Environmental and human risk hierarchy of pesticides: A prioritization method,based on monitoring,hazard assessment and environmental fate

A pesticide prioritization approach was developed and implemented in the Pinios River Basin of Central Greece. It takes under consideration the Level of Environmental Risk containing information on the frequency of occurrence of pesticides above environmental thresholds, the intensity of this occurrence and the spatial distribution as well as information about the fate and behavior of pesticides in the environment and the potential to have adverse impact on humans' health. Original 3-year monitoring data from 102 Stationary Sampling Sites located on rivers and their tributaries, reservoirs, streams and irrigation/drainage canals giving rise to a collection of 2382 water samples resulting in 7088 data sets, were included in this integrated prioritization study.Among 302 monitored active ingredients, 119 were detected at least once and the concentrations found in the aquatic systems for 41% of compounds were higher than the respective lowest Predicted Non-Effect Concentration (PNEC) values. Sixteen and 5 pesticides were found with risk ratios (MEC_max/PNEC) above 10 (high concern) and 100 (very high concern), respectively. However, pesticides with maximum Measured Environmental Concentration (MEC_max) values exceeding by 1000 times the respective lowest PNEC values were also found which were considered of extremely high concern; in the latter group were included prometryn, chlorpyrifos, diazinon, λ-cyhalothrin, cypermethrin, α-cypermethrin deltamethrin, ethalfluralin and phosmet. The sensitivity of the analytical methods used in the monitoring study was considered inadequate to meet the toxicological endpoints for 32 pesticides. The widest distribution of occurrence in the Stationary Sampling Sites of the monitoring program was found for the pesticides, prometryn, fluometuron, terbuthylazine, S-metolachlor, chlorpyrifos, diphenylamine, acetochlor, alachlor, 2,4-D, etridiazole, imidacloprid and lindane (γ-ΗCH). Among the 27 priority pesticides included in the Directive 2013/39/EU, in the present study 13 pesticides were considered as candidates for River Basin Specific Pollutants (RBSP) for the River Basin of Pinios. Among the 30 pesticide specific pollutants that were established by the Greek authorities, in the present study only 6 were considered as candidates for RBSP for the river basin of Pinios. As a result of the implementation of the prioritization approach developed in this study a total of 71 pesticides were identified as being RBSP for the river basin of Pinios. The higher Level of Environmental Risk was found to be exerted by the organophosphorus insecticide chlorpyrifos, followed by lindane and prometryn.The present study provides background information for important decisions to be made concerning the selection of pesticides which should be included in the target analyte list of new monitoring and screening programs of surface water quality in the Pinios River Basin. In addition, the prioritization approach proposed here can be useful for the development of River Basin Management Plans.     

Organochlorine and organophosphorous pesticide residues in the Ouémé River catchment in the Republic of Bénin

The Ouémé River is one of the most important rivers in the Republic of Bénin. It is 510 km long and its catchment drains 75% of the country. In this study, organochlorine and organophosphorous pesticide residues were measured in more than 35 sediment samples collected on nine locations along the Ouémé River from upstream to downstream. Except for one location, Tanéka-Koko, all areas were contaminated by more than 20 pesticides. Organochlorine pesticides identified in sediment samples included pp'-DDE, op'-DDD, pp'-DDD, op'-DDT, pp'-DDT, alpha-endosulfan, beta-endosulfan, endosulfan sulphate, alpha-HCH, beta-HCH, lindane, aldrin, dieldrin, endrin, telodrin, isodrin, cis- and trans-heptachlorepoxide, hexachlorbutadiene, hexachlorobenzene and octachlorostyrene. The organophosphorous pesticide chlorpyrifos, used in a new formulation to protect cotton, was also identified. In some areas, the concentrations of organochlorine pesticides in the sediment of the Ouémé River exceeded environmental quality standards and are reason for concern.     

Studies on the seasonal changes of phosphorus in the marine environments off Cochin

Studies were conducted to evaluate the changes of phosphorus in marine water and sediments of seven stations in the coastal areas off Cochin. Samples were collected on a monthly basis from January 2001 to December 2001. Results revealed higher levels of P in marine water samples collected during October-December 2001. The marine water P ranged from 0 to 0.38 ppm throughout the year. Speciation of P in marine sediment revealed that the Al bound P was maximum compared to Fe, Ca and organic bound P. Loosely bound and aluminium bound P was maximum during October-December especially in 10 and 20 m depth stations off Narakkal. Fe bound P was found to be least in June and September and highest during January-April. Low levels of Ca bound P were detected in samples collected during January-March and inorganic P was maximum in June and September. Organic bound P was maximum in 10 m depth stations and also during June and September. Phosphate fractions varied with locations and exhibited seasonal fluctuations.     

