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1.
The present work is the first attempt to compare the data of a comprehensive study of the origin and distribution of 16 priority pollutant polycyclic aromatic hydrocarbons (PAHs) in surface sediments (<63 μm) from 18 sampling stations, 9 from Sundarban of Bangladesh and 9 from Indian counterpart. Σ19PAHs concentration in sediments showed wide variations from 208.3 to 12,993.1 ng g?1 dry weight in Indian Sundarban, whereas 208.4 to 4,687.9 ng g?1 in the case of Bangladesh. Fluoranthene, pyrene, benzo(b)fluoranthene, benzo(a)pyrene and dibenzo(a,h)anthracene were predominant species for both the countries. The PAH diagnostic ratios indicated that the PAHs in sediments from both the countries were of mixed source of hydrocarbons of both petrogenic and pyrolytic origin. According to the numerical effect-based sediment quality guidelines, the levels of PAHs in the Sundarban wetland of Bangladesh and India should not exert adverse biological effects. The TEQ values calculated for samples from the Bangladesh and Indian Sundarban varied from 13.68 to 1,014.75 and 1.31 to 2,451 ng g?1 d.w. with an average of 221.02 and 358.63 ng g?1, respectively. The overall contamination status of PAH was higher in India than Bangladesh.  相似文献   

2.
The aim of the present work was to investigate links between the low-field magnetic susceptibility (MS) and chemical and mineral composition of sediments from several Croatian and Slovenian rivers, as well as to determine possible anthropogenic influence on these sediments. MS measurements are a fast and simple method, which serves as a proxy for the estimation of pollution in different environmental systems. The investigated rivers are predominantly unpolluted rivers from Croatian and Slovenian karstic and flysch areas, which belong to the Adriatic or the Black Sea watersheds: the Dragonja, the Mirna, the Ra?a, the Ri?ana, the Reka, the Rak, the Cerkni?nica, the Unec and the Ljubljanica rivers. It was assumed that, due to their mostly unpolluted status, they could serve as a database for natural MS background values for this region. For comparison, several rivers and a lake from the Celje old metallurgic industrial area (Slovenia) were also investigated: the Savinja, the Hudinja, the Voglajna rivers and Slivni?ko Lake. They form a sub-basin of the Sava River drainage basin. Sediments of the clean karstic and flysch rivers showed extremely low MS values, with mass susceptibility values ranging from 0.58 × 10?7 to 5.11 × 10?7 m3/kg, and isothermal remanent magnetism (IRM) values ranging from 0.71 to 7.88 A/m. In the Celje industrial area, river sediments showed much higher MS values, with mass susceptibility values ranging from 1.31 × 10?7 to 38.3 × 10?7 m3/kg, and IRM values ranging from 0.91 to 100.42 A/m. The highest MS value was found in the Voglajna River at Teharje-?tore, a point which showed a significant number of anomalies of toxic metals in earlier investigations. Semiquantitative determination of relations between grain size and concentration of magnetite was performed using the Thompson-Oldfield method. X-ray diffraction (XRD) mineralogical analysis showed that sediments of the Celje area have mostly quartz as major mineral, with relatively small amount of carbonate minerals, while in sediments of karstic rivers carbonate minerals prevail. Statistically significant correlations were obtained between MS and Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Ba in the Slovenian karstic region and between MS and Cr, Fe, Co, Ni and Zn in flysch drainage basins. On the contrary, no correlation of MS and Hg content was obtained.  相似文献   

