Galveston Bay: Temporal changes in the concentrations of trace organic contaminants in national status and trends oysters (1986–1994)

The temporal distributions for six classes of trace organic contaminants (chlordanes, DDTs, dieldrin, PAHs, PCBs, and butyltins) in oysters from six Galveston Bay sites from National Oceanic and Atmospheric Administration’s National Status and Trends (NS&T) Mussel Watch Program are compared with other NS&T sites from the Gulf of Mexico as well as all NS&T sites of the United States (East Coast, West Coast, and Gulf of Mexico). Decreases in the median for the Gulf-wide concentration of chlordanes, dieldrin, and butyltins occurred during 1986–1994. The Gulfwide median concentrations of DDTs, PAHs, and PCBs exhibited a strong cyclic distribution with time. For Galveston Bay oysters, “high” concentration is defined as the concentration greater than the median plus one standard deviation for all Gulf of Mexico sites. The percentage of sites having high concentrations during 1986–1994 for Galveston Bay oysters are 49% for dieldrin, 45% for butyltins, 40% for chlordanes, 38% for PCBs, 30% for PAHs, and 21% for DDTs. For PCBs, 43% of Galveston Bay oyster samples analyzed over the first 9 yr have concentrations high enough for potential biological effects to be observed in oysters. The percentages in other agents were chlordanes (22%), butyltins (22%), dieldrin (5%), and PAHs (4%). National Academy of Science-proposed regulatory limits for oysters were exceeded in only 2% of Galveston Bay samples for DDTs and 1% for PCBs. All other contaminants were below proposed NAS limits.     

Evaluating prey capture by larval mummichogs (Fundulus heteroclitus) as a potential biomarker for contaminants

We evaluated larval prey capture as a "behavioral biomarker" of contamination by examining feeding behavior of larval mummichogs (Fundulus heteroclitus) from many different sites, including a severely contaminated "Superfund" site, moderately contaminated sites, and reference areas. Prey capture ability was related to sediment contaminant levels. The levels of contaminants at a site were highly correlated with each other, so that the impact of individual contaminants was confounded. The number of captures of brine shrimp by mummichog larvae from all sites was highly variable, but significant negative correlations of prey capture were seen with mercury, lead, zinc, cadmium, and PCBs. As observed previously with adults, polyaromatic hydrocarbons (PAHs) did not appear to impair prey capture ability. The only site in which prey capture rates of 8-day old larvae were severely affected was the most highly contaminated Superfund site, Berry's Creek, NJ. This implies that larval prey capture is not as sensitive a behavioral biomarker for contamination as adult behavior studied previously.     

Tellurium isotopic composition of the early solar system—A search for effects resulting from stellar nucleosynthesis, Sn decay, and mass-independent fractionation

New precise Te isotope data acquired by multiple collector inductively coupled plasma mass spectrometry (MC-ICPMS) are presented for selected extraterrestrial and terrestrial materials. Bulk samples of carbonaceous, ordinary and enstatite chondrites as well as the metal and sulfide phases of iron meteorites were analyzed to search for nucleosynthetic isotope anomalies and to find evidence of formerly live ¹²⁶Sn, which decays to ¹²⁶Te with a half-life of 234,500 yr. None of the meteorites show evidence of mass dependent Te isotope fractionations larger than 2‰ for δ^126/128Te. Following internal normalization of the data to ¹²⁵Te/¹²⁸Te, the Te isotope ratios of all analyzed meteorites were found to be identical to a terrestrial standard, within uncertainties. This provides evidence that the regions of the solar disk that were sampled during accretion of the meteorite parent bodies were well mixed and homogeneous on a large scale, with respect to Te isotopes. The data acquired for bulk carbonaceous chondrites indicate that the initial ¹²⁶Sn/¹¹⁸Sn ratio of the solar system was <4 × 10⁻⁵, but this is dependent on the assumption that no redistribution of Sn and Te occurred since the start of the solar system. Five Archean sedimentary sulfides that display both mass dependent and mass-independent isotope effects for S yield internally normalized Te isotope data, which indicate that mass-independent Te isotope effects are absent. The mass dependent fractionations in these samples are constrained to be less than ∼1‰ for δ^126/128Te.     

