Seasonal Changes In Concentrations Research Articles

Seasonal changes in foliar calcium oxalate concentrations in conifer and hardwood trees: a potentially bioavailable source of cellular calcium and/or oxalate under stress

The present study compared seasonal changes in the concentrations of calcium oxalate (CaOx) crystals and total calcium (Ca) in the foliage of red spruce (Picea rubens Sarg.), white pine (Pinus strobus L.), black oak (Quercus velutina L.), and sugar maple (Acer saccharum Marshall) trees. Samples were collected from the same four replicate trees of each species starting in June 2014 through September 2015 for a total of six times for conifers and four times for hardwoods. Calcium oxalate was extracted from tissues using a method developed in our laboratory in 2015. The purity of the extracted CaOx was indicated by an r2 of 0.98 between Ca and oxalate (Ox) for the data pooled across all species and all sampling times. As expected, the concentrations of CaOx varied between species. We hypothesized that the only role of CaOx crystals is to bind excess Ca, so based on this hypothesis the concentrations of CaOx would increase over the growing season both in conifer and hardwood trees, and in conifers, its quantities would be higher in the older relative to the younger needles. However, we found, that for most species, CaOx concentrations were not significantly different from each other for all collection times. In addition, relative to total Ca, the percent of Ca that existed in the form of CaOx varied widely with species, time of collection within a species, and needle age. Thus, no specific trend was observed for CaOx accumulations with changes in seasons. Concentrations of CaOx were indeed higher in older spruce and pine needles. Based on the available literature on this topic and our data, this could mean that CaOx amounts are dynamic and are continuously being adjusted according to the metabolic needs of cells for either Ca or Ox while still performing the function of shedding off excess Ca.

Foliar heavy metals and stable isotope (δ13C, δ15N) profiles as reliable urban pollution biomonitoring tools

Anthropogenic heavy metal pollution is an important health issue in urban areas, and therefore rapid and inexpensive monitoring in time and space is desirable. This study aimed (i) to assess the suitability of Tilia cordata leaves as a valuable heavy metal bioindicator, including seasonal changes in concentrations and (ii) to evaluate the use of leaf carbon and nitrogen isotope composition (δ13C and δ15N) as novel indicators of urban heavy metal pollution. Leaves were collected from three different pollution intensity locations (Bilbao, Vitoria, and Muskiz) in the Basque Country (northern Spain). Analysis of leaf heavy metals related to traffic emissions and δ13C and δ15N determinations were carried out during July-October 2018. Leaf samples from Bilbao, the most populated and traffic-intense location, showed the highest concentration of heavy metals (mainly from polluted air). Additionally, the two urban areas, Bilbao and Vitoria, showed stronger correlation between these heavy metals, indicating a traffic-related source of emissions. The source of contamination (soil or air) in relation to elements and optimal sampling time is discussed herein. On the other hand, Pearson correlation analysis revealed significant trends between leaf δ13C and δ15N and the studied heavy metals, especially Pb, Cr and Cd, supporting the hypothesis of δ13C and δ15N as tools to distinguish locations according to their heavy metal pollution levels. To our knowledge, this is the first time that δ13C and δ15N have been used as monitoring tools in heavy metal pollution and consequently more research is still needed to calibrate this tool through extensive vegetation screening.

Seasonal contributions of nutrients from small urban and agricultural watersheds in northern Poland.

