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1.
Conventional methods that assessed the mercury (Hg) levels were not only an outcome of atmospheric pollution, but also the possibility of Hg contamination from the sample collection to laboratory analyses. Our studies used the direct mercury analyzer that measured Hg rapidly and precisely at ultra-trace concentrations with detection limit of 0.0015 ng g?1 on six favored desert plants and their surrounding soil in Kuwait. Analysis revealed elevated Hg concentrations in Tamarix chinensis Lour., and Salsola imbricate Forssk., among the chosen desert plants, especially during summer than in winter, thus labeling the qualities of a bio-indicator to Hg pollution. The overall parts-wise analysis on the six selected plants showed the elevated mean Hg concentrations in the leaves (0.89 ng g?1) followed by root (0.51 ng g?1) and stem (0.39 ng g?1) in the desert plants. Reasons attribute to the capability of these plant parts to absorb, accumulate, and assimilate Hg at varying concentrations. The overall mean Hg concentration was high in soil (2.24 ng g?1) in comparison with the mean Hg concentrations in the desert plants (0.60 ng g?1) irrespective of the two seasons. Translocation and bioaccumulation factors indicated low uptake of Hg translocation in the plant parts from the soil. Furthermore, the mean Hg concentration was found high in samples collected from Governorates (GIII) in comparison with the samples collected from other Governorates indicating the effect of pollution from various sources. The present study characterizes the selected plants as bio-indicators and also validates the impact of regional and seasonal variations to Hg pollution at ultra-trace levels in the arid ecosystem.  相似文献   

2.
The objective of this work was to study sorption–desorption and/or precipitation–dissolution processes of Hg(II) compounds considering an eventual contact of soils with Hg-bearing wastes. In addition, this study contributes new data about Hg(II) chemistry in alkaline systems. Saline and alkaline soils with low organic matter (<1 %) and high clay content (60–70 %) were obtained near a chlor-alkali plant. Batch techniques were used to perform the experiments using 0.1 M NaNO3 solutions. Total Hg(II) concentrations ranged from 6.2 × 10?8 to 6.3 × 10?3 M. Sorption of Hg(II) was evaluated at two concentration ranges: (a) 6.2 × 10?8 to 1.1 × 10?4 M, and (b) 6.4 × 10?4 to 6.3 × 10?3 M. At low Hg(II) concentrations, adsorption occurred with a maximum sorption capacity ranging from 4 to 5 mmol/kg. At high Hg(II) concentrations, sorption–precipitation reactions occurred and maximum sorption capacity ranged from 17 to 31 mmol/kg. The distribution of Hg(II) hydrolysis products showed that Hg(OH)2 was the predominant species under soil conditions. According to sorption experiments, X-ray diffraction and chemical speciation modelling, the presence of Hg(OH)2 in the interlayer of the interstratified clay minerals can be proposed. Hg(OH)2 was partially desorbed by repeated equilibrations in 0.1 M NaNO3 solution. Desorption ranged from 0.1 to 0.9 mmol/kg for soils treated with 5.8 × 10?5 M Hg(II), whereas 2.1–3.8 mmol/kg was desorbed from soils treated with 6.3 × 10?3 M Hg(II). Formation of soluble Hg(II) complexes was limited by low organic matter content, whereas neutral Hg(OH)2 was retained by adsorption on clay mineral surfaces.  相似文献   

3.
The Estero de Urías Lagoon (EUL) is an inner shelf barrier coastal lagoon, located in the Mexican Pacific Coast (SE Gulf of California). It is surrounded by Mazatlán City, one of the most important international tourist areas of Mexico. To provide a comprehensive reassessment of the concentration levels and spatial variability of Hg and 210Pb in the EUL, 40 surface sediment samples were analyzed for several geochemical variables (e.g. grain size distribution, organic matter and reference element concentrations) that could explain the observed variability of Hg and 210Pb. The Hg concentrations ranged from 23 to 214 ng g?1, whereas 210Pb activities varied from 20 to 56 Bq kg?1. No defined distribution pattern was observed for Hg and 210Pb concentrations in the lagoon and no evidence of a common atmospheric delivery route was observed. The sediments from EUL were found contaminated by Hg, and according to international guidelines 48 % of the sampling sites have concentrations that could be harmful to biota.  相似文献   