Farmworker children's residential non-dietary exposure estimates from micro-level activity time series

Farmworkers' children may have increased pesticide exposure through dermal absorption and non-dietary ingestion, routes that are difficult to measure and model. The Cumulative Aggregate Simulation of Exposure (CASE) model, integrates the complexity of human behavior and variability of exposure processes by combining micro-level activity time series (MLATS) and mechanistic exposure equations. CASE was used to estimate residential non-dietary organophosphate pesticide exposure (i.e., inhalation, dermal, and non-dietary ingestion) to California farmworker children and evaluate the micro-activity approach. MLATS collected from children and distributions developed from pesticide measurements in farmworkers' residences served as inputs. While estimated diazinon exposure was greater for inhalation, chlorpyrifos exposure was greater for the other routes. Greater variability existed between children (σ_B² = 0.22–0.39) than within each child's simulations (σ_W² = 0.01–0.02) for dermal and non-dietary ingestion. Dermal exposure simulations were not significantly different than measured values from dosimeters worn by the children. Non-dietary ingestion exposure estimates were comparable to duplicate diet measurements, indicating this route may contribute substantially to aggregate exposure. The results suggest the importance of the micro-activity approach for estimating non-dietary exposure. Other methods may underestimate exposure via these routes. Model simulations can be used to identify at-risk children and target intervention strategies.     

Cumulative risk assessment of chemical exposures in urban environments

We performed a cumulative risk assessment for people living in a hypothetical urban environment, called Urbania. The main aims of the study were to demonstrate how a cumulative risk assessment for a middle-sized European city can be performed and to identify the bottlenecks in terms of data availability and knowledge gaps. The assessment focused on five air pollutants (i.e., PM??, benzene, toluene, nonane and naphthalene) and six food pesticides (i.e., acetamiprid, carbendazim, chlorpyrifos, diazinon, imidacloprid and permethrin). Exposure predictions showed that PM??, benzene and naphthalene exposure frequently exceeded the standards, and that the indoor environment contributed more than the outdoor environment. Effect predictions showed that mixture and interaction effects were generally limited. However, model calculations indicated potential synergistic effects between naphthalene and benzene and between chlorpyrifos, diazinon and toluene. PM?? dominated the health impact expressed in Disability Adjusted Life Years (DALYs). We conclude that measures to reduce the health impact of environmental pollution should focus on the improvement of indoor air quality and the reduction of PM?? emissions. Cumulative risk assessment can be improved by (1) the development of person-oriented exposure models that can simulate the cumulative exposure history of individuals, (2) a better mechanistic understanding of the effects of cumulative stressors, and (3) the development of instruments to prioritize stressors for inclusion in cumulative risk assessments.     

Predictors of exposure to organophosphate pesticides in schoolchildren in the Province of Talca,Chile

BackgroundFew data exist in Latin America concerning the association between organophosphate (OP) urinary metabolites and the consumption of fruits and vegetables and other exposure risk variables in schoolchildren.MethodsWe collected samples of urine from 190 Chilean children aged 6–12 years, fruits and vegetables, water and soil from schools and homes, and sociodemographic data through a questionnaire. We measured urinary dialkylphosphate (DAP) OP metabolites and OP pesticide residues in food consumed by these 190 children during two seasons: December 2010 (summer) and May 2011 (fall). We analyzed the relationship between urinary DAP concentrations and pesticide residues in food, home pesticide use, and residential location.ResultsDiethylalkylphosphates (DEAP) and dimethylalkylphosphates (DMAP) were detected in urine in 76% and 27% of the samples, respectively. Factors associated with urinary DEAP included chlorpyrifos in consumed fruits (p < 0.0001), urinary creatinine (p < 0.0001), rural residence (p = 0.02) and age less than 9 years (p = 0.004). Factors associated with urinary DMAP included the presence of phosmet residues in fruits (p < 0.0001), close proximity to a farm (p = 0.002), home fenitrothion use (p = 0.009), and season (p < 0.0001).ConclusionsUrinary DAP levels in Chilean school children were high compared to previously reported studies. The presence of chlorpyrifos and phosmet residues in fruits was the major factor predicting urinary DAP metabolite concentrations in children.     

