Damijana Kastelec

Soil physical characteristics after EDTA washing and amendment with inorganic and organic additives

Soil washing has been established as suitable remediation technology, with most research focused on metal removing efficiency and toxic effect on plants, less on the influence on soil physical characteristics, which was the focus of this study. In soil column experiment highly contaminated soil and soil washed with EDTA, mixed with additives (gypsum, hydrogel, manure, peat) were tested. White clover was used as a soil cover. Yield, metal concentration in soil and plant, aggregate fractionation and stability, saturated hydraulic conductivity and soil water retention of the soil were measured. Soil washing decreased metal concentration in soil and plants, but yield of white clover on remediated soil was significantly lower compared to the original soil. Significant differences in water retention characteristics, aggregate fractionation and stability between original and remediated soil have been determined. Gypsum, hydrogel and peat increased plant available water, manure and peat increased yield on remediated soil.

Experimental evidence of false-positive Comet test results due to TiO2 particle--assay interactions.

Abstract We have studied the genotoxicity of TiO2 particles with a Comet assay on a unicellular organism, Tetrahymena thermophila. Exposure to bulk- or nano-TiO2 of free cells, cells embedded in gel or nuclei embedded in gel, all resulted in a positive Comet assay result but this outcome could not be confirmed by cytotoxicity measures such as lipid peroxidation, elevated reactive oxygen species or cell membrane composition. Published reports state that in the absence of cytotoxicity, nano- and bulk-TiO2 genotoxicity do not occur directly, and a possible explanation of our Comet assay results is that they are false positives resulting from post festum exposure interactions between particles and DNA. We suggest that before Comet assay is used for nanoparticle genotoxicity testing, evidence for the possibility of post festum exposure interactions should be considered. The acellular Comet test described in this report can be used for this purpose.

Prediction of cadmium concentration in selected home-produced vegetables

Soil contaminated with cadmium presents a potential hazard for humans, animals and plants. The latter play a major role in the transfer of cadmium to the food chain. The uptake of cadmium and its accumulation by plants is dependent on various soil, plants and environmental factors. In order to identify soil properties with statistically significant influence on cadmium concentration in vegetables and to reduce the collection of data, time and costs, regression models can be applied. The main objective of this research was to develop regression models to predict the concentration of cadmium in 9-vegetable species: zucchini, tomato, cabbage, onion, potato, carrot, red beet, endive and chicory, based on soil properties. Soil samples were collected from 123 home gardens of the Municipality of Celje and 59 of these gardens were also included in vegetable sampling. The concentration of elements (e.g. arsenic, cadmium, copper, lead, and zinc) in the samples was determined by Inductively Coupled Plasma Mass Spectrometry. Single (for cabbage, potato, red beet and chicory) and multiple (for tomato, onion, carrot and endive) linear regression models were developed. There was no statistically significant regression model for zucchini. The most significant parameter for the influencing the cadmium concentration in vegetables was the concentration of cadmium in soil. Other important soil properties were the content of organic matter, pH-value and the concentration of manganese. It was concluded that consuming carrots, red beets, endives, onions, potatoes and chicory which are grown in gardens with Cd concentrations (mgkg(-1) DW) above 2.4, 3.2, 6.3, 7.9, 8.3 and 10.9, respectively, might represent an important contribution to dietary Cd exposure.

Potential environmental factors that influence the nitrogen concentration and δ15N values in the moss Hypnum cupressiforme collected inside and outside canopy drip lines

Samples of the moss Hypnum cupressiforme were collected at 103 locations in forests of Slovenia. At each location, samples were taken at two types of sites: under tree canopies and in adjacent forest openings. The results show that the moss collected in the forest openings reflects the surrounding land-use characteristics and, consequently, the main N emission sources. For moss sampled under canopies, the characteristics of the forest at the moss-sampling locations are more important than the main emission sources outside the forest. A regression model was used to provide the nitrogen (N) concentration in moss from the forest openings in relation to the N concentration in moss under canopies and other environmental variables. The spatial distribution of the locations of the N concentrations and δ(15)N values in moss collected in the forest openings and under the canopies in relation to main N deposition sources is discussed.

Electrochemical EDTA recycling after soil washing of Pb, Zn and Cd contaminated soil

Recycling of chelant decreases the cost of EDTA-based soil washing. Current methods, however, are not effective when the spent soil washing solution contains more than one contaminating metal. In this study, we applied electrochemical treatment of the washing solution obtained after EDTA extraction of Pb, Zn and Cd contaminated soil. A sacrificial Al anode and stainless steel cathode in a conventional electrolytic cell at pH 10 efficiently removed Pb from the solution. The method efficiency, specific electricity and Al consumption were significantly higher for solutions with a higher initial metal concentration. Partial replacement of NaCl with KNO(3) as an electrolyte (aggressive Cl(-) are required to prevent passivisation of the Al anode) prevented EDTA degradation during the electrolysis. The addition of FeCl(3) to the acidified washing solution prior to electrolysis improved Zn removal. Using the novel method 98, 73 and 66% of Pb, Zn and Cd, respectively, were removed, while 88% of EDTA was preserved in the treated washing solution. The recycled EDTA retained 86, 84 and 85% of Pb, Zn and Cd extraction potential from contaminated soil, respectively.

