Radioactivity in trinitite six decades later

The first nuclear explosion test, named the Trinity test, was conducted on July 16, 1945 near Alamogordo, New Mexico. In the tremendous heat of the explosion, the radioactive debris fused with the local soil into a glassy material named Trinitite. Selected Trinitite samples from ground zero (GZ) of the test site were investigated in detail for radioactivity. The techniques used included alpha spectrometry, high-efficiency gamma-ray spectrometry, and low-background beta counting, following the radiochemistry for selected radionuclides. Specific activities were determined for fission products (90Sr, 137Cs), activation products (60Co, 133Ba, 152Eu, 154Eu, 238Pu, 241Pu), and the remnants of the nuclear fuel (239Pu, 240Pu). Additionally, specific activities of three natural radionuclides (40K, 232Th, 238U) and their progeny were measured. The determined specific activities of radionuclides and their relationships are interpreted in the context of the fission process, chemical behavior of the elements, as well as the nuclear explosion phenomenology.     

Biological monitoring of aromatic diisocyanates in workers exposed to thermal degradation products of polyurethanes

Exposure to diisocyanates was assessed by biological monitoring among workers exposed to the thermal degradation products of polyurethanes (PURs) in five PUR-processing environments. The processes included grinding and welding in car repair shops, milling and turning of PUR-coated metal cylinders, injection moulding of thermoplastic PUR, welding and cutting of PUR-insulated district heating pipes during installation and joint welding, and heat-flexing of PUR floor covering. Isocyanate-derived amines in acid-hydrolysed urine samples were analysed as perfluoroacylated derivatives by gas chromatography mass spectrometry in negative chemical ionisation mode. The limits of quantification (LOQs) for the aromatic diamines 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA) and 4,4'-methylenedianiline (4,4'-MDA) were 0.25 nmol l(-1), 0.25 nmol l(-1) and 0.15 nmol l(-1), respectively. The LOQ for the aliphatic diamines hexamethylenediamine (HDA), isophoronediamine (IpDA) and 4,4'-diaminodicyclohexyl methane (4,4'-DDHM) was 5 nmol l(-1). TDA and MDA were detected in urine samples from workers in car repair shops and MDA in samples from workers welding district heating pipes. The 2,4-TDA isomer accounted for about 80% of the total TDA detected. No 2.6-TDA was found in the urine of non-exposed workers. The highest measured urinary TDA and MDA concentrations were 0.79 nmol mmol(-1) creatinine and 3.1 nmol mmol(-1) creatinine, respectively. The concentrations found among non-exposed workers were 0.08 nmol mmol(-1) creatinine for TDA and 0.05 nmol mmol(-1) creatinine for MDA (arithmetic means). Exposure to diisocyanates originating from the thermal degradation of PURs are often intermittent and of short duration. Nevertheless, exposure to aromatic diisocyanates can be identified by monitoring diisocyanate-derived amines in acid-hydrolysed urine samples.     

Household willingness to pay for stream restoration on private and public land: Evidence from the Baltimore metropolitan region

Stream restoration is one of the most widely used interventions to mitigate urban stormwater impacts and improve water quality. Government agencies have typically focused urban stream restoration efforts on public lands that they already own, even though a substantial portion of stream miles in highly urbanized areas occur on privately owned land. Yet, limited research exists to distinguish household willingness to pay (WTP) for stream restoration occurring on private versus public land. In this study, we use a choice experiment to analyze how household WTP for stream restoration attributes vary by land ownership and distance to the restoration project. Our empirical results indicate that streambank stabilization approaches have positive WTP estimates that are substantially larger in magnitude than those related to riparian vegetation management for clearing or planting trees. In general, estimated total household WTP for each of the four restoration design scenarios on public land is higher than when the same restoration design is located on private land. Nonetheless, estimated household WTP for each restoration design scenario on private land is substantial, retaining the majority of the value found on public land in all cases.     

Environmental quality of Korean coasts as determined by modified Shannon–Wiener evenness proportion

The coast of the Korean peninsula experiences a range of human impacts, including pollution, shipping, reclamation, and aquaculture, that have motivated numerous local studies of macrobenthic organisms. In this paper, 1,492 subtidal stations were compiled from 23 studies (areas) to evaluate environmental quality on a broader scale. A common index in biomonitoring, Shannon–Wiener evenness proportion (SEP), could not incorporate azoic or single-species samples. This shortcoming was overcome by developing an inverse function of SEP (ISEP), which was positively correlated with independent measures of water quality available for nine sites and was not biased by the size of the sampling unit. Additionally, at Shihwa Dike, where samples were collected before and after reinstating a tidal connection with the ocean, ISEP values improved over time, as expected. Thus, it is now possible to assign Korean subtidal sites to seven ISEP “grades” and to use their values and trends to guide coastal management.     

电子探测系统——边境线安防的重大革命

在这个跨边境恐怖主义活动和非法移民问题多发的年代,世界上的许多国家都在寻找有效保护边境的方法.因此,如何保护被视为"最后一道防线"的周界防护系统国境线成为摆在各国面前的首要问题.     

Changes in Forest Area Along Stream Networks in an Agricultural Catchment of the Great Barrier Reef Lagoon

Scenes from the series of multispectral sensors on the Landsat satellites were used to map recent changes (between 1972 and 2004) in forest cover within and adjacent to stream networks of an intensively farmed region of the southern Great Barrier Reef catchment (Australia). Unsupervised ISODATA classifications of Tasseled-Cap transformed data (at 57 m ground resolution) mapped forest and cleared areas within 150 m of Pisoneer catchment waterways with 72.2% overall accuracy (K(hat) = 0.469), when adjusted for the size of each class. Although the user's accuracy was higher for the forest class (82.1 +/- 8.4% at alpha = 0.05), large errors of commission (34.2 +/- 8.3%) substantially affected map accuracy for the cleared class. The main reasons for misclassification include: (1) failure to discriminate narrowly vegetated riparian strips; (2) misregistration of scenes; and (3) spectral similarity of ground cover. Error matrix probabilities were used to adjust the mapped area of classes, resulting in a decline of forest cover by 12.3% and increase of clearing by 18.5% (22.4 km(2) change; 95% confidence interval: 14.3-29.6 km(2)) between 1972 and 2004. Despite the mapping errors, Landsat data were able to identify broad patterns of land cover change that were verified from aerial photography. Most of the forest losses occurred in open forest to woodland habitat dominated by Eucalyptus, Corymbia, and Lophostemon species, which were largely replaced by sugarcane cropping. Melaleuca communities were similarly affected, though they have a much smaller distribution in the catchment.