Change in the quantity and acute toxicity of pesticides sold in South African crop sectors, 1994–1999

BackgroundSouth African pesticide market sales data, for two years, 1994 and 1999, were audited to identify change in total and per hectare mass sold and acute toxicity indicator (ATI) (kg sold/rat oral LD50) in the grape, pome, stone fruit, potato and wheat sectors.ResultsTotal pesticide sales (62%), amount per hectare (42%) and number of active ingredients (23%) increased in 1999 compared to 1994 with the grape fruit sector, the most significant contributor over the two years. Total (14%) and per hectare ATI (19%) decreased in 1999, but not substantially with the potato sector the most significant contributor.ConclusionsToxic pesticides were still used in 1999 which highlights a need to develop alternative agricultural and non-chemical pest control methods that reduce usage of pesticides.     

Urinary concentrations of organophosphate and carbamate pesticides in residents of a vegetarian community

Few population studies have measured urinary levels of pesticides in individuals with vegan, vegetarian, or organic diets. The objectives of this study were to evaluate whether a vegan/vegetarian diet was associated with increased exposure to organophosphate and carbamate pesticides, and to evaluate the impact of organic consumption on pesticide exposure in vegans and vegetarians. In the current pilot study conducted in 2013–2014, we collected spot urine samples and detailed 24 h recall dietary data in 42 adult residents of Amirim, a vegetarian community in Northern Israel. We measured urinary levels of non-specific organophosphate pesticide metabolites (dialkylphosphates, (DAPs)) and specific metabolites of the current-use pesticides chlorpyrifos (3,5,6-trichloro-2-pyridinol (TCPy)), propoxur (-isopropoxyphenol (IPPX)), and carbaryl (1-naphthol). Six DAP metabolites were detected in between 67 and 100% of urine samples, with highest geometric mean concentrations for dimethylphosphate (19.2 μg/g). Creatinine-adjusted median concentrations of total DAPs and of TCPy were significantly higher in Amirim residents compared to the general Jewish population in Israel (0.29 μmol/g compared to 0.16, p < 0.05 for DAPs and 4.32 μg/g compared to 2.34 μg/g, p < 0.05 for TCPy). Within Amirim residents, we observed a positive association between vegetable intake and urinary TCPy levels (rho = 0.47, p < 0.05) and lower median total dimethyl phosphate levels in individuals reporting that > 25% of the produce they consume is organic (0.065 μmol/L compared to 0.22, p < 0.05). Results from this pilot study indicate relatively high levels of urinary organophosphate pesticide metabolite concentrations in residents of a vegetarian community, a positive association between vegetable intake and urinary levels of a chlorpyrifos specific metabolite, and lower levels of total dimethyl phosphate in individuals reporting higher intake of organic produce. Results suggest that consumption of organic produce may offer some protection from increased exposure to organophosphate pesticide residues in vegetarians.     

Disposal of obsolete pesticides,the case of Ethiopia

Ethiopia has accumulated obsolete pesticide stocks since pesticides were first imported in the 1960s due to prolonged storage of pesticides, inappropriate storage conditions because of poor storage facilities, the lack of trained staff and lack of national legislation for pesticide registration and monitoring system of pesticide use in the country. The first pesticide inventory conducted in 1995 led by FAO in collaboration with the government of Ethiopia had identified about 426 tonnes of obsolete pesticides mainly on state-owned agricultural farms and held by the Ministry of Health. However, these stocks have increased to over 1500 tonnes (including 200 active ingredients) as found in a detailed inventory conducted in 1999. The stocks included organochlorines (258.3 tonnes), organophosphates (155.4 tonnes), carbamates (58.5 tonnes), coumarines (14.9 tonnes), inorganics (30.2 tonnes), others (257.2 tonnes), mixed pesticides (70.4 tonnes) and unknown pesticides (307.1 tonnes) including both liquid and solid state formulations. The obsolete organochlorine pesticides stocks were mostly pesticides such as chlordane, DDT, dieldrin and lindane that are banned or restricted in most countries. The highest amount of a single active ingredient found was the organophosphate insecticide pirimiphos methyl (172.1 tonnes). All these stocks were disposed of in the first phase of disposal in Finland (during 2000–2003) by the hazardous waste management company Ekokem at a cost of about US$ 4.44 million. Another 1000 tonnes of obsolete pesticides have been identified and are currently being eliminated in a second disposal phase at a total cost of US$ 8 135 500. Along with the disposal process, a number of activities are being implemented to prevent future pesticides accumulation. These activities include the development and enforcement of pesticide policy, the implementation of Integrated Pest Management (IPM) and Integrated Vector Management (IVM), capacity building in terms of providing professional trainings, creating awareness among stakeholders on the environmental and human health hazard posed by obsolete pesticides as well as other actions to prevent their accumulation and enforcement of national legislations and policies related to pesticides use. However, pesticide use in the country is increasing. For instance, 12 years of pesticides import data (1996–2007) by the Ministry of Agriculture shows that 2973 tonnes of pesticides were imported between 1996–1998, 3670 tonnes between 1999–2001, 5079 tonnes between 2002–2004 and 8302 tonnes between 2005–2007. Moreover, 6 years of insecticide import data (1996/97–2001/02) by the Ministry of Health shows that around 919 tonnes of insecticides were imported between 1996/97–1997/98, 812 tonnes between 1998/99–1999/00 and 970 tonnes between 2000/01–2001/02 for malaria and other vector borne diseases control.     

