Cadmium Concentrations in New Zealand Pastures: Relationships to Soil and Climate Variables

Abstract

Cadmium (Cd) is a nonessential element that occurs at above-background concentrations in many New Zealand (NZ) soils. Most of this Cd is due to the historical application of single superphosphate that was made from Nauru phosphate rock containing between 400 and 600 mg Cd kg P. Pasture Cd uptake exacerbates the entry of Cd into animal products. We sought to determine the critical environmental factors affecting Cd uptake in NZ pastures and to calculate the likely Cd intake of sheep and cattle. We tested 69 pastures throughout NZ for a range of variables, including Cd. Soil Cd and pasture Cd were positively correlated with soil P and soil concentrations of other elements found in phosphate fertilizers. We found that no single environmental variable adequately predicted pasture Cd uptake. Nevertheless, pseudo-total soil Cd and Cd extracted using a 0.05 mol L Ca(NO) solution were positively correlated with pasture Cd. Although soil pH, soil Fe, and soil Cd provided an excellent predictor of the Ca(NO)-extractable soil Cd fraction, regression models explained just 38% of the variation of the Cd concentration in pasture grasses. Incorporating the effect of pasture species composition is a crucial next step in improving these models. A calculation of the likely exposure to Cd of sheep and cattle revealed that no pastures tested resulted in sheep and cattle ingesting Cd at a rate that would result in breaching muscle-tissue food standards. For offal products, which the NZ meat industry does not sell for human consumption, food safety standards exceedence was calculated in a few cases.

Regional accumulation characteristics of cadmium in vegetables: Influencing factors, transfer model and indication of soil threshold content

“…The results display a mean rootsquare error value of 0.17 and a variance (R 2 ) of 0.63, thus defining a good fit. Table 3 summarizes the PA analysis results of The moist environment increases the biological activity, producing soil acidity (Reiser et al, 2014). The study area is characterized by a dense network of rivers (Fig.…”

Research progressing of present contamination of Cd in soil and restoration method

“…In the US, 600 000 hm 2 of fields are suffering heavy metal pollution that need to be restored [19] . In New Zealand, it was found out that in some pastures there Cd content in soil was beyond the background value [6] . In the communiques issued by China's Ministry of Environment Protection and Ministry of State Land and Resource, it shows that Cd point beyond standard by 7% ranking the first among various heavy metal contamination, of which those of minus, slight, medium and heavy levels take 5.2%, 0.8%, 0.5% and 0.5% respectively [20] .…”

“…Nowadays Cd is widely used for electroplating, chemical industry, electronic industry and nuclear industry. Due to discharge of industrial waste water, waste gas, solids as well as irrigation with polluted water, and application of Cd containing pesticides and fertilizer (especially phosphorus contained fertilizer) and organic fertilizer, huge areas of land are polluted by Cd [3][4][5][6][7] . It is easily absorbed by plants that in soil of fields contaminated by cadmium which is then accumulated in human bodies as foods through the food chain [8] .…”

Long-Term Effect of Phosphate Fertilization on Cadmium Uptake by Oat and its Accumulation in Soil

“…Such relationship between soil pH and plant Cd has been widely reported in the literature [19,[31][32][33]56]. Wang et al [31] reported that the extractable Cd increased with lowering of soil pH and resulted in enhancing phytoextraction.…”

“…Wang et al [31] reported that the extractable Cd increased with lowering of soil pH and resulted in enhancing phytoextraction. Reiser et al [56] also showed that soil pH , soil Fe and soil Cd provided an excellent predictor of the Ca (NO 3 ) 2 -extractable soil Cd fraction, but they explained just 38 % of the variation of Cd concentration in pasture grasses.…”