Plants and soil amendments for remediation of soil affected by synthetic oil and gas production wastewater

Oil and gas production water (PW) is brought to the surface when hydrocarbon reservoirs deep within geologic strata are extracted. Large volumes of PW present environmental challenges when released to the land surface due to high levels of salinity and potentially toxic elements. The effects of PW on soil chemical properties and plant response were investigated in both growth chamber and field studies. In the growth chamber, wheat (Triticum aestivum) and red clover (Trifolium repens) were grown in soil which was flooded with synthetic PW. The PW was enriched with several metals (Na, Cu, Cr, Pb) and had an acidic pH (2.5) and EC of 33,650 dSm-1. Soil amendments included food waste compost, composted biosolids, gypsum (CaSO4) and NPK 10-10-10 fertilizer. Metal concentrations in soil and plants were determined using flame atomic absorption spectrophotometry. The food waste compost provided for maximal uptake by clover of Cu, Cr and Pb compared to all other amendments. In several soil treatments both wheat and clover behaved as metal hyperaccumulators having high bioconcentration factors (BCF, ratio of metal concentrations of plant tissue to soil). Clover was the most efficient in accumulating Cu and Cr in shoots (BCF = 22.2 and 30.6, respectively). Greatest metal uptake in both plant species occurred in either the biosolids or compost treatment. In a field study, plots were flooded with synthetic PW and grown to corn (Zea mays) and a turf mixture (Kentucky bluegrass, Poa pratensis and perennial ryegrass, Lolium perenne). Both corn and turf accumulated substantial soil Cu and Pb. Corn experienced significant die-off; however, turf survived the PW application. Turf mixtures, clover and/or wheat may be suitable for phytoremediation of PW-affected soil. Addition of organic amendments to soil may enhance metal uptake by plants