Evidence of Influence of Human Activities and Volcanic Eruptions on Environmental Perchlorate from a 300-Year Greenland Ice Core Record.

A 300-year (1700-2007) chronological record of environmental perchlorate, reconstructed from high-resolution analysis of a central Greenland ice core, shows that perchlorate levels in the post-1980 atm were two-to-three times those of the pre-1980 environment. While this confirms recent reports of increased perchlorate in Arctic snow since 1980 compared with the levels for the prior decades (1930-1980), the longer Greenland record demonstrates that the Industrial Revolution and other human activities, which emitted large quantities of pollutants and contaminants, did not significantly impact environmental perchlorate, as perchlorate levels remained stable throughout the 18th, 19th, and much of the 20th centuries. The increased levels since 1980 likely result from enhanced atmospheric perchlorate production, rather than from direct release from perchlorate manufacturing and applications. The enhancement is probably influenced by the emission of organic chlorine compounds in the last several decades. Prior to 1980, no significant long-term temporal trends in perchlorate concentration are observed. Brief (a few years) high-concentration episodes appear frequently over an apparently stable and low background (∼1 ng kg-1). Several such episodes coincide in time with large explosive volcanic eruptions including the 1912 Novarupta/Katmai eruption in Alaska. It appears that atmospheric perchlorate production is impacted by large eruptions in both high- and low-latitudes, but not by small eruptions and nonexplosive degassing.

Children's responses to entry failure: attention deployment patterns and self-regulation skills.

In this study the authors investigated associations among children's observed responses to failure in an analogue entry situation, their attention deployment patterns, and skills and processes associated with self-regulation. Participants were 54 kindergarten and first-grade students who were either aggressive-rejected or low aggressive-popular based on peer nominations. Inhibitory control predicted the tendency to respond to entry failure by stopping and watching the group's activity. Baseline vagal tone and other-directed attention predicted children's tendency to change entry strategies after failure. Parent-rated attention skills moderated the relation between children's attention deployment patterns during the entry task and their responses to entry failure. Children who engaged in more other-directed attention were less likely to turn to solitary play after entry failure but only if they had high or moderate levels of attentional control. Other-directed attention was related to repeating previous entry bids without modification after entry failure but only when children had high levels of attention problems.