Atmospheric short-chain-chlorinated paraffins in Melbourne, Australia – first extensive Southern Hemisphere observations

2017 ◽  
Vol 14 (2) ◽  
pp. 106 ◽  
Author(s):  
Robert W. Gillett ◽  
Ian E. Galbally ◽  
Melita D. Keywood ◽  
Jennifer C. Powell ◽  
Gavin Stevenson ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Metal Cutting ◽  
Short Chain ◽  
Ambient Atmosphere ◽  
Industrial Chemicals ◽  
Chlorinated Paraffins ◽  
Atmospheric Concentrations

Environmental contextThis study presents the first comprehensive set of ambient atmospheric concentrations of short-chain-chlorinated paraffins in the Southern Hemisphere. The data show a seasonal cycle with a summer maximum and a winter minimum. The seasonal cycle is consistent with temperature dependence of the vapour pressure of the short-chain-chlorinated paraffins resulting in partitioning between the atmosphere and other reservoirs with a secondary modulation by soil moisture. AbstractThe first extensive measurements of short-chain chlorinated paraffins (SCCPs) in the atmosphere of the Southern Hemisphere are presented. The analytical and sampling methodologies used in this Australian study were verified by systematic testing along with two inter-comparisons with Northern Hemisphere laboratories with established SCCP programs. In the ambient atmosphere of Melbourne, Australia, in 2013–14, there was a clear seasonal cycle in SCCP monthly averaged concentrations, these ranging from 28.4ng m–3 in summer to 1.8ng m–3 in winter. Air temperature was the factor most closely related to the seasonal cycle in SCCPs in Melbourne. The average SCCP concentrations observed indoors were less than those observed outdoors. Atmospheric concentrations of SCCPs in Melbourne are more than two orders of magnitude higher than concentrations in the background atmosphere. Surprisingly, the SCCP concentrations in Melbourne are similar to those observed in cities in Japan, South Korea and the United Kingdom, and less than those observed in China. Direct transport of SCCPs in the atmosphere from the Northern Hemisphere emissions to Melbourne is ruled out. Instead elevated concentrations in the Melbourne air-shed are most likely a result of the long-term import of SCCPs as industrial chemicals and within manufactured materials from the Northern Hemisphere so that the use of SCCPs in Melbourne and their consequent release to the environment has produced environmental reservoirs of SCCPs in Melbourne that are comparable with those in some Northern Hemisphere cities. The increase in SCCP concentrations from winter to summer is consistent with the temperature dependence of partitioning of SCCPs between the atmosphere and other reservoirs. Insufficient information exists on SCCP use and its presence in soils and sediments in Australia to indicate whether the atmospheric presence of SCCPs in Melbourne is a legacy issue due to its import and use as a metal cutting agent in past decades or due to ongoing imports of manufactured materials containing SCCPs today.

scholarly journals Sixty years of radiocarbon dioxide measurements at Wellington, New Zealand 1954–2014

2016 ◽  
Author(s):  
Jocelyn C. Turnbull ◽  
Sara E. Mikaloff Fletcher ◽  
India Ansell ◽  
Gordon Brailsford ◽  
Rowena Moss ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Co2 Emissions ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Fossil Fuel ◽  
Anthropogenic Sources ◽  
Deep Waters ◽  
Cape Grim

Abstract. We present 60 years of Δ14CO2 measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric Δ14CO2 record and records the rise of the 14C "bomb spike", the subsequent decline in Δ14CO2 as bomb 14C moved throughout the carbon cycle and increasing fossil fuel CO2 emissions further decreased atmospheric Δ14CO2. The initially large seasonal cycle in the 1960s reduces in amplitude and eventually reverses in phase, resulting in a small seasonal cycle of about 2 ‰ in the 2000s. The seasonal cycle at Wellington is dominated by the seasonality of cross-tropopause transport, and differs slightly from that at Cape Grim, Australia, which is influenced by anthropogenic sources in winter. Δ14CO2 at Cape Grim and Wellington show very similar trends, with significant differences only during periods of known measurement uncertainty. In contrast, Northern Hemisphere clean air sites show a higher and earlier bomb 14C peak, consistent with a 1.4-year interhemispheric exchange time. From the 1970s until the early 2000s, the Northern and Southern Hemisphere Δ14CO2 were quite similar, apparently due to the balance of 14C-free fossil fuel CO2 emissions in the north and 14C-depleted ocean upwelling in the south. The Southern Hemisphere sites show a consistent and marked elevation above the Northern Hemisphere sites since the early 2000s, which is most likely due to reduced upwelling of 14C-depleted and carbon-rich deep waters in the Southern Ocean. This developing Δ14CO2 interhemispheric gradient is consistent with recent studies that indicate a reinvigorated Southern Ocean carbon sink since the mid-2000s, and suggests that upwelling of deep waters plays an important role in this change.

