16 July 2011

Woodland Mortality from Land Application of Waste Hydrofracturing Fluid

Posted by John Freeland

The latest issue of the Journal of Environmental Quality contains a peer-reviewed research paper documenting the effects of flowback hydrofracturing fluid on a wood lot. The results reported in Land Application of Hydrofracturing Fluids Damages a Deciduous Forest Stand in West Virginia (Mary Beth Adams, USDA Forest Service Northern Research Station in Parsons, WV) indicate the effects of a June 2008 “frack water” dosing were swift and noticeable. From Adams:

During land application of the hydrofracturing fluids, field personnel observed damage symptoms on ground vegetation (herbaceous vegetation, small trees, shrubs), including browning and wilting of foliage, leaf scorch and curling, and leaf drop. Within a few days, almost 100% of ground vegetation within the perimeter of the fluid application area had died.

Within 7 to 10 d, overstory trees began showing similar damage symptoms, and many of them dropped their foliage, as evidenced by a large amount of green leaves on the forest floor. Leaf fall mass was estimated to be 714 kg ha−1, or about one quarter that recorded in a normal autumn leaf fall…

In late spring 2009, 51% of the trees within the perimeter had no foliage. By summer 2010, 2 yr after fluid application, 56% of the trees within the fluid application area were dead.

In the hydrofracturing process, water is typically mixed with sand and chemicals, including proprietary ingredients, then injected into shale formations. When successful, the high-pressure injection increases permeability and releases natural gas. After injection, most of the fluid flows back to the ground surface. This “flowback” water picks up additional dissolved and suspended “souvenirs” from its journey under ground, notably salts.

Adams concludes that high concentrations of sodium and calcium chlorides likely caused the damage to the trees and understory during the Forest Service experiment. The proprietary chemical ingredients of the fluid, however, and other potential contaminants derived from of the well cuttings are unknown. The study didn’t include a thorough, and expensive, chemical assay.

The problem with disposing brines in a forest is osmotic stress. The salts leach into the soil and cause osmotic pressure that deprives the roots of normal water uptake. The trees respond to what resembles severe drought by shedding leaves. Leaves contain stomata (stomates) that release water vapor during photosynthesis. Dropping leaves is a water conservation strategy.

Because the leaves need water to carry on photosynthesis, and the roots need photosynthate (products) normally sent down the phloem from the leaves, the tree starves. In the Adams experiment, American beech (Fagus grandifolia) had the highest mortality, while red maple (Acer rubrum) was less affected.

West Virginia, Colorado, and Arkansas, according to Adams, allow land disposal of hydrofracturing fluid. The initial salt and iron concentrations, and pH of the fluid used in the study described here met the conditions required to obtain a land disposal permit from the State of West Virginia.

Bottom line, a permit is no guarantee of protection and the environmental regulations pertaining to hydrofracturing need some improvement.

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