Assessment of some trace heavy metals and radioactivity concentration in water of Bendimahi River Basin (Van, Turkey)

The levels of heavy metals were determined in the water of Bendimahi River Basin, statistically analysed and compared to natural gross radioactivity concentration. Fifteen samples of water were collected from Bendimahi River and Van Lake for two seasons in 2005. Water samples were analyzed for eight trace elements and concluded together with gross-alpha and gross-beta radioactivity concentrations. Atomic absorption spectrometry (AAS) was used to determine the concentrations of heavy metals in water samples collected from Bendimahi River basin. Correlation analysis was made for radioactivity and heavy metal concentrations and the Pearson correlation coefficients between gross-alpha and gross-beta radioactivity and heavy metal were determined. The concentrations of all metals were found to be higher than WHO, EC, EPA and TSE-266 guidelines for drinking water, except for Zn and Cu. Generally, the heavy metal concentrations in water samples obtained in May and in August were found to be in sequence of Fe>Zn>Pb>Cr>Cu>Mn>Co>Cd and Fe>Zn>Cu>Pb>Cr>Mn>Co>Cd, respectively. The gross-alpha and gross-beta activity concentration varies between 0.063 and 0.782, 0.021 and 0.816 Bq l(-1) in samples collected in May, and 0.009 and 0.037, 0.081 and 3.116 Bq l(-1) in samples collected in August.     

Geochemical and radionuclide profile of Tuzla geothermal field, Turkey

Tuzla geothermal basin is situated in north-western Turkey on the Biga Peninsula, which is located at the west end of the Northern Anatolian Fault system. Soil and water samples were collected between August 2003 and June 2004 to initiate development of a geochemical profile of surface and subsurface waters in the geothermal basin and radionuclide concentrations in soils. All water samples were found to fall within Turkish Water Quality Class 4, meaning they were remarkably contaminated for any water consumption sector (industrial, human use or agricultural) based on sodium and chloride ions. Such waters could be used only after appropriate water treatment. The water samples are of the chloride type in terms of geochemical evaluation. Preliminary geochemical evidence shows that the N-S flowing part of the Tuzla River acts as a natural barrier within the basin. Heavy metal concentrations in the soil samples show slight elevations, especially those obtained from the east part of the basin where thermal springs are dominant. Geochemical calculations were carried out with PHREEQC software to determine equilibrium concentration of chemical species and saturation indices, by which it is suggested that chloride is the most important ligand to mobilize the heavy metals in the studied system. In addition, the activity concentration and gamma-absorbed dose rates of the terrestrial naturally occurring radionuclides were determined in the soil using gamma-ray spectrometry. The soil activity ranged from 42.77 to 988.66 Bq kg(-1) (averaging 138 Bq kg(-1)) for ( 238 )U, 13.27 to 106.31 Bq kg(-1) (averaging 32.42 Bq kg(-1)) for ( 232 )Th, and 99.28 to 935.36 Bq kg(-1) (averaging 515.44 Bq kg(-1)) for ( 40 )K. The highest value of ( 238 )U was found in the soil samples obtained from an area close to the hot spring.     

A study of background radioactivity level for Canakkale, Turkey

This study assesses the level of background radiation for Canakkale province of northwestern Turkey. Radon concentrations in indoor air were determined using CR-39 nuclear track detectors and ²²²Rn activity was found to be 167 Bq m^???3 (equivalent to an annual effective dose of 4.2 mSv). Measurements of outdoor gamma radiation (of terrestrial and cosmic origin) in air were performed using plastic scintillators, and the average absorbed gamma dose rate was found to be 66.4 nGy h^???1 (corresponding to an annual effective dose of 81.4 μSv). The radionuclide activity concentrations in soil samples collected from the study area were measured through gamma-ray spectrometry, and the average activities were determined as 94.55, 110.4, and 1,273 Bq kg^???1 for the natural radionuclides ²³⁸U, ²³²Th, and ⁴⁰K, respectively, and 19.39 Bq kg^???1 for the fission product ¹³⁷Cs. The natural radioactivity sources resulted in an annual effective dose of 184 μSv. The radioactivity levels of drinking water samples were measured as 0.0599 Bq l^???1 for gross-alpha activity and 0.0841 Bq l^???1 for gross-beta activity using a low-background counting technique (equivalent to an annual effective dose of 12.25 μSv). The results of this study show that the activity levels of radon in air, radionuclides in soil, and alpha activities in drinking water are higher compared to the data available for other Turkish cities and the world averages. On the other hand, the outdoor gamma dose rates in air and beta activities in drinking water are within natural limits.     

