Assessment of Pesticide Residue Content in Polish Agricultural Soils

Abstract

Pesticides belong to a group of xenobiotics harmful to humans and wildlife, whose fate and activity depends on their susceptibility to degradation. Therefore, the monitoring of their residue level in agricultural soils is very important because it provides very valuable information on the actual level of soil contamination and environmental risk resulting from their application. The aim of this study was to evaluate contemporary concentrations of organochlorine (OCPs) and non-chlorinated pesticides (NCPs) in arable soils of Poland as an example of Central and Eastern European countries. The results were assessed in relation to Polish regulations, which are more restrictive compared to those of other European countries. The sampling area covered the territory of arable lands in Poland (216 sampling points). The distribution of sampling points aimed to reflect different geographical districts, conditions of agricultural production, and various soil properties. The collected soil samples were extracted with organic solvents in an accelerated solvent extractor (ASE 2000). The OCPs, including α-HCH, β-HCH, γ-HCH, and p,p'DDT, p,p'DDE, and p,p'DDD, were extracted with a hexane/acetone mixture (70:30 v/v) and determined by gas chromatography with an electron capture detector (GC-μECD). NCPs included atrazine, carbaryl, and carbofuran were extracted with a dichloromethane/acetone mixture (50:50 v/v), while maneb was extracted by intensive shaking the sample with acetone (1:1 v/v) and ethylenediamine-tertraacetic acid. The NCPs were identified by a dual mass- spectrometry (GC-MS/MS). The total content of individual OCPs ranged from 0.61 to 1031.64 µg kg^-1, while the NCP concentrations were significantly lower, from 0.01 to 43.92 µg kg^-1. DDTs were detected in all soils samples (p,p'DDD (23.60 µg kg^-1) > p,p'DDT (18.23 µg kg^-1) > p,p'DDE (4.06 µg kg^-1), while HCHs were only in 4% of the analyzed samples (β-HCH (339.55 µg kg^-1) > α-HCH (96.96 µg kg^-1) > γ-HCH (3.04 µg kg^-1)), but in higher values than DDTs. Among NCPs, higher concentration was observed for carbaryl (<0.01-28.07 µg kg^-1) and atrazine (<0.01-15.85 µg kg^-1), while the lower for carbofuran (<0.01-0.54 µg kg^-1). Maneb was not detected in analyzed soils. Assessment of the level of soil pollution based on Polish regulations indicated that several percentages of the samples exceeded the criterion for OCPs, such as ∑3DDTs (14 samples; 6.5% of soils) and HCH congeners (α-HCH in one sample; 0.5% of soils), while NCP concentration, such as for atrazine, carbaryl and carbofuran were below the permissible levels or were not detected in the analyzed soils, e.g. maneb. The obtained results indicated that residues of the analyzed pesticides originate from historical agricultural deposition and potentially do not pose a direct threat to human and animal health. The behavior and persistence of pesticides in the soils depend on their properties. Significantly lower NCP concentration in the soils resulted from their lower hydrophobicity and higher susceptibility to leaching into the soil profile. OCPs are characterized by a high half-life time, which affect their significantly higher persistence in soils resulting from affinity to the soil organic phase.

Keywords: Keywords DDT/DDE/DDD; atrazine; biodegradation; carbaryl; carbofuran; contaminants; maneb; α-HCH; β-HCH; γ-HCH.

Figure 1

(a) Principal Component Analysis (PCA) ordination biplot (PCA 1 vs. PCA 2), eigenvectors of correlation matrix used to generate PCA components of soils contaminated by OCPs and NCPs pesticides, and seven measured soil variables for all data sets (n = 216). Arrows/lines in biplot represent variable loadings relative to each component. (b) Factor loading matrix; loading ≥ 0.5 in bold.

Figure 2

Sampling point map of research area (Poland).