Diffuse sources of pollution like agricultural or urban runoff are important factors in determining the quality of surface waters, although they are more difficult to monitor than point sources. The objective of our study was to verify assumptions that the inflow from agricultural nutrient sources is higher than from urbanized ones. It has been done by comparing the nutrients and organic matter concentrations and loads for three small streams in northern Poland (Pomerania Region). Two streams flowing through agricultural catchments and an urban stream flowing through the city of Gdansk were analysed. Concentrations of nutrients: N-NOn}{}{}_{3}^{-} N-NHn}{}{}_{4}^{+}, P-POn}{}{}_{4}^{3-}, total phosphorus, total nitrogen and COD were measured 1–3 times per month in the period from July 2017 to December 2018 in agricultural watersheds and from October 2016 to March 2018 for an urban stream. Seasonal changes in concentrations were analysed with descriptive statistics tools. Principal Component Analysis (PCA) was used to point out the most significant factors determining variations in nutrients and organic matter concentrations with respect to different seasons. The factors included a number of characteristics regarding the catchment and streams: total catchment area, stream length, watershed form ratio, stream slope, flow rate and land use with respect to paved areas, agricultural areas and green areas (parks, forests, meadows and pastures). Although concentrations of nitrogen compounds were higher in streams flowing through agricultural areas, our study showed that total concentrations of phosphorus were higher in the urban stream, especially in summer. In agricultural areas the summer concentrations of nutrients were not high, which was probably due to dense vegetation. The correlation between P-POn}{}{}_{4}^{3-} concentration and size of agricultural area in the catchment was observed in winter when no vegetation field cover exists. Our study shows an urgent need to monitor the nutrient loads carried with urban streams especially if discharged into receivers prone to eutrophication.

Sources and Trends of Persistent Organic Pollutants at Three Passive Monitoring Sites in South Africa

The Stockholm Convention on Persistent Organic Pollutants (SCPOPs) is an international treaty that operates under the patronage of the United Nations (UN) to control certain chemicals that are considered persistent organic pollutants (POPs). They are of great concern because of their adverse effects on human health and the environment. Exposure to POPs may lead to cancer, infertility, respiratory infections, and other health complications. It is therefore critical to study the degree of human and environmental exposure to these POPs. Passive air sampling was conducted in South Africa to evaluate the presence and trends of persistent organic pollutants at Barberspan (rural agricultural), Vanderbijl Park (urban industrial) and Molopo Nature Reserve (isolated nature reserve). Samples were collected in 2012. Passive air samplers using poly were used for sampling. The Buchi System B-811 automatic extractor was used to analyze for dichloro-diphenyl-trichlorethane (DDT), pentachlorobenzene (PeCB), hexechlorobenzene (HCB) polychlorinated biphenyls (PCBs) and hexachlorocyclohexane (HCH). Sampling was conducted for a period of one year. POPs concentrations were generally low at all sites, but Vanderbijl Park had the highest concentrations. Seasonal changes in concentrations were much the same at the three sites with temperatures and wind patterns being major factors. The presence of these chemicals in Molopo Nature Reserve and Barberspan is evidence of long range transportation over dry semi desert areas. Back-trajectories indicate possible sources, including areas where DDT is used for malaria control. The presence of POPs is areas they have never been in use poses health and environmental risks in these areas.

Seasonal changes in concentrations of trace elements and rare earth elements in shoot samples of Juncus effusus L. collected from natural habitats in the Holy Cross Mountains, south-central Poland

Selected trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Mn, Cu, Fe, Ni, Pb, Tl, U, Zn) and rare earth elements were determined in 13 samples of Juncus effusus collected from three investigation sites in the Holy Cross Mts., south-central Poland. Sampling was carried out four times during a vegetative season of 2014. Almost all the elements examined showed different seasonal trends in their concentrations, except for Ag, Co and Ni. Maximum concentrations of Ag in samples of three investigation sites were found in May (0.068, 0.062, 0.047 mg/kg) whereas Co (0.124, 0.070, 0.079 mg/kg) and Ni (1.8, 0.998, 2.8 mg/kg) in July, respectively. Mean concentrations of Mn and Cd were higher in shoots (558 and 2.35 mg/kg) than in roots (435 and 1.7 mg/kg). Both these elements revealed much higher concentrations in J. effusus than their typical contents in plant samples. Principal component method allowed us to allocate Ni, Ba, Cd and Cu to one group with the highest positive loadings. The most probable explanation for this correlation is that bioavailability of these metals is increased by J. effusus through a release of oxygen to the rhizosphere. Light rare earth elements concentrations predominate over heavy rare earth elements in the samples examined. A fractionation of lanthanides occurs during their transport from roots to shoots, although this transport is rather limited. All shoot samples have a strong positive Eu anomaly.