The Effects of Natural CO2 Enrichment on the Growth of Maize

SUMMARY Maize plants (Zea mays) were grown in a field influenced by a geothermal source of CO2 (CO2 spring Stavešinci, Slovenia). Yield parameters and the content of photosynthetic pigments, mineral nutrients, antioxidants and soluble sugars were measured and the photo-synthetic performance was followed in plants growing at different CO2 conditions. Growth parameters were negatively correlated with the soil CO2 concentration as measured at 20 cm depth. Analysis of A-Ci curves revealed lower maximum photosynthesis (CO2-saturated photosynthesis) and lower carboxylation efficiency in high CO2 plants when compared to low CO2 plants. Several biochemical parameters, as the decrease in chlorophyll content and the increase in antioxidants indicate stress in plants exposed to a high CO2 environment.

Experimental research on physiological response of elderly with cardiovascular disease during heat wave period

The fact that the environment and human beings interact with each other has been known for centuries. In the present study, elderly’s heart rate (HR) and blood pressure response to indoor thermal comfort and indoor air quality (IAQ) were investigated. Indoor thermal comfort was characterized by Humidex, IAQ by CO2 concentrations. The results show that HR increase which is a prognostic factor for cardiovascular mortality is related to an increase of heat burden and low air quality. Meanwhile blood pressure would decrease as physiological response to these conditions. Our study demonstrates that common impact of heat burden and poor air quality on blood pressure and HR is greater than impact of exposure to each of them. Planners and decision makers that work in the field of designing indoor environment for elderly people or other risk groups should be aware of interactive influence of the thermal environment and the air quality on health and that unsuitability conditions could be ascertained by the occupants’ physiological response.

Circadian rhythm of cholesterol synthesis in mouse liver: a statistical analysis of the post-squalene metabolites in wild-type and Crem-knock-out mice.

Circadian rhythms affect the total cholesterol levels in humans and animals, although their effect on cholesterol synthesis remain poorly understood. Here, we show for the first time that intermediates of the post-squalene portion of cholesterol synthesis also follow a circadian rhythm in the mouse liver. We used Crem-knock-out mice to investigate the effects of cAMP response element modulator (CREM) isoforms on cholesterol synthesis over time, as compared to wild-type mice. Multiple linear regression and cosinor statistical analysis were carried out on data obtained from 166 liver samples of mice, and the 24-h profiles were modelled across genotype, gender and zeitgeber time for lanosterol, 24,25-dihydrolanosterol, testis meiosis-activating sterol, and 7-dehydrocholesterol, along with cholesterol. The levels of these sterols were higher in female mice compared to males, although the genotype/gender factors showed no effects on the circadian oscillation of these sterols, except for 24,25-dihydrolanosterol. This study also highlights the importance of the statistical methods, where time, genotype and gender are the studied variables.

Hop (Humulus lupulus L.) response mechanisms in drought stress: Proteomic analysis with physiology

Drought is one of the major environmental devastating stressors that impair the growth and productivity of crop plants. Despite the relevance of drought stress, changes in physiology and resistance mechanisms are not completely understood for certain crops, including hop (Humulus lupulus L.). In this research the drought response of hop was studied using a conventional physiological approach (gas exchange techniques, fluorescence, relative water content measurements) and proteomic analysis (2D-DIGE). Plants of two cultivars (Aurora and Savinjski golding) were exposed to progressive drought in a pot experiment and analysed at different stress stages (mild, moderate and severe). Measurements of relative water content revealed a hydrostable water balance of hop. Photosynthesis was decreased due to stomatal and non-stomatal limitation to the same extent in both cultivars. Of 28 identified differentially abundant proteins, the majority were down regulated and included in photosynthetic (41%) and sugar metabolism (33%). Fifteen % of identified proteins were classified into the nitrogen metabolism, 4% were related to a ROS related pathway and 7% to other functions.

How lichens and mosses reflect atmospheric deposition of natural and artificial radionuclides

In a national survey in Slovenia, two biomonitors, the epiphytic lichen Hypogymnia physodes and the terrestrial moss Hypnum cupressiforme, were analysed for 210 Pb and 137 Cs. Further, the results for 210 Pb were compared with outdoor 222 Rn and with precipitation data. 210 Pb activity concentrations in moss carpets and lichen thalli ranged between 180-2450 and 200-1990 Bq kg -1 , respectively. 210 Pb showed similar spatial distributions in the two biomonitors with the highest levels in north-western and southern parts of the country, with a strong gradient to the eastern part, reflecting the movement of global air masses and the amount of precipitation. Increased 222 Rn concentrations over carbonate rocks were not reflected in lichen and moss 210 Pb levels. 137 Cs activity concentrations in lichens and mosses in the ranges 73-1400 and 49-600 Bq kg -1 , respectively, were obtained. There was a relatively good agreement between the two biomonitors, with the highest values in the northern part of the country.