Fisheries Science - Neurotoxic poisonings with fatal symptoms caused by consumption of Nassarius gastropods have been reported in Vietnam but the causative toxins have not been confirmed. In the... 相似文献
The dominant coastal bivalve in Vietnam, hard clams Meretrix spp., collected from the South Key Economic Zone (SKEZ), the Mekong River Delta, and the Central Coastal Zone (CCZ) were
analyzed for 21 trace elements. Comparison of the results from the three regions indicated that levels of most of the trace
elements, especially As, Mo, Sn, and Pb, were highest in the samples collected from the CCZ, whereas most of the trace elements
were found to be present at relatively low levels in samples from the SKEZ. The high concentrations of these trace elements
in the CCZ, a sparsely populated region with less human activity than the other two regions, were believed to have originated
from industrial waste produced in a shipyard. Although the trace element concentrations in the bivalves were within safe levels
for human-consumption criteria reported by the United State Food and Drug Administration and the European Commission, estimation
of cancer risk based on As concentration indicates that the hard clams from the CCZ pose a high risk to consumers. Thus, the
industrial waste produced in the less densely populated region might increase the health risk to consumers via the contamination
of bivalves commonly used as food. 相似文献
Paddy and Water Environment - The universal phenomena of global warming caused by climate change have direct linkage with different hydro-meteorological variables which in turn affect the... 相似文献
Fineroots (≤ 2 mm diameter) are dynamic components of the forest ecosystems and play important role in water and nutrient acquisition in forests. These roots are sensitive to forest fertilization and therefore, the response of fineroots to nutrient application would provide better understanding of the forest carbon and nutrient dynamics that will be helpful in sustainable forest management plans. Two fertilization treatments, including (1) F400: 400 g P2O5 (16.5%)/tree and (2) F600: 600 g P2O5 /tree, and F0: control (without fertilization), were applied in an Acacia mangium plantation with a planting density of 1100 trees/ha (3 m?×?3 m). The evaluation of fineroot growth across seasons showed that fertilization significantly increased production and subsequent mortality and decomposition. The total decomposition associated with F600 application was 7.95 tons ha?1 year?1, equaling 121% of F400 and 160% of the control. Mortality in F600 was 8.75 tons ha?1 year?1, equaling 111% of F400 and 198% of F0, while production in F600 was 10.40 tons ha?1 year?1, equaling 127% of F400 and 143% of F0. Fineroot production, mortality, and decomposition are seasonally dependent, with higher values measured in the rainy season than in the dry season. Stand basal area increment was significantly correlated with fineroot production (R2?=?0.75), mortality (R2?=?0.44), and decomposition (R2?=?0.48). This study showed that fertilization could facilitate fineroot production, which can then lead to a higher turnover of carbon and nutrients through the decomposition of the greater mass of the fineroots.
An alternative strategy to reduce the percolation threshold of carbon black (CB) in polymer blends was investigated using
random copolymer ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and a styrene-methyl methacrylate random
copolymer (SMMA). The target morphology was to selectively locate CB particles in the encapsulating layer of SMMA during melt
mixing. The CB used in this study is BP-2000 from Cabot and has a strong selective affinity to PS. Even when the CB was premixed
with SMMA, it moves to the PS phase during the melt mixing. However, we also observed the CB particles located at the interface
between SMMA and PS phases. Through this study it is found that the interaction between polymers and CB particles is critical
for selectively localizing CB particles in multi-component polymer blends. Although appropriate processing condition may retard
the movement of CB particles to the polymer phase with affinity, it cannot prevent it completely and locate them to the SMMA
phase, which is not thermodynamically favored. To locate CB particles in an encapsulating layer of ternary polymer blends,
first of all, polymers forming it should have selective affinity to CB. 相似文献
