Browsing by Author "Sengo, Joana"
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- Ecotoxicological assessment of the potential impact on soil porewater, surface and groundwater from the use of organic wastes as soil amendmentsPublication . Alvarenga, Paula; Mourinha, Clarisse; Farto, Marcia; Palma, Patrícia; Sengo, Joana; Morais, Marie-Christine; Cunha-Queda, CristinaThis study aimed to assess the potential impact on soil porewater, surface and groundwater from the beneficial application of organic wastes to soil, using their eluates and acute bioassays with aquatic organisms and plants: luminescence inhibition of Vibrio fischeri (15 and 30 min), Daphnia magna immobilization (48 h), Thamnocephalus platyurus survival (24 h), and seed germination of Lolium perenne (7 d) and Lactuca sativa (5 d). Some organic wastes' eluates promoted high toxic responses, but that toxicity could not be predicted by their chemical characterization, which is compulsory by regulatory documents. In fact, when organisms were exposed to the water-extractable chemical compounds of the organic wastes, the toxic responses were mare connected to the degree of stabilization of the organic wastes, or to the treatment used to achieve that stabilization, than to their contaminant load. That is why the environmental risk assessment of the use of organic wastes as soil amendments should integrate bioassays with eluates, in order to correctly evaluate the effects of the most bioavailable fraction of all the chemical compounds, which can be difficult to predict from the characterization required in regulatory documents. According to our results, some rapid and standardized acute bioassays can be suggested to integrate a Tier 1 ecotoxicological evaluation of organic wastes with potential to be land applied, namely luminescence inhibition of V fischeri, D. magna immobilization, and the germination of L. perenne and L sativa.
- Quality assessment of a battery of organic wastes and composts using maturity, stability and enzymatic parametersPublication . Alvarenga, Paula; Mourinha, Clarisse; Farto, Marcia; Palma, Patrícia; Sengo, Joana; Morais, Marie-Christine; Cunha-Queda, CristinaChemical and biological parameters (NH4+-N/NO3--N ratio, humification indices, and the activities of hydrolytic exoenzymes), commonly used to assess compost maturity and/or stability, were considered for the quality evaluation of a battery of organic materials, intended to be land applied. Acid and alkaline phosphatases, beta-glucosidase, proteases and beta-glucosaminidase activities proved to be reliable tests to distinguish the organic materials that were in an active stage of microbial activity, highly correlated to the chemical parameters NH4+-N content and NH4+-N/NO3--N ratio. In fact, these chemical parameters evidenced as important in the quality assessment of an organic material, strongly correlated with the biological parameters. The same was not true for the majority of the humification indices, which proved inadequate to compare the quality of such diverse organic materials. This was demonstrated by a multivariate statistical treatment of data, performed with these results in combination with results from the Dewar self-heating test, respiration activity and germination index, obtained in previous studies. Concluding, in a similar scenario, where the organic materials in evaluation are varied, both in the raw material an in the stability of the organic matter, the quality should be assessed by the integrated use of both chemical and biological parameters.