High levels of natural radioactivity in biota from deep-sea hydrothermal vents: a preliminary communication

Hydrothermal deep-sea vent fauna is naturally exposed to a peculiar environment enriched in potentially toxic species such as sulphides, heavy metals and natural radionuclides. It is now well established that some of the organisms present in such an environment accumulate metals during their lifespan. Though only few radionuclide measurements are available, it seems likely that hydrothermal vent communities are exposed to high natural radiation doses. Various archived biological samples collected on the East Pacific Rise and the Mid-Atlantic Ridge in 1996, 2001 and 2002 were analysed by ICP-MS in order to determine their uranium contents (²³⁸U, ²³⁵U and ²³⁴U). In addition ²¹⁰Po–Pb were determined in 2 samples collected in 2002. Vent organisms are characterized by high U, and Po–Pb levels compared to what is generally encountered in organisms from outside hydrothermal vent ecosystems. Though the number of data is low, the results reveal various trends in relation to the site, the location within the mixing zone and/or the organisms' trophic regime.     

Assessment of the global fallout of plutonium isotopes and americium-241 in the soil of the central region of Saudi Arabia

A radiochemical technique for determination of plutonium isotopes and 241Am in soil samples is tested against IAEA-standard reference materials to determine its accuracy and precision for reliable results. The technique is then used in the investigation of topsoil samples, collected from the natural environment of the central region of Saudi Arabia, to assess the effect of fallout accumulation of these radionuclides in the region. Plutonium and americium were sequentially separated from all other components of the sample by anion-exchange chromatography and co-precipitated with Nd3+ as fluorides. The precipitates were mounted on membrane filters and measured using a high-resolution alpha-spectrometer. The results of the analysis of the reference materials showed satisfactory sensitivity and precision of the technique. The results of the analyzed soil samples show activity levels ranging from < LLD to 0.089 and from 相似文献   

The contamination with organochlorine pesticides and heavy metals in surface water in Küçük Menderes River in Turkey, 2000-2002

This study was conducted from 2000 to 2002 to determine the residues of organochlorine pesticides (OCP) and metals in surface water of Kü?ük Menderes River in Turkey. The results showed that Kü?ük Menderes River was still polluted with organochlorine pesticide despite the existence of bans over a long time. The concentrations of pesticides depended on the sampling season and the tendency was not the same for all detected pesticides. The DDTs (DDT, DDD, DDE) were detected in most water samples. DDD showed a high concentration among DDTs. The highest concentration among organochlorine pesticides was heptachlor epoxide by 281 ng/l. However, the residues were lower than most polluted water from other sources in the world. In most cases, they were not detectable. The studied surface water metals varied from not detected to 0.258 mg/l, and the residues were low except for Ni, Cu, and Zn.     

