“Prediction is hard —partic ularly about the future ”
By James I. Drever | December, 2011
Back in 1989 I put together a model for the chemical evolution of a pit lake in a gold mine as part of an environmental impact statement. It was a primitive affair that said basically that if you had a lot more calcite than pyrite in the wall rock the lake would not be acid and if you had a plausible amount of pyrite undergoing oxidation, adsorption would take care of the heavy metals and arsenic. Calcium and sulfate concentrations would depend on the depth to which pyrite in the wall rock underwent oxidation (for which I made an arbitrary guess) and on evaporation, which was the main control on other major solutes. I used the same general approach to estimate the composition of runoff/ recharge from mine waste dumps.
TOURMALINE RESEARCH: UNLOCKING ALI BABA’S CAVE
By Georges Calas | October, 2011
Back in 1989 I put together a model for the chemical evolution of a pit lake in a gold mine as part of an environmental impact statement. It was a primitive affair that said basically that if you had a lot more calcite than pyrite in the wall rock the lake would not be acid and if you had a plausible amount of pyrite undergoing oxidation, adsorption would take care of the heavy metals and arsenic. Calcium and sulfate concentrations would depend on the depth to which pyrite in the wall rock underwent oxidation (for which I made an arbitrary guess) and on evaporation, which was the main control on other major solutes. I used the same general approach to estimate the composition of runoff/ recharge from mine waste dumps.
IS SCIENCE A CONTACT SPORT?
By Hap McSween | August, 2011
My university plays (American) football—these are big-time contests, held in a stadium that seats more than a hundred thousand spectators and televised more often than not. Watching a game not long ago, I was taken aback by the crowd’s vociferous reaction to a referee’s ruling against the home team. Based on an instant replay projected onto a gigantic screen at the top of the stadium, the ruling seemed fair to me. The referee was close to the action and obviously had some experience in such matters. But the crowd around me, none of whom I assume actually had any experience refereeing, was furious at the call and roared its displeasure.
WATER RESOURCES—SCIENCE AND VALUES
By James I. (Tim) Drever | June, 2011
The theme of this issue raises many questions beyond the technical problem of providing more fresh water where it is needed, whether for agriculture or domestic use. The problem is clear: water supplies, particularly groundwater supplies, are diminishing as a result of pollution and depletion of aquifers by extracting more water than the natural recharge. In many instances, the current rate of recharge is essentially zero and we are extracting “fossil” water that was recharged under previous more humid climatic regimes. At the same time, the human population is expanding, its diet is changing in a way that demands more water for agriculture, and climate change adds a level of uncertainty: current predictions include increased aridity in the subtropics.
TO BE EXPLORERS
By Hap McSween | February, 2011
Kipling’s poem is a powerful reminder that iron, the subject of this issue of Elements, is a raw material as essential to industry today as it was three hundred years ago. In 1709, Abraham Darby initiated the industrial revolution by being the first to use coke in iron smelting, which he accomplished at his ironworks on the banks of the River Severn in Shropshire, England. Iron accounts for over 90 percent of all metals consumed annually and, over recent decades, there has been a dramatic increase in the total amount of iron annually extracted from the Earth. In just the fifteen years between 1994 and 2009, global iron production grew from 1000 million to over 2200 million metric tons. Iron is one of the six most abundant metals in the Earth’s crust, so there is no danger of running out of minable deposits of iron. However, most of the iron produced for modern industry is only useful when alloyed with one or more of a number of other metals that act to increase its strength, machinability or corrosion resistance, or provide it with special properties, such as those associated with magnetism.