How batteries affect soil? Emergency

[handsomegirl@]

I heard that batteries can affect soil. I wanted to examine this and started to investigate into this problem.
I did experiment: I planted bean into 2 pots- 1st pot: soil without batteries, and 2nd pot: soil was mixed with batteries. After 4 days, plant from 1st pot grew normally and plant from 2nd pot grew not as well as the 1st pot (they were in the same place, conditions, etc.)
Can anyone explain me how batteries affect soil? I must present this experiment in 2 days as my chemistry project.

 

[LtStorm]

Well, I don't think they'd have a major effect unless they were broken open.

What kind of batteries, though? Just regular alkalines?

 

[handsomegirl@]

Regular alkines. I used AAA size alkaline batteries and they were opened.

Batteries contain Lead Acid and this toxic heavy metal affects seriously our environment, right?

 

[LtStorm]

Alkaline batteries are fairly inert. They're just zinc powder and manganese dioxide with potassium hydroxide (a.k.a. caustic potash) as an electrolyte. The only part of them that runs a risk of affecting plants is the caustic potash, which can screw with the alkalinity of the soil (but not by a whole lot; potash is found naturally in the soil in certain locations). This is why in most places in America you can just toss alkaline batteries in the trash, rather than having to dispose of them in a special manner (California has different laws that I believe are similar to Europe's).

As for the batteries containing lead, acid, and other toxic heavy metals; you're thinking of car batteries, which are very, very different from alkaline batteries. Those batteries contain lead and lead (IV) oxide with sulfuric acid as an electrolyte, all of which are nasty stuff. Lead, along with other heavy metals, does affect living things--plants and humans alike. Sulfuric acid, obviously, also will affect them and is nasty stuff if it leaks into the ground.

Of course, there are a ton of other types of batteries that all use different chemicals and metals in them from Lithium-ion batteries to NiCd Nickel-Cadmium batteries. All of these, obviously, will have different effects on plants, humans, and the environment at large.