Assessment of public exposure to naturally occurring radioactive materials from mining and mineral processing activities of Tarkwa Goldmine in Ghana

Studies have been carried out in a Goldmine in Ghana to determine the exposure of the public to naturally occurring radioactive materials from processing of gold ore. Direct gamma spectrometry and neutron activation analysis techniques were used to analyse soil, rock, water and dust samples from the mining environment. The mean activity concentrations measured for (238)U, (232)Th and (40)K in the soil/rock samples were 15.2, 26.9 and 157.1 Bq kg(?-?1), respectively. For the water samples, the mean activity concentrations were 0.54 and 0.41 Bq l(?-?1)) and 7.76 Bq l(?-?1) for (226)Ra, (232)Th and (40)K, respectively. The mean activity concentrations measured in the dust samples were 4.90 and 2.75 μBq m(?-?3) for (238)U and (232)Th, respectively. The total annual effective dose to the public was estimated to be 0.69 mSv. The results in this study compared well with typical world average values. The results indicate an insignificant exposure of the public from the activities of the Goldmine.     

Distributions of 210Pb around a uraniferous coal-fired power plant in Western Turkey

In the present study the spatial and the vertical distributions of 210Pb were investigated in the soils around a uranifereous coal fired power plant (CPP) in Yatagan Basin, in Western Turkey. The variation of 226Ra activity along the soil profiles was studied to assess the unsupported 210Pb distribution in the same samples. 226Ra was measured by gamma spectroscopy and 210Pb activities were determined from 210Po activities using radiochemical deposition and alpha spectroscopy. The total 210Pb activity concentrations in bulk core samples varied in the range of 38-250 Bq kg(-1) in the study sites and of 22-78 Bq kg(-1) in reference site. In the sectioned cores sampled from the study areas the ranges for activity concentrations of 226Ra, total 210Pb and unsupported 210Pb are 24-77; 39-344 and 4-313 Bq kg(-1), respectively. Corresponding ranges for reference site are 37-39; 39-122 and 1-83 Bq kg(-1).     

Radioactivities related to coal mining

Natural radioactivity concentrations due to the coal mining in Gabal El-Maghara, North Sinai, Egypt, were determined using gamma-ray spectroscopy. Coal, water and soil samples were investigated in this study. The (226)Ra, (232)Th and (40)K activity concentrations in coal before extraction were 18.5 +/- 0.5, 29.5 +/- 1.2 and 149.0 +/- 8.4 Bq kg(-1), respectively. These concentrations were reduced to 18-22% after extraction due to the clay removal of the coal ore. The activity contents of the water and soil samples collected from the surrounding area did not show any evidence of enhancement due to the mining activities. Absorbed dose rate and effective dose equivalent in the mine environment were 29.4 nGy h(-1) and 128.0 microSv a(-1), respectively. The measured activity concentrations in the mine environment and the surrounding areas (5 km away from the mine) are similar to that found in other regions in North and South Sinai. Based on the measurements of gamma-ray emitting radionuclides, the mine activity does not lead to any enhancement in the local area nor represents any human risk.     