Seasonal changes of the concentrations of mineral forms of nitrogen and phosphorus in watercourses in the agricultural catchment area (Bay of Puck, Baltic Sea, Poland)

Abstract The Baltic Region countries are obliged to meet the stringent limits of N and P discharge set by HELCOM for 2021. Area sources of pollution, including agriculture, are considered the main contributors of biogenic compounds. The Bay of Puck as an inner part of the Baltic Sea is particularly sensitive to eutrophication caused by nutrient inflow from agricultural lands. Rivers and streams inflowing to the Bay of Puck transport nitrogen and phosphorus compounds washed out from fields. The article discusses concentrations of nitrogen and phosphorus compounds measured during annual research (VII.2017 – VI.2018) at three watercourses: Płutnica, Reda and Błądzikowski Stream inflowing to the Bay of Puck. The concentrations ranged from 0.01 to 0.13 mg/L N-NO2, from 0.39 to 7.55 mg/L N-NO3, from 0.03 to 0.58 mg/L N-NH4, from 0.44 to 9.51 mg/L TN, from 0.05 to 0.45 mg/L P-PO4 and from 0.03 to 1.89 mg/L TP. Seasonal changes of nutrient concentrations were observed, with maximum concentrations of nitrates in August and September after application of fertilizers to arable land.

Inhibin-A and Inhibin-B in stallions: Seasonal changes and changes after down-regulation of the hypothalamic-pituitary-gonadal axis

The biological function of inhibin is mediated by two heterodimers, inhibin-A and inhibin-B. The relative importance of inhibin-A and –B in male reproductive function varies considerably across species with inhibin-B predominating in many species, whereas inhibin-A appears relatively more important in rams. Research reported to date in stallions has examined total or immunoreactive (ir) inhibin which does not distinguish the two heterodimers. Therefore, the objective of this study was to characterize changes in inhibin-A and inhibin-B concentrations in stallions: 1) across season for a period of one year, and 2) after downregulation of the hypothalamic-pituitary-gonadal (HPG) axis. In Study one, serum samples were obtained monthly from five stallions for a period of one year. Serum concentrations of inhibin-A, inhibin-B, testosterone and estrone sulfate were determined by ELISA. In Study two, stallions were treated with the GnRH antagonist, acyline (n = 4; 330 mg/kg acyline IM) or vehicle control (n = 4; vehicle alone) every five days for 50 days. Plasma concentrations of inhibin-A and –B were determined by ELISA at Days 0, 6, 12, 22, 37, 59, 80, 87 and 104 after initiation of acyline treatment. Testis volume was determined by ultrasonography at weekly intervals. In Study 1, both inhibin-A and inhibin-B showed seasonal changes in concentration with highest concentrations in increasing day length and lowest concentrations in short day lengths. Inhibin-B (overall mean 107.8 ± 4.1 pg/mL) was present at 4.7-fold higher concentrations in serum than inhibin-A (overall mean 23.0 ± 0.7 pg/mL). In Study 2, plasma concentrations of inhibin-B but not inhibin-A were significantly downregulated by administration of the GnRH antagonist, acyline. When the HPG axis was downregulated by acyline, testis volume was strongly correlated with inhibin-B (r = 0.73; P < 0.05) but not inhibin-A (r = 0.22; P = 0.20). In summary, inhibin-B appears to be the predominant form of inhibin in the stallion which undergoes seasonal regulation along with other reproductive parameters and is co-regulated with other endocrine parameters of the HPG axis.

