Heavy Metal Concentrations and Basal Respiration in Contaminated Substrates used in the Cuban Urban Agriculture

• Published in: Water, air, and soil pollution Vol. 232; no. 3
• Main Authors: Alfaro, Mirelys Rodríguez, Martín, Bernardo Calero, Ugarte, Olegario Muñiz, García, Anabel Rodríguez, da Silva, Fernando Bruno Vieira, do Nascimento, Clístenes Williams Araújo
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-03-2021; Springer; Springer Nature B.V
• Subjects: Agricultural pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biological activity; Cadmium; Climate Change/Climate Change Impacts; Earth and Environmental Science; Environment; Environmental monitoring; Farming systems; Farms; Food; Food contamination; Food safety; Heavy metals; Hydrogeology; Incubation period; Lead; Mercury; Mercury (metal); Metabolism; Metal concentrations; Microbial activity; Microbial contamination; Microorganisms; Morphology; Municipal solid waste; Pollutant load; Pollution; Pollution index; Pollution load; Refuse and refuse disposal; Respiration; Safety and security measures; Soil; Soil contamination; Soil microbiology; Soil microorganisms; Soil quality; Soil Science & Conservation; Solid impurities; Solid wastes; Structure-function relationships; Substrate inhibition; Substrates; Urban agriculture; Urban farming; Water Quality/Water Pollution; Zinc; Cadmium; Trace elements; Metal contamination; Mercury
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-021-05073-8

The input of heavy metals in agricultural systems depresses the soil quality and compromises the food safety owing to crop contamination. Metals also affect the structure, morphology, function, and activity of microorganisms in soils and substrates. Heavy metals can inhibit basic processes of microbial metabolism such as respiration. The present study aimed (i) to assess the relationship between cadmium (Cd), lead (Pb), zinc (Zn), and mercury (Hg) in contaminated organic substrates used in the Cuban urban farms (the so-called
organopónicos
) and the basal respiration; (ii) to study the changes in the basal respiration of substrates added with increasing metals concentrations; and (iii) to evaluate how increasing Hg concentrations in the substrates affect the basal respiration during a 135-day period. In general, the Cd, Pb, and Zn concentrations in the substrates of the
organopónicos
from Havana province are within the permissible values for organic substrates, while substrates prepared from municipal solid wastes from Havana and all substrates from Guantánamo province had metal concentrations exceeding the maximum permissible levels. The basal respiration was correlated negatively with the pollution load index. The toxic effect on microorganisms was also dependent on the metal concentration, the substrates, and the metal considered, with Cd and Hg having the most significant effect on diminishing microbial activity. Although Hg contamination reduced the basal respiration in the first 24 h of substrate-metal contact, at the 135th day of incubation, the basal respiration was higher than non-polluted substrates. This finding suggests the high metabolic activity of metal-resistant microorganisms in the substrates.