Trends in background levels of persistent organic pollutants at Kosetice observatory, Czech Republic.2) Part II. Aquatic and terrestrial environments 1996-2005

A multimedia sampling of ambient air, wet deposition, surface water, sediment, soil and biota has been performed at Kosetice background observatory in the southern Czech Republic since 1988. An integrated monitoring approach was applied to assess the current state, anthropogenic impacts, and possible future changes of terrestrial and freshwater environments. Average PCB concentrations in the individual matrices calculated from ten years of sampling on multiple sites varied between 2 ng g(-1) in sediment and 7 ng g(-1) in soil or moss. DDT concentrations were lower in moss and needles (2 ng g(-1) and 4 ng g(-1), respectively) than in sediment (11 ng g(-1)) and soil (20 ng g(-1)), while the HCH level was higher in moss and needles (5 ng g(-1) and 6 ng g(-1), respectively) than in soil or sediment (1 ng g(-1) and 2 ng g(-1), respectively). The highest average level of PAHs was found in soil (600 ng g(-1)), while it was lower in needles (230 ng g(-1)), moss (210 ng g(-1)) or sediment (210 ng g(-1)). Time related trends of concentration levels of persistent organic pollutants in all matrices were investigated. Moss and needle trend patterns resembled those of the ambient air, showing a slight concentration decrease of all compounds, except for hexachlorobenzene. The soil, water and sediment concentrations showed a similar decrease of PAHs, PCBs, and HCHs, but there was no clear trend for DDTs and HCB.     

Estimation of 210Po and 210Pb and its dose to human beings due to consumption of marine species of Ennore Creek, South India

A systemic study on the natural radionuclides such as (210)Po and (210)Pb in the environmental matrices and biota of Ennore Creek has been undertaken to establish a baseline data on the radiation profile of Ennore Creek environment. The environmental samples such as water, sediment, and biota (seaweeds, molluscs, crustaceans, and fishes) have been subjected to analyses. It has been observed that the concentration of (210)Po and (210)Pb in the water samples of Ennore Creek as 2.7 and 1.63 m Bq L(-1), respectively. The activity concentration of (210)Po and (210)Pb in the sediment sample was 17.9 and 28.9 Bq kg(-1), respectively. The bivalve mollusk Perna viridis have been identified to accumulate higher concentrations of (210)Po and (210)Pb suggesting that they could serve as bioindicator of radionuclides in the Ennore Creek environment. The committed effective dose for human beings was found at 81.13-216.8 and 2.1-297.2 μSv year(-1) for (210)Po and (210)Pb, respectively.     

Depth profiling of Pu, 241Am and 137Cs in soils from southern Belarus measured by ICP-MS and alpha and gamma spectrometry

The depth distribution of plutonium, americium, and 137Cs originating from the 1986 accident at the Chernobyl Nuclear Power Plant (NPP) was investigated in several soil profiles in the vicinity from Belarus. The vertical migration of transuranic elements in soils typical of the 30 km relocation area around Chernobyl NPP was studied using inductively coupled plasma mass spectrometry (ICP-MS), alpha spectrometry, and gamma spectrometry. Transuranic concentrations in upper soil layers ranged from 6 x 10(-12) g g(-1) to 6 x 10(-10) g g(-1) for plutonium and from 1.8 x 10(-13) g g(-1) to 1.6 x 10(-11) g g(-1) for americium. These concentrations correspond to specific activities of (239+240)Pu of 24-2400 Bq kg(-1) and specific activity of 241Am of 23-2000 Bq kg(-1), respectively. Transuranics in turf-podzol soil migrate slowly to the deeper soil layers, thus, 80-95%, of radionuclide inventories were present in the 0-3 cm intervals of turf-podzol soils collected in 1994. In peat-marsh soil migration processes occur more rapidly than in turf-podzol and the maximum concentrations are found beneath the soil surface (down to 3-6 cm). The depth distributions of Pu and Am are essentially identical for a given soil profile. (239+240)Pu/137Cs and 241Am/137Cs activity ratios vary by up to a factor of 5 at some sites while smaller variations in these ratios were observed at a site close to Chernobyl, suggesting that 137Cs is dominantly particle associated close to Chernobyl but volatile species of 137Cs are of relatively greater importance at the distant sites.     