scholarly journals Global marine plankton functional type biomass distributions: coccolithophores

2012 ◽  
Vol 5 (2) ◽  
pp. 491-520 ◽  
Author(s):  
C. J. O'Brien ◽  
J. A. Peloquin ◽  
M. Vogt ◽  
M. Heinle ◽  
N. Gruber ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Marine Phytoplankton ◽  
The North ◽  
Carbon Biomass ◽  
Time Period ◽  
The Pacific ◽  
Individual Contributions ◽  
June July

Abstract. Coccolithophores are calcifying marine phytoplankton of the class Prymnesiophyceae. They are considered to play an import role in the global carbon cycle through the production and export of organic carbon and calcite. We have compiled observations of global coccolithophore abundance from several existing databases as well as individual contributions of published and unpublished datasets. We estimate carbon biomass using standardised conversion methods and provide estimates of uncertainty associated with these values. The database contains 58 384 individual observations at various taxonomic levels. This corresponds to 12 391 observations of total coccolithophore abundance and biomass. The data span a time period of 1929–2008, with observations from all ocean basins and all seasons, and at depths ranging from the surface to 500 m. Highest biomass values are reported in the North Atlantic, with a maximum of 501.7 μg C l−1. Lower values are reported for the Pacific (maximum of 79.4 μg C l−1) and Indian Ocean (up to 178.3 μg C l−1). Coccolithophores are reported across all latitudes in the Northern Hemisphere, from the Equator to 89° N, although biomass values fall below 3 μg C l−1 north of 70° N. In the Southern Hemisphere, biomass values fall rapidly south of 50° S, with only a single non-zero observation south of 60° S. Biomass values show a clear seasonal cycle in the Northern Hemisphere, reaching a maximum in the summer months (June–July). In the Southern Hemisphere the seasonal cycle is less evident, possibly due to a greater proportion of low-latitude data. The original and gridded datasets can be downloaded from Pangaea (http://doi.pangaea.de/10.1594/PANGAEA.785092).

Short-Chain Chlorinated Paraffins in Zurich, Switzerland—Atmospheric Concentrations and Emissions

2015 ◽  
Vol 49 (16) ◽  
pp. 9778-9786 ◽  
Author(s):  
Pascal S. Diefenbacher ◽  
Christian Bogdal ◽  
Andreas C. Gerecke ◽  
Juliane Glüge ◽  
Peter Schmid ◽  
...  
Keyword(s):  
Short Chain ◽  
Chlorinated Paraffins ◽  
Atmospheric Concentrations

scholarly journals Sublethal Toxic Effects and Induction of gGutathione S-transferase by Short-Chain Chlorinated Paraffins (SCCPs) and C-12 alkane (dodecane) in Xenopus laevis Frog Embryos

2006 ◽  
Vol 75 (1) ◽  
pp. 115-122 ◽  
Author(s):  
B. Burýšková ◽  
L. Bláha ◽  
D. Vršková ◽  
K. Šimková ◽  
B. Maršálek
Keyword(s):  
Xenopus Laevis ◽  
Developmental Toxicity ◽  
Aquatic Organisms ◽  
Short Chain ◽  
Toxic Effects ◽  
Industrial Chemicals ◽  
Glutathione S Transferase ◽  
Commercial Mixture ◽  
Chlorinated Paraffins ◽  
Embryotoxic Effects

Short chain chlorinated paraffins (SCCPs) are important industrial chemicals with high persistence in the environment but poorly characterized ecotoxicological effects. We studied embryotoxic effects of commercial mixture of SCCP (carbon length C-12, 56% of chlorine; CP56-12) and non-chlorinated n-alkane (dodecane, C-12) in the 96h Frog Embryo Teratogenesis Assay - Xenopus (FETAX). Only weak lethal effects were observed for both substances (the highest tested concentration 500 mg/L of both chemicals caused up to 11% mortality). On the other hand, we observed developmental malformations and reduced embryo growth at 5 mg/l and higher concentrations. However, the effects were not related to chlorination pattern as both SCCPs and dodecane induced qualitatively similar effects. SCCPs also significantly induced phase II detoxification enzyme glutathione S-transferase (GST) in Xenopus laevis embryos even at 0.5 mg/L, and this biomarker might be used as another early warning of chronic toxic effects. Our results newly indicate significant developmental toxicity of both SCCPs and n-dodecane to aquatic organisms along with inductions of specific biochemical toxicity mechanisms.

