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.

Single application of sewage sludge--impact on the quality of an alluvial agricultural soil.

The effects of sewage sludge on soil quality with regard to its nutrient and heavy metal content, microbial community structure and ability to maintain specific soil function (degradation of herbicide glyphosate) were investigated in a three months study using an alluvial soil (Eutric Fluvisol). Dehydrated sewage sludge significantly increased soil organic matter (up to 20.6% of initial content), total and available forms of N (up to 33% and 220% of initial amount, respectively), as well as total and plant available forms of P (up to 11% and 170% of initial amount, respectively) and K (up to 70% and 47% of initial amount, respectively) in the upper 2 cm soil layer. The increase of organic matter was most prominent 3d after the application of sewage sludge, after 3 months it was no longer significant. Contents of nutrients kept to be significantly higher in the sewage sludge treated soil till the end of experiment. Contents of some heavy metals (Zn, Cu, Pb) increased as well. The highest increase was found for Zn (up to 53% of initial amount), however it was strongly bound to soil particles and its total content was kept below the maximum permissible limit for agricultural soil. Based on molecular fingerprinting of bacterial 16S rRNA gene and fungal ITS fragment on 3rd day and 3rd month after sewage sludge amendment, significant short term effects on bacterial and fungal communities were shown due to the sewage sludge. The effects were more pronounced and more long-term for bacterial than fungal communities. The mineralization of (14)C-glyphosate in the sewage sludge soil was 55.6% higher than in the control which can be linked to (i) a higher glyphosate bioavailability in sewage sludge soil, which was triggered by the pre-sorption of phosphate originating from the sewage sludge and/or (ii) beneficial alterations of the sewage sludge to the physical-chemical characteristics of the soil.