Transport and fate of organochlorine pesticides in the River Wuchuan,southeast China

Persistent organic pollutants (POPs) such as chlorinated pesticides are of global concern due to their widespread occurrence, persistence, bioaccumulation and toxicity to animals and human. This paper summarises recent research on 18 chlorinated pesticides in an important catchment in China, by determining their concentrations and behaviour in water, sediment, soil and plants. The concentrations of the total pesticides were in the ranges 187-893 ng l(-1) in river water, 8.53-210 ng g(-1) dry weight in soil, 2.66-13.45 ng g(-1) dry weight in river sediment, and 651-2823 ng g(-1) dry weight in plants. The predominance of beta-HCH as the major isomer of HCHs in all water, soil, sediment and plant samples was clearly observed, due to beta-HCH's resistance to biodegradation. On average beta-HCH accounted for 44%, 53%, 50%, and 46% of the total HCH concentration in water, soil, sediment and plant, respectively. Of the DDTs, DDE accounted for 48%, 43%, 53%, 55% of the total DDT, which suggested that DDT had been transformed to its metabolites, DDE and DDD, of which DDE was the more stable. The chlorinated pesticide levels in the River Wuchuan were generally below the guideline values in China, but some sites displayed levels in excess of EC Environmental Quality Standards for HCHs and DDTs. The results therefore provide important information on the current contamination status of a key agricultural watershed in China, and point to the need for urgent actions to evaluate the long-term fate and toxicity of such persistent compounds and an appropriate remediation strategy.     

Occurrence of selected antibiotics in Jiulongjiang River in various seasons, South China

The concentrations of six sulfonamides (SAs) and three tetracyclines (TCs) were investigated in Jiulongjiang River during the low water season and the high water season. They were monitored in both surface water and sediment. Total concentrations of all these antibiotics varied from 31 to 25,771 ng g(-1) in sediment samples. In water they ranged from 60 to 2607 ng L(-1) during the low water season and from ND (not detected) to 134 ng L(-1) during the high water season. At the sites nearby breeding farms, chlorotetracycline was found to have the highest concentration of 1036 ng L(-1) in water and 14,666 ng g(-1) in sediments. According to the published data, the concentrations of sulfamethazine, sulfameter and TCs at these sites were higher than that in most rivers. The concentrations during the low water season were tens to hundreds of times higher than that in the high water season. The lower concentrations of TCs in the high water season might result from both dilution and photo-degradation, while dilution and bio-degradation might lead to the lower concentrations of SAs. However, further study is needed to clarify the specific reasons. Concerning the relationship between sediment and water samples, the pseudo-partitioning values of TCs were much higher than SAs. It indicates that the TCs are prone to accumulate in the sediment.     

Outdoor 220Rn, 222Rn and terrestrial gamma radiation levels: investigation study in the thorium rich Fen Complex, Norway

The present study was done in the Fen Complex, a Norwegian area rich in naturally occurring radionuclides, especially in thorium ((232)Th). Measurement of radioactivity levels was conducted at the decommissioned iron (Fe) and niobium (Nb) mining sites (TENORM) as well as at the undisturbed wooded sites (NORM), all open for free public access. The soil activity concentrations of (232)Th (3280-8395 Bq kg(-1)) were significantly higher than the world and the Norwegian average values and exceeded the Norwegian screening level (1000 Bq kg(-1)) for radioactive waste, while radium ((226)Ra) was present at slightly elevated levels (89-171 Bq kg(-1)). Terrestrial gamma dose rates were also elevated, ranging 2.6-4.4 μGy h(-1). Based on long-term surveys, the air concentrations of thoron ((220)Rn) and radon ((222)Rn) reached 1786 and 82 Bq m(-3), respectively. Seasonal variation in the outdoor gamma dose rates and Rn concentrations was confirmed. Correlation analyses showed a linear relationship between air radiation levels and the abundance of (232)Th in soil. The annual outdoor effective radiation doses for humans (occupancy 5 h day(-1)) were estimated to be in the range of 3.0-7.7 mSv, comparable or higher than the total average (summarized indoor and outdoor) exposure dose for the Norwegian population (2.9 mSv year(-1)). On the basis of all obtained results, this Norwegian area should be considered as enhanced natural radiation area (ENRA).     

