Vital soil as basis for sustainable soil management, a survey of soil problems in The Netherlands and the way to tackle it, with an assessment for the South African situation

<em>In the past decades, soils in South Africa as well as The Netherlands have become increasingly deteriorated as a result of chemical and physical factors. Soil contamination, acidification, desiccation and erosion have caused negative impacts on land surfaces which are still on the increase. Soil functions like primary plant production, natural soil water clean up, basis and substrate for the above ground biodiversity and food chains, have become completely or partially impaired. The awareness, that soil is a vital and living system has to become the basis of soil policy and soil management. This paper is a plea for such an approach. It describes the various threats, what a vital soil is and which factors play a key role in this vital system: soil structure, buffer capacity, organic matter content, and the variety of soil organisms. It also indicates how the vitality of the soil should be monitored.</em

The implications of copper fungicide usage in vineyards for earthworm activity and resulting sustainable soil quality.

To investigate the impact of copper-containing fungicides (copper oxychloride) on earthworms in South African vineyards, field inventories of earthworms in and between vine rows were carried out and compared to directly adjacent grassland. Also copper content, pH, organic matter content, and soil porosity were determined in these soils. This was combined with laboratory experiments to study the impact of vineyard soil characteristics on the burrowing and dispersal behavior of earthworms. Moreover, the direct toxic action of copper oxychloride on different endpoints of the earthworms (survival and growth) was studied. Copper oxychloride had a negative impact on these endpoints (decreased growth and survival related to increased copper body content) as well as on the behavioral aspect (decreased burrowing rate and avoidance of copper-containing soil). Moreover, there was an inverse relation between burrowing activity and soil bulk density that could also be related to the copper content. This may lead to a decrease in sustainable soil quality in vineyards. © 2005 Elsevier Inc. All rights reserved.Articl

Incorporating biomarkers in ecological risk assessment of chemical contaminants of soils

Soil is an important but complex natural resource which is increasingly used as sink for chemicals. The monitoring of soil quality and the assessment of risks posed by contaminants have become crucial. This study deals with the potential use of biomarkers in the monitoring of soils and the assessment of risk resulting from contamination. Apart from an overview of the existing literature on biomarkers, the results of various of our field experiments in South African soils are discussed. Biomarkers may have potential in the assessment of risk because they can indicate at an early stage that exposure has taken place and that a toxic response has been initiated. It is therefore expected that early biomarkers will play an increasing role as diagnostic tools for determining exposure to chemicals and the resulting effects. They may have predictive value that can assist in the prevention or minimising of risks. The aim of this study was to investigate the possibilities of using our results on biomarker responses of soil dwelling organisms to predict changes at higher organisational levels (which may have ecological implications). Our recent experimental results on the evaluation of various biomarkers in both the laboratory and the field are interpreted and placed in perspective within the broader framework of response biology. The aim was further to contribute to the development and application of biomarkers in regulatory risk assessment schemes of soils. This critical review of our own and recent literature on biomarkers in ecotoxicology leads to the conclusion that biomarkers can, under certain conditions, be useful tools in risk assessment. Clear relationships between contamination loads in soil organisms and certain biomarker responses were determined in woodlice, earthworms and terrestrial snails. Clear correlations were also established in field experiments between biomarker responses and changes at the population level. This indicated that, in spite of the fact that direct mechanistic links are still not clarified, biomarkers may have the potential to provide early indications of forthcoming changes at higher organisational levels. Ways are proposed in which biomarkers could be used in the future in risk assessment schemes of soils and future research directions are suggested.<p> </p

Short- and long-term exposure of Lumbriculus variegatus (Oligochaete) to metal lead: Ecotoxicological and behavioral effects

Metals are naturally occurring constituents of the environment and although many are essential nutrients for living organisms, at higher concentrations they can be toxic. Some aquatic species can help understand and even predict the impact of those contaminants. Lumbriculus variegatus is a recommended species for use in sediment toxicity tests and is known to have a remarkable ability of segmental regeneration. Short- (10-day) and long-term (28-day) toxicity tests were used to test the effects of ametal on the survival, growth, and behavior of L. variegatus. This work aims to investigate and validate the use of behavior as a new parameter in standard toxicity tests. Worms were exposed to sediments contaminated with different levels of lead and the results indicated a positive relation between lead concentrations and mortality and growth: higher lead concentrations resulted in higher mortalities and strong inhibition of growth. An inhibition of behavior was observed and results suggested that although behavior could not be used in sediment toxicity tests, it proved useful as an addition to short-term tests and helps select sediments. Thus, exposure to sediments contaminated with lead affects the presence of this species in nature, because it interferes with growth and survival. © Taylor & Francis Group, LLC

Improvement of the phytoremediation efficiency of Neyraudia reynaudiana for lead-zinc mine-contaminated soil under the interactive effect of earthworms and EDTA

Abstract Slow plant growth, low biomass, and low bioavailability of heavy metals in soil are important factors that limit remediation efficiencies. This study adopted a pot cultivation method to evaluate the phytoremediation efficiency of Neyraudia reynaudiana, planted in contaminated soil from a lead-zinc mining area. The soil was inoculated with earthworms (Eisenia fetida), and mixed with the chelating agent ethylenediaminetetraacetic acid (EDTA) one month after planting. The addition of earthworms significantly increased the aboveground biomass of N. reynaudiana and activated heavy metals in the soil, thus facilitating heavy metal uptake by N. reynaudiana. The addition of EDTA significantly increased the incorporation and transport of heavy metals, reduced the uptake of heavy metals by the plant cell wall, and increased the proportions of cellular soluble constituents. Especially with regard to lead, inoculation with earthworms and EDTA application significantly promoted the accumulation efficiency of N. reynaudiana, increasing it 7.1-16.9-fold compared to the control treatment without earthworms and EDTA, and 1.5-2.3-fold compared to a treatment that only used EDTA