Impact of manure and artificial fertilizer application on metal and metalloid distributions in agricultural soils and crops

Abstract

The application of animal manure to agricultural soil is a very common practice to improve soils fertility, providing a rich source of organic matter and nutrients. However, the presence of certain trace elements in the manure can result in a threat for food safety and the environment. In addition to their potential toxic effects on crops, animal and humans, certain metals such as cadmium, chromium, copper, nickel, mercury, cobalt, lead and zinc may play a role in the emergence and spread of antibiotic resistance, as they can increase the selective pressure on bacteria. To evaluate holistically the impact of manure application on the concentration of metals and metalloids (metal(loid)s) in different environmental compartments, samples of manure, farmed and wild animal faeces, soils, crops and water were collected from farming environments in Austria, Czech Republic, Estonia, Portugal, Republic of Ireland and Great Britain. Inductively coupled plasma mass spectrometry was used to quantify 17 elements, namely vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, selenium, strontium, molybdenum, cadmium, mercury, antimony, barium, and lead. The data were analysed using Pearson correlation and Principal Components Analysis (PCA). The statistical analyses revealed that zinc, copper and potentially manganese can be used as markers of the presence and impact of manure in the environment. Minimum co-selective concentrations (MCC) for copper and zinc were exceeded in water and manure samples, indicating that these elements may act as drivers for bacterial antibiotic resistance. However, the results of the total concentration of metal(loid)s in crops and the bioavailable concentrations in soils did not show any significant differences between application of manure and artificial fertilizers. Other confounding effects, such as the soil matrix and/or the type of crops, seem to have a more significant effect on the concentration and distribution of the metal(loid)s in these systems.