Preliminary investigation of long-term changes in the stratospheric N2O abundances as a proxy for the Brewer-Dobson Circulation in a climate model, dynamical and chemical reanalyses and observations.

2021 ◽  
Author(s):  
Daniele Minganti ◽  
Simon Chabrillat ◽  
Quentin Errera ◽  
Maxime Prignon ◽  
Emmanuel Mahieu
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Climate Model ◽  
Swiss Alps ◽  
High Latitudes ◽  
Hemispheric Differences ◽  
Early Results ◽  
Long Term Trends

<p>The Brewer-Dobson Circulation (BDC) is a wintertime stratospheric circulation characterized by upwelling of tropospheric air in the tropics, poleward flow in the stratosphere, and downwelling at mid and high latitudes, with important implications for chemical tracer distributions, stratospheric heat and momentum budgets, and mass exchange with the troposphere. <br>Nitrous oxide (N2O) is continuously emitted in the troposphere, where has no sinks, and transported into the stratosphere, where is destroyed by photodissociaiton. The lifetime of N2O is approximately 100 years, which makes it an excellent long-lived tracer for transport studies in the stratosphere. <br>In this study, we investigate the long-term N2O changes in the stratosphere using a number a different datasets. We analyze the simulation from the state-of-the-art Chemistry-Climate Model WACCM (period: 1990-2014), together with the BASCOE Chemistry-Transport Model driven by five dynamical reanalyses (ERA5, ERA-Interim, JRA-55, MERRA, MERRA-2, period: 1996-2014), and the chemical reanalysis of Aura Microwave Limb Sounder version 3 (BRAM3, period: 2004-2013). We will also compare those gridded data to ground-based observations from Fourier transform infrared spectrometer at the Jungfraujoch station in the Swiss Alps. <br>The long-term trends of the N2O concentration are investigated using the Dynamic Linear Model (DLM). The DLM is a regression model based on the Bayesian inference, which allow fitting atmospheric data with four main components: a linear trend, a seasonal cycle, a number of proxies (solar cycle, ENSO, QBO ?) and an autoregressive process. DLM has the advantage that the trend and the seasonal and regression coefficients depend on time; DLM can therefore detect changes in the recovered trend, and modulations of the amplitude of the regressors with time. <br>Early results show that the datasets exhibit hemispheric differences in the long-term N2O changes in the lower stratosphere. In the Southern Hemisphere, the DLM fit of the N2O concentrations increases across the datasets, but the resulting trend is statistically significant only in limited regions of the stratosphere. In the Northern Hemisphere, the N2O fit does not change significantly in the considered period, resulting in a near-zero trend. These hemispheric differences are in line with previous studies of transport that identify different long-term trends of tracers and mean age of air between the hemispheres. <br>The fit through the DLM allows the amplitude of the seasonal cycle component to vary in time. Preliminary results indicate that the time variations depend on the hemisphere in the extra-tropical regions. In the Southern Hemisphere, the datasets generally show a constant amplitude of the seasonal cycle throughout the considered periods, with the largest values in the high latitudes in response to the polar vortex. In the Northern Hemisphere, the inter-annual variations of the seasonal cycle amplitude are stronger, with BRAM3 showing the largest modulations. In addition, larger differences arise in the amplitude of the seasonal component. WACCM simulates large amplitudes of the seasonal cycle, while the reanalyses show smaller values. <br>A more detailed analysis of the results will include ground-based observations, and the extension of the CTM runs to a longer period that matches the length of the WACCM run.</p>

scholarly journals Sixty years of radiocarbon dioxide measurements at Wellington, New Zealand: 1954–2014

2017 ◽  
Vol 17 (23) ◽  
pp. 14771-14784 ◽  
Author(s):  
Jocelyn C. Turnbull ◽  
Sara E. Mikaloff Fletcher ◽  
India Ansell ◽  
Gordon W. Brailsford ◽  
Rowena C. Moss ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Co2 Emissions ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Fossil Fuel ◽  
Anthropogenic Sources ◽  
Deep Waters ◽  
Cape Grim

