Earth/Environment

Superdeep diamonds born of surface carbon
Rare diamonds formed more than 600 kilometers below the Earth’s surface have revealed just how low carbon can go. Collected in Brazil, the diamonds contain minerals and quantities of a light form of carbon that match the makeup of parts higher up, in the Earth’s crust. An international team of researchers believes that a slab of oceanic crust sank and melted, contributing carbon to the diamonds before rising again to the surface in a hot plume. Studies of seismic waves created by earthquakes had suggested that crust could reach such depths, but the diamonds are first superdeep samples consistent with volcanic rock from the surface, the researchers report online September 15 in Science. —Devin Powell

Fossil fuels add nitrogen to oceans
To the list of things to worry about from fossil fuel burning, add nitrogen pollution in the oceans. Researchers from Korea and the United States have carefully measured nitrate and phosphate in the waters around Korea and Japan, and discovered that more nitrogen is entering the seas relative to phosphorus. The likely source, the team writes September 22 online in Science, is power plants upwind that spit reactive nitrogen into the air. From there, the molecules can be deposited on the sea surface and change its chemistry. —Alexandra Witze

New Zealand quakes linked
One magnitude 7.1 earthquake near Christchurch, New Zealand, helped hasten a nearby magnitude 6.3 tremor that took place five months later, seismologists have found. The second quake, in February 2011, killed more than 180 people and left parts of the city in rubble. A new analysis suggests that the first quake relieved stress along one geological fault in part by transferring stress to another one several kilometers to the east. That second fault then failed faster than it would have otherwise, Italian researchers reported online September 22 in Scientific Reports. —Alexandra Witze

Warming alters European fish abundance
Waters on the northern European continental shelf have warmed at four times the rate of seas globally since 1982, data from 28 years worth of research trawls show. The European scientists who analyzed these data had expected fish would compensate by moving to cooler climes. Instead, the same fish species tended to stay in any given area, the researchers report online September 15 in Current Biology. But abundances of 27 of the 50 predominant species did go up. Even after accounting for commercial fishing trends, the surveys found a relative boost in the abundance of smaller, faster maturing, warm-adapted species and drop in larger, slow-growing, cool-adapted residents. —Janet Raloff

Even low lead levels can hike blood pressure
Adults — especially black men — face a substantially elevated risk of hypertension if even fairly low levels of lead circulate in their bodies. CDC scientists correlated blood lead values with blood pressure in more than 16,000 men and women who took part in the National Health and Nutrition Examination Survey, a periodic analysis of health in a representative cross section of U.S. residents. The new analysis, reported online September 9 in Environmental Research, show that hypertension among black men with lead levels between 3.5 and 10 micrograms per deciliter was on average more than doubly as prevalent as in those with less than 0.7 micrograms per deciliter. —Janet Raloff

Global warming linked to intense early typhoons
The past decade has seen a sharp uptick in intense early typhoons — aka Pacific hurricanes. Ordinarily, category 4 or 5 storms don’t typically show up in the western North Pacific much before September. Indeed, until 2000 such intense typhoons occurred in May no more than about once a decade. Now they’re almost an annual May event, researchers from Taiwan and China report in the July-September Environmental Research Letters. The increasing frequency in early typhoons might be explained by a host of recent trends, the researchers say, including warmer sea surface temperatures, higher sea surface heights and especially increased water vapor in the lower atmosphere. —Janet Raloff

Weather not primary driver in rising food costs, study finds
A new study concludes that “the dominant causes” behind climbing global food prices are commodities speculation and the conversion of corn to ethanol biofuels. Yaneer Bar-Yam’s team at the New England Complex Systems Institute in Cambridge, Mass., compared the timing of weather-induced crop failures, the diversion of grains to livestock for meat production and other factors against cyclical changes in food prices. In a paper posted online September 22 at arXiv.org, these researchers argue that sharp politically destabilizing price spikes in 2007 and 2008 and again in 2010 and 2011 “are specifically due to investor speculation, while an underlying upward trend is due to increasing demand from ethanol conversion.” —Janet Raloff