3.
Levels and distributions of organochlorine pesticides (OCPs) and phenolic endocrine-disrupting chemicals (EDCs) in surficial sediments of the Shaying River, the largest tributary of the Huaihe River in eastern China, were investigated to understand their relationship with the hydrodynamics. Concentrations of total hexachlorocyclohexane isomers (ΣHCHs) and dichlorodiphenyltrichloroethanes (ΣDDT) were in the range of 26.7–119 and 9.64–214 ng g?1 with mean values of 104 and 80.7 ng g?1, respectively. Residues of HCHs in sediments can be considered as originating from the application of both technical mixtures and lindane in the past. According to the spatial distribution of (DDD + DDE)/ΣDDT ratios, the influence of recent DDT inputs was dominant upstream, whereas DDD prevailed downstream, due to anaerobic degradation. Concentrations of total phenolic EDCs (ΣEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) ranged widely from 425 to 3,953 ng g?1 with the highest level occurring in the middle reach. This accumulation could be attributed to the retransfer of surficial sediment from upstream, where the main sources are located. Spatial distribution of contaminants indicated that riverine hydrodynamics can significantly affect their behavior and fate in sediment. This evidence was further verified by multivariate statistical techniques such as Cluster Analysis (CA), Principle Component Analysis (PCA) and Discriminant Analysis (DA). The CA identified three distinct clusters reflecting the large complexity of river system like geography setting, hydrodynamic condition, etc. This finding was also confirmed by the DA. Furthermore, a PCA demonstrated that about 80.8 % of total spatial variance can be explained by the first three factors, which also indicated that contaminant spatial distributions are driven by local inputs, biodegradation and riverine hydrodynamics.  相似文献   

4.
The 1,750-km2 endorheic Honey Lake basin (California–Nevada, USA) was part of the 22,000-km2 Pleistocene Lake Lahontan pluvial lake system which existed between 5,000 and 40,000 years BP. The basin consists of two subbasins separated by a low elevation divide. Groundwater in the western subbasin has a maximum total dissolved solids (TDS) content of only ~1,300 mg/L; however eastern subbasin groundwater has a maximum TDS of ~46,000 mg/L. This TDS distribution is unexpected because 94% of surface water TDS loading is to the western subbasin. In situ reactions and upwelling thermal groundwater contributing to groundwater chemistry were modeled using NETPATH. The TDS difference between the subbasins is attributed to post-Lake Lahontan isostatic rebound about 13,000 years ago. Prior to rebound the subbasins did not exist and the low point of the basin was in the eastern area where hydraulic isolation from the larger Lake Lahontan and frequent desiccation of the basin surface water resulted in evaporite mineral deposition in accumulating sediments. After rebound, the terminal sink for most surface water shifted to the western subbasin. Although most closed basins have not been impacted by isostatic rebound, results of this investigation demonstrate how tectonic evolution can impact the distribution of soluble minerals accumulating in shallow basins.  相似文献   

5.
This paper presents a study on the Wular Lake which is the largest fresh water tectonic lake of Kashmir Valley, India. One hundred and ninety-six (196) water samples and hundred (100) sediment samples (n = 296) have been collected to assess the weathering and Anthropogenic impact on water and sediment chemistry of the lake. The results showed a significant seasonal variability in average concentration of major ions being highest in summer and spring and lower in winter and autumn seasons. The study revealed that lake water is alkaline in nature characterised by medium total dissolved solids and electrical conductivity. The concentration of the major ion towards the lake central showed a decreasing trend from the shore line. The order of major cations and anions was Ca2+ > Mg2+ > Na+ > K+ and HCO3 ? > SO4 2? > Cl?, respectively. The geochemical processes suggested that the chemical composition lake water is mostly influenced by the lithology of the basin (carbonates, silicates and sulphates) which had played a significant role in modifying the hydrogeochemical facies in the form of Ca–HCO3, Mg–HCO3 and hybrid type. Chemical index of alteration values of Wular Lake sediments reflect moderate weathering of the catchment area. Compared to upper continental crust and the post-Archean Shale, the sediments have higher Si, Ti, Mg and Ca contents and lower Al, Fe, Na, K, P, Zn, Pb, Ni, Cu content. Geoaccumulation index (Igeo) and US Environmental Protection Agency sediment quality standards indicated that there is no pollution effect of heavy metals (Zn, Mn, Pb, Ni and Co).The study also suggested that Wular Lake is characterised by both natural and anthropogenic influences.  相似文献   