4.
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   

5.
Presence of fluoride in groundwater is a public health problem in the so-called endemic fluorosis belt of the central Iran, where the groundwater is the major source of drinking water in most urban and rural areas. Therefore, an attempt has been made to determine the hydrogeochemical factors controlling fluoride enrichment in the groundwater resources at this belt. Fluoride concentrations ranged from 0.20 to 1.99 mg/L (1.02 ± 0.47) in groundwater samples. The presence of different F-bearing minerals and also clay minerals in the soils and aquifer materials was confirmed using XRD analysis. To identify probable sources of dissolved F? and investigate groundwater quality, multivariate statistical analyses were carried out. Geochemical modeling indicated that all samples were undersaturated with respect to fluorite, halite, gypsum and anhydrite and mostly oversaturated with respect to calcite and dolomite. Contrary to most high-fluoride regions in the World, the high F? content was dominated by Na–Cl- and Ca–SO4-type groundwater in the study area. Besides, fluoride showed negative relationship with pH and HCO3 ? in groundwater. In order to assess the bioavailability of fluoride in soils, a two-step chemical fractionation method was applied. The results showed that fluoride in soils mostly accompanied with the residual and water-soluble fractions and was poorly associated with soil’s bonding sites. Calculated aqueous migration coefficient demonstrated that fluoride in the studied soils was mobile to easily leachable to the groundwater. Finally, the results demonstrated that combination of water–rock interaction and influence of clay minerals is geochemical mechanism responsible for controlling fluoride enrichment in groundwater.  相似文献   

6.
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   

7.
Three sediment stations in Himmerfjärden estuary (Baltic Sea, Sweden) were sampled in May 2009 and June 2010 to test how low salinity (5–7 ‰), high primary productivity partially induced by nutrient input from an upstream waste water treatment plant, and high overall sedimentation rates impact the sedimentary cycling of methane and sulfur. Rates of sediment accumulation determined using 210Pbexcess and 137Cs were very high (0.65–0.95 cm?year?1), as were the corresponding rates of organic matter accumulation (8.9–9.5 mol C?m?2?year?1) at all three sites. Dissolved sulfate penetrated <20 cm below the sediment surface. Although measured rates of bicarbonate methanogenesis integrated over 1 m depth were low (0.96–1.09 mol?m?2?year?1), methane concentrations increased to >2 mmol?L?1 below the sulfate–methane transition. A steep gradient of methane through the entire sulfate zone led to upward (diffusive and bio-irrigative) fluxes of 0.32 to 0.78 mol?m?2?year?1 methane to the sediment–water interface. Areal rates of sulfate reduction (1.46–1.92 mol?m?2?year?1) integrated over the upper 0–14 cm of sediment appeared to be limited by the restricted diffusive supply of sulfate, low bio-irrigation (α?=?2.8–3.1 year?1), and limited residence time of the sedimentary organic carbon in the sulfate zone. A large fraction of reduced sulfur as pyrite and organic-bound sulfur was buried and thus escaped reoxidation in the surface sediment. The presence of ferrous iron in the pore water (with concentrations up to 110 μM) suggests that iron reduction plays an important role in surface sediments, as well as in sediment layers deep below the sulfate–methane transition. We conclude that high rates of sediment accumulation and shallow sulfate penetration are the master variables for biogeochemistry of methane and sulfur cycling; in particular, they may significantly allow for release of methane into the water column in the Himmerfjärden estuary.  相似文献   

8.
At present, the prior-established threshold values are widely used to classify contaminated agricultural soils with heavy metals under the cultivation of a variety of crops, without considering the different sensitivity of plants to heavy metals. Evaluation of the characteristics of cadmium transfer from a polluted calcareous soil to cultivated wheat crop and assessment of the efficiency of using the threshold values to reflect the soil pollution risk by cadmium in Zanjan Zinc Town area at the northwest of Iran were the goals of this study. Totally, 65 topsoil (0–20 cm) and corresponding wheat samples of an agricultural region in the proximity of a metallurgical factory were collected and analyzed for cadmium concentration. The results revealed that industrial activities strongly control cadmium distribution in the studied soils. Relatively high bioavailable cadmium contents (mean 0.77 mg kg?1) were found in the soils, notwithstanding their alkalinity. It was observed that just 22.5% of the studied area around the Zinc Town is covered by polluted soils with the cadmium concentration exceeding the maximum permissible concentration of 5 mg kg?1, whereas cadmium concentration in wheat grains of 19 sampled plants is higher than the threshold value of 0.2 mg kg?1. Among these polluted plants, a total of eight samples were grown in areas classified as unpolluted soils with cadmium, based on the soil threshold value. It seems that this misclassification of polluted soils is mainly related to the crop sensitivity to heavy metals uptake from the soil which should be considered.  相似文献   