Using moss and lichens in biomonitoring of heavy-metal contamination of forest areas in southern and north-eastern Poland

In the years 2014–2016 biomonitoring studies were conducted in the forest areas of south and north-eastern Poland: the Karkonosze Mountains, the Beskidy Mountains, the Borecka Forest, the Knyszyńska Forest and the Białowieska Forest. This study used epigeic moss Pleurozium schreberi and epiphytic lichens Hypogymnia physodes. Samples were collected in spring, summer and autumn. Approximately 500 samples of moss and lichens were collected for the study. In the samples, Mn, Ni, Cu, Zn, Cd, Hg and Pb concentrations were determined. Based on the obtained results, the studied areas were ranked by extent of heavy-metal deposition: Beskidy > Karkonosze Mountains > forests of north-eastern Poland. Some seasonal changes in concentrations of metals accumulated in moss and lichens were also indicated. There was observed, i.a., an increase in Cd concentration at the beginning of the growing season, which may be related to low emissions during the heating season. Analysis of the surface distribution of deposition of metals in the studied areas showed a significant contribution of nearby territorial emissions and unidentified local emission sources. The contribution of distant emission to Zn, Hg and Pb deposition levels in the Karkonosze and Beskidy region was also indicated.

Automated pollen monitoring system using laser optics for observing seasonal changes in the concentration of total airborne pollen

The development of a simple and automatic pollen measurement methodology is required to manage allergic problems caused by airborne pollen. We developed a device and algorithm to automatically monitor airborne pollen by using basic laser optics technology. The device measures the sideward and forward scattering intensities of laser light from each particle. Because this device provides detailed temporal variation in the pollen concentration, the dispersal dynamics of airborne pollen can be effectively analyzed. We compared the pollen counts obtained with the automated method and standard Hirst-type method. Scatter-plot graphs were constructed of the forward and sideward scattering intensities of the observed particles. An extract window methodology was used to estimate the concentrations of the major allergenic pollens. The extract window parameters were obtained for major types of allergenic pollen. The results suggest the possibility of developing a device for monitoring several types of airborne pollen simultaneously. We determined the standard extract window to be used for estimating the concentration of all types of airborne pollen together. A field experiment was performed to evaluate the automated monitoring system with the standard extract window. The estimated temporal variation pattern of the total airborne pollen concentration agreed well with the observed temporal variation pattern for the whole pollen season. The pollen monitor was able to estimate the overall features of seasonal changes in the total airborne pollen concentration.

Retrograde and destination transfer of sex steroid hormones in the spermatic cord vessels of the mature boar (Sus scrofa) in short-daylight and long-daylight periods, as well as vernal and autumnal equinox

The aim of this study was to examine the seasonal changes in concentration of steroid hormones in the spermatic cord vessels of the mature boar. Cytochrome P450 aromatase (P450arom) was also localized in the arteries and veins of the spermatic cord. Arterial blood was collected from the common carotid artery and from two branches of the testicular artery supplying the testis and epididymis to determine progesterone (P4), androstenedione (A2), testosterone (T2) and estradiol (E2) plasma concentrations. The greatest concentration of P4 was found in testicular artery during December (P<0.001), when compared with other periods and vessels. In contrast, the greatest A2 concentration was observed in the epididymal artery during the same season (P<0.001). Greater T2 concentrations were found in both testis and epididymal arteries than in common artery in March (P<0.001, P<0.001; respectively) and in September (P<0.01, P<0.001; respectively). The E2 concentration was weakly affected by seasonal periods, but greater E2 concentrations were found within vessels in the testis and epididymis than in the common artery. The P450arom was immunolocalized in all layers of the arteries and veins of the testicular spermatic cord. The intensity of P450arom staining was greater in December than in June (P<0.001). There were greater steroid concentrations in arterial vessels during December in comparison to June and this may explain the summer infertility in boars and may be related to the local retrograde and destination transfer into the spermatic cord area. The P450arom gene expression in this area seems to be involved in the conversion of T2 into E2 to enrich the testes and epididymis.

