Page 4 of In Darkness and Dank

Dammit.

Grumbling at his erection, Kittisak crawled off the cot to get dressed. He checked his boots twice before putting them on, and then he went to find Browning and Hutte.

They were waiting in the tent they shared together, and they sat Kittisak down as soon as he stepped inside. Kittisak immediately knew something was wrong. Browning’s usual jovial attitude was somber and Hutte’s brow was wrinkled up to his hairline, so the news couldn’t be good.

“What’s wrong?” Kittisak asked. “Did Bissell and Zimm drown themselves trying to hunt a Yacuruna again?”

“Nothing so fortunate,” Hutte grumbled.

“It’s about my theory of acidity and water sediment,” Browning said glumly. “You remember that there are three types of water here in the Amazon, yes? Blackwater, whitewater, and clearwater?”

“Yup, even though they don’t make any sense.” Kittisak shooed away a bug that seemed determined to investigate his nostrils. “Like, the Rio Solimões is whitewater even though it’s brown.”

“It makes perfect sense once you accept that it has nothing to do with color,” Browning tutted. “Now, the type of water we study is important because we’re looking for a specific pH level to find our acid-loving bacteria friends. Rivers like the Solimões are packed with sediment and very rich in nutrients, and I had posited that we’d find the bacteria we want thriving.”

“That’s where I got your twenty-two samples the other day, right?” Kittisak recalled having to scale down a very treacherous embankment to get said twenty-two samples, and he had cursed Browning every step of the way. “Down by that big log?”

“Indeed!” Browning nodded. “Whitewater tends to move very fast, so the sediment doesn’t have a chance to settle like it does in clearwater. That’s why whitewater rivers are such a striking brown color. Now, the samples you gathered were very acidic, so I thought my theory was correct.”

“I’m sensing a but here.”

“A big but,” Hutte chimed in. “The control samples we got when we were on the boat in the middle of the river were almost perfectly neutral.”

Kittisak stared.

“It means that the area you took your samples from was only a small pocket of acidity that doesn’t represent the true pH of a whitewater river,” Hutte explained. “This is the third time we’ve encountered these isolated areas of acidity, and it’s always where part of the current has been slowed down, like a creek or a small bay. A higher sediment content does not indicate a higher level of acidity.”

“So, it’s only the slower water that’s more acidic?” Kittisak tried.

“Not necessarily,” Brown replied. “Our samples from clearwater and other areas of whitewater are higher on the pH scale, so they’re actually more basic.”

“And clearwater is super slow moving because any sediment carried there settles?” Kittisak was surprised how much he’d been able to absorb while being terrified of being devoured by monstrous insects. “Because clearwater is actually clear. The one name that fits.”

“Well remembered, my boy,” Browning praised.

“Okay.” Kittisak snorted and swatted at the pesky bug again. “So, more sediment doesn’t equal more acid.”

Browning’s head dipped. “Yes, my theory was wrong, and I cannot explain why those specific areas of whitewater were different.”

“Blackwater appears to be the most acidic.” Hutte cleared his throat. “My theory is the high acidity results from the decay of surrounding trees and plants. Blackwater rivers run through the deepest parts of the forests here.”

Kittisak realized Hutte was looking at him expectantly, but he had no idea what he was supposed to be contributing to the conversation.

“Come on, our future botanist,” Hutte prodded. “What is a polyphenol found in most terrestrial plants that might contribute to acidity?”

“Oh!” Kittisak gasped. “Tannins!”

“Very good.”

“As the leaves and stuff go down into the water and the soil, they rot and release tannins. Like how tannins are released during fermentation with wine.” Kittisak might have made wine in his dormitory bathroom a time or two. “So, we need to find blackwater, yeah?”

“Yes, but we also need to find the source of the acidic pockets we found in the whitewater as well,” Browning replied. “The acidophilic bacteria we’re looking for was there, though only in very small numbers, and it got us thinking about that little tributary river we found yesterday.”

“The one that wasn’t on the map?” Kittisak recalled.

“Yes. It seems to run through a very dense region of the forest, and our initial samples from it were acidic. Given the location and the pH tests, it’s blackwater.” Hutte held up a finger. “And we found no other acidity any farther upstream in the whitewaters of the Solimões.”

Kittisak stared again.

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