Circulating levels of Persistent Organic Pollutants (POPs) among elderly men and women from Sweden: Results from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS)

Persistent Organic Pollutants (POPs) are a huge group of chemicals that have been linked to various adverse health effects in humans. Large epidemiological studies investigating gender differences in levels of POPs in the elderly are limited and the results from these are not always consistent. The present study was undertaken to examine the background levels of a broad range of POPs in human plasma samples among elderly men and women from Sweden and to assess the influence of gender. Levels of 23 POPs were determined in plasma samples collected during 2001–2004 from 1016 (50.2% women) 70 year-old participants from the population-based Prospective Study of the Vasculature in Uppsala Seniors (PIVUS). Measurements were performed using high resolution gas chromatography with high resolution mass spectrometry (HRGC-HRMS) and the POPs studied were 16 polychlorinated biphenyls (PCBs), five organochlorine (OC) pesticides, one dioxin, and one brominated flame retardant. The concentrations of the selected POPs were found similar, or comparable, to other studies of non-occupationally exposed populations from Sweden and Europe. Differences in levels of POPs between men and women were assessed by using Wilcoxon rank-sum (Mann–Whitney) test. Significant (p < 0.0001) gender differences in levels of specific POPs were observed and a number of POP concentrations were found to differ between men and women. More specifically, levels of HCB, OCDD, and PCB congeners #74, #105, and #118 were found to be higher in women, while the rest of the majority of POPs were higher in men.     

Assessment of organochlorine pesticide residue levels in dairy milk and buffalo milk from Jaipur City, Rajasthan, India

The widespread application of pesticides in agriculture, public health, and industry and in and around the home can result in the accumulation of pesticides in the environment. Therefore, a survey has been conducted during 1993-1996 to investigate the magnitude of contamination of bovine milk with organochlorine pesticide (OCP) residues from Jaipur City, Rajasthan, India. Milk samples, i.e., dairy (toned and whole) and buffalo milk, were collected seasonally, and pesticide residues were assessed using a gas chromatograph (GC) with an electron capture detector (ECD). The results indicate that all the milk samples were contaminated with dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDE and p,p'-dichlorodiphenyldichloroethane [DDD]), isomers of hexachlorocyclohexane (HCH; alpha, beta, and gamma), heptachlor and its epoxide, and aldrin. Seasonal variations of these pesticide residue levels were also observed in all the milk samples. Samples collected during winter season were found to contain higher residue levels as compared to other seasons.     

7Be to 210Pb concentration ratio in ground level air in Belgrade area

7Be to 210Pb concentration ratios in ground level air on two monitoring stations (MS1 and MS2) in Belgrade area were determined from 1996 to 2001. The average monthly concentrations of 7Be in ground level air were in the range of 0.6-18.3 mBq/m3 and exhibited one or two summer/early fall maxims and one minimum in winter. The maximum concentrations for 210Pb were generally observed in the fall, with the average concentrations in the range of 1.09 x 10(-4) to 30.9 x 10(-4) Bq/m3. The 7Be/210Pb ratios were in the range of 1.7-12.7 (MS1) and 1.8-11.3 (MS2), with summer maxims and late fall/winter minimums. The mean Radionuclides Loading Indices values approach zero except for 1996/1997 (MS1) and 2001 (MS2) due to higher concentrations of 7Be and 210Pb. The mean monthly concentrations of both radionuclides exhibited lognormal distributions. There is significant correlation between the 7Be/210Pb activities ratio and the air stability classes A + B + C for both monitoring stations (correlation coefficients 0.61-0.65), and no correlation with D class and E + F classes. Correlation was found between the activity of 7Be and air stability classes A + B + C (0.46-0.68), and E + F (0.38 for MS1), while for 210Pb, a moderate correlation (0.38-0.40) was found with the E + F air stability classes.     

Apparent 85Kr ages of groundwater within the Royal watershed, Maine, USA

Specific 85Kr activity is mapped from 264 domestic and municipal wells sampled during 2002-2004 in the Royal watershed (361 km2), Maine. Gas samples are collected at 20 m, 40 m, and > 50 m interval depths within the unconfined aquifers. Gas extraction for 85Kr from wells is obtained directly via a wellhead methodology avoiding conventional collection of large sample volumes. Atmospheric 85Kr input to the recharge environment is estimated at 1.27 Bq m(-3) by time-series analyses of weighted monthly precipitation (2001-2004). Numerical simulation of Kr gas transport through the variable unsaturated zones to the water table suggests up to 12-year time lags locally, thus biasing the 85Kr groundwater ages. Apparent 85Kr ages suggest that approximately 70% of groundwater near 20 m depth was recharged less than 30 years BP (2004). Mass-age transport modeling suggests that post mid-1950s recharge penetrates to part of the basin's floor and that older groundwater seeps from the underlying fractured bedrock may occur.     

