With the growth of gardens in the city, organizations such as the Center for Food Safety have also wondered about the effects of water pollution on garden plants on urban areas. This worry isn't new. Since the early 1980s the Environmental Protection agency has had concerns about the effects of acid rain and other water pollution on plants.
Although there is evidence that plants can be affected by water pollution, today plants are just as likely to be used as a solution to water pollution as they are seen to be affected by the problem. Studies by companies such as Exxon and DuPont and the U.S. Department of Energy are showing promise in the field of phytoremediation. In this process, plants are seen as a natural filter, absorbing pollution and leaving clean water behind.
Other organizations such as the Union for Concerned Scientists say that city gardens provide a way to block some of the pollution from entering local water tables by preventing runoff. Runoff from sources such as rain, burst pipes or open fire hydrants is a significant source of water pollution. Especially when this water picks up pollutants from sources such as parking lots or highways. Gardens planted near these locations can absorb the water so that the pollutants stay in those locations rather than being carried into the local sewer systems.
Just like human beings, plants can be affected by the presence of pollutants. Because plants absorb many of their nutrients through water, the effects of acid rain and other pollutants can especially harm them. According to the EPA, plants that are exposed to acid rain are less able to absorb nutrients through their root systems. This weakens the plant's overall structure. Additionally, polluted water can contain minerals such as aluminum that can harm the plant if it absorbs them.
Plants that are regularly fertilized are less prone to harm from lack of nutrients caused by acid rain pollution. This is because gardeners regularly fertilize their crops, both with liquid fertilizer, natural amendments such as compost and minerals such as calcium and lime. The fertilizers frequently replace minerals that are leeched out of the soil due to acid rain.
Although it may seem that vegetables that take up water from polluted sources would be filled with those pollutants themselves, this is not always the case according to Scott Cunningham of DuPont Research, a branch of DuPont researching phytoremediation. Cunningham said that many plants are loaded with microbes and fungi that break down chemicals found in water pollution, while other plants act as filters by keeping chemicals out of the fruit of the plants.