9.
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   

10.
This article presents the results on distribution and enrichment pattern of acid-leachable trace metals (ALTMs) from roadside soil of Miri city, Sarawak, East Malaysia. The city is one of the fastest developing in the Malaysian region with huge petroleum resources. ALTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd along with organic carbon and carbonates (CaCO3) were analyzed in 37 soil sediments collected from roadside. The enrichment of ALTMs [especially Cu (0.4–13.1 μg g?1), Zn (9.3–70.7 μg g?1), Pb (13.8–99.1 μg g?1)] in the roadside soils indicate that these metals are mainly derived from sources related to traffic exhausts, forest fires and oil refineries. The comparative study and enrichment pattern of elements indicates that Mn, Cu, Zn and Pb are enriched multi-fold than the unpolluted soil and Ni, Pb, Cd in some samples compared to Sediment Quality Guidelines like Lowest Effect Level (LEL) and Effects Range Low (ERL) in the region which is mainly due to the recent industrial developments in the region.  相似文献   

11.
Changing global climatic conditions and the continuous eutrophication of aquatic ecosystems have led to increased frequency, duration and toxicity of cyanobacterial blooms worldwide. This makes the provision of time series information on cyanotoxins extremely crucial for effective monitoring and management of water resources. The objective of the present study was to investigate seasonal and annual changes in microcystins (MCs), cylindrospermopsins (CYNs), saxitoxins (STXs), neo-saxitoxin (neo-STX) and anatoxin-a (ATX-a) concentrations in 11 public water supply reservoirs in the semiarid region of Brazil, from 2004 to 2011. Per time, at least one cyanotoxin was present in all the investigated reservoirs. High levels of MCs, CYNs, STXs and Neo-STX were detected simultaneously in Carpina, Duas Unas, Ipojuca, and Jucazinho reservoirs. All the investigated reservoirs had significant concentrations of MCs. The highest levels of MCs were found in Carpina (303,300.0 ng g?1) and Duas Unas (122,053.9 ng g?1) reservoirs, while the lowest concentration of the hepatotoxins was recorded in Ipojuca (10.3 ng g?1) reservoir. On the other hand, CYN was detected in four reservoirs, STXs and Neo-STX in ten reservoirs and ATX-a in two reservoirs. The first record of CYN in Carpina reservoir was obtained in 2006. In addition, Carpina reservoir had the highest concentration of STXs and Neo-STX in the dry and rainy seasons, respectively. The high concentration of cyanotoxins observed in most samples obtained from semiarid reservoirs in Brazil demonstrates the need for regular monitoring and updated management programs.  相似文献   

12.
Genetically engineered Pseudomonas putida reporters (BMB-PL and BMB-ME), which, respectively, carried phnS-luxCDABE and merR-egfp cassette, were used to determine bioavailable phenanthrene and mercury. Over a spiked range of concentrations and aged for 6 days in red soil samples, the reporters were tested to determine the optimal assay conditions and the bioavailable phenanthrene (0–60 mg kg?1) and Hg2+ (0–240 μg kg?1) were evaluated by the signal of the relative fluorescent units and relative luminescence units. Single contamination was carried out and good correlations were obtained between signal strength and pollutant concentrations, whereas interference and bioavailability repression were observed in dual-contamination experiments. Other heavy metal ions at nanomolar level did not interfere with BMB-ME measurement while BMB-PL showed some response to other polycyclic aromatic hydrocarbons or their intermediate products during degradation. Comparing high-performance liquid chromatography methods with the bacterial reporters, both BMB-ME and BMB-PL appeared to have a detection limit (mercury <40 μg kg?1; phenanthrene <24 mg kg ?1) similar to the instrumental analysis. Although physical parameters may affect the interaction of pollutants with bioreporter cells, advantages include the inherent biological relevance of the response, rapid response time, and potential for field deployment. Our results strongly suggest that the BMB-ME and BMB-PL bioreporters constitute an adaptable system for easily detecting the bioavailability of mercury and phenanthrene in the red soils.  相似文献   

