N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone, also known as 6PPD quinone, was recently identified as a toxic chemical that causes acute mortality in coho salmon following exposure to urban runoff. Despite its potential occurrence in receiving waters worldwide, there is no information about the toxicity of 6PPD quinone to other aquatic species. In this study, to assess the aquatic toxicity of 6PPD quinone to freshwater fish and crustacean species, we performed standardized 48−96 h acute toxicity tests of 6PPD quinone with four species (Danio rerio, Oryzias latipes, Daphnia magna, and Hyalella azteca). In contrast to the high toxicity observed in coho salmon in a previous study (24 h LC 50 of 0.79 μg/L), 6PPD quinone did not exhibit acute lethal toxicity to any species at its maximum water solubility. The absence of acute lethality of 6PPD quinone to tested species indicates that the urban runoff toxicity observed for the species can be attributed to other chemicals. The observed large discrepancy in toxicity (by a factor of ∼100) might be due to the specific toxicity of 6PPD quinone to coho salmon. Further research is needed to reveal the underlying mechanisms of the observed difference, which will be useful for both urban runoff management and aquatic toxicology.

The origin and evolution of solar system bodies, including water on the Earth, have been discussed based on the assumption that the relevant ingredients were simply silicates and ices. However, large amounts of organic matter have been found in cometary and interplanetary dust, which are recognized as remnants of interstellar/precometary grains. Precometary organic matter may therefore be a potential source of water; however, to date, there have been no experimental investigations into this possibility. Here, we experimentally demonstrate that abundant water and oil are formed via the heating of a precometary-organic-matter analog under conditions appropriate for the parent bodies of meteorites inside the snow line. This implies that H2O ice is not required as the sole source of water on planetary bodies inside the snow line. Further, we can explain the change in the oxidation state of the Earth from an initially reduced state to a final oxidized state. Our study also suggests that petroleum was present in the asteroids and is present in icy satellites and dwarf planets.

Paleoceanographic changes in the Akita Basin during the Miocene were investigated using biomarker analysis of source rocks from the Onnagawa and Kusanagi formations in the Yashima area (eastern basin margin) and the Shonai Plain (central basin). During the Nishikurosawa Stage (~13 Ma), the homohopane index indicated a slightly oxidizing depositional environment. At this time, the Japan Sea was an open marginal sea and an oxidizing environment; thus, organic matter preservation in the Akita Basin was low. In the Early Onnagawa Stage (~12 Ma), the Japan Sea became semi-closed because of uplift of the proto-Northeastern Japan Arc. This change is reflected in the pristane/phytane ratio and homohopane index that suggest the Yashima and Shonai Plain areas became reducing, which enhanced organic matter preservation. The depositional environment of the Kusanagi Formation (Shonai Plain) was more reducing than that of the Onnagawa Formation (Yashima area). During the Middle Onnagawa Stage (10 Ma), the homohopane index showed that the Onnagawa Formation (Yashima area) had shifted to an oxidizing depositional environment. Additionally, the C 27 /C 27 + C 29 sterane ratio indicated that algae were responsible for the higher overall primary production in the Middle Onnagawa Stage. This high primary productivity was associated with localized coastal upwelling, which resulted in generally high organic matter content in the Middle Onnagawa Formation. In the Shonai Plain area (Kusanagi Formation), bottom water conditions remained anoxic; however, sedimentary organic matter content did not increase because there was no upwelling in the area. During the Late Onnagawa Stage (8 Ma), the seafloor environment in the Shonai Plain area also became oxidizing. As a result of enhanced organic matter decomposition, overall sedimentary organic matter content decreased.Our results demonstrate that local variations in primary productivity and bottom water conditions are recorded in the sedimentary record and emphasize the importance of geographic and tectonic settings to the deposition and preservation of organic-rich source rocks. Thus, this study was able to describe spatio-temporal changes over the entire Akita Basin.