Water and sediment quality of dry season pools in a dryland river system: the upper Leichhardt River, Queensland, Australia

This article presents the geochemical characteristics and physicochemical properties of water and sediment from twelve semi-permanent, dryland pools in the upper Leichhardt River catchment, north-west Queensland, Australia. The pools were examined to better understand the quality of sediments and temporary waters in a dryland system with a well-established metal contamination problem. Water and sediment sampling was conducted at the beginning of the hydroperiod in May and September 2007. Water samples were analyzed for major solute compositions (Ca, Na, K, Mg, Cl, SO(4), HCO(3)) and water-soluble (operationally defined as the <0.45 μm fraction) metals (Cd, Cu, Pb, Zn). Sediment samples were analyzed for total extractable and bioaccessible metals (As, Cd, Cu, Pb, Zn), elemental composition and grain morphology. At the time of sampling a number of pools contained water and sediment with elevated concentrations, compared to Australian regulatory guidelines, of Cu (maximum: water 28 μg L(-1); sediment 770 mg kg(-1)), Pb (maximum: water 3.4 μg L(-1); sediment 630 mg kg(-1)) and Zn (maximum: water 150 μg L(-1); sediment 780 mg kg(-1)). Concentrations of Cd and As in pools were relatively low and generally within Australian regulatory guideline values. Localized factors, such as the interaction of waters with anthropogenic contaminants from modern and historic mine wastes (i.e. residual smelter and slag materials), exert influence on the quality of pool waters. Although the pools of the upper Leichhardt River catchment are contaminated, they do not appear to be the primary repository of water and sediment associated metals when compared to materials in the remainder channel and floodplain. Nevertheless, a precautionary approach should be adopted to mitigating human exposure to contaminated environments, which might include the installation of appropriate warning signs by local health and environmental authorities.     

液相色谱-串联质谱法测定水体、沉积物及土壤中全氟化合物

建立了水、沉积物及土壤中13种全氟化合物(PFCs)的富集、净化、浓缩的前处理方法及快速液相色谱三重四级杆串联质谱的分析方法。9种全氟羧酸、2种典型全氟磺酸、2种磺酰铵衍生前体物的响应因子与质量浓度的线性关系良好。添加回收实验表明,13种全氟化合物在水、土壤和沉积物中的回收率为52.3%~119.3%,变异系数为2.3%~19.4%,方法检出限分别为0.015~0.472 ng/L、0.012~0.875 ng/g、0.004~0.743 ng/g。该法成功应用于实际样品的测定,沉积物和土壤中分别检测到3种和10种全氟化合物。     

Quantification and source identification of polycyclic aromatic hydrocarbons in sediment, soil, and water spinach from Hanoi, Vietnam

Polycyclic aromatic hydrocarbons (PAHs) were quantified in sediment, soil, and plant material from Hanoi, Vietnam, and an aquatic production system in peri-urban Hanoi. The sum of the concentration of 16 US-EPA priority PAHs ( summation PAH16) ranged between 0.44 and 6.21 mg kg(-1) dw in sediment and between 0.26 and 1.35 mg kg(-1) dw in soil, with decreasing concentrations from the urban area to the peri-urban area, indicating contributions from urban and industrial sources. Double plots of diagnostic source ratios indicate that PAHs originate from mixed petrogenic and pyrogenic sources, the latter being predominant. The predominance of low molecular weight (LMW) PAHs in the sediment samples suggests that petrogenic sources are more prevalent in the water environment than in the soil. In contrast, high molecular weight (HMW) PAHs dominated in water spinach which probably reflects the plant's uptake of particle-bound PAHs that originate from pyrogenic sources.     

