Toxicity of metalaxyl, azoxystrobin, dimethomorph, cymoxanil, zoxamide and mancozeb to Phytophthora infestans isolates from Serbia

A study of the in vitro sensitivity of 12 isolates of Phytophthora infestans to metalaxyl, azoxystrobin, dimethomorph, cymoxanil, zoxamide and mancozeb, was conducted. The isolates derived from infected potato leaves collected at eight different localities in Serbia during 2005-2007. The widest range of EC(50) values for mycelial growth of the isolates was recorded for metalaxyl. They varied from 0.3 to 3.9 μg mL(-1) and were higher than those expected in a susceptible population of P. infestans. The EC(50) values of the isolates were 0.16-0.30 μg mL(-1) for dimethomorph, 0.27-0.57 μg mL(-1) for cymoxanil, 0.0026-0.0049 μg mL(-1) for zoxamide and 2.9-5.0 μg mL(-1) for mancozeb. The results indicated that according to effective concentration (EC(50)) the 12 isolates of P. infestans were sensitive to azoxystrobin (0.019-0.074 μg mL(-1)), and intermediate resistant to metalaxyl, dimethomorph and cymoxanil. According to resistance factor, all P. infestans isolates were sensitive to dimethomorph, cymoxanil, mancozeb and zoxamide, 58.3% of isolates were sensitive to azoxystrobin and 50% to metalaxyl. Gout's scale indicated that 41.7% isolates were moderately sensitive to azoxystrobin and 50% to metalaxyl.     

Radium-226 in water, sediments, and fish from lakes near the city of Elliot Lake, Ontario, Canada

Ra-226 was measured by alpha-emission spectroscopy in water, sediments, and fish (tissues and gut contents), from five lakes in a watershed containing U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent non-industrialized watershed. Ra-226 transfer parameters from lake water and sediments to fish tissues, and annual intakes by humans consuming fish, were estimated. Mean dissolved 226Ra levels ranged from approximately 76 mBq litre(-1) in water of the most affected lake, to < 10 mBq litre(-1) in control lakes. Levels in summer were consistently higher than in fall or winter; no consistent variation with depth was noted. Sediment levels ranged from approximately 3000 mBq g(-1) dry wt in one study lake to < 100 mBq g(-1) dry wt of sediment in control lakes. Bone 226Ra concentrations were higher than in muscle. The lake trout (Salvelinus namaycush), a predatory secondary consumer, had bone 226Ra levels (< 20 mBq g(-1) dry wt) that did not show significant site variation. In contrast, bottom feeding whitefish had significantly more 226Ra in bone tissue (to 38 mBq g(-1) dry wt in the lake whitefish, Coregonus clupeaformis, and 76 mBq g(-1) in round whitefish, Prosopium cylindraceum) in study lakes than in controls (< 20 mBq g(-1) dry wt). Ra-226 levels in lake trout muscle were low and showed erratic variation among lakes whereas levels in whitefish muscle did not vary significantly among study and control sites. Lake herring (= cisco, Coregonus artedii), a planktivorous fish taken only from Quirke Lake, had mean 226Ra levels of 18 and 1.4 mBq g(-1) dry wt in bone and muscle, respectively. Gut 226Ra levels, highest in lake trout from McCabe and Quirke Lakes (126 +/- 53, 64 +/- 44 mBq g(-1) dry wt, respectively), and just detectable in McCabe and Elliot Lake whitefish (24 +/- 2, 36 +/- 14 mBq g(-1) dry wt, respectively), were below detection in lake trout and whitefish from other lakes. Concentration ratios (CRs) of 226Ra from water to muscle ranged from 8 to 14 in lake trout, 7 to 14 in whitefish, and 4 to 6 in lake herring. The water to bone CRs varied from 81 to 142, 314 to 548, and 126 to 272 in the same species. CRs were always < 1 between sediments and fish tissues. Annual intake of 226Ra by human consumers of these fish was estimated to provide an effective dose of 0.003 mSv year(-1). This represents a small fraction of both natural background (> 2 mSv year(-1)) and the public dose limit (5 mSv year(-1)).     

Modeling competitive adsorption of molybdate, sulfate, selenate, and selenite using a Freundlich-type multi-component isotherm

This study examined the interactions of MoO4(2-) + SO4(2-), MoO4(2-) + SeO4(2-), and MoO4(2-) + SeO3(2-) systems on gamma-Al2O3 to better understand the competitive adsorption of these anions in the natural environment. The Freundlich isotherms of anionic adsorption onto gamma-Al2O3 in single and binary solutes were also investigated to estimate the competition between these anions. Experimental results indicate that a higher concentration of competitive solute yields a higher efficiency of the competitive solute's prevention of MoO4(2-) adsorption. The most significant result was found in the MoO4(2-) + SeO3(2-) system. The Freundlich isotherm constant (n) increases with the competitive solute concentration. The suitability of a Freundlich-type isotherm, the Sheindorf-Rebuhn-Sheintuch (SRS) equation, and the modified SRS equation in representing the competitive adsorption of MoO4(2-), SO4(2-), SeO4(2-), and SeO3(2-) on gamma-Al2O3 surface, was also examined. Each set of isotherm data was found to conform to linear SRS expressions, allowing competition coefficients to be derived on a concentration basis for each binary-solute system. The competition coefficient aij and relative affinity coefficients alphaij can be seen as a way to quantify competitive interactions. The proposed SRS and modified SRS equations are simple mathematical expressions accounting for competitive interactions of anions present in a mixture for the range of concentrations over which each individual component exhibits Freundlich behavior.     

Radionuclides (lead-210, polonium-210, thorium-230, and -232) and thorium and uranium in water, sediments, and fish from lakes near the city of Elliot Lake, Ontario, Canada

Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g(-1) dry wt in laketrout and 230 mBq g(-1) dry wt in one lake whitefish) than in muscle (< 50 mBq g(-1) dry wt in all cases), and generally higher in fish from study lakes than from controls, but no consistent differences were observed among fish species. Similarly, 210Po levels were higher in bone (208 +/- 33 mBq g(-1), in laketrout) than muscle (maximum 26 +/- 4 mBq g(-1), in laketrout), and in study lake populations compared to controls. Laketrout 210Po bone concentrations were higher than previously reported in Canada. Levels of 230Th, 232Th, and Th were below detection limits (20 mBq g(-1), 0.05 microg g(-1)) in body tissues in all fish species. Bone levels of U (14.6 +/- 3.0 microg g(-1), in lake whitefish) were higher than in muscle (most < 0.05 microg g(-1), except 0.12 +/- 0.04 and 0.08 +/- 0.03 microg g(-1) in lake whitefish) in fish from waters affected by industrial activity. In control lakes, bone and muscle levels were lower and not significantly different from each other. Muscle levels did not vary consistently with location. Concentration of 210Pb and U was seen from water and 'gut' material (taken as a surrogate for diet) to bone in laketrout and whitefish, and of U from water to muscle in whitefish, but in no case from sediments to tissues. Human intakes of 210Pb, 210Po, 230Th, 232Th, and U from consuming one meal of fish (375 g) per week could, in aggregate, represent an annual effective dose < 15% of the public dose limit (5 mSv). Monitoring biota living near the decommissioned Elliot Lake U operations, especially of 210Pb levels in fish muscle, with further assessment of human doses attributable to local fish and other animals in the diet, should continue. Because radionuclide effects on fish health (and on other non-human organisms) are of increasing concern, neoplasms, malformations, and reproductive anomalies in local fish deserve examination.     

Evaluation of cadmium, copper, zinc, and iron concentrations and tissue distributions in the benthic crab, Dorippe granulata (De Haan, 1841) from Tolo Harbour, Hong Kong

The distributions of copper, zinc, iron, and cadmium among the tissues of Dorippe granulata were determined. The highest copper concentrations were found in the haemolymph (c. 53 microg ml(-1)) while the highest iron concentrations occurred in the gills (c. 720 microg g(-1) dry weight) and the highest zinc concentrations in the exoskeleton (c. 200 microg g(-1) dry weight). By comparison, concentrations of the non-essential metal, cadmium, were low in all tissues (mean = 10 microg g(-1) dry weight). The highest value was recorded from the midgut gland of a female crab (18.5 microg Cd g(-1) dry weight). Concentrations of copper, zinc, and iron were positively correlated with tissue-hydration levels. Such a relationship was not found for cadmium. The findings are discussed with regard to trace-metal levels found in temperate and tropical brachyurans from clean and polluted localities.     

Source apportionment of daily fine particulate matter at Jefferson Street, Atlanta, GA, during summer and winter

The primary emission source contributions to fine organic carbon (OC) and fine particulate matter (PM2.5) mass concentrations on a daily basis in Atlanta, GA, are quantified for a summer (July 3 to August 4, 2001) and a winter (January 2-31, 2002) month. Thirty-one organic compounds in PM2.5 were identified and quantified by gas chromatography/mass spectrometry. These organic tracers, along with elemental carbon, aluminum, and silicon, were used in a chemical mass balance (CMB) receptor model. CMB source apportionment results revealed that major contributors to identified fine OC concentrations include meat cooking (7-68%; average: 36%), gasoline exhaust (7-45%; average: 21%), and diesel exhaust (6-41%; average: 20%) for the summer month, and wood combustion (0-77%; average: 50%); gasoline exhaust (14-69%; average: 33%), meat cooking (1-14%; average: 5%), and diesel exhaust (0-13%; average: 4%) for the winter month. Primary sources, as well as secondary ions, including sulfate, nitrate, and ammonium, accounted for 86 +/- 13% and 112 +/- 15% of the measured PM2.5 mass in summer and winter, respectively.     

Exposure to PCBs, through inhalation, dermal contact and dust ingestion at Taizhou, China--a major site for recycling transformers

Air samples containing gaseous and particulate phases were collected from e-waste workplaces and residential areas of an intensive e-waste recycling area and compared with a reference site. The highest total concentration of PCBs was detected at transformer recycling workshops (17.6 ng m(-3)), followed by the residential area (3.37 ng m(-3)) at Taizhou, and the lowest was obtained at the residential area of the reference site, Lin'an (0.46 ng m(-3)). The same trend was also observed with regards to PCB levels in dust samples. The highest average PCBs level of 2824 ng g(-1) (dry wt) was found in the transformer recycling workshops, and was significantly higher than that of residential areas of Taizhou (572 ng g(-1) dry wt) and Lin'an (42.4 ng g(-1) dry wt). WHO-PCB-TEQ level in the workshops of Taizhou was 2216 pg TEQ(1998)g(-1) dry wt or 2159 pg TEQ(2005)g(-1) dry wt, due to the high abundance of PCB 126 (21.5 ng g(-1) dry wt), which contributed 97% or 99% of WHO-PCB-TEQs. The estimated intake of PCBs via dust ingestion and dermal absorption by transformer recycling workers were 77.5×10(-5) and 36.0×10(-5) pg WHO-PCB-TEQ(1998)kg(-1)d(-1), and 67.3×10(-5) and 31.3×10(-5) pg WHO-PCB-TEQ(2005)kg(-1)d(-1), respectively.     

A 40+ year record of Cd,Hg, Pb,and U deposition in sediments of Patroon Reservoir,Albany County,NY, USA

Sediments of the Patroon Creek watershed (33 km(2)) are known to contain significant concentrations of heavy metals derived from two industrial sites within the watershed. Mercury Refining, Inc (Mereco) has stored and recycled Hg from 1955 to the present day, and National Lead Industries (NLI) manufactured aircraft components containing Cd, Pb, and U from 1958 to 1984. Here we present the first record of heavy metal deposition as preserved in a 3-m long sediment core collected in 1999 from Patroon Reservoir, a small water body (1.3 ha) downstream of the industrial sites. Bulk sediment samples were collected from the core at 0.05-m intervals and analyzed for total Cd, Pb, and U by ICP-MS and total Hg by CVAAS. Total Hg increases from less than 1 mg kg(-1) (dw) below 1.68 m, to a maximum of 6.2 mg kg(-1) at 0.80 m, and then declines to the sediment-water interface. Total Cd, Pb, and U concentrations increase abruptly above 1.68 m to maximum values of 25, 320, and 3600 mg kg(-1) (dw), respectively, and then decline gradually upwards. By correlating metal profiles with industrial history, we conclude that the 1.68 m horizon was deposited no earlier than 1958, the beginning of aircraft component manufacturing at NLI. The average, apparent sedimentation rate within the reservoir has a minimum value of approximately 0.04 m year(-1) for the 41-year period from 1958 to 1999. In the interval 0--1.68 m, average concentrations of Cd, Hg, Pb, and U are 1.69, 1.50, 461, and 13 mg kg(-1), respectively. These levels are comparable with other lake, reservoir and stream sediments that have been moderately to severely impacted by industrial pollution and are above levels expected to be detrimental to aquatic organisms.     

Radium-226 in cattails, Typha latifolia, and bone of muskrat, Ondatra zibethica (L.), from a watershed with uranium tailings near the city of Elliot Lake, Canada

Radium-226 concentrations were measured in the main food plants (cattails, Typha latifolia) and bone of adult muskrats (Ondatra zibethica (L.)), taken from a study area near Quirke Lake in the Serpent River drainage basin. This watershed receives drainage containing radionuclides from the U tailings near the City of Elliot Lake, Ontario, Canada. Two control sites (one local, one 130 km distant) were also sampled. Radium-226 levels in cattails varied by plant part and place of collection. Roots sampled in the study area had the highest mean (226)Ra level (1135.0 mBq g(-1)), stems and leaves had 284.2 and 275.9 mBq g(-1), respectively (dry-weight basis, n = 6 in all cases). Local and distant control cattails carried much lower (226)Ra levels (20.2 and 15.2 mBq g(-1) dry weight, respectively, using pooled equal portions of all plant parts, n = 3 in both cases). Muskrats from waters with mean total (226)Ra levels in the period, 1984-1987 greater than 75.0 mBq litre(-1) ('study-high' sites), near U tailings within 10 km of Quirke Lake, had a mean (geometric) bone level of (226)Ra of 344.9 mBq g(-1) (dry-weight basis, n = 36); those from nearby waters, containing < 75.0 mBq litre(-1) of (226)Ra ('study-low' sites), had a mean bone level (80.3 mBq g(-1), n = 9) similar to animals taken in unaffected local control areas 20 km from the tailings (79.1 mBq g(-1), n = 12); animals from the distant control area, near Sudbury, Ontario, had the lowest mean burden (11.5 mBq g(-1), n = 24). Levels were unrelated to age or sex of the animals. Dry-weight based (226)Ra concentration ratios (bone concentration/plant tissue concentration) were calculated to range from 0.3-1.4 in the study-high area to 2.4-6.3 in the local control area. Wet-weight based concentration ratios were about 4.3 times higher. Concentration ratios were similar to values calculated for other species and in general agreement with values calculated for humans. The muskrat is judged to be a useful indicator (biomonitor) of environmental (226)Ra levels as there is a highly significant positive correlation coefficient (r = 0.74) between bone and ambient (water) concentrations of the radionuclide (F79 = 95.04, P < 0.0001) Estimated yearly (226)Ra intake by people eating muskrats was calculated to be below the current allowable level set by Canadian regulatory authorities.     

Rates of removal of sediment associated radiocaesium from the plynlimon experimental catchments, Powys, UK

Inventories of weapons-test and Chernobyl derived (137)Cs within the upper Wye and upper Severn catchments have been estimated using a variety of techniques. Transport rates of radiocaesium from the catchments have been determined from measurements of radionuclide activities on suspended and bedload sediments. Radiocaesium transport coefficients calculated from the results of 0.46-5.42 x 10(-3) y(-1) for freshly deposited Chernobyl (137)Cs contrast with that for older weapons-test fallout (137)Cs deposits (0.035-0.36 x 10(-3) y(-1)). These results show that freshly deposited Chernobyl (137)Cs is presently being lost at a significantly higher rate than weapons-test derived (137)Cs. For (137)Cs from both sources, residence times in the undisturbed upper Wye catchment are significantly higher than in the afforested upper Severn catchments.     

Comparative study of the effects of MCPA, butylate, atrazine, and cyanazine on Selenastrum capricornutum

The herbicides MCPA, butylate, atrazine and cyanazine are extensively used in Canadian agriculture and information regarding their effects on indigenous biota is scarce. Phytotoxicity assessments were conducted in the laboratory on the common green alga Selenastrum capricornutum using both the active ingredient of the herbicides and their formulated products (for MCPA and butylate). Endpoints determined after the 96 h exposure included algal population growth inhibition (IC50-cell counts), percent lethality (LC50-flow cytometry derived) and photosynthetic electron transport inhibition (EC50-fluorescence induction). Pesticide formulations had greater toxic effects than the active ingredient alone. The 96 h IC50 (50% Inhibition Concentration) and LOEC (Lowest Observable Effects Concentration) using cell counts of S. capricornutum were 18.4 and 8.9 mg l(-1) respectively for MCPA-active ingredient and for MCPA-formulated, these were 0.62 and 0.0062 mg l(-1) respectively. Those for butylateactive ingredient were 61.0 and 8.3 mg l(-1) and for butylate-formulated 1.46 and 0.17 mg l(-1), respectively. The triazines active ingredient, which are photosynthetic inhibitors, had greater effects than either the MCPA or butylate. The IC50 for cyanazine and atrazine were 0.059 and 0.026 mg l(-1), respectively. By comparing the IC50 and LC50 values for the tested active ingredients, it was found that the effects of atrazine were algicidal, whereas those of cyanazine, butylate and MCPA were algistatic.     

Effects of lead on root growth, cell division, and nucleolus of Allium cepa

The effects of different concentrations of lead nitrate on root growth, cell division, chromosome morphology and nucleolus in root tip cells of Allium cepa were studied. The concentrations of lead nitrate (Pb(NO(3))(2)) were 10(-7), 10(-6), 10(-5), 10(-4), 10(-3) and 10(-2) m. It was observed that lead reduces root growth and causes mitotic irregularities, including c-mitosis, anaphase bridges, and chromosome stickiness. Also, interphase cells with micronuclei, irregularly shaped nuclei and nuclei with decomposed nuclear material were noticed. The c-mitotic effect reached its maximum in the meristem at above 10(-4) m Pb, when practically almost all the anomalous dividing cells are of this type. After treatment with Pb, there were many similar silver-stained particulate materials scattered in the nucleus in short, rounded meristem cells and in long, oblong root cap cells.     

Vapour pressures, aqueous solubilities, Henry's Law constants, and octanol/water partition coefficients of a series of mixed halogenated dimethyl bipyrroles

Basic physical-chemical properties of five bromine and chlorine containing mixed halogenated dimethyl bipyrroles (HDBPs) were determined using established methods. Subcooled liquid vapour pressures (P(o)(L,25)), aqueous solubilities (S(w,25)), and octanol/water partition coefficients (K(ow)) were determined using the gas chromatography-retention time, generator column, and slow-stirring methods, respectively. Henry's Law constants (H25) were estimated using experimentally-derived P(o)(L) and S(w,25) data. Values of all four properties were generally similar to those reported for other polyhalogenated aromatic compounds [P(o)(L,25) = (7.55-191) x 10(-6) Pa; S(w,25) = (1.0-1.9) x 10(-5) g/l; log K(ow) = 6.4-6.7; H25 = 0.0020-0.14 Pa m3/mol]. The effect of replacing a chlorine with a bromine atom significantly decreased P(o)(L,25) (log P(o)(L,25) = -0.4197 (# bromine atoms) - 2.643, p<0.01) and H25 (log H25 = -0.508 (# bromine atoms) + 0.394, p<0.02). There were no significant effects of bromine/chlorine substitution on S(w,25) or K(ow). A simple Level I equilibrium partitioning model predicted the environmental behaviour of HDBPs to be similar to a tetrabrominated diphenyl ether. Only slight differences in behaviour amongst HDBP congeners were predicted since substitution of a bromine for a chlorine (Cl/Br substitution) atom had less effect than H/Cl or H/Br substitution on P(o)(L,25), S(w,25), H25, and K(ow).     

Levels of polychlorinated biphenyls, organochlorine pesticides, mercury, cadmium, copper, selenium, arsenic, and zinc in the harbour seal, Phoca vitulina, in Norwegian waters

Residue levels of the chlorinated hydrocarbons polychlorinated biphenyls (PCBs), total DDT, alpha-, beta- and gamma-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and oxychlordane in blubber, and the elements mercury, cadmium, copper, selenium, arsenic, and zinc in liver, of 82 harbour seals, Phoca vitulina, were determined. The seals were found dead or dying in Norwegian waters during the disease outbreak caused by a morbilli virus in 1988. Of the chlorinated hydrocarbons, the highest concentrations were found of PCBs, which were 2-4 times higher than the total DDT concentrations. P,p'-DDE was the main contributor to the total DDT, and constituted about 80%. The PCB and total DDT concentrations ranged from 0.4-38 and 0.1-8.8 mg kg(-1), respectively. The mercury concentrations ranged from 0.1-89 mg kg(-1). Significantly higher mean levels of PCBs (13 mg kg(-1) and mercury (16 mg kg(-1)) were found in blubber and liver, respectively, of seals from the Southern coast of Norway, as compared to the corresponding mean levels in seals from the Oslofjord (8.8 and 4.1 mg kg(-1)), and at the Northwestern coast (5.8 and 7.9 mg kg(-1)), respectively. A significant positive correlation was found between the concentrations of selenium and mercury. When the seals were grouped according to sex and age, females of ageclass > 1 and pups of both sexes had significantly lower PCB and total DDT levels than males ageclass > 1. Significantly higher hepatic mercury levels were found in seals ageclass > 1 as compared to pups. Only low levels of the other organochlorines, cadmium and arsenic, were found. Copper and zinc were considered to be present at normal physiological levels. The present organochlorine and heavy metal concentrations gave no support to suggestions that organochlorines and heavy metal pollution may be directly involved in the observed seal deaths.     

Congener specific accumulation and toxic assessment of polychlorinated biphenyls in common cormorants, Phalacrocorax carbo, from Lake Biwa, Japan

Isomer-specific accumulation of polychlorinated biphenyls (PCBs) including di-, mono- and non-ortho congeners and hepatic P-450 activities were determined in adult common cormorants from Lake Biwa, Japan. The mean total PCB levels in male and female birds were 7.2 +/- 6.1 and 2.1 +/- 0.74 microg g(-1) wet wt, respectively, in the liver. The highly biomagnified congeners were IUPAC 126, 153, 169, 180 and 194, whereas a higher degree of biotransformation could be observed in both meta-para chlorine unsubstituted congeners in the cormorant liver. The estimated metabolic index also showed that common cormorants had higher PB-type enzyme activities than some avian and marine mammals but poor MC-type enzyme activities. The concentrations of non-ortho coplanar congeners were in the order of IUPAC 126 > IUPAC 169 > IUPAC 77 with mean values 6.1 +/- 5.9, 1.3 +/- 1.4 and 0.43 +/- 0.26 ng g(-1) wet wt, respectively. The calculated mean 2,3,7,8-TCDD toxic equivalent (TEQ) concentration in cormorants was 1.8 +/- 1.7 ng g(-1) wet wt and was dominated by IUPAC 118, followed by IUPAC 126. A significant increase of ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-deethylase (PROD) activities was observed with estimated TEQ of PCBs in the cormorants, suggesting that the current contamination level is sufficient for altering their biochemical responses.     

Effects of changes in sulfate,ammonia, and nitric acid on particulate nitrate concentrations in the southeastern United States

A thermodynamic equilibrium model, Simulating Composition of Atmospheric Particles at Equilibrium (SCAPE2), was used to investigate the response of fine particulate NO3(-) to changes in concentrations of HNO3, NH3, and SO4(2-) in the southeastern United States. The data consisted of daily, 24-hr time resolution measurements from the Aerosol Research Inhalation Epidemiology Study (ARIES) Jefferson Street (Atlanta) site and five other sites of the Southeastern Aerosol Research and Characterization Project (SEARCH). Reductions of total NH3 (gas-phase NH3 plus particulate NH4(+)), total NO3(-) (HNO3 plus particulate NO3(-)), SO4(2-), or combined total NO3(-) (HNO3 plus particulate NO3(-)) with SO4(2-) were used to estimate the effects of changing emission levels. The conversion of SO2 to SO4(2-) and NO2 to HNO3 involves additional nonlinear reactions not incorporated into the model. For all sites, fine particulate NO3(-) concentrations decreased in response to reductions of either NH3 or total NO3(-), but the particulate NO3(-) decreases were greater for the NH3 reductions than for the total NO3(-) reductions. Particulate NO3(-) concentrations increased in response to reductions of SO4(2-). For the combined reduction (total NO3(-) plus SO4(2-)), the resulting particulate NO3(-) concentrations were on average no different than the base-case NO3(-) levels. Measurements of fine particulate NO3(-) and HNO3 support the modeling conclusions and indicate that particulate NO3(-) formation is limited by the availability of NH3 at most times at all SEARCH sites.     

Temporal concentration changes of DEET,TCEP, terbutryn,and nonylphenols in freshwater streams of Hesse,Germany: possible influence of mandatory regulations and voluntary environmental agreements

Background, aim, and scope  

The present study focuses on the temporal concentration changes of four common organic pollutants in small freshwater streams of Hesse, Germany. The substances (tris(2-chloroethyl)phosphate (TCEP), the technical isomer mixture of 4-nonylphenol (NP), 2-(t-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine (terbutryn), and N,N-diethyl-m-toluamide (DEET)) are subject to differing regulations. Whereas the use of NP and the related nonylphenolethoxylates (NPEOs) are almost completely banned under EU directive 2003/53/EC, the herbicide terbutryn is only restricted for use as a herbicide in the majority of member states of the European Union (EU). In contrast, TCEP and DEET are not regulated by legislation, but have been replaced in some products through consumer pressure. The impact of regulation on the environmental concentrations of these pollutants is discussed.     

A study of polonium-210 distribution aspects in the riverine ecosystem of Kaveri, Tiruchirappalli, India

Distribution of a natural radionuclide (210Po) in water, sediment and biota was quantified along a 95 km reach of the Kaveri River, India. It is observed that the soft tissues of animals concentrated a higher level of 210Po than the hard parts like shell and bone. The ranges of 210Po activity in biological samples were 2.32-10.78 Bq kg(-1) wet (aquatic weeds), 18.94-28.55 Bq kg(-1) wet (plankton), 32.51 to 46.17 Bq kg(-1) wet (snail), 57.42 to 105.78 Bq kg(-1) wet (bivalve), 12.13 to 19.10 Bq kg(-1) wet (prawn) and 1.86 to 4.17 Bq kg(-1) wet (fish). The concentration factors (CFs) for the aquatic organisms ranged from 10(3) to 10(4), indicating a high affinity of 210Po for organic moieties. The bivalve mollusc, Lamellidens marginalis, accumulated higher concentrations of 210Po, suggesting that it could serve as a biomonitor of 210Po radionuclide in riverine systems. Further, the levels of 210Po in water, sediment and biological samples from impoundments were higher than those from stations located in the open river. This may be largely due to aerial inputs of the radionuclide, accumulation of radionucliderich silt and organic matter, and increased biological production in the impounded water body.     

Determination of source contributions to ambient PM2.5 in Kaohsiung, Taiwan, using a receptor model

Ambient particulates of PM2.5 were sampled at three sites in Kaohsiung, Taiwan, during February and March 1999. In addition, resuspended PM2.5 collected from traffic tunnels, paved roads, fly ash of a municipal solid waste (MSW) incinerator, and seawater was obtained. All the samples were analyzed for twenty constituents, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metallic elements. In conjunction with local source profiles and the source profiles in the model library SPECIATE EPA, the receptor model based on chemical mass balance (CMB) was then applied to determine the source contributions to ambient PM2.5. The mean concentration of ambient PM2.5 was 42.69-53.68 micrograms/m3 for the sampling period. The abundant species in ambient PM2.5 in the mass fraction for three sites were OC (12.7-14.2%), SO4(2-) (12.8-15.1%), NO3- (8.1-10.3%), NH4+ (6.7-7.5%), and EC (5.3-8.5%). Results of CMB modeling show that major pollution sources for ambient PM2.5 are traffic exhaust (18-54%), secondary aerosols (30-41% from SO4(2-) and NO3-), and outdoor burning of agriculture wastes (13-17%).