Projects / Programmes
Toxic metals and organometallic compounds in the terrestrial environment
| Code |
Science |
Field |
Subfield |
| 1.08.00 |
Natural sciences and mathematics |
Control and care of the environment |
|
| Code |
Science |
Field |
| P305 |
Natural sciences and mathematics |
Environmental chemistry |
| Code |
Science |
Field |
| 1.04 |
Natural Sciences |
Chemical sciences |
Toxic metals, organometallic compounds, terrestrial environment, chemical speciation, toxicity testing
Researchers (18)
Organisations (2)
Abstract
Presently, various wastes containing inorganic and organic pollutants are disposed of in landfills or accumulated in wastewaters. Toxicity of elements depends on both total concentration and chemical forms in which they appear in environmental compartments. During the disposal and decomposition of different waste materials such as sewage sludge and municipal wastes, several toxic compounds may be released or formed either by microbiological or chemical pathways. Toxic metals and organometallic compounds represent an important group of pollutants in sewage sludge and landfill leachates. Due to the complexity of the sample matrices, organometallic compounds were not frequently investigated in sewage sludge and in landfill leachates. In order to evaluate their environmental, toxicological and sanitary impacts, it is necessary to follow the pathways of organometallic compounds formation, their species transformations and their mobility in different environmental compartments. The disposal of sewage sludge on land or inadequate maintenance of landfills could represent latent environmental threat due to potential leaching of different pollutants to surface and underground waters. To protect the aquatic environment several toxic compounds were introduced to the priority list of pollutants under the Water Framework Directive. Among metals nickel, cadmium, lead and mercury and their chemical compounds as well as tributyltin are considered.
Today there are a lot of data available on total metal concentrations in sewage sludge and landfill leachates. However, there is a lack of information on elemental chemical speciation, in particular regarding their toxic organometallic compounds. There is also insufficient information on transformation of metal species by microorganisms or chemicals present in sewage sludge and landfill leachates. Distribution of chemical species of elements between particulate matter and colloids, including nano particles play a key role in mobility of toxic metal species. This information is also necessary in evaluation of the environmental fate of toxic metal compounds. Therefore, in the proposed project a comprehensive investigation will be performed on the occurrence, toxicity and mobility of chromium, nickel, cadmium, lead, mercury and tin in sewage sludge and landfill leachates. Transformation and mobility of selected organometallic compounds (organocadmium, organolead, organomercury and organotin compounds) will also be studied. For this purpose new reliable, selective and sensitive analytical procedures will be developed for chemical speciation of highly toxic organometallic species in complex sample matrices by hyphenated chromatographic and mass spectrometric techniques. There is evidence that organometallic compounds could inhibit respiration rate and nitrification process in activated sludge, while their presence in landfill leachates requires measures for their effective removal before the release of leachates in the surface waters. To follow the species transformation and methylation processes in sewage sludge and landfill leachates enriched stable or radioactive isotopes will be used. New analytical approach by field flow fractionation and size-exclusion chromatography will be applied to characterize the distribution of different metal species between dissolved, colloidal and particulate matter in compartments of samples investigated. Adverse effects of organometallic compounds and their transformation products on the environment will be studied with suitable toxicity testings. Based on the knowledge on the fate of organometallic compounds in sewage sludge and landfill leachates measures can be taken to prevent their potential release to the terrestrial and aquatic environment. Finally, reliable analytical procedures will be recommended for regular monitoring of highly toxic organometallic compounds in complex matrices of sewage sludge and landfill leachates.
Significance for science
The proposed investigation is actual and considerably contributed to the basic research in the field of chemical speciation and sizing of metals and their chemical species in wastewaters. The investigation followed the world trends of solving the acute environmental problems of waste disposal and trends in the field of environemntal protection. In the project advanced analytical approaches, which included the synthesis and the use of enriched stable isotopes in combination with speciation analysis were applied to follow the processes of chemical species formation and transformation in landfill leachates. Based on the comprehensive knowledge, gained within the project tasks, on the fate of organometallic compounds in sewage sludge and landfill leachates, measures were recommended in order to prevent the potential release of pollutants investigated into the terrestrial and aquatic environment. The results significantly contributed towards a better understanding of cycling of hazardous metals in the terrestrial environment, considering also formation of their more toxic organometallic compounds, which can significantly contribute towards overall toxicity, a fact often overlooked.
Significance for the country
The fate and role of trace elements in the environment and living organisms depend not only on their total concentrations but also on different chemical forms in which they are present. An insufficient data exist on the occurence of highly toxic organometalic compounds in sewage sludge and landfill leachates. There is evidence that the presence of toxic metals and organometallic compounds in activated sludge could contribute to significant loss in treatment efficiency. Moreover, there are limited options for disposal of the contaminated sludge. The presence of toxic metals and organometallic compounds in landfill leachates also requires measures for their effective removal before the release of leachates in the surface waters. Based on the comprehensive knowledge, gained within the project tasks, on the fate of organometallic compounds in sewage sludge and landfill leachates, measures were recommended in order to prevent the potential release of pollutants investigated into the terrestrial and aquatic environment. We have demonstrated that iron nanoparticles can be used for efficient remediation of tributyltin and in great extent also trimethyltin from landfill leachates. The results of the proposed research will also help wastewater treatment plants and municipal waste landfills in Slovenia and world-wide in better management of wastes that will have positive environmental and economic impacts. The proposed investigations will therefore significantly contribute to protection of the Slovenian environment and its cultural heritage and improved also to quality of life. The protection of the environment and guarantee for quality of life for future generations is the main priority not only in Slovenia, but also in EU and other countries worldwide.
Most important scientific results
Annual report
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2012,
2013,
final report,
complete report on dLib.si