6.
Damming of the North Anna River in 1972 created Lake Anna, a cooling water source for the Dominion nuclear power plant as well as a popular recreation site in Spotsylvania and Orange counties, Virginia, USA. Previously dated (210-Pb) sediment cores from seven locations within the lake and three locations in the adjoining Waste Heat Treatment Facilities (WHTF) were analyzed for trace metals (Al, Ba, Zn, Cd, Cu, Fe, Mn and Pb) and polychlorinated biphenyls (PCBs) to examine the environmental evolution of the reservoir system. The reservoir has a history of mining activities in its watershed and unusually elevated concentrations of PCBs were found in fish tissues from previous studies. Therefore, dated sediment cores provided the framework for both the temporal and spatial analysis of possible sources and flux histories for both trace metals and PCBs. The trace metals results suggest that, though the upper reaches are relatively less impacted, the old mine tailings from the now ceased mining activities in the watershed of Contrary Creek tributary continue to dominate the sediment chemistry of the lower portion of the lake basin, signified by sediment enrichment of Pb, Cd, Cu, and Zn. Lagoon-2 of the WHTF also seems to be receiving unusually high loadings of Cd (12.5 ± 1.07 μg/g) that is probably associated with waste materials from the nuclear power plant that maintains the lagoons. PCB sediment concentrations were relatively low in the lower sections of the basins with values typically being <3.5 ng/g. The upper reaches of the basin had several PCB hotspots, with the surface sediments of Terry’s Run tributary having values as high as 53.13 ng/g. The spatial distribution of PCBs seems to suggest the upper reaches of the basin as the probable source, with the unusually high concentrations near bridges suggesting a possible link between the PCBs and old bridge fill materials. The oldest lacustrine sediments also had relatively high trace metals and PCB values signifying a probable role of soil disruption and sediment reconcentration during reservoir construction.  相似文献   

7.
The technique of diffusive gradients in thin films (DGT) was applied to obtain high-resolution vertical profiles of trace metals in sediment porewater of a eutrophic lake, Lake Chaohu. All sampling sediments were under anaerobic conditions with Eh values below 0, the redox potential profile in M4 was relatively stable, and higher Eh values in M4 than that in M1 were observed due to hydrodynamic effects. Fe, Mn and As exhibited closely corresponding profiles due to the co-release of Fe and Mn oxides and the reduction of As. Higher Fe and Mn concentrations and lower As concentrations were observed in M1 of the western half-lake than those in M4 of the eastern half-lake due to different sources and metal contamination levels in the two regions. Cu and Zn showed increasing concentrations similar to Mn and Fe at 1–2 cm depth of sediments, while DGT measured Co, Ni, Cd and Pb concentrations decreased down to 3–4 cm in the profiles. Co, Ni, Cu, Zn, Cd and Pb showed insignificant regional concentration variances in the western and eastern half-lakes. According to the R(C DGT/C centrifugation) values, the rank order of metal labilities decrease as follows: Fe (>1) > Cu, Pb, Zn (>0.9) > Co, Ni, Cd (>0.3) > Mn, As (>0.1).  相似文献   

8.
El Bey river, which drains 60% of the pollutant load of several urban cities in the northeast of Tunisia, provides a good example of the transfer of organic and metallic pollutants that result from industrial and urban activity, and can be used to show how these charges are transported and discharged into the Gulf of Tunis. Persistent organic pollutants (PAH and PCB) in dissolved, particulate matter, bed sediments, and three wastewater effluents in El Bey watershed were analyzed. PAH (∑14PAHs) concentration ranged from 0.248 to 9.955 mg L?1 and from 0.836 to 28.539 mg L?1 in dissolved and particulate fraction respectively. The particulate/dissolved partition coefficient value (Kd) was less than one which confirmed the affinity of PAH to be adsorbed. In sediment, the high-molecular weight PAHs were found principally with percentage between 50 and 100% witch present 239.99 to 5362.19 μg kg?1, which is relatively higher in comparison with other estuaries river. Contrary to PAH patterns, PCB were bound to dissolve fraction. Kd (PCB) value (Kd?>?1) reflected this affinity which is related to environment energy. The spatial distribution and profile of analyzed organic pollutants confirmed the direct impact of wastewater effluent on the organic pollution level in three compartment of El Bey watershed and his profiles suggested different transport patterns.  相似文献   

