Impacts of shale gas wastewater leaks on neighboring crops: Physiological and morphological responses of tomatoes

As shale gas extraction expands, the volume of flowback and produced water (FPW) from hydraulic fracturing increases, raising concerns about the potential ecological risks of leaks. In this work, we mixed tap water with different proportions of FPW to simulate various leak scenarios. Tomatoes were irrigated using these mixtures or using FPW treated with multi-stage pre-treatment and advanced membrane technologies to assess the effects on tomato seed germination, plant vigor, element accumulation, and fruit gene expression. Compared to tap water irrigation, all three dilution ratios of FPW inhibited seed germination and growth to varying degrees, significantly reduced tomato biomass and fruit yield, and caused the fruit to exceed safe limits for Pb and Cr. In the lowest dilution group, the germination rate was only 17 %, and total biomass decreased by 55 %. Even in the highest dilution group, fruit yield was 11 % lower than the control. Additionally, the dilution showed high salt accumulation toxicity, with yellowing at the edges of the leaves. Applying treated FPW accelerated tomato growth and increased the yield of tomato hairs, with total biomass rising by 38 %. Finally, a large number of differentially expressed genes were detected in the fruits irrigated with FPW. These genes are irelated to carbon and nitrogen metabolism, affecting the synthesis of carbohydrates and proteins. These findings provide insights into the risks associated with shale gas FPW leakage and offer guidance for the reuse of treated FPW.