남극 장보고과학기지 인근에서 채취한 눈시료 내의 주요 이온성분들의 고해상도 계절변동성 연구

A continuous series of 60 snow samples was collected at a 2.5-cm interval from a 1.5-m snow pit at a site on the Styx Glacier Plateau in Victoria Land, Antarctica, during the 2011/2012 austral summer season. Various chemical components (δD, δ 18 O, Na + , K + , Mg 2+ , Ca 2+ , Cl ? , SO 4 2? , NO 3 ? , F ? , CH 3 SO 3 ? , CH 3 CO 2 ? and HCO 2 ? ) were determined to understand the highly resolved seasonal variations of these species in the coastal atmosphere near the Antarctic Jang Bogo station. Based on vertical profiles of δ 18 O, NO 3 ? and MSA, which showed prominent seasonal changes in concentrations, the snow samples were dated to cover the time period from 2009 austral winter to 2012 austral summer with a mean accumulation rate of 226 kg H 2 O m ?2 yr ?1 . Our snow profiles show pronounced seasonal variations for all the measured chemical species with a different pattern between different species. The distinctive feature of the occurrence patterns of the seasonal variations is clearly linked to changes in the relative strength of contributions from various natural sources (sea salt spray, volcanoes, crust-derived dust, and marine biogenic activities) during different short-term periods. The results allow us to understand the transport pathways and input mechanisms for each species and provide valuable information that will be useful for investigating long-term (decades to century scale periods) climate and environmental changes that can be deduced from an ice core to be retrieved from the Styx Glacier Plateau in the near future.

Long-term and seasonal trend decomposition of Maumee River nutrient inputs to western Lake Erie.

Cyanobacterial blooms in western Lake Erie have recently garnered widespread attention. Current evidence indicates that a major source of the nutrients that fuel these blooms is the Maumee River. We applied a seasonal trend decomposition technique to examine long-term and seasonal changes in Maumee River discharge and nutrient concentrations and loads. Our results indicate similar long-term increases in both regional precipitation and Maumee River discharge (1975-2013), although changes in the seasonal cycles are less pronounced. Total and dissolved phosphorus concentrations declined from the 1970s into the 1990s; since then, total phosphorus concentrations have been relatively stable, while dissolved phosphorus concentrations have increased. However, both total and dissolved phosphorus loads have increased since the 1990s because of the Maumee River discharge increases. Total nitrogen and nitrate concentrations and loads exhibited patterns that were almost the reverse of those of phosphorus, with increases into the 1990s and decreases since then. Seasonal changes in concentrations and loads were also apparent with increases since approximately 1990 in March phosphorus concentrations and loads. These documented changes in phosphorus, nitrogen, and suspended solids likely reflect changing land-use practices. Knowledge of these patterns should facilitate efforts to better manage ongoing eutrophication problems in western Lake Erie.

Seasonal variation of auxin in stem cambial region of Pinus sihestris L.

Investigation of auxin from the stem cambial region of adult &lt;i&gt;Pinus silvestris&lt;/i&gt; trees by diffusion to agar, and by extraction revealed both seasonal variation and gradients along the stem. Variation in dynamics of auxin efflux and the effect of the size of tissue blocks are used as arguments in the critical discussion of the concept of auxin regulation of cambial activity by way of simple seasonal concentration changes.

