Phytotoxicity of Phenanthrene and Its Nitrogen Polycyclic Aromatic Hydrocarbon Analogues in Ageing Soil

Abstract

The impacts of phenanthrene and its nitrogen-containing analogues (N-PAHs) on seedling emergence and plant biomass of two terrestrial plant species, Lactuca sativa (lettuce) and Lolium perenne (rye grass), were investigated in soil over a 21-day exposure period. The data over 0-90-day soil-chemical contact time revealed that seedling emergence and plant biomass were significantly affected by N-PAHs even at the lowest concentration of 10 mg/kg. N-PAH amended soils showed greater inhibitory effects on seedling emergence and early plant biomass than phenanthrene amendments with incubations overtime. The degree of inhibition (% inhibition) on seedling emergence over time was 33.3 % (lettuce) and 46.7 % (rye grass) for the phenanthrene, and 53.3 % (lettuce) and 93.3 % (rye grass) for the N-PAHs, respectively, suggesting greater sensitivity of seedling emergence and early plant biomass on N-PAH-contaminated soil. The results from this study will contribute to data gaps for poorly managed chemicals/chemical groups for environmental risk assessment and might be useful in the development of new approaches for hazard assessment of contaminated systems.

Assessment of the effects of phenanthrene and its nitrogen heterocyclic analogues on microbial activity in soil

“…From the results, it can be seen that increased soil-contaminant-contact time showed removal of chemicals as well as reductions in the extraction of the remaining chemicals in soil; this may be due to volatilization, sorption and/or biodegradation (Welp and Brümmer 1999 ; Semple et al 2003 ; Anyanwu and Semple 2015b ). In soil for example, organic contaminants are known to undergo irreversible sorption.…”

“…Further, Welp and Brümmer ( 1999 ) reported that a decrease in the bioavailability/extractability of organic contaminants is mostly due to sorption. In addition, biodegradative processes are known to contribute to loss (Towell et al 2010 ; Anyanwu and Semple 2015b ). Irrespective of the low concentrations measured, the inhibitory and/or stress effects on soil indigenous microbes were still obvious.…”

“…These chemicals are semi-volatile, persistent, toxic, ubiquitously distributed (Švábenský et al 2009 ; EC 2011 ; Anyanwu et al 2013 ), and are widely produced by industrial activities (petroleum derived, combustion sources and biological sources) (Švábenský et al 2009 ; Hazardous Substance Data Bank 2010 ; EC 2011 ; Anyanwu and Semple 2015a ). Due to their widespread distribution in the environment, and their physico-chemical properties, they are potentially carcinogenic, mutagenic, teratogenic and genotoxic (Bleeker et al 2002 ; EC 2011 ; IARC 2012 ; Anyanwu and Semple 2015a , b , c ). It has been reported that not only homocyclic aromatic compounds, but also heterocyclic compounds contribute to the changes in microbial activity in soil (Anyanwu and Semple 2015a , b ).…”

“…Due to their widespread distribution in the environment, and their physico-chemical properties, they are potentially carcinogenic, mutagenic, teratogenic and genotoxic (Bleeker et al 2002 ; EC 2011 ; IARC 2012 ; Anyanwu and Semple 2015a , b , c ). It has been reported that not only homocyclic aromatic compounds, but also heterocyclic compounds contribute to the changes in microbial activity in soil (Anyanwu and Semple 2015a , b ). From both toxicological and epidemiological studies, many heterocyclic aromatics have shown to be highly toxic (Hazardous Substance Data Bank 2010 ; EC 2011 ).…”

“…From both toxicological and epidemiological studies, many heterocyclic aromatics have shown to be highly toxic (Hazardous Substance Data Bank 2010 ; EC 2011 ). Although the available published data are limited, there are considerable evidence indicating their toxicity to humans and ecological receptors (Bleeker et al 2002 ; Hazardous Substance Data Bank 2010 ; EC 2011 ; Brar et al 2010 ; IARC 2012 ; Anyanwu et al 2013 ; Anyanwu and Semple 2015a , b , c ).…”