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531.
The mobilisation of metals (Al, Fe, Cd, Cu, Mn, Ni, Pb, Sn, Zn) from contaminated estuarine sediment has been examined using commercially available surfactants. Metal release by the anionic surfactant, sodium dodecyl sulphate (SDS), increased with increasing amphiphile concentration up to and above its critical micelle concentration (CMC). Metal mobilisation by the bile acid salt, sodium taurocholate, and the nonionic surfactant, Triton X-100, however, did not vary with amphiphile concentration. SDS was the most efficient surfactant in mobilising metals from the sample, and Cd, Cu and Ni were released to the greatest extents (12-18% of total metal at [SDS] > CMC). Metal mobilisation appeared to proceed via complexation with anionic amphiphiles and denudation of hydrophobic host phases. Surfactants may play an important role in the solubilisation of metals in the digestive environment of deposit-feeding animals and, potentially, in the remediation of metal-contaminated soil and sediment. 相似文献
532.
River sediments are basic components of our environment. It also constitutes a major source of persistent bioaccumulative
toxic chemicals which may pose threats to ecological and human health even after contaminants are no longer released from
point and non-point sources. Therefore, the aim of this study was to investigate the mobility and the availability of metals
in sediments from different sites along the Nile River in Cairo district using sequential chemical extraction technique. The
speciation data showed that most metals were associated with organic/sulfide and residual fractions. The order of total metal
concentrations in sediment samples was found to be Fe > Mn > Zn > Ni > Cu ≥ Cr > Pb > Cd. 相似文献
533.
Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in
their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during
the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands
in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen
(N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter
receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive,
but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments
associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland
plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances
the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus]. 相似文献
534.
G.J. Hancock C. LeslieS.E. Everett S.G. TimsG.J. Brunskill R. Haese 《Journal of environmental radioactivity》2011,102(10):919-929
The construction of high resolution chronologies of sediment profiles corresponding to the last 50-100 years usually entails the measurement of fallout radionuclides 210Pb and 137Cs. The anthropogenic radionuclide, 137Cs, originating from atmospheric nuclear weapons testing can provide an important “first appearance” horizon of known age (1954-1955), providing much-needed validation for the sometimes uncertain interpretations associated with 210Pb geochronology. However, while 137Cs usually provides a strong signal in sediment in the northern hemisphere, total fallout of 137Cs in the southern hemisphere was only 25% that of the north and the low activities of 137Cs seen in Australian and New Zealand sediments can make its horizon of first appearance somewhat arguable. Low 137Cs fallout also limited the size of the 1963-1964 fallout peak, a peak that is usually seen in northern hemisphere sediment profiles but is often difficult to discern south of the equator.This paper shows examples of the use of nuclear weapons fallout Pu as a chronomarker in sediment cores from Australia (3 sites) and New Zealand (1 site). The Pu profiles of five cores are examined and compared with the corresponding 137Cs profiles and 210Pb geochronologies. We find that Pu has significant advantages over 137Cs, including greater measurement sensitivity using alpha spectrometry and mass spectrometric techniques compared to 137Cs measurements by gamma spectrometry. Moreover, Pu provides additional chronomarkers associated with changes in the Pu isotopic composition of fallout during the 1950s and 1960s. In particular, the 238Pu/239+240Pu activity ratio shows distinct shifts in the early 1950s and the mid to late 1960s, providing important known-age horizons in southern hemisphere sediments. For estuarine and near-shore sediments Pu sometimes has another significant advantage over 137Cs due to its enrichment in bottom sediment relative to 137Cs resulting from the more efficient scavenging of dissolved Pu in seawater by sediment particles. 相似文献
535.