Industry-level changes in microbial contamination on market hog and broiler chicken carcasses between two locations in the slaughter process

Pork and poultry products have been implicated in a substantial proportion of microbial foodborne illnesses such as salmonellosis and campylobacteriosis. Understanding the similarities and differences between the effectiveness of interventions applied during slaughter to the two commodities can help identify opportunities to reduce the risk of foodborne illness. This study uses data from two national surveys and censored data techniques to assess the concentrations of microbial contamination on broiler chickens and market hogs at two points in the slaughter process. Statistical distributions are fitted to estimate the average concentrations of microbial contamination, the variability in these concentrations, and the average reduction in contamination between the two locations for pork and chicken produced in the United States. The concentrations of Salmonella and generic Escherichia coli (GEC) are estimated for hog carcasses; the concentrations of Salmonella, GEC, and Campylobacter are estimated for chicken carcasses. These datasets are also used to study the magnitude of seasonal changes in concentrations of microbial contamination and to demonstrate the potential utility of using the reduction in the average aerobic plate count between the pre-evisceration and post-chill stages of the slaughter process as an indicator of the corresponding reduction in other species of bacteria. The study finds interventions for hog carcasses achieve much larger reductions in contamination than those applied to chicken. However, the variability in the concentration of Salmonella contamination on pork is significantly higher, suggesting an opportunity to decrease risk by ensuring more consistent reductions across the industry. The study also finds, for both commodities, that the log10 reductions in the concentrations of GEC are similar to the log10 reductions in Salmonella, while the log reduction in Campylobacter on chicken was substantially greater than for both GEC and Salmonella. Additional analyses demonstrate modest seasonal increases in contamination only on hog carcasses as well as demonstrating that reductions in APC are indicative of reductions in all other organisms, suggesting its potential as an effective indicator organism.

English

The present investigation reveals the seasonal changes in concentration of physico-chemical parameters in river Ganga at Allahabad. Water samples under investigations were collected from the different sites viz: Phaphamau, Dashashumedh Ghat & Sangam of Allahabad during summer, monsoon & winter seasons in year 2013-14. The physico-chemical parameter as Temperature, pH , Dissolved Oxygen (DO) , Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) , Total alkalinity (TA) , Total Hardness (TH) , Total Dissolve Solids (T.D.S) , Turbidity & Chloride were used to analyse the pollution index of river Ganga at selected sites. A correlation matrix test was carried out to check the significant relationship among the physico-chemical parameters (significance level 0.05). Water Quality Index (WQI) was also calculated for all three sampling sites at Allahabad in three seasons. The results revealed that the water quality was severely polluted in monsoon and moderately polluted in winter season.

PM2.5 and tropospheric O3 in China and an analysis of the impact of pollutant emission control

This study reviewed the status of PM2.5 and tropospheric O3 observations in China (15–55°N, 72–136°E). Initially, the distribution of tropospheric O3 over the globe and China was determined based on satellite observations made during 2010–2013. The annual mean values were 29.78 DU and 33.97 DU over the globe and China, respectively. The distribution of PM2.5 and seasonal changes in concentrations in China were then simulated using an aerosol chemistry–climate coupled model system, with an annual mean value of 0.51 × 10−8 kg m−3. The contributions from five different aerosols to the simulated PM2.5 concentrations in different seasons were also determined. The relationships among the emissions of aerosols, greenhouse gases and their precursors and radiative forcings were determined with reference to the (IPCC AR5) Intergovernmental Panel on Climate Change the Fifth Assessment Report. From these relationships, the possible effects of controlling O3 precursors and (PM) particulate matter on the climate were considered. The influence of the control of O3 precursors was not totally clear, and reducing emissions of short-lived greenhouse gases and black carbon was considered a secondary measure for short-term (the next 50 years) climate-change mitigation. Reducing emissions of CO2 is still the best strategy for meeting the target of a global average rise in surface air temperature of less than 2 °C. Near- and short-term emission reduction strategies are important for both effective environmental protection and climate-change mitigation.