Annual variation in the levels of metals and PCDD/PCDFs in soil and herbage samples collected near a cement plant

In May 2000, the levels of a number of metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sn, Tl, V and Zn) and polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in soil and herbage samples collected near a cement plant from Sta. Margarida i els Monjos (Catalonia, Spain). To determine the temporal variation in the concentrations of metals and PCDD/PCDFs, in May 2001 soil and herbage samples were again collected at the same sampling points and analyzed for the levels of metals and PCDD/PCDFs. In general terms, metal concentrations in soils did not change between May 2000 and May 2001, while significant decreases in the levels of Cr, Ni and V were found in herbage. On the other hand, no significant differences in the mean I-TEQ values of PCDD/PCDFs were found in soil and herbage samples. The results of this survey show that according to the annual variation in the levels of metals and PCDD/PCDFs the environmental impact of the cement plant on the area under its direct influence is not relevant.     

Temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in mothers' milk from Sweden, 1972–2011

Temporal trends of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in mothers' milk are still quite rare. Data are particularly scarce when it comes to concentrations from the last decade, 2000 and onwards. The aims of the present study were to assess temporal trends of PCDD, PCDF and DL-PCB in mothers' milk from Stockholm, 1972–2011 and to compare the results with previous analysis of some of the older samples.The samples were analyzed by high resolution GC/MS and results were statistically evaluated for the periods, 1972–2011 and 2002–2011. The rate of which ∑PCDDs, ∑DL-PCBs and the ∑TEQ are decreasing (on pg/g fat WHO-TEQ2005) is higher in the last decade compared to the 40 year period, 1972–2011. A similar trend is indicated, but not confirmed, for ∑TEQ of PCDFs, probably due to too many PCDF congeners below LOQ in the period 2002–2011. Concentrations of ∑PCDDs, ∑PCDFs, ∑DLPCBs and ∑TEQ, all expressed as pg/g fat on TEQ-WHO2005-basis, show a statistically significant decline over time, 5.8–6.8% per year, 1972–2011. The last ten years the annual declines for ∑PCDDs, ∑DL-PCBs and ∑TEQ are 9.2–11% and for ∑PCDF, 5.4%. Congener specific trend analysis, 2002–2001, of PCDDs and DL-PCBs showed the same pattern, while the PCDF congeners showed no such general trend. The results from the re-analysis showed good agreement with slightly lower ∑TEQ1998 pg/g fat concentrations in six out of seven samples and mean difference of 13% in ∑TEQ1998. The study shows that time series can be elongated from previous studies, as long as the sample population remains the same.     

Trends in the dissolution of metals from sediments collected during the Umitaka-Maru cruises using the microwave-acid digestion technique

Sediment samples were collected during the research vessel Umitaka-Maru cruises in the Gulf region from 15–16 December 1993 and 15–27 December 1994, from 19 and 24 locations, respectively. These samples were subjected to trace metal analysis to determine the 1991 Gulf War oil spill environmental impact in the area. The samples investigated are texturally classified into two main sediment classes: sand and mud. The total concentrations of lead, nickel, and vanadium found in the sediments from individual stations were investigated. The differences in trace metal concentrations reflect the variation in the overall composition of their host sediments. To better appraise the trace element composition of their host sediments and to determine the factors governing the trace metal distribution, the data were sub-divided into five groups among 1993 collections and seven groups during 1994. The concentration ranges of all three metals, lead (0.2–4.85), nickel (4.90–86.00), and vanadium (2.00–38.00) varied in different stations among the groups. The partitioning of trace elements between the detrial and non-detrital fractions of the sediments shows that: 1) The high concentrations of elements in mud is coupled with the increase in the detrital fraction; 2) In muddy sand sediments, nickel is bonded to the structural lattice of detrital minerals, whereas vanadium and lead held in the environmentally mobile fraction; and, 3) In sandy mud sediments, Ni is found in the detrital fraction, whereas V to slightly less extent and Pb show their non-detrital nature. The data were compared with unpolluted sediments throughout the ROPME Sea and worldwide, so the effect of anthropogenic enrichment upon the absolute concentration of the elements is minimal.     

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived (222Rn) decay products 214Pb and 210Pb. The samples were taken by using a single-filter technique and gamma-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214Pb and 210Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214Pb and 210Pb within the whole year was found to be 1.4+/-0.27 Bq m(-3) and 1.2+/-0.15 mBq m(-3), respectively. Different 210Pb:214Pb activity ratios during the year varied between 1.78 x 10(-4) and 1.6 x 10(-3) with a mean value of 8.9 x 10(-4) +/- 7.6 x 10(-5). From the ratio between the activity concentrations of the radon decay products 214Pb and 210Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5+/-0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air.