Science Inventory

Suspect-screening analysis of a coastal watershed before and after Hurricane Florence using high-resolution mass spectrometry

Citation:

Hedgespeth, M., J. McCord, K. Phillips, M. Strynar, D. Shea, AND E. Nichols. Suspect-screening analysis of a coastal watershed before and after Hurricane Florence using high-resolution mass spectrometry. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 782:146862, (2021). https://doi.org/10.1016/j.scitotenv.2021.146862

Impact/Purpose:

Climate change is expected to bring more frequent and intense storms such as Hurricane Florence to the coastal plain region of North Carolina – this specific storm resulted in an extreme amount of rainfall. Our study shows that in eastern North Carolina the Jacksonville Land Treatment Site (LTS), a forested wastewater reuse site that spray irrigates treated wastewater over a large area of forest, was surprisingly resilient to Hurricane Florence and the extreme amount of rainfall received at the site. Under normal conditions, wastewater that is irrigated at the LTS, though treated, still contains chemicals which then enter the soil, groundwater, and eventually are released into streams located on the site and downstream of the site. We expected that the extreme rainfall from Hurricane Florence would result in a release of chemicals present in soils and groundwater on the site. However, Hurricane Florence appeared to dilute the chemicals in groundwater and streams on site and in streams downstream of the site. This chemical dilution likely also continued months after the storm due to emergency spraying conducted by LTS operators to lower the hurricane-diluted wastewater in its large storage reservoirs. The LTS was also able to cope with the large water influx in terms of the changes in groundwater levels below the surface. This indicates that forested water reuse systems similar to the LTS may also be robust to the increasing frequency of storms and extreme rainfall events brought about by climate change in the future, and that such events will not exacerbate chemical input from these systems into the environment.

Description:

On September 14, 2018, Hurricane Florence delivered ~686 mm rainfall to a 106 km2 watershed in coastal North Carolina, USA. A forested land treatment site comprises one third of the watershed wherein municipal wastewater effluent is spray-irrigated onto 8.9 km2 of forest. This communication provides insight for land treatment function under excess water duress as well as changes in organic chemical composition in on- and off-site waters before (June 2018) and after (September & December 2018) Hurricane Florence's landfall. We compare the numbers and relative abundances of chemical features detected using suspect screening high resolution mass spectrometry in waste-, ground-, and surface water samples. Values for upstream and receiving waters in September were lower than for sampling events in June and December, indicating an expected dilution effect across the watershed. Chemical diversity was greatest for all surface water samples in December, but only upstream surface water showed a dramatic five-fold increase in relative chemical abundance. Chemical abundance in on-site water and downstream surface water was equal to or lower than the September storm dilution effect. These data suggest that the land treatment system is functionally and hydrologically robust to extreme storm events and contributed to dilution of upstream chemical reservoirs for downstream receiving waters for months after the storm. Similar systems may embody one water reuse strategy robust to the increasing occurrence of extreme precipitation events.