Car parts, motor oil, paint cans, plastic jugs, and other manmade trash washed in or tossed in the territory’s ghuts are likely to blame for elevated levels of toxins in the soil, according to a first-of-its-kind study published this week.
Brittany Lancellotti, a researcher with Virgin Islands EPSCOR, found high concentrations of chromium, arsenic nickel, lead, mercury, zinc, and other pollutants in the dry roadside stream beds.
Lancellotti said more study was needed to be certain about the relationship between ghut garbage and the chemicals. The presence of improperly discarded items — like vehicle batteries — and the proximity to heavily traveled roadways and shopping centers matched concentrations of the heavy metals and volatile organic compounds. These compounds, called VOCs, can come from car exhaust, heavy industries like oil refining, paints and solvents, or even cooking oils.
Lancellotti, whose background is in soil science and watershed hydrology, was setting up equipment for another study when she and researchers from the University of the Virgin Islands noticed debris in the ghuts, she said.
“We were thinking, what is the human impact looking like on the guts in terms of heavy metals and VOCs that could be leaching from the trash and all the improperly discarded things we were finding in the ghuts,” Lancellotti said Friday. “We decided to study it.”
Lancellotti and team picked 30 sites on St. Croix to test for 12 heavy metals. All the study sites were near roads, most near commercial centers, so it was not clear how much of these chemicals existed in areas of the island with less human activity.
Many of the ghuts are dry most of the year, filling with water during storms. This stormwater picks up pollutants from roads and parking lots, sweeping chemicals and litter along the way. This mixes with trash purposefully thrown in.
“Because we have these hot spots, from what the statistics are showing us, we think the illegal dumping part is a plausible explanation because it’s not super widespread,” she said. “That is kind of a positive spin on it because we can target individuals. We don’t know who is doing this but we can try to spread more awareness and say, look, before you dump this car battery or dump this bag of trash, you should know it’s maybe going downstream or going into the groundwater or something like that.”
The study, published in Springer Nature-affiliated Scientific Reports, said some of the chemical concentrations found went beyond levels considered safe:
“Elevated lead, mercury, and zinc concentrations were correlated with commercial building density, suggesting an unnatural origin of these elements in stream bed sediment. At some sites, levels of arsenic, cadmium, chromium, nickel, lead, thallium, or zinc exceeded regulatory limits. The most prevalent VOCs at both developed and undeveloped sites were benzene and toluene. Sub-groups of heavy metals identified by principal component analysis indicated potential pollution sources, including fuel combustion (chromium, nickel, arsenic, selenium), vehicle exhaust, oil refining, and gasoline leaks (2-butanone and xylenes), and plastics (acetone and styrene). Our results suggest USVI intermittent streams require further research attention and intervention strategies for pollution reduction.”
Some of the chemicals could also be from corroded pipes or metal structures. Lancellotti hoped to continue her work by studying guts far from commercial or industrial centers as a way of comparing.
“It’s really an unknown,” she said. “We really want this piece of research in particular to really highlight how ghuts are ignored in a research and a conservation sense. We don’t want to alarm people in terms of soil toxicity but we do want to spread the word about how important guts are as links between the land and the sea.”
She hoped raising awareness would help change behavior about what goes in the ghuts and spur future studies.
“We really do want to spread the word on how important ghuts are in terms of connectors between the land and the sea. You know, we don’t know a lot of that in the Virgin Islands. There are many many examples from around the world of how the land and the sea are interconnected, and that’s by streams — even if they don’t run all year round like other systems. There’s still evidence that they are probably really important so we should protect them. We shouldn’t dump trash in them,” she said. “They also are really an important point to connect surface and groundwater.”