Distribution of gamma-ray emitting radionuclides in the marine environment of the Burullus Lake: II. Bottom sediments

The sediment compartment has the ability to trap large amounts of radionuclides and to indicate the radiological impact of pollution. The present work shows the results obtained related to the concentrations of ¹³⁷Cs and natural radionuclides in sediment in the Burullus Lake, Egypt. The average values of ²²⁶Ra, ²³²Th, and ⁴⁰K in the bottom sediments collected from the east of the Burullus Lake ranged from 10.3 to 21.8 Bq/kg, from 11.9 to 34.4 Bq/kg, and from 268 to 401 Bq/kg, respectively. The study has shown that ⁴⁰K concentration is nearly uniform throughout the studied area while ²²⁶Ra and ²³²Th are more concentrated in the northeastern shore. Lake sediments showed contamination with ¹³⁷Cs (2.7–15.9 Bq/kg). The ¹³⁷Cs sediment activities indicated higher concentrations in the off-shore sites. Concentrations of all γ -ray emitting radionuclides except ⁴⁰K in water samples were below the detection limits. The ⁴⁰K sediment–water distribution coefficients of the near-shore samples were higher than the off-shore samples.     

Assessment of environmental radioactivity for Batman, Turkey

The province of Batman, located in southern Anatolia, has a population of approximately 500,000. To our knowledge, there exists no information regarding the environmental radioactivity in this province. Therefore, gamma activity measurements in soil, building materials and water samples and an indoor radon survey have been carried out in the Batman province. The mean activity concentrations of the natural radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) and a fission product (¹³⁷Cs) were 35 ± 8, 25 ± 10, 274 ± 167 and 12 ± 7 Bq kg^???1, respectively, in the soil samples. The concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the selected building materials ranged from 18 to 48 Bq kg^???1, 8 to 49 Bq kg^???1 and 68 to 477 Bq kg^???1, respectively. All the calculated radium equivalent (Ra_eq) activity values of the building material samples are lower than the limit of 370 Bq kg^???1, equivalent to a γ-dose of 1.5 mSv year^???1. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in tap waters collected from the study area were determined with mean specific activity concentrations of 42 ± 15, 35 ± 9 and 524 ± 190 mBq L^???1, respectively. Indoor radon measurements were made at 95 dwellings in Batman using a CR-39 detector. The radon concentration levels were found to vary from 23 to 145 Bq m^???3. The arithmetic mean of the measured radon concentration levels was found to be 84 Bq m^???3 with a standard deviation value of 23 Bq m^???3. The measurement results obtained in this study did not significantly differ from those taken in other parts of the country. The data generated in this study can be used to determine whether the Batman province is in a normal or high background radiation area and provides a valuable database for future estimations of the impact of radioactive pollution.     

Effect of sampling method on contaminant measurement in pore-water and surface water at two uranium operations: can method affect conclusions?