Abstract. We present 60 years of Δ14CO2 measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest direct atmospheric Δ14CO2 record and records the rise of the 14C bomb spike and the subsequent decline in Δ14CO2 as bomb 14C moved throughout the carbon cycle and increasing fossil fuel CO2 emissions further decreased atmospheric Δ14CO2. The initially large seasonal cycle in the 1960s reduces in amplitude and eventually reverses in phase, resulting in a small seasonal cycle of about 2 ‰ in the 2000s. The seasonal cycle at Wellington is dominated by the seasonality of cross-tropopause transport and differs slightly from that at Cape Grim, Australia, which is influenced by anthropogenic sources in winter. Δ14CO2 at Cape Grim and Wellington show very similar trends, with significant differences only during periods of known measurement uncertainty. In contrast, similar clean-air sites in the Northern Hemisphere show a higher and earlier bomb 14C peak, consistent with a 1.4-year interhemispheric exchange time. From the 1970s until the early 2000s, the Northern and Southern Hemisphere Δ14CO2 were quite similar, apparently due to the balance of 14C-free fossil fuel CO2 emissions in the north and 14C-depleted ocean upwelling in the south. The Southern Hemisphere sites have shown a consistent and marked elevation above the Northern Hemisphere sites since the early 2000s, which is most likely due to reduced upwelling of 14C-depleted and carbon-rich deep waters in the Southern Ocean, although an underestimate of fossil fuel CO2 emissions or changes in biospheric exchange are also possible explanations. This developing Δ14CO2 interhemispheric gradient is consistent with recent studies that indicate a reinvigorated Southern Ocean carbon sink since the mid-2000s and suggests that the upwelling of deep waters plays an important role in this change.

scholarly journals Abiotic and biogeochemical signals derived from the seasonal cycles of tropospheric nitrous oxide

2010 ◽  
Vol 10 (11) ◽  
pp. 25803-25839
Author(s):  
C. D. Nevison ◽  
E. Dlugokencky ◽  
G. Dutton ◽  
J. W. Elkins ◽  
P. Fraser ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Coastal Upwelling ◽  
Seasonal Cycles ◽  
Mixing Ratios ◽  
Stratospheric Temperature ◽  
Deep Ocean Water

Abstract. Seasonal cycles in the mixing ratios of tropospheric nitrous oxide (N2O) are derived by detrending long-term measurements made at sites across four global surface monitoring networks. These cycles are examined for physical and biogeochemical signals. The detrended monthly data display large interannual variability, which at some sites challenges the concept of a "mean" seasonal cycle. The interannual variability in the seasonal cycle is not always correlated among networks that share common sites. In the Northern Hemisphere, correlations between detrended N2O seasonal minima and polar winter lower stratospheric temperature provide compelling evidence for a stratospheric influence, which varies in strength from year to year and can explain much of the interannual variability in the surface seasonal cycle. Even at sites where a strong, competing, regional N2O source exists, such as from coastal upwelling at Trinidad Head, California, the stratospheric influence must be understood in order to interpret the biogeochemical signal in monthly mean data. In the Southern Hemisphere, detrended surface N2O monthly means are correlated with polar lower stratospheric temperature in months preceding the N2O minimum, suggesting a coherent stratospheric influence in that hemisphere as well. A decomposition of the N2O seasonal cycle in the extratropical Southern Hemisphere suggests that ventilation of deep ocean water (microbially enriched in N2O) and the stratospheric influx make similar contributions in phasing, and may be difficult to disentangle. In addition, there is a thermal signal in N2O due to seasonal ingassing and outgassing of cooling and warming surface waters that is out of phase and thus competes with the stratospheric and ventilation signals. All the seasonal signals discussed above are subtle and are generally better quantified in high-frequency in situ data than in data from weekly flask samples, especially in the Northern Hemisphere. The importance of abiotic influences (thermal, stratospheric influx, and tropospheric transport) on N2O seasonal cycles suggests that, at many sites, surface N2O mixing ratio data by themselves are unlikely to provide information about seasonality in surface sources (e.g., for atmospheric inversions), but may be more powerful if combined with complementary data such as CFC-12 mixing ratios or N2O isotopes.

scholarly journals The Global Distribution of Atmospheric Eddy Length Scales

2012 ◽  
Vol 25 (9) ◽  
pp. 3409-3416 ◽  
Author(s):  
Elizabeth A. Barnes ◽  
Dennis L. Hartmann
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Winter Season ◽  
Global Distribution ◽  
Correlation Lengths ◽  
Weather Forecasts ◽  
European Centre ◽  
Medium Range ◽  
Upper Level

The correlation lengths of vorticity anomalies from temporal averages are examined in the 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis dataset. It is shown that, in the annual mean, eddies in the Southern Hemisphere are significantly larger than those in the Northern Hemisphere. The eddy vorticity lengths exhibit a strong seasonal cycle, with the largest scales occurring in the winter season. The maximum zonal eddy lengths closely follow the contours of the strong upper-level winds, while the maximum meridional lengths are found in jet exit regions and in the stratosphere.

Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Convection Zone ◽  
Solar Surface ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Magnetic Buoyancy ◽  
Alpha Effect ◽  
Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Active Regions ◽  
Hemispheric Preference ◽  
Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

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