Determination Of Background Levels Research Articles

Contamination and genotoxicity biomarker responses in bivalve mussels from the major Lithuanian rivers.

European inland waters are under continuous threat of anthropogenic pollution. Determination of background level of biomarker response and subsequent classification of the impact increases the applicability of results. In the current study, we evaluate the range of chemical contamination by measuring the concentrations of metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the levels of environmental genotoxicity by using the micronuclei and nuclear bud tests in bivalve mussels of the major Lithuanian rivers. Second, we aimed to evaluate the association between chemical contamination and genotoxicity biomarker responses. Finally, we set to determine the background level of genotoxic effects. Such value (summed frequency of MN and NB) was assessed-6‰. On that basis, we develop a scale of potential genotoxic impact and perform ranging sites into five categories. The results clearly indicate the existence of significant differences in the levels of chemical pollution and genotoxicity in different sites. Increased levels of studied parameters were assessed at the areas affected by municipal and industrial effluents, road runoff, combustion products, and in the area contaminated by accidental spillage. On the other hand, downstream decrease of contamination level, presumably associated with biological degradation and photochemical oxidation, were also observed. Genotoxicity parameters were associated with PAH and metal concentrations measured in mussel tissues as well as in sediments. Results also indicate that in situ genotoxicity assessment performed in the areas affected by long-term contamination of municipal origin might be not sufficiently precise. Study highlights the necessity to combine genotoxicity assessment with chemical analysis. Environ. Mol. Mutagen. 61:338-354, 2020. © 2019 Wiley Periodicals, Inc.

Determination of background levels and pollution assessment for seven metals (Cd, Cu, Ni, Pb, Zn, Fe, Mn) in sediments of a Mediterranean coastal lagoon

The determination of background levels of trace metals in soils and sediments is a key point for the proper assessment of pollution degree. This study demonstrates the suitability of integrating geological and statistical methods for the reliable determination of background levels, applying it to the sediments of Lake Albufera, a wetland of international importance that is highly eutrophic. The procedure followed includes sampling of sediment cores at different points of the lake, including reference sites, and the subsequent statistical analysis of the data, comprising descriptive statistics, probabilistic plots and modal analysis. The final proposal of background levels considers the data subset separated by the statistical analysis and the spatial and age characteristics of sediments, proving the usefulness of jointly using geological and statistical methods. The upper limits of the background populations, defined as the mean+2σ and expressed in mg/kg, are Cd (0.38), Cu (28.8), Ni (25.9), Pb (25.5), Zn (88.6), Fe (2.2%) and Mn (345.7). Background levels proposed for different parts of Spain, found in an extensive literature review, are also provided in this article. Once determined the background levels, the assessment of pollution degree of sediments using pollution indexes indicates that the top 25 to 30cm of sediments has a pollution level between moderate and severe in the peripheral sites, which are nearest to the pathways of contamination, and that the north zone of the lake is the most polluted by the group of the five metals, including Cd, Cu, Ni, Pb and Zn.

Determination of background levels on water quality of groundwater bodies: A methodological proposal applied to a Mediterranean River basin (Guadalhorce River, Málaga, southern Spain)

Determine background levels are a key element in the further characterisation of groundwater bodies, according to Water Framework Directive 2000/60/EC and, more specifically, Groundwater Directive 2006/118/EC. In many cases, these levels present very high values for some parameters and types of groundwater, which is significant for their correct estimation as a prior step to establishing thresholds, assessing the status of water bodies and subsequently identifying contaminant patterns. The Guadalhorce River basin presents widely varying hydrogeological and hydrochemical conditions. Therefore, its background levels are the result of the many factors represented in the natural chemical composition of water bodies in this basin.The question of determining background levels under objective criteria is generally addressed as a statistical problem, arising from the many aspects involved in its calculation. In the present study, we outline the advantages of applying two statistical techniques applied specifically for this purpose: (1) the iterative 2σ technique and (2) the distribution function, and examine whether the conclusions reached by these techniques are similar or whether they differ considerably. In addition, we identify the specific characteristics of each approach and the circumstances under which they should be used.

Métodos de análise multivariada no estabelecimento de valores de referência de qualidade para elementos-traço em solos

A distribuição natural dos teores de elementos-traço nos solos é muito variável. Assim, o estabelecimento de valores de referência de qualidade (VRQs) a partir das médias ou dos intervalos globais de concentração dos elementos, muitas vezes, é pouco adequado. Por essa razão, propôs-se estabelecer os VRQs para elementos-traço no Estado do Espírito Santo, a partir de grupos de solos obtidos com base em atributos físicos e químicos. Foram utilizadas a análise de correlação de Pearson, a análise fatorial com extração dos fatores em componentes principais (AF), a análise de agrupamento hierárquico (AAH) e a análise discriminante (AD). A análise da correlação de Pearson e a análise fatorial revelaram que as variáveis Fe, Mn, Ti, silte+argila e carbono orgânico (CO) são atributos de solo importantes para a distribuição dos elementos-traço nos solos estudados. O uso da análise de agrupamento possibilitou a formação de quatro grupos de solo e diminuiu a variabilidade dos teores de elementos-traço nos solos pela formação de grupos mais homogêneos, além de evidenciar a relação dos diferentes solos em um mesmo grupo com a pedologia e o material de origem. Os VRQs determinados a partir dos grupos de solo, em geral, apresentaram valores inferiores, bem como menor amplitude, entre os percentis 90 e 75, em relação aos obtidos quando se utilizou o universo amostral.

