Killing Hour - Lisa Gardner [118]
“It can.” Knowles glanced up at her. “Basically, I’m measuring the amount of microsiemens per centimeter in the water, which gives me an idea of the dissolved content. Water on its own has no electrical conductivity. But water that has a lot of salt or other dissolved minerals in it will have a higher level of conductivity. More microsiemens per centimeter. So, in a roundabout way, we’re trying to tell where this water has been.”
He looked at the meter, then pulled the probe from the sample. “All right. According to my handy dandy salinity meter, this water has a reading of fifteen thousand microsiemens per centimeter. So, bearing in mind all my earlier caveats, what does that tell us?”
They all looked at him blankly, and he generously filled in. “The water has good conductivity. Not high enough to be salt water, but there’s a fair amount of dissolved content in this sample. Maybe minerals or ions. Something that conducts electricity better than water alone.”
“The water is contaminated?” Mac asked hesitantly.
“The water is high in dissolved content,” Knowles reiterated stubbornly. “At this moment, we can’t conclude anything more than that. Now, the logical thing would be to run tests for various minerals, which might answer your question. But we can’t do that, so let’s try pH.”
He set aside the first meter and inserted a second. He watched the meter, then frowned at it, then pulled out the tip and muttered, “Goddamn probe. Hang on a sec.”
He wiped the tip. Blew on the tip. Then gave the whole thing a small whack with his hand. With a grunt of satisfaction, he finally returned the probe to the water. The second time didn’t make him any happier.
“Well, shit on a stick, this is no good.”
“What’s wrong?” Kimberly asked.
“Sample must be too small for the probe, or my meter’s out of whack. To believe this thing, the pH is three-point-eight, and that just ain’t happening.”
This time, he banged the probe twice against the desk. Then he tried again.
“What does three-point-eight mean?” Mac asked.
“Acidic. Very acidic. Eat-holes-in-your-clothes level of acidic. Basic is a perfect seven-point-oh. Most fish and algae need at least six-point-five to survive; snails, clams, and mussels require seven-point-oh; while insects, suckers, and carp can go as low as six. So when we’re testing ponds and streams with any sort of aquatic life, generally we’re at least in the sixes. Now, in Virginia, rainfall has a pH of four-point-two to four-point-five, so pure rainwater would test low, but we know this isn’t pure rainwater thanks to the salinity test. Three-point-eight,” he was still shaking his head. “That’s ridiculous.”
He glanced at the meter again, gave a final growl of disgust, and yanked out the probe.
“What’s it saying?” Mac asked intently.
“Same garbage as before, three-point-eight. I’m sorry, but the sample has got to be too small. That’s all there is to it.”
“You’re three for three.” Kimberly spoke up quietly. “Three tests, three similar results. Maybe the water is that acidic.”
“It doesn’t make any sense, especially when you consider that any pH reading we’re getting now is actually higher than the original pH at the source. Frankly, we just don’t see pH readings below four-point-five. It doesn’t happen. Well, except maybe in cases of acid mine drainage.”
Mac straightened immediately. “Tell us about acid mine drainage.”
“Not much to tell. Water spills out of the mine or goes through tailings of the mine, getting contaminated as it goes. The pH ends up extremely low, possibly in the twos.”
“And that would be extremely rare? Something unusual in this state?”
Knowles gave Mac a look. “Buddy, there aren’t many places in the world that have pH readings in the twos, let alone in the state of Virginia.”
“Where is this mine?” Kimberly said urgently.
“You mean mines, s as in plural, as in coal mines. We’re loaded with them.”
“Where?”
“Southwestern Virginia mostly. There’s a good seven counties, I think.” Knowles was looking at Ray for confirmation.