reactive-metal and pyrite-metal concentrations in several cases revealed more complex
behavior and a positive correlation between reactive-metal concentrations and pore water metal concentrations. 相似文献
13.
Tidal freshwater marshes exist at the interface between watersheds and estuaries, and thus may serve as critical buffers
protecting estuaries from anthropogenic metal pollution. Bi-weekly samples of newly deposited marsh sediments were collected
and analyzed for Cu, Zn, and Fe concentrations over 21 months from July 1995 to March 1997 in five distinct habitats at the
head of Bush River, Maryland. Bi-weekly anthropogenic metal enrichments ranged from 0.9–4.7. Anthropogenic excess metal loadings
averaged over 1996 ranged from 6–306 and 25–1302 μg cm−2 year−1 between sites for Cu and Zn, respectively. Based on Fe-normalized trace metal signatures, Susquehanna River sediment does
not significantly contribute to upper Bush River. Organic matter was found to dilute total metal concentrations, whereas past
studies suggested organics enhance labile metal content. Analysis of metal input pathways shows that marsh metals are primarily
imported from nearby subtidal accumulations of historic watershed material by tidal flushing.
Received: 29 April 1999 / Accepted: 7 December 1999 相似文献
14.
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
15.
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
16.
John R. Kelly 《Estuaries and Coasts》1997,20(2):365-380
This paper summarizes evidence that most of the considerable nitrogen loading (~8, 470 mmol total N m?2 yr?1) to Boston Harbor (Massachusetts, USA) is expelled to shallow shelf waters of Massachusetts Bay, where it strongly influences ecological dynamics. Examination of nitrogen concentrations in the harbor, compared with loading, indicated that removal processes are active in the harbor. Comparison to other estuarine systems showed that the harbor’s nitrogen concentrations are consistent with its loading, if they are corrected for tidal flushing effects on the water residence time. Furthermore, extensive measurements of sediment denitrification confirmed that rates of N2 gas loss are high in an absolute sense (~600–800 mmol N m?2 yr?1) but nonetheless remove only a small portion (<10%) of the annual land-derived nitrogen loading. Burial in sediments apparently removes only about 2% of the N input, implying export to offshore environments as the major removal process (~88–90% of N input). Western Massachusetts Bay receiving waters were examined for a signature of export from the harbor. Data consistently show a gradient of decreasing nitrogen concentrations from the harbor to about 10–20 km into the bay. In many cases, plots of nitrogen concentrations versus salinity show nearly conservative mixing character, which implies virtual export. Seasonally, the data suggest most of the export from the harbor in winter is as dissolved inorganic forms (NH4 +, NO3 ?, NO2 ?). In summer, export is dominated by the outflow of organic nitrogen forms. Chlorophyll export is evident as well, suggesting that the nutritional coupling of the harbor and bay in summer involves organic fertilization of the bay’s surface water. Finally, high-resolution studies over different stages of the tidal cycle help refine understanding of the advection of chlorophyll and stimulation of in situ chlorophyll growth at the seaward edge of the tidal excursion into the bay. 相似文献
17.
A large river ice jam and associated flooding in February 1996 on the Blackfoot and Clark Fork Rivers of western Montana
mobilized large amounts of fine-grained sediment. Metal concentrations in sediment downstream from a reservoir containing
large amounts of contaminated sediment were enriched in metals after the ice jam, while open reaches above the reservoir were
diluted by ice-jam processes. This varied response shows the importance of understanding ice jam events to sediment and metal
transport and suggests that ice jams must be considered as important agents affecting sediment metal concentrations in rivers.
Received: 4 December 1997 · Accepted: 23 February 1998 相似文献
18.
The aqueous mobility and potential bioavailability of metals and metalloids in road runoff in a ‘wet–dry’ tropical location
were assessed by analysing metal and metalloid concentrations in particulate, total dissolved and labile dissolved phases
in runoff waters. Road-derived Al, Cu, Pb, Sb and Zn concentrations were substantially elevated in runoff when compared to
receiving creek waters. Median dissolved concentrations in road runoff exceeded those in creek waters by up to an order of
magnitude. Leaching experiments of road sediments confirmed that several metals and metalloids were released in high concentrations
from road sediments. Labile Zn and Cu concentrations measured by diffusion gradients in thin films (DGT) showed that almost
all dissolved Zn and up to half of dissolved Cu in runoff waters and in road sediment leachate were potentially bioavailable.
