Matakite Maata

Ozone in the Pacific tropical troposphere from ozonesonde observations

Ozone vertical profile measurements obtained from ozonesondes flown at Fiji, Samoa, Tahiti, and the Galapagos are used to characterize ozone in the troposphere over the tropical Pacific. There is a significant seasonal variation at each of these sites. At sites in both the eastern and western Pacific, ozone mixing ratios are greatest at almost all levels in the troposphere during the September-November season and smallest during March-May. The vertical profile has a relative maximum at all of the sites in the midtroposphere throughout the year (the largest amounts are usually found near the tropopause). This maximum is particularly pronounced during the September-November season. On average, throughout the troposphere, the Galapagos has larger ozone amounts than the western Pacific sites. A trajectory climatology is used to identify the major flow regimes that are associated with the characteristic ozone behavior at various altitudes and seasons. The enhanced ozone seen in the midtroposphere during September-November is associated with flow from the continents. In the western Pacific this flow is usually from southern Africa (although 10-day trajectories do not always reach the continent) but also may come from Australia and Indonesia. In the Galapagos the ozone peak in the midtroposphere is seen in flow from the South American continent and particularly from northern Brazil. High ozone concentrations within potential source regions and flow characteristics associated with the ozone mixing ratio peaks seen in both the western and eastern Pacific suggest that these enhanced ozone mixing ratios result from biomass burning. In the upper troposphere, low ozone amounts are seen with flow that originates in the convective western Pacific.

Shipboard determinations of the distribution of 13C in atmospheric methane in the Pacific

Measurements of the mixing ratio and δ 13 C in methane (δ 13 CH 4 ) are reported from large, clean air samples collected every 2.5° to 5° of latitude on four voyages across the Pacific between New Zealand and the West Coast of the United States in 1996 and 1997. The data show that the interhemispheric gradient for δ 13 CH 4 was highly dependent on season and varied from 0.5‰ in November 1996 with an estimated annual mean of 0.2-0.3‰. The seasonal cycles in δ 13 CH 4 reveal three distinct latitude bands differentiated by phase. Maxima occur in January-February for the extratropical Southern Hemisphere, in September-October for the tropics, and in June-July for the extratropical Northern Hemisphere. The data are compared with results from a three-dimensional transport and atmospheric chemistry model that simulates the observed latitudinal structure of either δ 13 CH 4 or the methane mixing ratio well, but not both simultaneously. The requirement that a methane source-sink budget be consistent with both types of data clearly imposes stricter constraints than arise from either mixing ratio or isotopic data alone. The seasonal δ 13 CH 4 data in the extratropical Southern Hemisphere are used to estimate a value for the net fractionation in the CH 4 sink of 12-15‰, which is larger than can be explained by current laboratory measurements of a kinetic isotope effect for the OH + CH 4 reaction and soil sink processes. The hypothesis that the discrepancy is caused by competitive reaction of active chlorine with methane in the marine boundary layer is discussed.

Reducing mortality risk by targeting specific air pollution sources: Suva, Fiji

Health implications of air pollution vary dependent upon pollutant sources. This work determines the value, in terms of reduced mortality, of reducing ambient particulate matter (PM2.5: effective aerodynamic diameter 2.5μm or less) concentration due to different emission sources. Suva, a Pacific Island city with substantial input from combustion sources, is used as a case-study. Elemental concentration was determined, by ion beam analysis, for PM2.5 samples from Suva, spanning one year. Sources of PM2.5 have been quantified by positive matrix factorisation. A review of recent literature has been carried out to delineate the mortality risk associated with these sources. Risk factors have then been applied for Suva, to calculate the possible mortality reduction that may be achieved through reduction in pollutant levels. Higher risk ratios for black carbon and sulphur resulted in mortality predictions for PM2.5 from fossil fuel combustion, road vehicle emissions and waste burning that surpass predictions for these sources based on health risk of PM2.5 mass alone. Predicted mortality for Suva from fossil fuel smoke exceeds the national toll from road accidents in Fiji. The greatest benefit for Suva, in terms of reduced mortality, is likely to be accomplished by reducing emissions from fossil fuel combustion (diesel), vehicles and waste burning.

First Reprocessing of Southern Hemisphere Additional Ozonesondes (SHADOZ) Ozone Profiles (1998–2016): 2. Comparisons With Satellites and Ground‐Based Instruments

Abstract The Southern Hemisphere ADditional OZonesonde (SHADOZ) network was assembled to validate a new generation of ozone-monitoring satellites and to better characterize the vertical structure of tropical ozone in the troposphere and stratosphere. Beginning with nine stations in 1998, more than 7,000 ozone and P-T-U profiles are available from 14 SHADOZ sites that have operated continuously for at least a decade. We analyze ozone profiles from the recently reprocessed SHADOZ data set that is based on adjustments for inconsistencies caused by varying ozonesonde instruments and operating techniques. First, sonde-derived total ozone column amounts are compared to the overpasses from the Earth Probe/Total Ozone Mapping Spectrometer, Ozone Monitoring Instrument, and Ozone Mapping and Profiler Suite satellites that cover 1998-2016. Second, characteristics of the stratospheric and tropospheric columns are examined along with ozone structure in the tropical tropopause layer (TTL). We find that (1) relative to our earlier evaluations of SHADOZ data, in 2003, 2007, and 2012, sonde-satellite total ozone column offsets at 12 stations are 2% or less, a significant improvement; (2) as in prior studies, the 10 tropical SHADOZ stations, defined as within ±19° latitude, display statistically uniform stratospheric column ozone, 229 ± 3.9 DU (Dobson units), and a tropospheric zonal wave-one pattern with a 14 DU mean amplitude; (3) the TTL ozone column, which is also zonally uniform, masks complex vertical structure, and this argues against using satellites for lower stratospheric ozone trends; and (4) reprocessing has led to more uniform stratospheric column amounts across sites and reduced bias in stratospheric profiles. As a consequence, the uncertainty in total column ozone now averages 5%.

