Does land that was an orchard in the 1940s still carry arsenic today? Orchards used arsenic-based pesticides for decades. Those chemicals can linger long after the trees are gone.
You collect soil samples from three school campuses with different land-use histories. One school was built on a former orchard. You dig 15 cm deep at three spots per campus. An Innovox system reads each sample's arsenic level in parts per million (ppm).
The former orchard site shows an average of 58.7 ppm of arsenic. The other two schools show much lower levels.
Hypothesis
The hypothesis is that locations that were used during the 1940s as orchards will have the most arsenic in the soil.
Heavy metals are dense metal elements that can poison soil for decades. Arsenic, a heavy metal used in pesticides sprayed on orchards in the 1940s, left contamination that persists in the ground today. In this project, a former orchard site shows an average of 58.7 ppm of arsenic, while other school sites show much lower levels.
Harmful chemicals can get into the ground and stay there for decades after their original use ends. Arsenic-based pesticides sprayed on orchards in the 1940s still make the soil unsafe where schools now stand. This project collects soil samples from campuses with different land-use histories to measure how long those toxins linger.
Arsenic is a toxic element that lingers in soil long after the source is gone. Orchards in the 1940s used arsenic-based pesticides, and soil testing shows those chemicals are still present decades later. One former orchard site measured an average of 58.7 ppm of arsenic — far above levels found at sites with different land-use histories.
Pesticide residue — the trace of bug-killing spray that stays in soil long after it was used — can persist for generations after spraying stops. Soil samples dug 15 cm deep at a school built on former orchard land showed arsenic levels averaging 58.7 ppm. Schools on land without orchard history showed much lower arsenic, revealing how these chemical traces linger in soil decades after their last application.
Method & Materials
You will plot on a map where to take samples, dig a 15 cm. deep hole with a clean shovel, remove 125 ml. of dirt from the bottom of the hole, put dirt in a plastic sandwich bag, label the bag, and test the samples with an Innovox system.
You will need 15 plastic bags, a shovel, a garden rake, a testing kit, a black permanent marking pen, a measuring cup, and an Innovox system.
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The results showed that Selah Intermediate School had the most arsenic and it was the only school that was an orchard in the 1940s. This suggests that the hypothesis should be accepted.
Why do this project?
This science project is interesting because it shows how land use in the past can affect the environment today.
Also Consider
Variations to consider include testing more schools and samples, testing the samples more than once, and testing the samples before the ground freezes.
Full project details
Additional information and source material for this project are available below.
