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BackgroundLittered cigarette butts represent potential point sources for environmental contamination. In areas with substantial amounts of cigarette litter, environmental hazards may arise as chemical components are leached from the filters and smoked tobacco.ObjectiveThe three main aims of this study were: (1) to quantify the amount of Al, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Sr, Ti and Zn leached from cigarette butts, (2) to determine the relationship between the pH of the aqueous soaking solution and metal concentration leached and (3) to determine the relationship between the period of soaking in aqueous solution and metal concentration leached.MethodsSmoked cigarette butts and unsmoked cigarettes were added to phials containing aqueous solutions of pH 4.00, 5.00 and 6.00 (±0.05). The metal concentration of the resultant leachates was measured via inductively coupled plasma optical emission spectroscopy (ICP-OES) 1 day, 7 days and 34 days after sample addition.ResultsAll metals were detected in leachates 1 day after sample addition (with the exception of Cd) and were released at varying rates. No clear relationship between pH within the range typical of precipitation and metal concentration leached was observed.ConclusionsBased on the gradual release of multiple metals over the full 34-day study period, cigarette litter was found to be a point source for metal contamination. The apparent rapid leaching of other metals may increase the risk of acute harm to local organisms.

Over the past decades, tropical stalagmite  18 O records have provided valuable insight on glacial and interglacial hydrological variability and its relationship to a variety of natural climate forcings. The transition out of the penultimate glaciation (MIS 6) represents an important target for tropical hydroclimate reconstructions, yet relatively few such reconstructions resolve this transition. Particularly, comparisons between Termination 1 and 2 provide critical insight on the extent and influence of proposed climate mechanisms determined from paleorecords and model experiments spanning the recent deglaciation. Here we present a new compilation of western tropical Pacific hydrology spanning 0-160 kyBP, constructed from eleven different U/Th-dated stalagmite  18 O records from Gunung Mulu National Park in northern Borneo. The reconstruction exhibits significant precessional power in phase with boreal fall insolation strength over the 0-160 kyBP period, identifying precessional insolation forcing as the dominant driver of hydroclimate variability in northern Borneo on orbital timescales. A comparison with a network of paleoclimate records from the circum-Pacific suggests the insolation sensitivity may arise from changes in the Walker circulation system. Distinct millennial-scale increases in stalagmite  18 O, indicative of reduced regional convection, occur within glacial terminations and may reflect a response to shifts in inter-hemispheric temperature gradients. Our results imply that hydroclimate in this region is sensitive to external forcing, with a response dominated by largescale temperature gradients.

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Understanding controls on the stable isotopic composition of precipitation and vapor in the West Pacific Warm Pool is vital for accurate representation of convective processes in models and correct interpretation of isotope-based paleoclimate proxies, yet a lack of direct observational evidence precludes the utility of these isotopic tracers. Results from a measurement campaign at Manus Island, Papua New Guinea from 28 April to 8 May 2013 demonstrate variability in the stable isotopic composition (δD and δ 18 O) of precipitation and vapor in individual precipitation events and over a 10 day period. Isotope ratios in water vapor and precipitation progressively increased throughout the period of measurement, coincident with a transition from high to low regional convective activity. Vapor isotope ratios approached equilibrium with seawater during the quiescent period and likely reflected downwind advection of distilled vapor and re-evaporation of rainfall during the period of regional convection. On a 5 min timescale across individual storms, isotope ratios in precipitation were strongly correlated with isotope ratios in surface vapor. However, individual precipitation isotope ratios were not strongly correlated with surface meteorological data, including precipitation rate, in all storms. Yet across all events, precipitation deuterium excess was negatively correlated with surface temperature, sea level pressure, and cloud base height and positively correlated with precipitation rate and relative humidity. Paired surface precipitation and vapor isotope ratios indicate condensation at boundary layer temperatures. The ratio of these paired values decreased with increasing precipitation rate during some precipitation events, suggesting rain re-evaporation and precipitation in equilibrium with an isotopically distinct upper level moisture source. Results from the short campaign support the interpretation that isotope ratios in precipitation and vapor in the western tropical Pacific are indicators of regional convective intensity at the timescale of days to weeks. However, a nonstationary relationship between rain rate and stable isotope ratios in precipitation during individual convective events suggests that condensation, rain evaporation, moisture recycling, and regional moisture convergence do not always yield an amount effect relationship on intraevent timescales. Key Points:• Consistent amount effect is not observed in storms • Deuterium excess correlated with variables related to convective activity • Rain to vapor isotope ratios indicate rain evaporation and distinct upper level vapor sourcesSupporting Information:• Supporting Information S1• Data Set S1