New Topsoil Sampler for the Assessment and Monitoring of Forest Soil Contamination

Cezary Kabala,Bernard Galka,Siarhei Yurkouski

doi:10.3390/f12010079

Abstract

The forest litter and underlying mineral topsoil are typically sampled and analyzed separately although they are in a dynamic balance, which ensures macro- and microelement cycling in the forest ecosystem, including the flux and accumulation of xenobiotics in the contaminated sites. Although the national legal regulations specify single limits of element concentration for the entire “topsoil” layer, irrespectively of the kind of materials resting at the earth surface down to the specified depth, the direct analysis of bicomponent forest topsoil (litter + mineral topsoil) was problematic because of the lack of a suitable sampler. The paper presents a comparative analysis of Cu, Pb, and Zn concentrations in the forest topsoil layers (0–25 cm), sampled using a new construction sampler invented for a joint collection of the litter layer and underlying mineral layer (to the specified depth). Litter samples (using a steel frame), mineral topsoil samples (0–25 cm, using gouge auger after litter removal), and mixed topsoil samples (0–25 cm, including litter) were collected in 16 replicates from four variably contaminated plots (copper mining and smelting area) afforested with poplar or pine. Pseudo-total concentration of Cu, Pb, and Zn was analyzed after sample digestion in aqua regia. The concentration of elements in the samples consisting of jointly collected litter and mineral layer was noticeably higher than in the samples consisting of the mineral topsoil only, which confirmed the effective inclusion of the litter. The concentrations of trace elements measured in the samples of jointly collected litter and mineral topsoil did not differ (NIR Fisher test at p < 0.05) from the concentrations calculated using the data for litter and mineral soil separately collected and analyzed, which confirmed the usefulness of the new sampler for reliable collection of the forest topsoil samples without skipping any material which may influence the results of soil contamination assessment and risk assessment.

Highlights

Soil sampling strategies and techniques depend on the aim of an investigation, land use, ecosystem and soil type, and available budget [1,2]
The concentration of elements in the samples consisting of jointly collected litter and mineral layer was noticeably higher than in the samples consisting of the mineral topsoil only, which confirmed the effective inclusion of the litter
The concentrations of trace elements measured in the samples of jointly collected litter and mineral topsoil did not differ (NIR Fisher test at p < 0.05) from the concentrations calculated using the data for litter and mineral soil separately collected and analyzed, which confirmed the usefulness of the new sampler for reliable collection of the forest topsoil samples without skipping any material which may influence the results of soil contamination assessment and risk assessment

Summary

Introduction

Soil sampling strategies and techniques depend on the aim of an investigation, land use, ecosystem and soil type, and available budget [1,2]. Forest soils are common objects of studies on water cycling, quality and retention [13,14], and carbon cycling and sequestration in relation to climate change [15,16,17]. Beside the unique scientific projects and problem-oriented inventories, large scale monitoring programs (i.e., on a regional, national, and continental scale) were launched to determine both the spatial and temporal trends in relation to environmental factors and human impacts [18,19,20,21]. Where the observation of the temporal variation has a priority, it is essential to minimize the impact of spatial variability and maximize the reliability of the mean values for the representative plots [1,22]. The typical solution is a respectively high number of primary samples (replicates) from the plot, fitted to the expected or observed local variability [2,23]

Objectives

Methods

Results

Discussion

Conclusion