I've had, indeed am having, great fun teaching my Environmental Chemists but up until now, it has been wholly theoretical. That's fine with me, because things are most likely to go pear-shaped in my scientific world if I step up to a lab-bench. But the contract says I am to run six 3 hour practical sessions and I'm now half-way through that ordeal. My first idea was to analyse the chemical content of 'our' mountainy river as it descends from a peat hag about 370m high down past and beyond our farmlet at maybe 200m. I suggested hypotheses that a) there might be more nitrate in the water below our neighbour's stock-yard and b) that the pH might increase as the river passed among fields that had been 'sweetened' with crushed lime-stone. I then invited 'the lads' to think out their own ideas and then we could test them by measuring some physico-chemical parameters like pH, turbidity and, indeed, nitrate in each of several samples. We managed to eke out 2 sessions doing this on water that I'd spent a Saturday bottling up.
The Darwinday storm took down many trees including at least 7 of our hawthorns Crataegus monogyna which were blown out of our ditches and field-walls over the last 6 weeks. But we didn't lose any ash Fraxinus excelsior. Sure we lost lots of twigs and a couple of hefty branches from that species but none were uprooted. That set me to thinking that maybe ash is so firm in its foundations because its roots penetrate the soil wide and deep, whereas the roots of hawthorn are shallow and insubstantial. Whatever, I thought it should be a) possible and b) interesting to see if neighbouring ash and hawthorn acquired a different mineral makeup because they were tapped into different strata. OR maybe ash, the species, regardless of location, filtered out and concentrated some key elements to better express their Fraxinushood; and hawthorn likewise its Crataegusness. So yesterday I got up even earlier than usual to cut off some branches from both species at two different geographical locations. When I arrived in the lab, I explained my idea and we all set to scraping the soft bark off the cut twigs into four separate piles so that we could 'digest' them into a mineral-rich soup for analysis. Lesson one: it takes rather a long time to scrape even a couple of grams off a twig with a pen-knife. Expecting that these modern boys do not habitually carry a pen-knife, I brought in a half-dozen of my own which turned out to have been bought in five different countries. And at least two of the boys was fascinated by these sharp functional objects: having never seen a marlin-spike, let alone used one making a eye splice.
As a further scientific comparison I suggested that we use a) the old-fashioned method of boiling the material up in nitric acid and hydrogen peroxide or b) the microwave digester which can crank up the temperature to 200oC by heating up under pressure. It was real science (so rare even in college laboratory lessons) because nobody knew what the answer might be. We quickly learned that a mess of plant, peroxide and acid will boil over as quick as milk on a very hot stove. So that was a bust and required more twigs to be scraped to start that experiment again. But that was pretty good because you could see it happening; work out why the cocktails behaved in that messy way; and modify the protocol. The computer-driven microwave digester isn't as flexible and behaves like a black-box through which miracles are wrought, so is a far less valuable learning experience. I can't give you any results yet because it took us the whole session just prepping the samples, but we're set for a flying start next week.
These students have just finished a 10 week independent research project on all sorts of wild material - worms, sea-weed, rushes, aspirin and sewage sludge. I was chatting to Seaweed Man about his project as he used a torque wrench to open one of the vials from the microwave digester. If it needs that sort of kit just to open and close the lid, you know it's really not safe to have me anywhere close. ANNyway, he said that next time he would tri-digest his sea-weed samples. "Wow" I said, bamboozled and impressed by yet another technical term from the world of chemistry, "d'ye intend to run it through the machine three times?". It took him that split second to realise the depths of my ignorance. "No, I'm going to . try . digest . my . samples next time". Eeeee, 'ow we larfed!