HYDROCARBONS IN SOIL FROM BASRA OIL-RICH GOVERNORATE

Basra is a rich-oil region; its soil is expected to be contaminated with petroleum hydrocarbons. However, there is no previous study that has estimated the levels of hydrocarbons in Basra soil. After 2003 numerous operations by several international oil companies are underway. Therefore, the determination of background levels of petroleum hydrocarbons is a priority from environmental point of view. The present study was carried out to determine the distribution and seasonal variations of petroleum hydrocarbons in ten sites in Basra Governorate, southern Iraq. The results obtained in this study can service as baseline for future environmental impact assessment of oil operations.

Quantitative determination of urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine, 8-oxo-7,8-dihydroguanine, 8-oxo-7,8-dihydroguanosine, and their non-oxidized forms: daily concentration profile in healthy volunteers

We developed a new method for the simultaneous quantitative determination of 8-oxo-7,8-hydro-2′-deoxyguanosine (8-oxodGuo), 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydroguanosine (8-oxoGuo), and the corresponding non-oxidized forms, 2′-deoxyguanosine (dGuo), guanine (Gua) and guanosine (Guo), in human urine samples by liquid chromatography–tandem mass spectrometry. Differences in the ionization of analytes in different urine batches with variable matrix effects were effectively compensated for by internal standardization with stable isotope-labelled analytes. The method was sensitive enough to allow the determination of background levels of these biomarkers and was applied to characterize the inter- and intraindividual variability of biomarkers in the diurnal profile of concentrations in 24 healthy volunteers. When normalized for creatinine, none of the biomarkers was affected by sampling time, thus ruling out any circadian rhythm for nucleic acid oxidation in urine.

Determination of urinary styrene metabolites in the general Italian population by liquid chromatography-tandem mass spectrometry.

To apply mass spectrometry-based techniques for the determination of background levels of metabolites of widespread organic solvents, such as styrene, in unexposed subjects from the general population. The study population consisted of 129 healthy Italian subjects, not occupationally exposed to styrene (67 men; 37% smokers). Urinary levels of mandelic acid (MA) and phenylglyoxylic acid (PGA) were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Using LC-MS/MS, we were able to detect the peaks of MA and PGA in 100% of samples. The distribution of styrene metabolites was log-normal, the geometric means of MA and PGA concentrations being 0.443 mg/g creatinine [geometric standard deviation (GSD) 2.34] and 0.107 mg/g creatinine (GSD 3.49), respectively. The reference intervals estimated for MA and PGA were 0.084-2.339 and 0.009-1.238 mg/g creatinine, respectively. The application of highly sensitive and selective mass spectrometry-based analytical techniques could be useful in the definition of reference values for metabolites of organic pollutants and for better assessment of low-level occupational exposure to organic solvents.

GEOCHEMICAL CHARACTERIZATION OF STREAMBED SEDIMENT IN THE UPPER ILLINOIS RWER BASIN

ABSTRACT: Geochemistry of fine-fraction streambed sediments collected from the upper illinois River basin was surveyed in the fall of 1987 as part of the U.S. Geological Survey National Water-Quality Assessment pilot projects. The survey included 567 samples analyzed for 46 elements. Three distinctive distribution patterns were found for seven U.S. Environmental Protection Agency priority pollutants surveyed, as well as for boron and phosphorus: (1) enrichment of elements in the Chicago urban area and in streams draining the urban area relative to rural areas, (2) enrichment in main stems relative to tributaries, and (3) enrichment in low-order streams at high-population-density sites relative to low-population-density sites. Significant differences in background concentrations, as measured by samples from low-order streams, were observed among five subbasins in the study area. Uncertain geochemical correspondence between low-order, background sites and high-order, generally metal enriched sites prevented determination of background levels that would be appropriate for high-order sites. The within-sample ratio of enriched elements was variable within the Chicago area but was constant in the Illinois River downstream from Chicago. Element ratios imply a composite fine-fraction sediment in the Illinois River of 35–40 percent Des Plaines River origin and 60–65 percent Kankakee River origin.

Halothane metabolism in cirrhotic rats.

A rat model was used to determine whether the metabolism of halothane is changed in the presence of cirrhosis and whether exacerbation of liver dysfunction is correlated with such a change. Cirrhosis was produced by gavaging enzyme-induced male Wistar rats with carbon tetrachloride in corn oil once weekly for 12 weeks. Control rats received corn oil only. After a 3-week period without treatment, blood and urine were collected from each rat for determination of background levels of inorganic fluoride, bromide, and trifluoroacetic acid (halothane metabolites) and for assessment of liver function. Rats were then anesthetized with 1.05% halothane in 50% oxygen for 3 h. Following anesthesia, serial blood and urine samples were taken to monitor halothane metabolism and liver function. No differences were observed between cirrhotic and non-cirrhotic rats in serum levels and urinary excretion of halothane metabolites. However, serum levels of SGOT and SGPT were significantly increased about 1.5-fold in the noncirrhotic group and about 2.5-fold in the cirrhotic group after anesthesia. The increased levels observed in the cirrhotic group were significantly greater than in the noncirrhotic group. The results imply that the exacerbation of liver dysfunction after halothane anesthesia is most likely related to an indirect effect, such as change in liver blood flow, rather than to toxic metabolites.