9.
The distribution and bioavailability of Hg in vegetable-growing soils collected from the estuary areas of Jiulong River, China, were studied. Concentrations of Hg in top-soils, soil profiles and plant samples were measured with the method of hydride generation atomic fluorescence spectrometry after microwave digestion. Mercury species in soils were determined with the sequential extraction procedures based on Kingston method. Results showed that Hg concentrations in top-soils ranged from 49.8 to 1,685 ng g?1, with an average of 510 ng g?1 which was more than twice higher than the mercury limit (250 ng g?1 at pH < 6.5) of soil quality set for edible agricultural products in China (HJ 332-2006). High levels of Hg were found to mainly distribute in the top-soils from the northern, western and southern part of the estuary areas. Hg concentrations decreased with the increases of profile depths, except for one sample (S15) in which Hg level in the depth of 0–20 cm was found lower than that in the 20–40 cm. Hg in most of soil samples in non-mobile forms accounted for 46–82 % of total Hg in soils, while Hg in the mobile forms only 0.6–8.7 %. No significant correlation of Hg concentrations between the vegetables and the soils was observed in the studied areas, which indicates that the transfer factors could only reflect the abilities of Hg uptake and accumulation in a specific plant, but they are unsuitable to be used as the general indexes for the mobility and bioavailability of Hg in soils.  相似文献   

10.
辽东湾周边河流沉积物碎屑矿物组成及其物源意义   总被引:2,自引:0,他引:2  
王利波  李军  赵京涛  翟滨 《沉积学报》2013,31(4):663-671
对辽东湾周边七条河流下游段河漫滩沉积物的碎屑矿物进行了鉴定,分析了轻重矿物组分的差异、流域基岩类型和沉积物粒度对碎屑矿物组成的影响。轻矿物组成以石英和长石占绝对优势。由于辽东湾西侧河流(六股河、小凌河和大凌河)和东侧河流(双台子河、大辽河、复州河)位于两个构造块体之上,不同的基岩类型导致重矿物组合差别很大。湾西河流普通角闪石含量低、金属矿物含量高,湾东河流则相反,这两种组分能有效区分辽东湾东西两侧的河流,同时也可将滦河与上述河流区分开。石榴子石和普通辉石含量特征可区分湾西三条河流,特征为大凌河前者含量高,小凌河后者含量高,六股河两者含量都很低。绿帘石和阳起石的含量在湾东河流沉积物中差别较大,特征为双台子河前者含量高,大辽河后者含量高,复州河两者含量都很低。七条河流片状矿物和碳酸盐矿物含量低的特征有别于黄河沉积物。  相似文献   

11.
The characteristics of nitrogen fractions in the surface sediments of lakes from Eastern Plain Region, Yunnan-Guizhou Plateau Region, Northeast China Region, Qinghai-Tibet Plateau Region and Mongolia-Xinjiang Plateau Region were investigated and the differences of five lake regions on nitrogen fractionation were discussed. The results indicated that organic nitrogen (Norg) was the major nitrogen fraction accounting for 76.38–92.02 % of Ntot in sediments. The rank order of average Norg and Ntot of sediments in five lake regions was: Yunnan-Guizhou Plateau Region > Northeast China Region > Mongolia-Xinjiang Plateau Region > Qinghai-Tibet Plateau Region > Eastern Plain Region. The exchangeable nitrogen had a similar distribution as organic nitrogen in the studied sediments. NH4 +–N is the main exchangeable nitrogen of sediments in the studied lakes except in Lake Qinghai and Lake Yamdrok which contained higher nitrate concentrations than ammonium. Fixed ammonium (Nfix) in the sediments of studied lakes was irregularly distributed with the values ranging from 99.45 to 329.02 mg/kg. TOC was significantly and positively correlated with ammonium, nitrate, Norg and Ntot, while Nfix was negatively correlated with nitrate probably due to electrostatic attraction between Nfix and nitrate in layers of sediments.  相似文献   

12.
Karst areas have much higher ecological vulnerability and are prone to be contaminated. Organochlorine pesticides (OCPs) were detected in waters and sediment from the two sites of the karst Nanshan underground river system, China, to understand the sources and transport of OCPs in the underground river systems. Obviously, seasonal variations were found both in the waters and the sediments. Detected OCPs ranged from 61 to 936 ng L?1 in the groundwaters and 51–3,842.0 ng g?1 in the underground sediments, respectively. OCPs in groundwaters were mixture of younger and older residues from commercial sources. The maximum OCPs in the sediments of the underground river were historically older residues from commercial sources. The sources of OCPs in the waters and sediments of the underground river indicated that the surface systems play an important role in OCPs transport and pollution in the underground river. Karst features were liable for the transport behavior.  相似文献   

