Leaf Spectra Changes of Plants Grown in Soils Pre- and Post-Contaminated with Petroleum Hydrocarbons

Abstract

Leaks from accidents or damage to pipelines that transport liquid petroleum hydrocarbons (PHC) such as gasoline and diesel are harmful to the environment as well as to human health, and may be hard to detect by inspection mechanisms alone when they occur in small volumes or persistently. In the present study, we aim to identify spectral anomalies in two plant species (Brachiaria brizantha and Neonotonia wightii) linked to contamination effects at different developmental phases of these plants. To do so, we used spectroscopy and remote sensing approaches to detect small gasoline and diesel leaks by observing the damage caused to the vegetation that covers simulated pipelines. We performed a contamination test before and after planting using gasoline and diesel volumes that varied between 2 and 16 L/m3 soil, in two experimental designs: (i) single contamination before planting, and (ii) periodic contaminations after planting and during plant growth. We collected the reflectance spectra from 35 to approximately 100 days after planting. We then compared the absorption features positioned from the visible spectral range to the shortwave infrared and the spectral parameters in the red edge range of the contaminated plants to the healthy plants, thus confirming the visual and biochemical changes verified in the contaminated plants. Despite the complexity in the indirect identification of soil contamination by PHCs, since it involves different stages of plant development, the results were promising and can be used as a reference for methods of indirect detection from UAVs (Unmanned Aerial Vehicles), airplanes, and satellites equipped with hyperspectral sensors.

Potential effects of soil petroleum contamination on decomposition of Artemisia annua plant litter

“…7,8 According to structural equation modeling, the inhibitory effects of petroleum contamination on litter decomposition are mainly attributable to changes in litter chemical traits, characterized by increases in their lignin and TPH contents. Subsequently, these changes, also observed in studies by Al-Areeqi et al, 6 Gürtler et al 15 and Fig. 2 Activity of litter-decomposing enzymes in different litters.…”

“…Subsequently, these changes, also observed in studies by Al-Areeqi et al , 6 Gürtler et al . 15 and Sotnikova et al , 16 led to significant decreases in litter lignocellulases. Regarding the effects of TPH in litter, A. annua can absorb contaminants from the soil, transport them to aboveground organs, and sequester them in tissues.…”

“…11,13,14 Furthermore, both spectral and chemical analyses have indicated that soil petroleum contamination signicantly increases the lignin content of plant leaves and roots while also remarkably affecting the contents of cellulose and soluble components of leaves. 15,16 Moreover, several studies have reported that petroleum fraction contamination can signicantly reduce the nitrogen and/ or phosphorus content of the leaves of Vicia faba, Triticum aestivum, and Avena sativa while increasing the contents of copper and manganese in these species. [17][18][19] These alterations are likely to impact the availability 20,21 and toxicity of dead plant residues to microbial decomposers, consequently affecting litter decomposition.…”