Behavior of trace metals during composting of mixed sewage sludge and tropical green waste: A combined EDTA kinetic and BCR sequential extraction study in New Caledonia

Klein Perrine, Gunkel-Grillon Peggy, Juillot Farid, Feder Frédéric, Kaplan Hélène, Thery Gaël, Pain Anthony, Bloc Meryle, Leopold Audrey. 2023. Behavior of trace metals during composting of mixed sewage sludge and tropical green waste: A combined EDTA kinetic and BCR sequential extraction study in New Caledonia. Environmental Monitoring and Assessment, 195:589, 22 p.

Résumé : The aim of the study was to assess the impact of composting on the release dynamics and partitioning of geogenic nickel (Ni), chromium (Cr) and anthropogenic copper (Cu) and zinc (Zn) in a mixture of sewage sludge and green waste in New Caledonia. In contrast to Cu and Zn, total concentrations of Ni and Cr were very high, tenfold the French regulation, due to their sourcing from Ni and Cr enriched ultramafic soils. The novel method used to assess the behavior of trace metals during composting involved combining EDTA kinetic extraction and BCR sequential extraction. BCR extraction revealed marked mobility of Cu and Zn: more than 30% of the total concentration of these trace metals was found in the mobile fractions (F1 + F2) whereas Ni and Cr were mainly found in the residual fraction (F4). Composting increased the proportion of the stable fractions (F3 + F4) of all four trace metals studied. Interestingly, only EDTA kinetic extraction was able to identify the increase in Cr mobility during composting, Cr mobility being driven by the more labile pool (Q1). However, the total mobilizable pool (Q1 + Q2) of Cr remained very low, < 1% of total Cr content. Among the four trace metals studied, only Ni showed significant mobility, the (Q1 + Q2) pool represented almost half the value given in the regulatory guidelines. This suggests possible environmental and ecological risks associated with spreading our type of compost that require further investigation. Beyond New Caledonia, our results also raise the question of the risks in other Ni-rich soils worldwide.

Mots-clés géographiques Agrovoc : Nouvelle-Calédonie

Mots-clés libres : Composting, Trace elements, Sequential extractions, Kinetic extractions, XANES, New Caledonia, Organic amendments, Waste

Classification Agris : P02 - Pollution
Q70 - Traitement des déchets agricoles

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

Auteurs et affiliations

• Klein Perrine, CIRAD-PERSYST-UPR Recyclage et risque (NCL) - auteur correspondant
• Gunkel-Grillon Peggy, UNC (NCL)
• Juillot Farid, IRD (NCL)
• Feder Frédéric, CIRAD-PERSYST-UPR Recyclage et risque (FRA) ORCID: 0000-0001-8434-5193
• Kaplan Hélène, IAC (NCL)
• Thery Gaël, Université Paris-Saclay (FRA)
• Pain Anthony, IAC (NCL)
• Bloc Meryle, CDE (NCL)
• Leopold Audrey, IAC (NCL) - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/605251/)

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