Social group membership does not modulate automatic imitation in a contrastive multi-agent paradigm.

A key prediction of motivational theories of automatic imitation is that people imitate in-group over out-group members. However, research on this topic has provided mixed results. Here, we investigate the possibility that social group modulations emerge only when people can directly compare in- and out-group. To this end, we conducted three experiments in which we measured automatic imitation of two simultaneously shown hands: one in-group and one out-group hand. Our general hypothesis was that the in-group hand would be imitated more than the out-group hand. However, even though both explicit and implicit manipulation checks showed that we succeeded in manipulating participants' feelings of group membership, we did not find support for the predicted influence of group membership on automatic imitation. In contrast to motivational theories, this suggests that group membership does not influence who we do or do not imitate, not even in a contrastive multi-agent paradigm.

Geochemistry and toxicity of a large slag pile and its drainage complex in Sudbury, Ontario.

Slag piles from mining activities are common worldwide, but in contrast to mine tailings the environmental impact of runoff from slag piles is less documented. This study was designed to assess the geochemistry and potential toxicity of water draining a large, 62.2ha slag pile in Sudbury, Ontario. The Coniston slag pile contains 12-20Mt of slag from smelting local Ni-Cu ore between 1913 and 1972. Slag leaching experiments confirmed slag is a source of sulphate (SO4), heavy metals (including Fe, Al, Ni, Co, Cu, Zn, Pb, Cr, Mn) and base cations (Ca, K, Mg, Na). Concentrations of some metals draining through slag in column experiments were similar to concentrations measured at the base of the slag pile, although base cations, SO4 and pH were much higher, possibly because of water inputs interacting with the surrounding basic glaciolacustrine landscape. The high pH rapidly precipitates metals, leading to high accumulations in surface sediments in the pond-wetland complex draining from the pile. Away from the pile's base, vegetation cover increases, which increases dissolved organic carbon (DOC) and nutrient concentrations in runoff along with metals with strong binding affinities (e.g. Cu). Total metal concentration in water and sediment exceed provincial guidelines, particularly near the slag pile, however WHAM7 modeling indicated the free metal ion concentration in water is very low. Nevertheless, 48-h toxicity experiments showed that water with greater concentrations of solutes collected close to the slag negatively impacts D. magna, suggesting water draining the slag pile can adversely impact biota in nearby drainage areas.

The impact of drought and air pollution on metal profiles in peat cores.

Peat cores have long been used to reconstruct atmospheric metal deposition; however, debate remains regarding how well historical depositional patterns are preserved in peat. This study examined peat cores sampled from 14 peatlands in the Sudbury region of Ontario, Canada, which has a well-documented history of acid and metal deposition. Copper (Cu) and lead (Pb) concentrations within individual peat cores were strongly correlated and were elevated in the upper 10 cm, especially in the sites closest to the main Copper Cliff smelter. In contrast, nickel (Ni) and cobalt (Co) concentrations were often elevated at depths greater than 10 cm, indicating much greater post-depositional movement of these metals compared with Cu and Pb. Post-depositional movement of metals is supported by the observation that Ni and Co concentrations in peat pore water increased by approximately 530 and 960% for Ni and Co, respectively between spring and summer due to drought-induced acidification, but there was much less change in Cu concentration. Sphagnum cover and (210)Pb activity measured at 10 cm at the 14 sites significantly increased with distance from Copper Cliff, and the surface peat von Post score decreased with distance from Copper Cliff, indicating the rate of peat formation increases with distance from Sudbury presumably as a result of improved Sphagnum survival. This study shows that the ability of peat to preserve deposition histories of some metals is strongly affected by drought-induced post-depositional movement and that loss of Sphagnum due to air pollution impairs the rate of peat formation, further affecting metal profiles in peatlands.