Relative abundance and treatment reduction of viruses during wastewater treatment processes — Identification of potential viral indicators

Waterborne pathogenic viruses discharged from wastewater treatment plants (WWTPs) pose potential public health risks. In the present study, we investigated the relative abundance, occurrence, and reduction of eleven different viruses at two WWTPs in southern Arizona over a 12-month period, from August 2011 to July 2012. Influent and effluent samples from the two WWTPs were collected monthly. Viruses were concentrated using an electronegative filter method and quantified using TaqMan-based quantitative PCR (qPCR) assays for each of the virus types (i.e., genogroup I, II and IV noroviruses, sapovirus, enterovirus, group A rotavirus, Aichi virus, pepper mild mottle virus, adenovirus, and JC and BK polyomaviruses), with murine norovirus internal control for the monitoring of extraction-RT-qPCR efficiencies. The pepper mild mottle virus, a plant virus, was found to be the most prevalent virus in both influent and effluent wastewater (annual mean concentration of 3.7–4.4×106copies/L and 4.6–6.3×105 copies/L in influent and effluent wastewater, respectively), showing a low reduction by the treatment processes (0.76–0.99 annual mean log10 reduction), and no significant seasonal change in concentration. Aichi virus, a human enteric virus, was also found in greater abundance, and showed lower reduction during wastewater treatment than other human enteric viruses. Our results suggest that these viruses could be used as potential indicators of wastewater reclamation system performance, with respect to virus occurrence and removal.

Seasonal changes in the concentrations of plant secondary metabolites and their effects on food selection by Microtus oeconomus

Using cafeteria trials conducted during June–September 2008 in Qinghai Province, China, we investigated the selection of 20 plant species by root voles (Microtus oeconomus). It was found that both favored and edible plant groups of root voles comprised 6 species, while the remaining 8 species were anorectic plants. Three plant secondary metabolites (PSMs): flavonoids, condensed tannins, and total phenols, exhibited seasonal changes in concentration; being lowest at June and gradually increasing from July to August/September. Total phenols was the only factor included in the best model of generalized linear models, indicating that total phenols was the most important factor deterring food selection by root voles. In contrast, tannins had a weak effect on food selection by root voles. This study indicated that PSMs play an important role in food selection by root voles; however, the effects of PSMs depend on the type of PSMs. Furthermore, this finding partly verifies the hypothesis that PSMs contribute to the defense strategy of plants, significantly influencing plant selection by root voles.

Seasonal variation, chemical behavior and kinetics of uranium in an unconfined groundwater system

The seasonal changes in the concentration of uranium in an unconfined groundwater system in Cyprus have been investigated and compared to corresponding changes of boron and salinity, to better understand the chemical behavior of uranium in the respective system. Uranium concentration measurements were performed by alpha spectroscopy after selective pre-concentration, whereas boron concentration analysis and electrical conductivity measurements were carried out by photometry using azomethine-H and an electrical conductivity electrode, respectively. The experimental data show that seasonal variations are mainly related to rainwater infiltration and the specific chemical behavior of a species. Increased levels of uranium and boron in natural water systems are attributed to the increased stability of the uranium(VI)-carbonato complexes and the boric acid, which are in natural waters the predominant chemical species for uranium and boron, respectively. Dilution/dissolution processes govern the seasonal concentration changes of uranium and boron in a groundwater system, however redox-reactions resulting in the reduction of U(VI) to U(IV) affect significantly the concentration of uranium in the respective system, particularly under suboxic conditions.

Research on the Non-Point Pollution Loads in the Lake Uluabat Basin

Lake Uluabat, having an international significance and subject to the Ramsar Convention, is fed by the basin of Mustafakemalpasa Stream which runs through fertile lands utilized for livestock breeding and agriculture. In this study, total amount of nitrogen (TN) and phosphorus (TP) loads of non-point pollutants (agriculture, livestock breeding, vegetation, surface runoff and small settlements) was calculated. It was found out that most intensive pollution load stemmed from livestock breeding which causes dispersion of 13653.57 tons·year-1 of TN and 3224.45 tons·year-1 of TP into the Lake Uluabat. Additionally, seasonal changes in concentration of TN and TP were observed during the period of 2008-2009 in Lake Uluabat. It was concluded that the rise of agricultural activities in summer months was the reason underlying the increase in pollution during the months in question.