Kobayashi J Kinoshita K Mizukawa K Sakurai T Imaizumi Y Takada H Suzuki N 《Chemosphere》2011,82(5):745-750
To evaluate the dietary uptake of polychlorinated biphenyls (PCBs) from live food, we investigated the dietary uptake and depuration kinetics of PCBs in a marine benthic fish (marbled sole, Pseudopleuronectes yokohamae) by using as food live sandworms (Perinereis nuntia) that were laboratory-exposed to field-collected PCB-contaminated sediment. Marbled sole were fed the PCB-contaminated sandworms for 28 d and then uncontaminated sandworms for 56 d. The assimilation efficiencies (AEs) of 84 PCB congeners via the gastrointestinal tract (GIT) to the muscle of the fish ranged from 0.21 to 0.78; whole-body AEs would be lower than those of muscle because of the lower PCB concentrations, on a lipid basis. The AEs determined in this study were lower than those in other studies that used PCB-spiked commercial pelletized food. The lower AEs found in this study might be attributable to differences in the food administered (live sandworms vs. commercial pellet food), possibly because of low digestibility of sandworm lipids by marbled sole. In addition, the AEs in this study tended to increase with increasing log octanol-water partition coefficients (KOW) up to about seven, although AEs in the other studies using commercial pelletized food did not increase with increasing log KOW. This result suggests the co-transport of highly hydrophobic PCB congeners along with lipids and fatty acids from the digested sandworms into the GIT epithelium cells. The growth-corrected half-lives of 26 PCB congeners in the muscle of fish ranged from 20 to 107 d. 相似文献
536.
Impact of different land uses on polycyclic aromatic hydrocarbon contamination in coastal stream sediments 总被引:2,自引:0,他引:2
PAHs are ubiquitous environmental pollutants that can cause adverse health and ecological effects. In the present study, we examined the impact of land use on the concentration and composition of PAHs in 28 coastal stream sediments on the Island of Oahu, Hawaii. In densely populated urban areas, the concentration range of total PAHs in the stream sediments affected by mixed residential and industrial activities (RI) are 0.40-9.05 ppm, which is significantly higher than the 0.36-4.21 ppm detected in the stream sediments affected predominantly by urban residential land uses (UR). The stream sediments affected by agricultural activities (AG) reported a concentration range of 0.09-2.14 ppm, which is lower than those of the RI and UR stream sediments. The molecular weight of PAH is a factor, as only high molecular weight (HMW) PAHs were significantly affected by land uses (ANOVA P = 0.009). Correlation analysis showed that only in the UR stream sediments were significant correlations observed between PAH concentration and two anthropogenic indicators: population density (r = 0.57, P = 0.027) and vehicle density (r = 0.55, P = 0.034). The fractional concentrations of PAHs were analyzed by using PCA analysis, which led to the separate clustering of the RI and AG stream sediments and suggest distinct PAH sources between the two land uses. Two PAH source indicators, including Ant/(Ant + Phe) and Fl/(Fl + Py), indicates that PAHs sources in the RI stream sediments are most likely of petroleum origin, while PAHs in the UR and AG stream sediments most likely came from combustion activities. In addition, the concentration and relative potency of carcinogenic PAHs in the coastal stream sediments exhibited similar patterns as the total PAH concentration with respect to land uses. 相似文献
537.
Immobilization of lead and cadmium from aqueous solution and contaminated sediment using nano-hydroxyapatite 总被引:5,自引:0,他引:5
Zizhong Zhang Mengyan Li Wei Chen Shuzhen Zhu Nannan Liu Lingyan Zhu 《Environmental pollution (Barking, Essex : 1987)》2010,158(2):514-382
The effectiveness and mechanism of nano-hydroxyapatite particles (nHAp) in immobilizing Pb and Cd from aqueous solutions and contaminated sediment were investigated. The maximum sorption amount (Qmax) of Pb and Cd in aqueous solution was 1.17 and 0.57 mmol/g. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) surface and depth analysis indicated that dissolution-precipitation is the primary immobilization mechanism for Pb, while surface complexation and intraparticle diffusion account for Cd sequestration. Different amounts of nHAp (0-10% nHAp/dry weight) were added to the contaminated sediment. Sequential extraction showed that nHAp could effectively reduce the exchangeable fraction of Pb and Cd in the sediment and significantly reduce the concentration in porewater. The results in this study showed that nHAp can immobilize Pb and Cd in sediment effectively. 相似文献
538.
