Soil contamination and the uptake of lead by vegetable crops : Risks of lead contaminated soil

Lood uit bodemverontreinigingen wordt opgenomen door moestuingewassen die daarop worden geteeld. Deze gewassen kunnen een gezondheidsrisico vormen als zij worden geconsumeerd. Uit onderzoek van RIVM en Alterra blijkt nu dat bij hoge concentraties lood in de bodem de opname minder wordt. Hierdoor bevatten de gewassen op deze bodems minder van dit metaal dan aanvankelijk werd gedacht. Door dit inzicht kunnen gezondheidsrisico's van de consumptie van deze wassen beter worden voorspeld. Voor het onderzoek, dat in opdracht van het ministerie van Infrastructuur en Milieu (I&M) wordt uitgevoerd, is de bestaande methode om de opname van lood te modelleren, verbeterd. Op basis van een nieuwe dataset kan de opname van lood in gewassen en het effect van het loodgehalte in de bodem nauwkeuriger worden voorspeld. Door de verbeterde risicobeoordeling kan preciezer worden aangegeven in welke situaties gezondheidsrisico's aanvaardbaar zijn. Als dat het geval is, is minder vaak aanvullend gewasonderzoek nodig. Dat spaart onderzoekskosten uit, en kan bovendien minder vertraging veroorzaken voor de uitvoering van (her)inrichtingsprojecten. Ook wordt zo onterechte bezorgdheid bij bewoners voorkomen.Soil contamination with lead is often a bottleneck in the use of soil when growing vegetables. After consumption of the crops lead may cause a range of health effects such as behavioral problems and learning disabilities. Children under six years old are most at risk. Hence, the prediction of lead uptake by vegetables and potatoes is an importart part of the assessement of human health risks of vegetable gardens. Based on a new data set an improved methodology for calculating the absorption of lead has been developed. This dataset contains data of 2800 samples and 32 different crops. For each sample data included the soil lead content, crop lead concentration, soil pH, clay and organic matter content was taken up. Soil-plant uptake relations were derived for the different crops resulting in an improved model for the prediction of risks. The model proved that the uptake factor of lead (expressed as the ratio between plant concentration and soil concentration) at high lead soil levels gradually decreases. With the new model the prediction of health risks is improved. This means that, for the risk assessment of contaminated sites, less additional crop research is necessary. This saves not only research costs and time but it prevents also unwarranted concern among owners of home gardens.Ministerie van Infrastructuur en Milie

Effects of Calcium Phosphates on the (Im)Mobilization of Metals and Nutrients, on the Biological Activity and on the Plant Health from Multi-contaminated Urban Soils

International audienceTwo smelters in the North of France emitted potentially toxic metals for more than a century and today, the resulting contamination represents a risk to human health and affects also the biodiversity. To limit health risks and to improve the soil quality, a study using calcium phosphates (monocalcium phosphate, dicalcium phosphate and a mixture of both salts) and Lolium perenne L was conducted. Through this preliminary investigation, we will try to shed some light about (i) the effects of a sustainable amount of calcium phosphates on the agronomic, biological (microbial and fungi communities) and physiological parameters (chlorophyll a and b, antocyanins, carotenoids) as well as the phytoavailability of potentially toxic metals and nutrients in time, and (ii) the potential use of contaminated biomass from ryegrass as a source of new valorisation ways instead of using it as contaminated compost by gardeners. Although slight variations in pH and significant increases of assimilable phosphorus after adding calcium phosphates were registered, the physiology of plants and the biological parameters were statistically unchanged. The germination of the ryegrass seeds was favoured with calcium phosphates regardless the contamination level of the studied soils. No clear effects of calcium phosphates on the microbial and fungi communities were detected. In contrast, results indicated relationships between the physicochemical parameters of soils, their contamination level and the composition of fungal communities. Indeed, for one of the soils studied, calcium could limit the transport of nutrients, causing an increase in fungi to promote again the transfer of nutrients. Surprisingly, the phytoavailability of Pb increased in the most contaminated soil after adding dicalcium phosphate and the mixture of phosphates whereas a slight decrease was highlighted for Cd and Mn. Although minor changes in the phytoavailability of potentially toxic metals were obtained using calcium phosphates, the ability of ryegrass to accumulate Zn and Ca (up to 600 and 20,000 mg kg−1, respectively) make possible to qualify this plant as a bio ‘ore’ resource. © 2019, Springer Nature Switzerland AG