13.
Twenty-eight polychlorinated biphenyls (PCB) congeners were measured in surface sediments from Chaohu Lake to assess their characteristics, potential risk, and the correlation with lake trophic status. PCB levels ranged from 11.074 to 42.712 ng g?1 dry weight (d.w.) in the western lake and 2.017 to 20.189 ng g?1 d.w. in the eastern lake. The highest concentrations were found at the sites near the inlets of western lake tributary rivers where big cities and industrial centers are located. Congeners concentrations showed decreasing order of tetra-CB > tri-CB > deca-CB (PCB-209 detected) > penta-CB > hexa-CB > di-CB > hepta-CB > Octa-CB. It indicated that light and heavy Aroclor mixtures were simultaneously used surrounding the lake basin. PCB levels in the western lake are potentially dangerous to humans and the local fauna. There was a significant positive relationship between tetra-CB (one abundant PCB congener) concentration distribution and sediment grain size in the 16–64 μm fraction, whereas a negative correlation was found in the 4–8 μm fraction. Furthermore, PCB distributions were positively correlated with the total organic carbon of sediments and lake trophic status, especially in the more seriously polluted western lake zone. However, the correlation completely disappeared in eastern lake zone. It suggested that PCB contamination might be attributed to industrial wastewaters and domestic sewages from western lake basin, reaching the lake through rivers, rains and floods.  相似文献   

14.
With few available soil organic carbon (SOC) profiles and the heterogeneity of those that do exist, the estimation of SOC pools in karst areas is highly uncertain. Based on the spatial heterogeneity of SOC content of 23,536 samples in a karst watershed, a modified estimation method was determined for SOC storage that exclusively applies to karst areas. The method is a “soil-type method” based on revised calculation indexes for SOC storage. In the present study, the organic carbon contents of different soil types varied greatly, but generally decreased with increasing soil depth. The organic carbon content decreased nearly linearly to a depth of 0–50 cm and then varied at depths of 50–100 cm. Because of the large spatial variability in the karst area, we were able to determine that influences of the different indexes on the estimation of SOC storage decreased as follows: soil thickness > boulder content > rock fragment content > SOC content > bulk density. Using the modified formula, the SOC content in the Houzhai watershed in Puding was estimated to range from 3.53 to 5.44 kg m?2, with an average value of 1.24 kg m?2 to a depth of 20 cm, and from 4.44 to 14.50 kg m?2, with an average value of 12.12 kg m?2 to a depth of 100 cm. The total SOC content was estimated at 5.39 × 105 t.  相似文献   

15.
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   

16.
In this study, natural and artificial radionuclide activity concentrations in surface soils of Kücük Menderes Basin have been measured using gamma spectroscopy. The soil samples were collected from agricultural lands in the Kücük Menderes Basin in Turkey. The activity concentrations of 226Ra, 232Th, 40K and 137Cs in the soils were found to be range of 12.63 ± 2.28–72.51 ± 11.23, 11.45 ± 2.4–58.12 ± 4.76, 234.8 ± 14.85–1058.52 ± 24 Bq kg?1 dw and 2.31 ± 0.18–7.75 ± 1.14 Bq kg?1, respectively. The natural gamma radioactivity of the terrestrial radionuclides in soil samples and the gamma absorbed dose rate, the annual effective dose equivalent, the radium equivalent activity, the external hazard index, were calculated and compared with the international recommended values.  相似文献   

17.
Unsafe lead (Pb) concentrations in leafy vegetables raised in urban and peri-urban agricultural production systems have been reported across cities in Northern Nigeria, even though Pb concentrations in soils are within regulatory safe levels. This study examined the soil enrichment, adsorption and chemical species of Pb in urban garden fields irrigated with untreated wastewater at three industrial locations in Kano, northern Nigeria. Total Pb in the soil profiles ranged from 9 to 91 mg kg?1 and decreased rapidly from the surface to the subsurface layer, but attaining nearly constant concentration at depth ≥1.2 m in the profiles. The potentially labile Pb maintained fairly constant concentration with depth up to 0.9 m, but decreased fairly rapidly with depth thereafter. There was a significant Pb enrichment of the soils, extending up to 30–60 cm depth in the soil profiles. The adsorption of Pb by the soils increased drastically with pH, and attained maximum adsorption at pH ≥ 7.0 in the surface layer, and at pH ≥ 6 in the subsurface layer. The surface soils adsorbed between 85 and 97 % of added Pb at pH ≤ 5. Free Pb2+ activities in soil solution accounted for between 46 and 87 % at pH 5–7 of total dissolved Pb (PbT). The quantifiable chemical species of Pb in solution consisted mainly of PbOH+, PbSO 4 · , PbCl+ and PbOH 2 · which accounted for between 0.9 and 26 % of PbT in soil solution at pH ≥ 5.0, but declining to between 0.1 and 2.1 % at pH ≥ 7.5. There was no apparent equilibrium between Pb2+ activities and known Pb-compounds in the soils. It was concluded from the data that reports of excess Pb concentrations in leafy vegetables raised in these soils are consistent with high free Pb2+ activities maintained in soil solution by these predominantly sandy-textured soils.  相似文献   