This paper describes a comparison of two methods of sediment pore-water sampling and two methods of surface water sampling that were used in a broader investigation of cause(s) of adverse effects on benthic invertebrate communities at two Saskatchewan uranium operations (Key Lake and Rabbit Lake). Variables measured and compared included pH, ammonia, DOC, and trace metals. The two types of sediment pore-water samples that were compared are centrifuged and 0.45-microm filtered sediment core samples vs. 0.2-microm dialysis (peeper) samples. The two types of surface water samples that were compared are 53-microm filtered Van Dorn horizontal beta samples vs. 0.2-microm dialysis (peeper) samples. Results showed that 62% of the sediment core pore water values were higher than the corresponding peeper pore-water measurements, and that 63% of the Van Dorn surface water measurements were lower than corresponding peeper surface water measurements. Furthermore, only 24% and 14% of surface water and pore-water measurements, respectively, fell within +/-10% range of one another; 73% and 50%, respectively, fell within +/-50%. Although somewhat confounded by differences in filtering method, the observed differences are believed to primarily be related to small, vertical differences in the environment sampled. Despite observed differences in concentrations of toxicologically relevant variables generated by the different sampling methods, the weight of evidence (WOE) conclusions drawn from each set of exposure data on the possible cause(s) of in situ toxicity to Hyalella azteca from a related study were the same at each uranium operation. However, this concurrence was largely due to other dominant lines of evidence. The WOE conclusions at Key Lake were dominated by the toxicity response of H. azteca in relation to exposure chemistry, where as the WOE conclusions at Rabbit Lake were informed by exposure chemistry, the toxicological response of H. azteca, and whole-body contaminant concentrations in the test organisms. Had these multiple lines of evidence not been available, differences in exposure chemistry generated by the different sampling methods could have substantially influenced the identification of potential causes of in situ toxicity.     

Application of neural-based modeling in an assessment of pollution with mercury in the middle part of the Warta River

The level of pollution with various mercury species (organomercury, water- and acid-soluble mercury, mercury bound to humic matter and to sulphides) of the floodplain soils and sediments from middle part of the Warta River has been assessed using self-organizing maps (SOM). Chemometric evaluation allowed identification of moderately (median 173-187 ng g(-1), range 54-375 ng g(-1) in soil and 130 ng g(-1), range 47-310 ng g(-1) in sediment) and heavily polluted samples (662 ng g(-1), range 426-884 ng g(-1)). Heavily polluted were located mainly below and in the area of the Poznań city. Statistical comparison of mercury species distribution in floodplain soils of the Warta River shows different patterns for moderately and heavily polluted samples. In heavily polluted soils the contribution of mobile mercury (sum of organomercury species, water- and acid soluble species) is lower (4.2%) than in moderately polluted soils (6.1%). Higher contribution of mobile mercury was observed in sediments of the Warta River (12%). In case of moderately polluted samples, statistical differences in the contribution of mercury species are relatively low and thus the environmental risk from mercury deposited in aquatic system of the Warta River is relatively low. However, higher water levels and heavy floods may incite remobilisation of some organomercuries (2.2-2.9 ng g(-1) in soil and 10 ng g(-1) in sediment) and acid-soluble species of mercury (2.6-2.9 ng g(-1) in soil and 0.5 ng g(-1) in sediment).     

Distribution and risk assessment of polycyclic aromatic hydrocarbons (PAHs) from Liaohe estuarine wetland soils

Thirty-one surface soil samples were collected from Liaohe estuarine wetland in October 2008 and May and August 2009. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), identified as priority pollutants by the US EPA, were measured by gas chromatography. PAHs were predominated by three- and four-ring compounds. The total PAH concentrations ranged from 704.7 to 1,804.5 μg/kg with a mean value of 1,001.9 μg/kg in October 2008, from 509.7 to 1,936.9 μg/kg with an average of 887.1 μg/kg in May 2009, and from 293.4 to 1,735.9 μg/kg with a mean value of 675.4 μg/kg in August 2009. The PAH concentration detected at most sites shared the same pattern, with maximum concentrations during the autumn (October) and minimum concentrations during the summer (August). The ecological risk assessment of PAHs showed that adverse effects would occasionally occur in the soils from Liaohe estuarine wetland based on the effects range low (ERL)/effects range median and the toxic equivalency factors. The results revealed that some of the individual PAHs were in excess of ERL which implied possible acute adverse biological effects. The BaP(eq) values in some sites surpassed the Dutch target value. Therewith, quite a part of soils in the wetland were subjected to potential ecological risks.