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991.
Juvenile coho salmon, Onchorynchus kisutch, were exposed to 95mTc in both saltwater and freshwater to study the biokinetic behavior of this element in an anadromous fish. In freshwater, equilibrium whole-body concentration factors (CF5) ranged from 28 to 32 in two separate experiments, in sharp contrast to an equilibriumCF of < 5 in saltwater. While the uptake kinetics were unimodal in saltwater, in freshwater, biomodal uptake kinetics were observed.Technetium-95m retention was biphasic in freshwater depuration experiments, an initial rapid loss of 21% to 26% of the steady-state activity with an elimination half-life of 3 to 5 days was followed by a slower loss rate, with a whole-body elimination half-life ranging from 23 to 33 days. In saltwater, retention was monophasic with an elimination half-life of 5–16 days. Dramatic decreases in 95mTc body burdens when freshwater-labeled fish are transferred to Tc-labeled saltwater indicate that the changes in physiology accompanying saltwater acclimation lead to the loss of 95mTc.  相似文献   
992.
Limpets collected at three locations along the Turkish Mediterranean coast were analyzed for zinc, copper, cadmium, lead, chromium, nickel, iron, arsenic and strontium. Average metal concentrations in samples taken from busy harbor areas and near sewage outfalls differed little from those collected in primarily agricultural areas. Generally, an inverse relationship of metal concentration with size is seen. The average levels found in these samples are of the same order of magnitude as those in limpets from other regions of the world and thus should serve as a good indication of current background levels in this region.  相似文献   
993.
994.
Three data sets of suspensate concentrations, collected under different sampling plans, were analyzed to develop a minimal sampling period, consistent with a predetermined precision. Individual samples collected during any part of a given day were within ±50% of the daily average. In the main channel of the estuary, a monthly sampling scheme closely approximated a weekly pattern; however, seasonal sampling was unsatisfactory. Outside the main channel, weekly, monthly, and seasonal sampling patterns did not differ greatly. Variability in suspensate concentrations must be considered when calculating sediment flux in estuarine and coastal waters.  相似文献   
995.
996.
1 IntroductionThe El Ni’o atmospheric physics oscillation is anabnormal phenomenon involved in the tropical Pacificocean- atmosphere interactions. Studies on the El Ni(ophenomenon are very attractive (Lin et al., 2000; Linet al., 2001, 2002; Wang, 2001; Feng et al., 2001;Feng et al., 2002; Liu et al., 2002; Wei and Chen,2003; Xie et al., 2002; Zhu et al., 2002; