Concentrations In July Research Articles

Seasonal changes of lead mobility in sediments in algae- and macrophyte-dominated zones of the lake

This study examined lead (Pb) pollution in algae- and macrophytes-dominated sediments, using diffusive gradient in thin films (DGT) and dialysis (HR-Peeper) techniques. Lead pollution varied by season in the two different ecotype sediments. In the algae-dominated zone, the highest concentrations of DGT-labile Pb and dissolved Pb occurred in April and July, respectively. The reductive dissolution of Fe/Mn oxides was identified as an important driver for Pb releases in April and July. This was supported by the decrease of the reducible fraction of Pb in sediments during those sampling periods. Furthermore, dissolved organic matter (DOM) complexation with Pb in sediments also significantly increased the dissolved Pb concentrations in July. The Pb-DOM complexes accounted for 95% of the total chemical species of Pb in pore water, calculated by Visual MINTEQ 3.1 model. Low concentrations of labile and dissolved Pb were observed in October and January; these resulted from the formation of Pb-sulfide precipitates and adsorption by Fe/Mn oxides. It was supported by the high rate of Pb(HS)2 precipitation (saturation index > 0), at 36%, in October samples and the high reducible fraction of Pb in sediments in January samples. In the macrophytes-dominated region, there was a decrease of labile and dissolved Pb concentrations in April and July. It is likely because of the uptake of Pb by submerged macrophyte roots and the Fe/Mn plaques in the root surface. High concentrations of labile and dissolved Pb were observed in October and January, likely resulting from the DOM complexation with Pb in sediments. This was supported by the fact that the Pb-DOM complexes accounted for 90% and 87% of the total chemical species of Pb in October and January, respectively.

Türkiye’de Yayılış Gösteren Altı Ağaç Türünün Yapraklarındaki Kimyasal Bileşenlere Demir-Çelik Fabrikası ve Yoğun Trafiğin Etkileri

Abstract
 
 Aim of study: Tree
 planting can play an important role in improving the quality of the urban
 environment. On the other hand, air pollutants can affect growth and health of
 trees. We studied the impacts of air pollution caused by the iron- steel
 factory and dense traffic on leaf chemical composition and also tree tolerance
 to the air pollution using six tree species (Maple, Ash tree, Cypress, Black
 pine, Sycamore and Aspen).  
 
 Material and Methods: The fresh leaf and
 needle sampling was carried out in April and July, and analyzed for
 photosynthetic pigments, peroxidation level, hydrogen peroxide, enzymatic
 antioxidants and non-enzymatic antioxidants. 
 
 Main results: Although there were
 statistically significant variations in the studied chemical compositions of
 the fresh leaf and needle samples between the six tree species, the pollution
 types and time, each chemical factor acted different ways with the pollution
 types and time according to tree species. In general, the pigment values, MDA,
 H2O2 and APX, concentrations in July were lower than
 those in April, whereas CAT, SOD, proline and protein concentrations in July
 were higher than those in April. Maple tree was more resistant to the traffic
 pollution, while Ash tree was more tolerant to both the pollution types. Among
 all trees, Aspen was found more susceptible to the traffic pollution
 
 Research highlights: The results could be
 used in the future research directions to improve our understanding of the role
 of individual tree species in air pollution reduction and also set up a
 healthy, well managed urban forest which can provide many ecological benefits
 to urban environment.

Effects of photoperiod on nutrient digestibility, hair follicle activity and cashmere quality in Inner Mongolia white cashmere goats.

ObjectiveThis study investigated the effects of photoperiod on nutrient digestibility, hair follicle (HF) activity and cashmere quality in Inner Mongolia white cashmere goats.MethodsTwenty-four female (non-pregnant) Inner Mongolia white cashmere goats aged 1 to 1.5 years old with similar live weights (mean, 20.36±2.63 kg) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group:10 to 16 h light, n = 12) and a short daily photoperiod group (SDPP group: 7 h light:17 h dark, n = 12). All the goats were housed in individual pens and fed the same diets from May 15 to October 15, 2015. The digestibility of crude protein (CP), dry matter (DM), and neutral detergent fiber (NDF) were measured in different months, along with secondary hair follicle (SHF) activity, concentration of melatonin (MEL), and cashmere quality.ResultsAlthough there was no significant difference in the live weights of goats between the SDPP and NDPP groups (p>0.05), the CP digestibility of goats in the SDPP group was significantly increased compared to the NDPP group in July, September, and October (p<0.05). For the DM and NDF digestibility of goats, a significant increase (p<0.05) was found during in September in the SDPP group. Furthermore, compared to the NDPP group, the SHF activity in July, the MEL concentration in July, and the cashmere fiber length and fiber weight in October were significantly increased in the SDPP group (p<0.05).ConclusionThe cashmere production of Inner Mongolia white cashmere goats was increased without obvious deleterious effects on the cashmere fibers in the SDPP group (metabolizable energy, 8.34 MJ/kg; CP, 11.16%; short daily photoperiod, 7 h light:17 h dark).

Assessment of spatial and temporal variations in trace element concentrations using honeybees (Apis mellifera) as bioindicators

With the increase in anthropogenic activities metal pollution is also increased and needs to be closely monitored. In this study honeybees were used as bioindicators to monitor metal pollution. Metal pollution in honeybees represents pollution present in air, water and soil. Concentrations of As, Cs, Hg, Mo, Sb, Se, U and V were measured. The aim of this study was to assess spatial and temporal variations of metal concentrations in honeybees. Samples of honeybees were taken at five different regions in Serbia (Belgrade - BG, Pančevo - PA, Pavliš - PV, Mesić - MS, and Kostolac - TPP) during 2014. Spatial variations were observed for Sb, which had higher concentrations in BG compared to all other regions, and for U, with higher concentrations in the TPP region. High concentrations of Sb in BG were attributed to intense traffic, while higher U concentrations in the TPP region are due to the vicinity of coal fired power plants. In order to assess temporal variations at two locations (PA and PV) samples were taken during July and September of 2014 and June, July, August and September of 2015. During 2014 observing months of sampling higher concentrations in July were detected for Sb and U in BG, which is attributed to lifecycle of plants and honeybees. During the same year higher concentrations in September were observed for As, Sb in PA and Hg in PV. This is due to high precipitation during the peak of bee activity in spring/summer of 2014. No differences between months of sampling were detected during 2015. Between 2014 and 2015 statistically significant differences were observed for Hg, Mo and V; all elements had higher concentrations in 2014. This is in accordance with the trend of reduction of metal concentrations in the bodies of honeybees throughout the years in this region.

Amines in boreal forest air at SMEAR II station in Finland

Abstract. We measured amines in boreal forest air in Finland both in gas and particle phases with 1 h time resolution using an online ion chromatograph (instrument for Measuring AeRosols and Gases in Ambient Air – MARGA) connected to an electrospray ionization quadrupole mass spectrometer (MS). The developed MARGA-MS method was able to separate and detect seven different amines: monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA), propylamine (PA), and butylamine (BA). The detection limits of the method for amines were low (0.2–3.1 ng m−3), the accuracy of IC-MS analysis was 11–37 %, and the precision 10–15 %. The proper measurements in the boreal forest covered about 8 weeks between March and December 2015. The amines were found to be an inhomogeneous group of compounds, showing different seasonal and diurnal variability. Total MMA (MMA(tot)) peaked together with the sum of ammonia and ammonium ions already in March. In March, monthly means for MMA were &lt; 2.4 and 6.8 ± 9.1 ng m−3 in gas and aerosol phases, respectively, and for NH3 and NH4+ these were 52 ± 16 and 425 ± 371 ng m−3, respectively. Monthly medians in March for MMA(tot), NH3, and NH4+ were &lt; 2.4, 19 and 90 ng m−3, respectively. DMA(tot) and TMA(tot) had summer maxima indicating biogenic sources. We observed diurnal variation for DMA(tot) but not for TMA(tot). The highest concentrations of these compounds were measured in July. Then, monthly means for DMA were &lt; 3.1 and 8.4 ± 3.1 ng m−3 in gas and aerosol phases, respectively, and for TMA these were 0.4 ± 0.1 and 1.8 ± 0.5 ng m−3. Monthly medians in July for DMA were below the detection limit (DL) and 4.9 ng m−3 in gas and aerosol phases, respectively, and for TMA these were 0.4 and 1.4 ng m−3. When relative humidity of air was &gt; 90 %, gas-phase DMA correlated well with 1.1–2 nm particle number concentration (R2=0.63) suggesting that it participates in atmospheric clustering. EA concentrations were low all the time. Its July means were &lt; 0.36 and 0.4 ± 0.4 ng m−3 in gas and aerosol phases, respectively, but individual concentration data correlated well with monoterpene concentrations in July. Monthly means of PA and BA were below detection limits at all times.

Investigating missing sources of glyoxal over China using a regional air quality model (RAMS-CMAQ)

Currently, modeling studies tend to significantly underestimate observed space-based glyoxal (CHOCHO) vertical column densities (VCDs), implying the existence of missing sources of glyoxal. Several recent studies suggest that the emissions of aromatic compounds and molar yields of glyoxal in the chemical mechanisms may both be underestimated, which can affect the simulated glyoxal concentrations. In this study, the influences of these two factors on glyoxal amounts over China were investigated using the RAMS-CMAQ modeling system for January and July 2014. Four sensitivity simulations were performed, and the results were compared to satellite observations. These results demonstrated significant impacts on glyoxal concentrations from these two factors. In case 1, where the emissions of aromatic compounds were increased three-fold, improvements to glyoxal VCDs were seen in high anthropogenic emissions regions. In case 2, where molar yields of glyoxal from isoprene were increased five-fold, the resulted concentrations in July were 3–5-fold higher, achieving closer agreement between the modeled and measured glyoxal VCDs. The combined changes from both cases 1 and 2 were applied in case 3, and the model succeeded in further reducing the underestimations of glyoxal VCDs. However, the results over most of the regions with pronounced anthropogenic emissions were still underestimated. So the molar yields of glyoxal from anthropogenic precursors were considered in case 4. With these additional mole yield changes (a two-fold increase), the improved concentrations agreed better with the measurements in regions of the lower reaches of the Yangtze River and Yellow River in January but not in July.

Seasonal occurrence, removal and risk assessment of 10 pharmaceuticals in 2 sewage treatment plants of Guangdong, China

ABSTRACT A long-term investigation, which covered 10 sampling campaigns over 3 years, was performed to evaluate the occurrence, removal and risk of 10 pharmaceuticals in 2 full-scale sewage treatment plants (STPs) in Guangdong, South China. Target pharmaceuticals except for clofibrate and ibuprofen were detected in every sample, with mean concentrations of 12.5–685.6 and 7.9–130.3 ng/L in the influent and effluent, respectively. Salicylic acid was the most abundant compound in both the influents and effluents in the two STPs. For most pharmaceuticals, the seasonal variation in the influent showed the highest concentrations in January and lowest concentrations in July due to their consumption and rainfall. Ibuprofen and fenoprofen presented high removal rates (>90%) and some of the targets such as gemfibrozil, mefenamic acid, tolfenamic acid and diclofenac were detectable with significantly higher mass loads in effluents than in influents. Studies of the five efficiently eliminated pharmaceuticals show that the primary treatment and secondary treatment contributed to most pharmaceutical removal, the anoxic tank made a negligible contribution to their elimination. According to the results produced from the calculation of the risk quotient, only diclofenac might pose a risk to the aquatic environment.

The Evaluation of the Concentration of Bivalent Basic Cations in Surface Water of the National Nature Reserve Čičov Oxbow

Abstract During the years 2013–2014, the concentrations of bivalent basic cations Ca2+ and Mg2+ were evaluated in the water of the Čičov tributary, which belongs to the National Nature Reserve of the basin of the river Danube. On the basis of the results obtained, it can be stated that the average concentration of calcium for the whole reference period was 59.63 mg.dm−3. Minimum average concentration depending on the time of sampling was found in November (48.42 mg.dm−3) and maximum in July (70.73 mg.dm−3). We assume that this above average concentrations in the summer could be due to the lower surface of the water due to higher evaporation. Depending on the places of sampling points, the lowest average concentration (58.10 mg.dm−3) for the whole reference period was at the mouth of the Čilizian brook and the top (60.32 mg.dm−3) in the first side shoulder. The analysis of variance detected highly statistically significant effect of the year and month of collection on changes in the concentration of calcium. The average concentration of magnesium for the whole reference period was 14.54 mg.dm−3. As for the time of collection, the highest average concentrations for the entire observation period were found during the summer, with the maximum average concentration in July (16.94 mg.dm−3) and minimum in February (10.81 mg.dm−3). The lowest average magnesium concentration for the entire reference period, regarding to the sampling points, was measured in the north-eastern part of the nature reserve (14.28 mg.dm−3) and the highest one at the mouth of the Čilizian brook into the National Nature Reserve (14.72 mg.dm−3).

Impact of season and different vitamin D thresholds on prevalence of vitamin D deficiency in epidemiological cohorts-a note of caution.

We investigated the impact of different cut-offs on the prevalence of 25-hydroxyvitamin D [25-(OH)D] deficiency. We used baseline data of 4149 participants (45-75 years, 50% women) of the population-based Heinz Nixdorf Recall study. Serum 25-(OH)D was measured with the Roche Cobas assay. Quartiles (p25, p50, and p75) were calculated. Data were stratified by months, sex, and age. According to the recommendations of 'Dachverband Osteologie', Endocrine Society and National Institute of Health we used 25-(OH)D thresholds of 12, 20, and 30 ng/ml to estimate vitamin D deficiency. Overall the median of 25-(OH)D was 19.8 ng/ml (p25 = 14.4 ng/ml, p75 = 26.6 ng/ml), with highest concentrations in July (p50 = 23.8 ng/ml, p25 = 18.2 ng/ml, and p75 = 31.2 ng/ml) and lowest in March (p50 = 15.8 ng/ml, p25 = 11.5 ng/ml, and p75 = 20.6 ng/ml). Prevalence of vitamin D deficiency rose from 16, 51 up to 83% using the cut-offs of <12, <20 ng/ml, and <30 ng/ml, respectively. With respect to seasonal variance, prevalence of vitamin D deficiency rose to 92% in February/March using the cut-off <30 ng/ml (<12: 28%, <20 ng/ml: 71%) whereas in June/July prevalence of vitamin D deficiency decreased to 71% (<12: 6%, <20 ng/ml: 30%). The chance to attest the diagnosis of vitamin D deficiency for cut-off 12 ng/ml in March is 6.4-fold higher than in June, for cut-off 20 ng/ml, 5.5-fold higher and for cut-off 30 ng/ml, 3.1-fold higher. Guidelines to define vitamin D deficiency revealed extremely different prevalence rates ranging between 6 and 92%. Accounting for collection time and antecedent sun exposure are important to reduce bias in research studies and improve decision-making in clinical care. Vitamin D thresholds have to be rethought.

Assessment of spatial and seasonal changes in groundwater nitrate pollution of agricultural lands through ordinary and indicator kriging techniques

ABSTRACTGeostatistical approaches (ordinary kriging (OK) and indicator kriging (IK)) were used in this study to investigate the spatial and temporal variations in groundwater nitrate concentrations in Çarşamba plain of Turkey. Groundwater samples were taken in April 2012, July 2012, September 2012 and March 2013 from 78 groundwater wells. The experimental semivariograms were often fitted well by a Gauss model for April 2012 and September 2012, whereas a spherical model was fitted to experimental semivariograms for July 2012 and March 2013. Spatial distribution maps revealed that groundwater nitrate concentrations were above the threshold value of 50 mg L−1 specified for drinking water in 4.3% of the study area in April 2012, 40.8% in July 2012, 32.8% in September 2012 and 19.1% in March 2013. Probability maps created with IK showed that 3.1% and 3.2% of the total area had very strong probability (0.8–1.0) of exceeding the threshold nitrate concentration in July 2012 and September 2012, respectively. Current findings revealed that groundwater nitrate concentrations changed seasonally and increased much more in summer. It was concluded that OK and IK may yield significant outcomes for groundwater management, identification of risky sites for potential pollution and identification of the sites with excessive fertilizer uses.

Evaluation of regional background particulate matter concentration based on vertical distribution characteristics

Abstract. Heavy regional particulate matter (PM) pollution in China has resulted in an important and urgent need for joint control actions among cities. It is advisable to improve the understanding of the regional background concentration of PM for the development of efficient and effective joint control policies. With the increase of height the influence of source emission on local air quality decreases with altitude, but the characteristics of regional pollution gradually become obvious. A method to estimate regional background PM concentration is proposed in this paper, based on the vertical characteristics of periodic variation in the atmospheric boundary layer structure and particle mass concentration, as well as the vertical distribution of particle size, chemical composition and pollution source apportionment. According to the method, the averaged regional background PM2.5 concentration in July, August and September 2009, being extracted from the original time series in Tianjin, was 40 ± 20, 64 ± 17 and 53 ± 11 μg m−3, respectively.

Long-range fine particulate matter from the 2002 Quebec forest fires and daily mortality in Greater Boston and New York City.

During July 2002, forest fires in Quebec, Canada, blanketed the US East Coast with a plume of wood smoke. This “natural experiment” exposed large populations in northeastern US cities to significantly elevated concentrations of fine particulate matter (PM2.5), providing a unique opportunity to test the association between daily mortality and ambient PM2.5 levels that are uncorrelated with societal activity rhythms. We obtained PM2.5 measurement data and mortality data for a 4-week period in July 2002 for the Greater Boston metropolitan area (which has a population of over 1.7 million people) and New York City (which has a population of over 8 million people). Daily average PM2.5 concentrations were markedly increased for 3 days over this period, reaching as high as 63 μg/m3 for Greater Boston and 86 μg/m3 for New York City from background ambient levels of 4–48 μg/m3 in the non-smoke days. We examined temporal patterns of natural-cause deaths and 24-h ambient PM2.5 concentrations in July 2002 and did not observe any discernible increase in daily mortality subsequent to the dramatic elevation in ambient PM2.5 levels. Comparison to mortality rates over the same time periods in 2001 and 2003 showed no evidence of impact. Results from Poisson regression analyses suggest that 24-h ambient PM2.5 concentrations were not associated with daily mortality. In conclusion, substantial short-term elevation in PM2.5 concentrations from forest fire smoke were not followed by increased daily mortality in Greater Boston or New York City.Electronic supplementary materialThe online version of this article (doi:10.1007/s11869-015-0332-9) contains supplementary material, which is available to authorized users.

Characterization of the Major Ions of Coal Creek Near Cedar City, Utah

The major ions of Coal Creek near Cedar City, in southwest Utah, were measured to determine if there were any differences in ion concentrations in July of 2014 as compared with spring measurements of 2012 and 2013. Past analyses have shown higher ion concentrations in lower regions of Coal Creek despite the apparent lack of water input. This research is aimed to better characterize these abrupt increases in concentration and determine if these trends varied when samples were acquired in the summer vs. in the spring when sample acquisition has occurred in the past. Environmental water samples were collected at evenly spaced locations in Coal Creek from State Route 14 Mile Marker 7 westward to where the creek intersects with Main Street in Cedar City. Ion concentrations were determined in water samples collected every other day for 3 consecutive weeks using Ion Chromatography (IC) and Atomic Absorption Spectroscopy (AA). The spatially intensive sampling revealed two previously unknown low volume springs that are highly concentrated in the major ions and discharge into the creek. Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was used to characterize trace metal concentrations within the water tributaries, in addition to IC to determine bulk anion content in the creek. The high ion concentrations of springs correlated well with known geologic features near the creek, such as faulted gypsum layers creating springs as well as evaporate deposits, both of which explain the doubling of ion concentrations seen in the examined section of Coal Creek.

Systematic evaluation of ozone control policies using an Ozone Source Apportionment method

Ground-level ozone is a secondary pollutant that causes serious health and environmental damage. One of the main challenges in controlling ground-level ozone is to identify the categories of ozone precursor species that contribute the most to ozone levels, and the regions from which they are emitted. In this study, we apply a photochemical model source apportionment tool to identify the contributions of various precursors to seasonal ozone levels in Hong Kong (HK) and the Pearl River Delta (PRD) region, according to their source regions and categories. We establish a full precursor contribution matrix for the ozone concentrations in all cities within the HK/PRD region. This matrix can be used to rank the relative importance of precursors by source region/category for each city. It can also be used to show how the precursor emissions from any city/category affect ozone levels in neighboring cities. The results show substantial seasonal variation in the source contributions from the HK/PRD region. During ozone episodes, precursors from the region accounted for 68–80% of ozone concentrations in July and 35–55% in October, but only 19–32% in January and April. For all of the cities in the PRD, the top three precursor categories contributing to ozone episodes were mobile, point and area sources. Biogenic and point sources were more important in July than in October. In contrast, the ranking of contributing source regions showed considerable variation across cities and seasons, implying substantial variations in the ways in which precursors from one city affect ozone levels in neighboring cities. Our results show that source contribution and impact analysis can be very useful for evaluating the ozone control strategies of local governments. For the PRD region, a local reduction in mobile, area and point sources, together with regional collaborations on pollution control, are of particular importance in effectively reducing episodic ozone concentrations.

Urinary Concentrations of Benzophenone-type UV Filters in U.S. Women and Their Association with Endometriosis

Benzophenone (BP)-type UV filters are widely used in a variety of personal care products for the protection of skin and hair from UV irradiation. Despite the estrogenic potencies of BP derivatives, few studies have examined the occurrence of these compounds in human matrices. Furthermore, associations among exposure to these compounds and estrogen-dependent diseases (such as endometriosis) have not been examined previously. In this study, we determined the concentrations of five BP derivatives, 2-hydroxy-4-methoxybenzophenone (2OH-4MeO-BP), 2,4-dihydroxybenzophenone (2,4OH-BP), 2,2'-dihydroxy-4-methoxybenzophenone (2,2'OH-4MeO-BP), 2,2',4,4'-tetrahydroxybenzophenone (2,2',4,4'OH-BP), and 4-hydroxybenzophenone (4OH-BP), in urine collected from 625 women in Utah and California, using liquid chromatography (LC)-tandem mass spectrometry (MS/MS). The association of urinary concentrations of BP derivatives with an increase in the odds of a diagnosis of endometriosis was examined in 600 women who underwent laparoscopy/laparotomy (n = 473: operative cohort) or pelvic magnetic resonance imaging (n = 127: population cohort), during 2007-2009. 2OH-4MeO-BP, 2,4OH-BP, and 4OH-BP respectively were detected in 99.0%, 93.3%, and 83.8% of the urine samples analyzed, whereas the detection rates for 2,2',4,4'OH-BP and 2,2'OH-4MeO-BP were below 6.0%. Significant regional differences (higher concentrations in California) and monthly variations (higher concentrations in July and August) were found for urinary concentrations of 2OH-4MeO-BP and 2,4OH-BP. In addition, urinary concentrations of 2OH-4MeO-BP and 2,4OH-BP tended to be higher in more affluent, older, and leaner women. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for the urinary concentrations of BP derivatives and the odds of an endometriosis diagnosis; ORs increased across quartiles of 2OH-4MeO-BP and 2,4OH-BP concentrations, but a significant trend was observed only between 2,4OH-BP and the odds of an endometriosis diagnosis in the operative cohort (OR = 1.19; 95% CI = 1.01, 1.41). When women in the highest quartile of 2,4OH-BP concentrations were compared with women in the first three quartiles, the OR increased considerably (OR = 1.65; 95% CI = 1.07, 2.53). Given that 2,4OH-BP possesses an estrogenic activity higher than that of 2OH-4MeO-BP, our results invite the speculation that exposure to elevated 2,4OH-BP levels may be associated with endometriosis.

Iron plays a role in nitrate drawdown by phytoplankton in Lake Erie surface waters as observed in lake-wide assessments

Phytoplankton interactions with iron (Fe) were examined in surface waters of Lake Erie during summer thermal stratification. Lake-wide sampling in June and September 2005 was conducted using a continuous surface water sampler (1 m sampling depth) and in July at 18 hydrographic stations (5 m sampling depth). In situ measurements of photosynthetic efficiency (maximum quantum yield of photosystem II) and phytoplankton community composition were measured using fast repetition rate fluorometry and a phytoplankton pigment-specific fluorometer, respectively, during June and September. High ratios (73%–85%) of intracellular Fe to particulate Fe coincident with increases in chlorophyll a (Chl a) concentrations in the western and central basins in June and July imply that the majority of Fe in these regions was associated with intracellular pools. Correlations between intracellular Fe and Chl a were frequently observed when Heterokontophyta and Pyrrophyta dominated the phytoplankton community. Assimilation of Fe by the phytoplankton strongly influenced its partitioning between the dissolved and particulate phase. Dissolved iron (&lt;0.45 µm) concentrations were proportional to Chl a concentrations and both dissolved iron and Chl a were inversely proportional to nitrate concentrations in July and September, suggesting that dissolved iron influenced both nitrate drawdown and Chl a concentrations in Lake Erie surface waters in summer.

Outdoor investigation of air quality around Bandar Abbas - Iran oil refinery

Aims: This study has been conducted to assess air pollution, with respect to particulate matter less than 10 μm in diameter (PM 10 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), nitrogen dioxide (NO 2 ), hydrogen sulfide (H 2 S), and the Air Quality Index (AQI), in a location at close proximity to the Bandar Abbas-Iran oil refinery. Materials and Methods: In this study, a location with close proximity to Bandar Abbas oil refinery was selected as the sampling station. The Air Sampling period was from June to September 2010. In order to assess PM 10 concentrations, the samples were collected using a high volume sampler with fiberglass filters. To measure the concentrations of other air pollutants, including, SO 2 , CO, H 2 S, and NO 2 , real-time instruments were used. With regard to air pollutant concentrations, the AQI values were calculated and for the wind rose, the effect of the oil refinery on Bandar Abbas was evaluated. Results: According to the results from the present study, PM 10 , SO 2 , nd NO 2 concentrations were higher than the recommended values of the national ambient air standards. The maximum PM 10 and SO 2 concentrations and their resultant AQI values were observed in August and September, respectively. Other air pollutants had their highest concentrations in July and September, but in no case did they exceed the standard values. Conclusion: The three most significant outdoor problems with the air quality around Bandar Abbas oil refinery were the NO 2 , SO 2 , and PM 10 levels.

Seasonal Variation in Blood Drug Concentrations and a Potential Relationship to Vitamin D

The most important enzyme in hepatic drug metabolism is cytochrome P450 3A4. Published in vitro data indicate that vitamin D may up-regulate the expression of the CYP3A4 gene. Individual vitamin D levels are highly dependent on sunlight exposure and show great seasonal variability in northern countries. The aim of the present study was to investigate whether plasma concentrations of CYP3A4 drug substrates exhibit seasonal changes compatible with a stimulatory effect of vitamin D on drug metabolism. Three immunosuppressants (tacrolimus, sirolimus, and cyclosporine) were analyzed, because these CYP3A4 drug substrates are subject to long-term use and repeated concentration determinations. In addition, mycophenolic acid was included in the analysis as a control drug independent of CYP3A4 metabolism. Concentration-to-dose ratios were extracted from the Karolinska Therapeutic Drug Monitoring database and compared between the 3-month periods of lowest and highest vitamin D levels. Sirolimus and tacrolimus levels showed seasonal variability that was highly consistent with changes in vitamin D; for example, significantly lower drug concentrations in July to September than in January to March. As expected, no significant difference was evident for mycophenolic acid, but this result was also the case with cyclosporine, possibly due to cross-reactivity of CYP3A4-mediated metabolites with the immunoassay used for quantification. In conclusion, there is cyclic variation in blood levels of important immunosuppressants throughout the year that correlates with UV light-dependent changes in vitamin D levels. Even though a causal relationship remains to be established, it is suggested that individual differences in vitamin D may contribute to variability in drug metabolism and disposition.

