Influence of soil temperature and moisture on biochemical biomarkers in earthworm and microbial activity after exposure to propiconazole and chlorantraniliprole.

Predicted climate change could impact the effects that various chemicals have on organisms. Increased temperature or change in precipitation regime could either enhance or lower toxicity of pesticides. The aim of this study is to assess how change in temperature and soil moisture affect biochemical biomarkers in Eisenia fetida earthworm and microbial activity in their excrements after exposure to a fungicide - propiconazole (PCZ) and an insecticide - chlorantraniliprole (CAP). For seven days, earthworms were exposed to the pesticides under four environmental conditions comprising combinations of two different temperatures (20°C and 25°C) and two different soil water holding capacities (30% and 50%). After exposure, in the collected earthworm casts the microbial activity was measured through dehydrogenase activity (DHA) and biofilm forming ability (BFA), and in the postmitochondrial fraction of earthworms the activities of acetylcholinesterase (AChE), catalase (CAT) and glutathione-S-transferase (GST) respectively. The temperature and the soil moisture affected enzyme activities and organism's response to pesticides. It was determined that a three-way interaction (pesticide concentration, temperature and moisture) is statistically significant for the CAT and GST after the CAP exposure, and for the AChE and CAT after the PCZ exposure. Interestingly, the AChE activity was induced by both pesticides at a higher temperature tested. The most important two-way interaction that was determined occurred between the concentration and temperature applied. DHA and BFA, as markers of microbial activity, were unevenly affected by PCZ, CAP and environmental conditions. The results of this experiment demonstrate that experiments with at least two different environmental conditions can give a very good insight into some possible effects that the climate change could have on the toxicity of pesticides. The interaction of environmental factors should play a more important role in the risk assessments for pesticides.

Abundance and biomass responses of microbial food web components to hydrology and environmental gradients within a floodplain of the River Danube.

This study investigated the relationships of time-dependent hydrological variability and selected microbial food web components. Samples were collected monthly from the Kopacki Rit floodplain in Croatia, over a period of 19 months, for analysis of bacterioplankton abundance, cell size and biomass; abundance of heterotrophic nanoflagellates and nanophytoplankton; and concentration of chlorophyll a. Similar hydrological variability at different times of the year enabled partition of seasonal effects from hydrological changes on microbial community properties. The results suggested that, unlike some other studies investigating sites with different connectivity, bacterioplankton abundance, and phytoplankton abundance and biomass increased during lentic conditions. At increasing water level, nanophytoplankton showed lower sensitivity to disturbance in comparison with total phytoplankton biomass: this could prolong autotrophic conditions within the floodplain. Bacterioplankton biomass, unlike phytoplankton, was not impacted by hydrology. The bacterial biomass less affected by hydrological changes can be an important additional food component for the floodplain food web. The results also suggested a mechanism controlling bacterial cell size independent of hydrology, as bacterial cell size was significantly decreased as nanoflagellate abundance increased. Hydrology, regardless of seasonal sucession, has the potential to structure microbial food webs, supporting microbial development during lentic conditions. Conversely, other components appear unaffected by hydrology or may be more strongly controlled by biotic interactions. This research, therefore, adds to understanding on microbial food web interactions in the context of flood and flow pulses in river-floodplain ecosystems.

Effects of olive mill waste (OMW) contaminated soil on biochemical biomarkers and reproduction of Dendrobaena veneta.

Olive oil industry is economically important in Mediterranean countries. Disposal of olive mill waste (OMW) presents an environmental concern in those countries due to its high salinity and its high level of polyphenols. In order to reuse OMW, those properties have to change either through the filtration process and addition of adsorbents or by composting. One of the most important organisms in composting of organic wastes is earthworms. However, data on the effects of OMW on earthworms are scarce. The main aim of our study was to investigate whether OMW contaminated soil (OMW CS) causes adverse effects on molecular and organism level in epigeic earthworm Dendrobaena veneta and on microbiological activity. Changes of measured biochemical biomarkers (AChE, CAT, GST, lipids, MDA) varied depending on the quantity of added OMW CS and the exposure duration. Oxidative stress occurred after 7 days of exposure, while in most cases enzyme activity recovered after 28 days. At the highest ratio of contaminated soil (50%), reproduction was completely inhibited. The second aim was to investigate the impact of earthworms on phenol degradation and microbial activity, indicating an important role in the bioremediation of contaminated soils. Our results show that above a certain quantity an OMW CS has an adverse effect on earthworms, while the impact of earthworms on soil microbial activity was positive but transient. Yet, as the results also imply that earthworms have an impact on phenol degradation, they can be used to help remediation of OMW CS and its subsequent usage in agriculture. However, the quantity of OMW CS that can be safely added should be determined first.

Multidisciplinary Approach to Agricultural Biomass Ash Usage for Earthworks in Road Construction.

Agricultural biomass has great bioenergy potential due to its availability, and it is a carbon-free energy source. During biomass incineration, biomass ash is formed, which is still considered as a waste without proper disposal and management solutions. Various biomass ash utilization options were investigated, mainly concerning engineering issues (the mechanical characterization of newly produced building materials or products), and there is a lack of knowledge of environmental issues arising from this "waste" material utilization in civil engineering practice. The main aim of this research is discussion of a different agricultural biomass characteristics as a fuel, the impact of agricultural biomass ashes (ABA) on the mechanical properties of stabilized soil with a particular emphasis on the environmental impacts within this kind of waste management. The results of this study indicate improved geotechnical characteristics of low-plasticity clay stabilized by lime/ABA binder. In addition to mechanical characterization for materials embedded in road embankments and subgrades, appropriate environmental risk assessment needs to be performed, and the results of this study indicate that the amount of ABAs added to the soil for roadworks should not have adverse effects on the soil fauna in the surrounding environment.