Partial identification and nutritional analysis of Kiribati algae

A chemical analysis of the edible algae from the island of Beru in Kiribati revealed it contained relatively high concentrations of Mg2+ and Ca2+ ions. A fair amount of protein and other minerals such as Na+, K+, Cu2+, Mn2+, Zn2+ and Fe2+ ions are also present in it. The scientific identification revealed that the algae are made of a mixture of different species, which are not an entirely new species just discovered. In fact, the two major types of algae that were identified (Lyngbya perelegans and Chroococcus minutus) are known to exist in Hawaii, some areas in Europe and parts of South East Asia.

Response of Marginopora vertebralis (Foraminifera) from Laucala Bay, Fiji, to Changing Ocean pH

Increased CO2 emissions into the atmosphere lead to increased concentrations of dissolved CO2 in the ocean. A chemical reaction between the dissolved CO2 and seawater produces HCO3 −, CO3 2− and H+ ions. These H+ ions increase the acidity of seawater and decrease the pH. Increased acidity and decreased availability of CO3 2− ion affect calcite and aragonite production by marine calcifiers in the ocean. To assess potential responses of the larger benthic foraminifer Marginopora vertebralis to ocean acidification, we performed growth experiments at three pH levels [7.5, 7.8, 8.1 (ambient seawater)] for 11 weeks. Specimens were stained with the fluorescent compound Calcein ( 40 µmole/l) prior to treatment, allowing identification of calcite added during the treatment period. At pH 8.1, specimens increased their test weight by 8.4%, at pH 7.8 growth was 4.2%, and at pH 7.5, growth was only 3.2%. These differences represent a significant relationship between ocean pH and test growth (i.e., calcification). In addition, several specimens in the pH 8.1 treatment underwent asexual reproduction during the experiment, while no reproduction was observed in the pH 7.8 or 7.5 treatments. These results indicate that ocean acidification predicted to occur by the end of the 21st century will cause a decline in population densities of Marginopora vertebralis in their natural environment, as consequences of both reduced growth rates and rates of reproduction. And because the tests of these foraminifers are important components of carbonate sediments on coral cays and tropical beaches, a decline in their rates of sediment production will exacerbate the consequences of rising sea level.

Surface ozone profiles at selected South Pacific sites

Surface ozone profiles were studied at Fiji (18.1oS, 178.2oE), Samoa (14.3oS, 170.6oW), Tahiti (18.0oS, 149.0oW), and San Cristobal, Galapagos (0.9oS, 89.6oW) from 1997-2003. Surface ozone levels at these Pacific sites showed a wintertime maximum and a summertime minimum with the lowest mixing ratios occurring at Tahiti and Galapagos, while the highest mixing ratios occurred at Fiji. The seasonal trends at each site were found to be dependent on the varying photochemical sink strength and the changing transport regimes in each season. It was established that the reduced photochemical sink strength in winter was one of the major reasons for the observed increase in surface ozone levels at each site in that season. The presence of the South Pacific Convergence Zone particularly for the Western Pacific (Fiji, Samoa and Tahiti) is the other factor contributing to the observed seasonality and variability in surface ozone levels. The changing frequency of transport from the southern mid-latitude (from high altitudes) is the only transport regime at the boundary layer having the most significant influence on the surface ozone levels at these Pacific sites.

The effect of varying ozone concentration on surface UV-B radiation: a Fiji perspective

Projects studying the effect of column ozone levels on UV-B radiation reaching the surface of the Earth as part of a wider global observation of vertical profiling were initiated by NASA/NOAA in the 1990s. A comparison of the changes in UV-B radiation as a function of ozone concentration revealed a negative correlation. We have shown for the first time in Fiji that a similar trend exists but with more scatter. Previous studies at this site (USP) have shown that the atmospheric concentration of aerosols varies seasonally and this may have a bearing on the scatter of the results.

Methane Concentration in Fiji Air: A Study of its Emission Trends and Source Strengths

In this study we have developed an in house capacity at the Chemistry Department, the University of the South Pacific, to analyze methane in ambient air to a precision of 1.5% using a custom converted Gas Chromatograph with FID detector. The technical support to develop this capacity was provided by our overseas partner, National Institute of Water and Atmospheric Research (NIWA). The air samples were collected from known sources of methane such as the digester at the sewage treatment plant, rubbish dump, wetlands, sugar cane burning in the western side of Viti Levu, geothermal emission in Vanua Levu, rice farms and cattle farms from September 2001 to June 2002 and were analyzed. Through inter-laboratory measurements involving NIWA a mean drift of 0.8% was obtained. The methane concentration in the ambient air has a seasonal cycle with a minimum during late January and a maximum during the July to August period. The digester at the sewage plant recorded the maximum concentration of approximately 70 ppmv followed by Lami rubbish dump with values ranging from 4.37 – 13.35 ppmv. The data from cattle farms, wetlands, rice farms and hot springs recorded emissions in the range of 2.00 – 5.11 ppmv, 1.85 – 4.25 ppmv, 1.77 – 2.62 ppmv and 2.06 – 1.90 ppmv respectively.