Impacts of Asian summer monsoon on seasonal and interannual variations of aerosols over eastern China

China is located in a large monsoon domain; variations in meteorological fields associated with the Asian summer monsoon can influence transport, deposition, and chemical reactions of aerosols over eastern China. We apply a global three‐dimensional Goddard Earth Observing System (GEOS) chemical transport model (GEOS‐Chem) driven by NASA/GEOS‐4 assimilated meteorological data to quantify the impacts of the East Asian summer monsoon on seasonal and interannual variations of aerosols over eastern China. During the summer monsoon season, four channels of strong cross‐equatorial flows located within 40°E–135°E are found to bring clean air to China from the Southern Hemisphere. These channels have the effect of diluting aerosol concentrations in eastern China. In the meantime, rain belts associated with the summer monsoon move from southeastern to northern China during June–August, leading to a large wet deposition of aerosols. As a result, aerosol concentrations over eastern China are the lowest in summer. Sensitivity studies with no seasonal variations in emissions indicate that the Asian summer monsoon can reduce surface layer PM2.5 (particles with a diameter of 2.5 μm or less) aerosol concentration averaged over eastern China (110°E–120°E, 20°N–45°N) by about 50–70%, as the concentration in July is compared to that in January. We also compare simulated PM2.5 concentrations in the weak monsoon year of 1998 with those in the strong monsoon year of 2002, assuming same emissions in simulations for these 2 years. Accounting for sulfate, nitrate, ammonium, black carbon, organic carbon, as well as submicron mineral dust and sea salt, surface layer PM2.5 concentration averaged over June–August and over eastern China is 7.06 μg m−3 (or 44.3%) higher in the weak monsoon year 1998 than in the strong monsoon year 2002, and the column burden of PM2.5 is 25.1 mg m−2 (or 73.1%) higher in 1998 than in 2002. As a result, over eastern China, the difference in summer aerosol optical depth between 1998 and 2002 is estimated to be about 0.7. These results have important implications for understanding air quality and climatic effects of aerosols in eastern China.

Composition and Toxic Potential of Cyanoprokaryota in Vacha Dam (Bulgaria)

ABSTRACTSome species of Cyanoprokaryota produce toxins that affect animals and humans. Most of the freshwater basins in Bulgaria, including dams, are relatively well studied in terms of the phytoplankton composition, but the data for presence of cyanotoxins are limited. The aim of our study was to evaluate the diversity, distribution and quantitative development of the phytoplankton as well as the presence of cyanotoxins in the public reservoir Vacha. We have collected water and phytoplankton samples from Vacha reservoir at different time points. All water samples were analyzed for presence of cyanotoxins by ELISA, and tested for cytotoxicity on cell cultures in vitro. Physicochemical parameters, including water temperature, pH, total nitrogen and total phosphorus were measured. Algae, belonging to seven divisions (Cyanoprokaryota, Chlorophyta, Xantophyta, Dinophyta, Euglenophyta, Bacillariophyta and Criptophyta) were identified. A potentially toxic cyanoprokaryote Aphanizomenon flosaquae was detected in blooming concentrations in July and August 2008 as well as in July 2009 together with Microcystis aeruginosa. The water sample collected in August 2008 contained 0.25 ppb microcystins/nodularins. The total microcystins/nodularins concentration in the water samples collected in September 2009 was 0.5 ppb. The viability of HeLa cells was affected mainly after 48 h of exposure to the collected water samples.