13.
In order to better understand phosphorus (P) cycling and origins in the sediment of the Lake Illawarra, two sediment cores were extracted in November, 2010 and a modified sequential extraction scheme (SEDEX) was used to profile the exchangeable P (Pex), reactive Fe/Al-bound P (Preac), reductive Fe/Al-bound P (Predu), authigenic apatite P (Pauth), detrital P (Pdet), organic P (Porg) and residual P (Presi). The total sedimentary P (TP) ranged from 93 to 437 μg g?1, and was dominated by inorganic P. The average percentage of each fraction of P in the sediment followed the sequence: Preac (28.6 %) > Presi (23.5 %) > Pauth (19.1 %) > Predu (17.0 %) > Porg (4.9 %) > Pex (4.7 %) > Pdet (2.2 %). The profiles of TP and Porg showed two peak values with depth, which were matched to land use history in the Lake Illawarra catchment. The sediment depth profiles indicated that Fe oxyhydroxides play a predominant role in the P cycle in the sediments of the lagoon. This is supported by significant positive correlation between Preac and reactive Fe and a negative correlation between Pauth and Fe. Pauth and Preac concentrations were also well negatively correlated, possibly a result of competitive equilibrium between Fe and Ca for P. The estimated P burial efficiency was up to 82 % for this lagoon, which is likely related to the high sediment accumulation rate and the high value of R Fe-P. In addition, the bioavailable P, which consists of Pex, Preac, and Porg, represented a significant proportion of the sedimentary P pool, accounting, on average, for 38 % of the TP. This result indicates that the sediment is a potential internal source of P for this lake ecosystem.  相似文献   

14.
Increasing sediment loads entering the Lake Tanganyika ecosystem are hastening the need for improved understanding of the linkages between catchment characteristics and influent sediment transport and loading. Sediment loads of two catchments at the southern end of the lake were estimated for October 1998–December 1999, and catchment characteristics determined using GIS. It was found that both sediment yields and loads were higher from the catchment of the Lunzua River (19.8 t km?2 and 20,114 t, respectively) compared with that of the Kalambo (4.1 t km?2 and 12,197 t) in 1999. These differences were both attributed to the smaller size and higher road density of the Lunzua catchment, and suggest that previous recommendations regarding the positioning of underwater lake reserves fail to take into account the low sediment retention capacity of small mountainous rivers. Differences between the study rivers in the transport of suspended sediments, organic matter, and bedload sediments into the lake were also found, the latter determined by the novel application of the 'McLaren Model'.  相似文献   

15.
16.
Hydrography of the eastern Arabian Sea and associated chemical and biological responses were studied during the withdrawal phase of summer monsoon 2003. The shelf region off the southwest coast of India (10°N–15°N) continued to exhibit upwelling of colder (<28.5 °C), nutrient rich (nitrate >2.0 μM, phosphate >0.8 μM, silicate >4.0 μM) and relatively low oxygenated waters (~180 μM). The vertical advection of nutrients, coupled with anthropogenic terrestrial inputs, enhanced the levels of chlorophyll and primary productivity near the coastal margin off Cochin. The influence of both natural and anthropogenic nutrient loadings on the coastal system of the western continental shelf of India leads to eutrophication and hypoxia with negative impacts on the environment in general and fisheries in particular.  相似文献   

17.
A set of forty-one surface sediment samples were collected in River Pánuco and its adjoining lagoon areas in NE Mexico to identify the enrichment pattern of trace elements. The samples were analyzed for sediment texture, carbonates, organic carbon and acid leachable trace elements (ALTEs) using autoclave method [Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, V, Be, Ba, Sr, As]. Geochemical results of Fe, Cr, Ni, Co, V and Sr in zone 1 indicate that erosion in the upland region (Sierra Madre Oriental Mountains) is very high. The above feature is supported by the supremacy of finer sediments (82.12 %), carbonates (44.67 %) and organic carbon (10.74 %), which are brought down from the drainage basin. The overall average concentration of ALTEs Mn (607 μg g?1), Cu (28.29 μg g?1), Ni (16.56 μg g?1), Pb (46.11 μg g?1), Cd (1.81 μg g?1) and Zn (92.18 μg g?1) indicates higher values than the lowest effect level (LEL) and effects range low (ERL) of environmental indicators. The results suggest that they are due to the increase in oil refineries, metal based industries, shipping activities and the effluent input which could enter the biological cycle and might create human health problems.  相似文献   

