Clark Magnet students dredge up positive sediment test results
Apparently, not everything is going down the drain.
Testing results from underwater sediment samples gathered by Clark Magnet High School students in September proved that certain conditions are, in fact, improving.
Students in an environmental geographic information systems, or GIS, class made an excursion to the mouth of the Los Angeles River and collected soil samples that later contradicted the group’s hypothesis about high mercury and lead levels in the water.
Water and soil from the Los Angeles River and surrounding area are getting cleaner and less toxic, according to test results, though there’s still room for improvement.
“It looks like some of the metals have gone down, so that was great news,” said Dominique Evans-Bye, the class instructor. “I was really happy to see that.”
The GIS class tested nine metals found around the Long Beach harbor area, looking to see if toxins were above the permissible exposure limits for marine sediment set by the National Oceanic and Atmospheric Administration.
Students made trips on Sept. 13 and Sept. 19 but only collected samples on the latter date aboard a Los Angeles County Office of Education’s marine science floating laboratory.
In all, 17 soil samples were collected with the goal of testing for pollutants in areas where a GIS class from Clark found high levels of contaminants in 2007.
The samples were tested at Long Beach State’s Institute for Integrated Research in Materials, Environments and Society.
Six of nine metals saw their totals drop in comparison to results from 2007, though the collection sample areas weren’t exactly the same.
“We hoped that the results would be lower than the 2007 level, and it was nice to see that most were,” student Shaye Holladay McCarthy said. “Some did go up, too, so it was great to have that info.”
Metals such as cadmium, lead and mercury had a decreased presence.
For instance, the permissible exposure limit for cadmium is 4,210 parts per billion, or ppb.
In 2007, the GIS class collected nine samples that were over 3,000 ppb, while four nearly reached the permissible level. This year, all of the 17 samples were less than 2,000 ppb, with 10 under 1,000 ppb.
Fourteen of 17 results for mercury, which has a permissible level of 700 ppb, were below 200 ppb, with none higher than 300 ppb.
Lead’s exposure level of 112,000 ppb wasn’t close to being broached — the highest samples were just over 75,000 ppb.
The most problematic metal was zinc, as seven of 17 samples were either at the permissible limit of 271,000 ppb or above.
The students conducted the sampling and testing as part of their land-and-water entry submission for the Lexus Eco Challenge contest.
Information from testing was also forwarded to the Los Angeles Police Department’s dive team, which often does diving in the same waters.
Since the trip, Evans-Bye’s GIS students have been on tour at various events, explaining their methods and results.
Students spoke at the California Science, Technology, Engineering and Mathematics showcase Oct. 28 and at the Environmental Systems Research Institute’s ocean GIS forum in Redlands on Wednesday.
“We’re honestly all amazed by this,” Holladay McCarthy said of the findings. “There’s always a bit of nerves, which isn’t a bad thing. But it’s fun to show our work and what we’ve accomplished.”
