Large-Scale Structure of the Carina Nebula

Observations obtained with the Midcourse Space Experiment (MSX) satellite reveal for the first time the complex mid-infrared morphology of the entire Carina Nebula (NGC 3372). On the largest size scale of approximately 100 pc, the thermal infrared emission from the giant H ii region delineates one coherent structure: a (somewhat distorted) bipolar nebula with the major axis perpendicular to the Galactic plane. The Carina Nebula is usually described as an evolved H ii region that is no longer actively forming stars, clearing away the last vestiges of its natal molecular cloud. However, the MSX observations presented here reveal numerous embedded infrared sources that are good candidates for sites of current star formation. Several compact infrared sources are located at the heads of dust pillars or in dark globules behind ionization fronts. Because their morphology suggests a strong interaction with the peculiar collection of massive stars in the nebula, we speculate that these new infrared sources may be sites of triggered star formation in NGC 3372.     

Assessing the influence and distribution of shrimp pond effluent in a tidal mangrove creek in north-east Australia

Effluent from a land based shrimp farm was detected in a receiving creek as changes in physical, chemical and biological parameters. The extent and severity of these changes depended on farm operations. This assessment was conducted at three different stages of shrimp-pond maturity, including (1) when the ponds were empty, (2) full and (3) being harvested. Methods for assessing farm effluent in receiving waters included physical/chemical analyses of the water column, phytoplankton bioassays and nitrogen isotope signatures of marine flora. Comparisons were made with an adjacent creek that served as the farms intake creek and did not directly receive effluent. Physical/chemical parameters identified distinct changes in the receiving creek with respect to farm operations. Elevated water column NH(4)(+) (18.5+/-8.0 microM) and chlorophyll a concentrations (5.5+/-1.9 microg/l) were measured when the farm was in operation, in contrast to when the farm was inactive (1.3+/-0.3 microM and 1.2+/-0.6 microg/l, respectively). At all times, physical/chemical parameters at the mouth of the effluent creek, were equivalent to control values, indicating effluent was contained within the effluent-receiving creek. However, elevated delta(15)N signatures of mangroves (up to approximately 8 per thousand) and macroalgae (up to approximately 5 per thousand ) indicated a broader influence of shrimp farm effluent, extending to the lower regions of the farms intake creek. Bioassays at upstream sites close to the location of farm effluent discharge indicated that phytoplankton at these sites did not respond to further nutrient additions, however downstream sites showed large growth responses. This suggested that further nutrient loading from the shrimp farm, resulting in greater nutrient dispersal, will increase the extent of phytoplankton blooms downstream from the site of effluent discharge. When shrimp ponds were empty water quality in the effluent and intake creeks was comparable. This indicated that observed elevated nutrient and phytoplankton concentrations were directly attributable to farm operations.     

工程地球化学：——研究的主要问题及其应用

本文对工程地球化学形式进行了分类，它们反映了由人类技术活动对地球化学环境所造成的不同类型的影响。基于已有的知识，对工程地球化学体系和过程的代表类型进行了分析。研究表明，工程地球化学的理论研究和实际应用可能集中于两大方向：（１）研究工程地球化学体系形成和发展的规律。这些体系起源于各种工农业活动与地球化学环境之间的相互作用，通常又是这些互相作用的结果；（２）发展地球化学优化方法来改善地质建造的工程性质     

Using nitrogen stable isotope ratios (delta 15N) of macroalgae to determine the effectiveness of sewage upgrades: changes in the extent of sewage plumes over four years in Moreton Bay, Australia

Nitrogen loading to aquatic ecosystems from sewage is recognised worldwide as a growing problem. The use of nitrogen stable isotopes as a means of discerning sewage nitrogen in the environment has been used annually by the Ecosystem Health Monitoring Program in Moreton Bay (Australia) since 1997 when the technique was first developed. This ("sewage plume mapping") technique, which measures the delta(15)N isotopic signature of the red macroalga Catenella nipae after incubation in situ, has demonstrated a large reduction in the magnitude and spatial extent of sewage nitrogen within Moreton Bay over the past 5 years. This observed reduction coincides with considerable upgrades to the nitrogen removal efficacy at several sewage treatment plants within the region. This paper describes the observed changes and evaluates whether they can be attributed to the treatment upgrades.     

Relative potency of PAHs and heterocycles as aryl hydrocarbon receptor agonists in fish

The relative potency of polycyclic aromatic compounds as aryl hydrocarbon receptor (AhR) agonists in fish was determined using data on CYP1A induction or AhR binding for 74 polycyclic aromatic hydrocarbons (PAHs) and heterocycles in teleost, avian, or mammalian systems from 18 published papers. Each PAH was assigned a fish potency factor relative to the potency of 2,3,7,8-tetrachlorodibenzo-p-dioxin as an AhR agonist. Two and three ring unsubstituted PAHs were generally inactive in fish, avian, and mammalian systems. Benzo[k]fluoranthene and indeno[1,2,3-cd]pyrene were consistently the most potent PAHs, with fish potency factors of 0.001-0.002. Common structural features associated with higher potency PAHs included 4-6 rings containing fluoranthene or phenanthrene structures with an exposed bay region. These results show that PAHs can have similar potency as many dioxin-like PCBs, and AhR mediated toxicity should be considered in assessing the risks of PAHs in fish.