Researchers from New Zealand has found a way to predict levels of cadmium – a potential threat to human health – in soil.
The team from New Zealand’s Lincoln University, published Cadmium Concentrations in New Zealand Pastures: Relationships to Soil and Climate Variables in the Mar. 21, 2014 edition of the Journal of Environmental Quality the article also aims to give some solutions to the problems.
Many of the New Zealand’s pasture soils have become enriched in cadmium — a toxic heavy metal that is readily taken up by grasses and then transferred to the cattle and sheep that graze them. The concern is that if cadmium concentrations rise to unsafe levels in meat and dairy products, human health and New Zealand’s agricultural economy could be jeopardized.
That so far hasn’t happened. However, because much of the cadmium in the nation’s pasture soils originates from mined phosphate fertilizers that farmers continue to use, Kiwi farmers whose soils test high in the metal are being advised to apply low-cadmium fertilizers, for example. and reduce phosphorus applications overall.
In the study led by Brett Robinson scientists found that soil pH, iron concentrations, and total cadmium levels were all excellent predictors of the potentially bioavailable fraction of soil cadmium. At the same time, they were relatively poor predictors of the actual cadmium concentrations measured in pasture grasses.
So the question now becomes, how can cadmium be managed? The metal is difficult to remove from soil once it’s there, so one important solution is to keep what’s already present locked up and unavailable to plants. Robinson’s work indicates one way to achieve this. In the study, concentrations of plant-available cadmium rose as pH declined, suggesting that maintaining neutral or high soil pH levels whenever possible will reduce uptake of the metal by grasses—and ultimately by livestock.
In January, the EPA withdrew a controversial rule governing the reporting of cadmium and cadmium compounds, admitting the regulation had caused serious confusion and uncertainty.
The rule was a precedent-setting move that was troubling for businesses, according to Lynn Bergeson, managing director of law firm Bergeson & Campbell, PC. Writing in Chemical Processing, Bergeson said the regulations required that any companies that manufactured or imported cadmium in the past ten years, or even proposed doing so, submit to the EPA any data they have that bears on the chemical’s health or environmental effects.