Atmospheric nitrogen deposition to the Mullica River-Great Bay Estuary

Measurements of nitrate and ammonium in precipitation and associated with aerosols were conducted at Rutgers University Marine Field Station in Tuckerton, New Jersey from March 2004 to March 2005 to characterize atmospheric nitrogen deposition to the Mullica River-Great Bay Estuary. The arithmetic means of nitrate and ammonium concentrations for precipitation samples were 2.3mgL(-1) and 0.42mgL(-1), respectively. Nitrate and ammonium concentrations in aerosol samples averaged 3.7microgm(-3) and 1.6microgm(-3), respectively. Wet deposition rates appeared to vary with season; the highest rate of inorganic nitrogen deposition (nitrate+ammonium) occurred in the spring with an average value of 1.33kg-Nha(-2)month(-1). On an annual basis, the total (wet and dry) direct atmospheric deposition fluxes into the Mullica River-Great Bay Estuary were 7.08kg-Nha(-2)year(-1) for nitrate and 4.44kg-Nha(-2)year(-1) for ammonium. The total atmospheric inorganic nitrogen directly deposited to the Mullica River-Great Bay Estuary was estimated to be 4.79x10(4)kg-Nyear(-1), and the total atmospheric inorganic nitrogen deposited to the Mullica River watershed was estimated to be 1.69x10(6)kg-Nyear(-1). Only a fraction of the nitrogen deposited on the watershed will actually reach the estuary; most of the nitrogen will be retained in the watershed due to utilization and denitrification during transport. The amount of N reaching the Mullica River-Great Bay Estuary indirectly is estimated to be 5.07x10(4)kg-Nyear(-1), approximately 97% is retained within the watershed. This atmospheric nitrogen deposition may stimulate phytoplankton productivity in the Mullica River-Great Bay ecosystem.     

Mobile Learning in a Human Geography Field Course

This article reports on reusable mobile digital learning resources designed to assist human geography undergraduate students in exploring the geographies of life in Dublin. Developing active learning that goes beyond data collection to encourage observation and thinking in the field is important. Achieving this in the context of large class sizes presents several challenges. Combining in situ learning with spatially accurate historical and contemporary multimedia, a set of location-aware digital mobile tools, or mediascapes, was developed. How scaffolding can be achieved in such a context, focusing on the development of students’ observational, enquiry, and thinking skills in the field was explored.     

Inhabiting the Imaginary: Factory Women at Home on Batam Island, Indonesia

Batam Island, Indonesia, located a short ferry ride away from Singapore, is a place where tourism and industry have been developed simultaneously and a border area where “developed” and “developing” nations meet. Government officials, investing international corporations and the “factory women” who work in the island's industrial estates arrive in Batam ‐ native to none of them ‐ with their own preconceptions and goals. When challenges not foreseen through master planning arise, the authorities cling ever more tightly to their physical and structural development model: the nearby city‐state of Singapore. Conversely, the factory workers who travel intranationally to work in this export processing zone (EPZ) find their objectives contested in the face of the Master Plan, corporate agendas and ethnic fusions characterising this transnational capitalist space. Entering into the homes of three groups of women migrants living and working in Batam, the relationship between the private realm that they inhabit and the social contexts in which they participate publicly is investigated. Some of the choices that women make at and about home are identified, and their ability to “micro‐resist” these external structures is explored. At home, the dynamic relationship between the Batam development project and the women's own hopes and visions of the place ‐ sometimes parallel and sometimes incongruous ‐ are revealed. As they experience life on Batam, their “social imaginaries” of it are shaped into various new realities, and their homes, removed from the confines of the factory floor, thus become spaces of release from these tensions.