18.
For determination of atrazine isotherms in agricultural soils of Fars Province, composite soil samples from 0 to 5 cm depth with textures of silty clay loam, clay loam and loam were collected. In order to form the atrazine isotherms, 10, 50 and 100 µg atrazine g?1 soil was added to the soil samples. Soluble atrazine in water:soil ratios of 10:1, 50:1 and 200:1 was measured after 3-h shaking. Finally, for each cases of applied atrazine, water extractable atrazine was determined and quantified using gas chromatography instrument. The results indicated that there was a linear relationship between the logarithms of water extractable atrazine and added atrazine for different water:soil ratios. A general equation of WEA = K(WS) α (AA) β is obtained experimentally between water extractable atrazine, µg g?1(WEA), and added atrazine, µg g?1 (AA), where K, α and β are absorption constants; WS is the water:soil ratio, g g?1. For the loam, silty clay loam and clay loam soil textures, the α were 0.49, 0.23 and 0.13, respectively, the β were 0.55, 0.806 and 0.21, respectively, and the K were 1.44, 0.78 and 25.38, respectively.  相似文献   

19.
Due to the intensified industrial activities and excessive application of agrochemicals and organic waste materials over the last few decades, there is a great concern about the accumulation of potentially toxic elements (PTEs) in soils from north of Khuzestan Province, southwestern Iran. Therefore, a comparative study with a total number of 300 composite soil samples (0–10 cm) from industrial, urban, agricultural, forest, and rangelands; and 26 samples from the major types of soils parent materials was conducted to examine sources, pollution status, and the effects of soil properties, land use types, and the local lithology on the total concentrations of As, Pb, and Cu (measured using atomic absorption spectrometer (AAS) equipped with graphite furnace) in the soils studied. The mean values of Pb and Cu were 12.2?±?4.6 and 13.5?±?7.6 mg kg?1, respectively, slightly higher than the background values of the study area, but lower than the guideline values of Iranian Environmental Quality Standard for Soils. However, the mean values of As (1.72?±?1.15 mg kg?1) were lower than both background values and the guideline values of Iranian Environmental Quality Standard for soils. The greatest values of the geo-accumulation index (I geo), enrichment factor (EF), and the concentrations of Pb, Cu, and As were arranged as industrial > urban > agriculture > rangelands = forest land uses. The results also indicated that concentrations of all PTEs were greater in soils as compared to those in parent materials. Using principal component analysis (PCA), the origin of Cu and Pb with moderate to high enrichments was attributed to the inputs from both natural and anthropogenic sources. However, As was found to be mainly influenced by lithogenic origin.  相似文献   

20.
The remobilization of iron, manganese, cobalt, cadmium, copper and zinc in the pore water of estuarine sediment cores at Yingkou was assessed using diffusive equilibrium in thin films and diffusive gradients in thin films techniques. A relatively anoxic system (+33.7 to ?224.1 mV) in the sediment cores might cause the reductive release of iron, manganese and cobalt into pore water from the estuarine sediment. High-average concentrations of iron (47.85 μg ml?1) and manganese (3.81 μg ml?1) were observed using diffusive equilibrium in thin films on the sediment core, but the concentration of cobalt (18.02 ng ml?1) was relatively low. A strong correlation between iron and cobalt was observed based on the vertical profiles of the metals. Manganese and iron were more readily released from the solid phase to the solution. The peak cobalt, copper and zinc concentrations were observed in the upper layer (2–4 cm) measured using diffusive gradients in thin films. However, the peak iron, manganese and cobalt concentrations were located in the deeper layer (≥7 cm). In addition, the concentration profiles measured using diffusive gradients in thin films of cobalt, copper and zinc were independent of the iron, manganese and cobalt distribution with respect to depth.  相似文献   

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