Comparisons of dissolved metal concentrations in receiving waters affected by road runoff with ecosystem guideline levels,
indicated a risk of reaching toxic levels of Cu and Zn in the receiving waters in the absence of adequate treatment or dilution.
Low dilution rates of road runoff are likely to occur during late ‘dry’ season/early ‘wet’ season storms which have the potential
to produce high metal concentrations derived from long periods of accumulation of road sediment at a time when creek flow
rates are at their annual minimum. 相似文献
19.
Phillipe Monbet 《Estuaries and Coasts》2004,27(3):448-459
Cadmium (Cd) variations were investigated over an annual cycle (12 surveys between February 1998–January 1999) in the Morlaix
estuary (Brittany, France) in both the water column and the benthic compartment in relation to hydrological conditions. The
drainage basin of the Morlaix River estuary is predominantly agricultural in character. Dissolved Cd concentrations in the
water column varied from 0.04 to 0.48 nM. Particulate Cd concentrations ranged from 1 to 64 nmol g−1. These concentrations reach levels commonly observed in estuaries affected by heavy industrial activities. Extensive agricultural
activities in the drainage basin may be responsible for Cd levels above pristine conditions. Metal concentrations varied significantly
over the seasonal cycle and the dissolved fraction exhibited high values in summer months. Particulate concentrations were
always lowest during this season. In the benthic compartment, Cd concentrations in surface sediment varied from 0.4 to 5.0
nmol g−1 and from 0.2 to 5.0 nM in porewaters. Concentrations in sediment were slightly affected by Cd contamination and temporal
changes were important over the seasonal cycle. The variations seem to be controlled by the succession of sedimentation and
erosion processes, which are tightly linked to seasonal changes in river discharge. A box model was constructed based on known
Cd sources and sinks in the estuary. Cd is chiefly brought into the estuary by the Morlaix River and accumulates within the
estuary. The accumulation within the estuary represents from 6.3 to 7.2 kg yr−1. 相似文献
20.
The present study describes variations in the vertical fluxes measured concurrently with sediment traps at both a shallow
water (4 m) and a deeper water (7.5 m) position in a coastal lagoon in April 1995. A tripod equipped with five sediment traps
(trap openings at 0.35 m, 0.75 m, 1.05 m, 1.40 m, and 1.80 m above the seabed) was placed at the shallow water position. This
tripod was deployed three times during the study period and deployment periods varied between 2 d and 5 d. The second sediment
trap, placed at the deep water position in the central part of the lagoon, measured vertical flux for intervals of 12 h at
1.4 m above the seabed. The horizontal distance between the sediment traps was 8 km. The average maximum vertical flux at
the shallow water position reached 27.9 g m−2 d−1 during a period of high, westerly wind speeds, and a maximum vertical flux of 16.9 g m−2 d−1 was reached at the deep water position during a period of high, easterly wind speeds. Both strong resuspension events were
closely related to increased wave shear stress derived from surface waves. Maximum wave-induced resuspension rate was 10 times
higher at the shallow water position and 3.8 times higher at the deep water position compared with the net sedimentation rate
in the lagoon. Small resuspension events occurred at the shallow water position during periods of increased current shear
stress, Estimations of conditions for transport of sediment between shallow water and deep water showed that particles must
be resuspended to a height between 3 m and 4 m and that current speeds must be higher than about 0.1 m s−1. An average sedimentation rate of 3.8 g m−2 d−1 was obtained at the shallow water position during a period without wave shear stress and low current shear stress. This rate
measured by sediment traps is similar to a net sedimentation rate in the lagoon of 4.4 g m−2 d−1, which was determined by radiocarbon dating of a sediment core (Kristensen et al. 1995). 相似文献