A Facility to Investigate Effects of Elevated Soil Gas Concentration on Vegetation

Abstract

A facility has been developed at the University of Nottingham at which natural gas can be injected into soil to investigate the effects on the soil ecology and on the growth and development of plants. The facility involves 18 plots, 12 of which are equipped with a regulated and metered gas supply. The gas is released from a diffusive point source 1 m below the centre of each plot. Permanent pasture grass, wheat and bean were gassed from gas was injected into additional plots of each species to determine the effects of a new leak on a fully established crop. Spatial and temporal variability of soil gas concentrations were determined by two complementary methods. First, by daily extraction of soil gas samples from permanently buried sample pipes that come to diffusive equilibrium with the adjacent soil gas concentration. Second, by intermittent extraction of soil gas samples from bar holes inserted on a 50-cm grid. Contour plots of spatial variation were then constructed from the bar hole data.Methane (CH 4 ) concentrations near the centres of the plots were variable. They could reach values of up to 80% gas, but decreased rapidly away from the area of peak concentration. No relationship was found between gas flow rate or soil gas concentration and atmospheric pressure or other meteorological parameters. Soil structure affected gas dispersion, and an inverse relationship was found between CH 4 and O 2 concentrations.The grass showed visible symptoms within 44 days, whereas wheat and bean developed symptoms after four months. These symptoms included a circle of chlorosis in grass and poor development and leaf chlorosis for the wheat and bean. When the same species were gassed from mid-May; the wheat and bean showed no visible symptoms but the late-gassed grass also developed a further circle of yellowing.

Plant Family-Specific Impacts of Petroleum Pollution on Biodiversity and Leaf Chlorophyll Content in the Amazon Rainforest of Ecuador

“…Organic molecules from crude oil can penetrate living plants through their roots and leaves from where the hydrocarbon compounds can be transported into the plant vascular system and intercellular spaces leading to cell and tissue damage. Cell injury can be the principal cause of photosynthetic inhibition because hydrocarbons tend to accumulate in the chloroplasts, which explains the reduced photosynthetic activity in vegetation affected by hydrocarbons [5–7, 11, 16–18]. On one hand, hydrocarbons in plants reduce plant transpiration.…”

Detecting the effects of hydrocarbon pollution in the Amazon forest using hyperspectral satellite images

“…Experimental data generated under controlled conditions have demonstrated that plants exposed to pollutants exhibit stress symptoms (Horvitz, 1982(Horvitz, , 1985Smith et al, 2005a) which manifest themselves primarily in lower levels of chlorophyll content. Stress levels do, however, depend on plant tolerance to both concentration and exposure period (Smith et al, 2005b;Noomen et al, 2006).…”

El efecto de los gases de relleno sanitario en el crecimiento vegetal

“…La emisión de biogás producto de la DA de la FO de los RSU se ha ligado con inhibición de la germinación, crecimiento raquítico y pérdida de la vegetación en RESA (Smith et al 2005), sin embargo los estudios realizados son escasos y se desconoce la manera en la que cada uno de esos gases del biogás alteran el metabolismo vegetal, ya sea a nivel de la raíz o de la parte aérea.…”