Samples of water, sediment and suspended particulates were collected from 13 sites in the middle and lower reaches of the
Yellow River in China. Phthalic acid esters (PAEs) concentrations in different phases of each sample were determined by Gas
Chromatogram GC-FID. The results are shown as follows: (1) In the Xiao Langdi–Dongming Bridge section, PAEs concentrations
in water phase from the main river ranged from 3.99 × 10−3 to 45.45 × 10−3 mg/L, which were similar to those from other rivers in the world. The PAEs levels in the tributaries of the Yellow River
were much higher than those of the main river. (2) In the studied branches, the concentration of PAEs in sediment for Luoyang
Petrochemical Channel (331.70 mg/Kg) was the highest. The concentrations of PAEs in sediment phase of the main river were
30.52 to 85.16 mg/Kg, which were much higher than those from other rivers in the world. In the main river, the concentration
level of PAEs on suspended solid phases reached 94.22 mg/Kg, and it reached 691.23 mg/Kg in the Yiluo River – one tributary
of the Yellow River. (3) Whether in the sediment or on the suspended solid phases, there was no significant correlation between
the contents of PAEs and TOC or particle size of the solid phase; and the calculated Koc of Di (2-Ethylhexyl) Phthalate (DEHP)
in the river were much less than the theoretical value, which inferred that PAEs were not on the equilibrium between water
and suspended solid phases/sediment. (4) Among the measured PAEs compounds, the proportions of DEHP and di-n-butyl phthalate
(DBP) were much higher than the others. The concentrations of DEHP exceeded the Quality Standard in all the main river and
tributary stations except those in the Mengjin and Jiaogong Bridge of the main river. This indicates that more attention should
be paid to pollution control and further assessment in understanding risks associated with human health. 相似文献
539.
By the method of P fractionation, we examined sedimentary P fractions in Lake Dianchi before and during cyanobacterial blooms,
namely in April 2004 and August 2004, respectively. In this study, the whole lake is divided into four areas to discuss P
fractions in sediment and the relationship between them and water quality or the nutrient status. The results show that where
the water body was much more eutrophic (higher levels of total phosphorus, total nitrogen, chlorophyll and trophic status
index) in Lake Dianchi, there can be more potentially available phosphorus (BD–P and NaOH–P) and less no available phosphorus
(HCl–P and residual P) in the corresponding sediments. Statistical analysis and statistical plots are used to compare the
distribution of every P fraction during cyanobacterial blooms with that before cyanobacterial blooms, and the results indicate
that the different P fractions had the different mobility. HCl–P and residual P were relatively stable, while NaOH–P, BD–P
and NH4Cl–P were more mobile. BD–P can intensively be released from sediment to water and consequently promote cyanobacterial
blooms, and at the same time the NaOH–P concentration increased in sediment, which can result from that BD–P released can
be partly immobilized to NaOH–P. During cyanobacterial blooms BD–P can be as a source, but NaOH–P as a sink. Besides, total
phosphorus in sediment had no significant differences between two samplings. 相似文献
540.
Seasonal variation of the concentrations of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were measured by ICP-AES
in the water and sediment from the Saricay Stream, Geyik Dam and Ortakoy Well in the same basin. Comparisons between trace
metal concentrations in water and sediment in three sources (Stream, Dam and Well) were made. The concentrations of a large
number of trace metals in the water and sediment were generally higher in the Stream than in the Well and Dam, particularly
in summer. Trace metal concentration ranges in sediments of the Saricay Stream and its sources showed very wide ranges (as
mass ratio): Co: 5–476 μg g−1, Cr: 15–1308 μg g−1, Cu: 7–128 μg g−1, Fe: 1120–13210 μg g−1, Mn: 150–2613 μg g−1, Ni: 102–390 μg g−1, Pb: 0.7–31.3 μg g−1 and Zn: 18–304 μg g−1, whereas Cd was not detected. Trace metal concentration ranges found in waters were: Co: 9.5–20.7 μg L−1, Cr: 20.3–284 μg L−1, Cu: 170–840 μg L−1, Fe: 176–1830 μg L−1, Mn: 29.3–387 μg L−1, and Ni: 4.3–21.9 μg L−1. Among the trace metals studied, Cd and Zn in two seasons and Pb in winter were usually not detected or in the recommended
levels. In addition, Cd was not detected in the sediment during the winter season. The analysis of variance (one-way ANOVA)
and correlation matrix was employed for the sediment and water samples of the two field surveys (summer and winter) comparison.
The three sources showed differences in metal contents. The metal levels in sediments displayed marked seasonal and regional
variations, which were attributed to anthropogenic influences and natural processes. In the Saricay Stream, high values of
metals during the dry season showed an anthropological effect from small industry firms, e.g.: an olive mill and a dairy farm
or water dilution during summer seasons. Finally, the pollution in this basin probably originated from small industrial, low
quality coal-burned thermal power plants, and particularly agricultural and domestic waste discharges. 相似文献