Effects of humic acids from landfill leachate on plants: An integrated approach using chemical, biochemical and cytogenetic analysis

Abstract

Biological process treatment of landfill leachate produces a significant amount of sludge, characterized by high levels of organic matter from which humic acids are known to activate several enzymes of energy metabolism, stimulating plant growth. This study aimed to characterize humic acids extracted from landfill sludge and assess the effects on plants exposed to different concentrations (0.5, 1, 2 and 4 mM C L) by chemical and biological analysis, to elucidate the influence of such organic material and minimize potential risks of using sludge in natura. Landfill humic acids showed high carbon and nitrogen levels, which may represent an important source of nutrients for plants. Biochemical analysis demonstrated an increase of enzyme activity, especially H-ATPase in 2 mM C L landfill humic acid. Additionally, cytogenetic alterations were observed in meristematic and F cells, through nuclear abnormalities and micronuclei. Multivariate statistical analysis provided integration of physical, chemical and biological data. Despite all the nutritional benefits of humic acids and their activation of plant antioxidant systems, the observed biological effects showed concerning levels of mutagenicity.

Humic Substances Mitigate the Impact of Tritium on Luminous Marine Bacteria. Involvement of Reactive Oxygen Species

“…The presence of phenolic and other redox-active functional groups in HS accounts for their capability of reducing toxic impacts of organic and inorganic oxidizers [ 9 , 10 , 11 ], similar to the redox activity of other natural phenolic compounds [ 12 , 13 ]. The biological activity of HS is intensively discussed now [ 14 , 15 , 16 , 17 , 18 , 19 ].…”

Characterization of wastewater from landfills - amount and type of humic substances extracted from leachate

“…These GI values were lower than the value obtained for HS commercial liquid fertilizer Humistar® that reached 154%. It is possible to said that HS and HA showed absence of phytotoxicity because the GI are greater than 60% [30] and confirmed that the humic susbtances have a positive effect in the plant growth [31]. Overall, it seems that leachate may be used to produce liquid organic fertilizers an important way to valuing this type of waste.…”

Correlation Biological Activity and Physicochemical Properties of Humic Acids in Aqueous Solutions

“…At the same time, there are quite numerous data in the literature on the negative effect of HS on the state of living organisms. For example, HS can also inhibit plant growth [12], cause expression of heat shock proteins [13,14], modulate biotransformation enzymes because of oxidative stress [15][16][17], inhibit photosynthetic oxygen release in plants [18][19][20][21], alter ionic homeostasis in freshwater animals [22][23][24][25], as well as have hormonelike effects on water crustaceans [26,27], amphibians [28], fish [29,30] and other animals [31,32].…”