18.
Lake margin sedimentary systems can provide highly sensitive records of sedimentary response to climate change. The Middle Old Red Sandstone of Northern Scotland comprises a thick succession of cyclic lacustrine sediments. Within this succession the deepest lake phase, the Achanarras fish bed, allows bed‐scale correlation over 160 km across the basin. This provides a unique opportunity to examine the character of synchronous lake margin deposits, and their response to climatically driven lake level fluctuations, across a large continental basin. Detailed characterization of two separate lake margin systems was carried out utilizing multiple sections in western Orkney, in the north, and Easter Ross, in the south. Seven facies have been recognized, which include upper and lower shoreface, deep lake, shallow lake, playa, turbidite and fluvial facies. Differences in vertical and lateral facies stacking patterns reflect the response of these systems to climatically driven fluctuations in lake level. Comparison of the northern and southern systems examined highlights the variable response of lake margin systems to the same climatic change and related lake level fluctuations. In the south, a greater fluvial influence is recognized on the development of the lake margin successions, whereas in the northern example, which lay on the downwind margin of the lake, shore zone facies are more commonly developed. The variability recognized can be accounted for by regional variations in sediment supply, coastal physiography, lake size, bathymetry and potential fetch. Lake level stability is also recognized as a major control on the development of lake margin sedimentary systems, as is the linked or unlinked relationship of the catchment and the lake basin climate for which a conceptual model is proposed.  相似文献   

19.
Karst areas have much higher ecological vulnerability and are easy to be contaminated by polycyclic aromatic hydrocarbons (PAHs), which are introduced as health risk pollutants. PAHs ratios were used to understand the sources and transport behavior of PAHs conducted in the karst Nanshan Underground River, China. Water, sediments from the underground river and water, sediments, soil from the surface were collected monthly in 2011 and 2012. Abundant PAHs were found both in the underground river and in the surface system. The detected ΣPAHs concentrations varied from 353 to 13,203 ng L?1 in the groundwaters and content from 169 to 12,038 ng g?1 in the sediments of the underground river. The ratios of anthracene to anthracene, plus phenanthrene and fluoranthene to fluoranthene, plus pyrene indicated that PAHs were delivered in the groundwaters from combusted grass, wood, and coal, while in the sediments were a mixture of non-combusted petroleum, grass, wood, coal and combusted grass, wood, coal. The similarities in sources between an underground river and surface system indicated that farmlands play a major role for the transport of PAHs and contamination in the underground river. Karst features are liable for the transport behavior.  相似文献   

20.
Lerma River is one of the largest rivers in Mexico. Over the past 20 years, unplanned population growth occurred along its course and the river has been used as the only outlet for industrial and domestic wastewater disposal. The aim of the present study was to determine trace metals such as Cr, Ni, Cu, Zn, Fe, Pb, and arsenic concentrations at the upper layer of sediments of the Lerma River meander in La Piedad, Michoacan, Mexico. Sediment samples were collected from eight different sites during the rainy and dry seasons. All samples were physically characterized, and concentration values of trace metals and As were determined. On the basis of protection criteria for freshwater sediments, concentrations of Fe, Zn, Cu, Ni, and Pb were found to exceed the lowest effect level; moreover, the concentrations were found to exceed the severe effect level at some sites, particularly for Cu. Statistical analyses showed significant differences between sampling seasons for Fe and As, and among sites for Ni, Cu, Zn, and Pb. In addition, the enrichment factor indicates the following order Zn > Cr > Cu > Ni > Pb > As, and the geoaccumulation index (I geo) indicates contamination in the following order Zn > Cr > Cu > Ni > As > Pb. The Lerma River meander in La Piedad shows a reduction in pollution by trace metals and arsenic near the drain area and downstream of the meander. However, there are significantly higher concentrations of these elements in sediments of sites located in the middle part of the city.  相似文献   

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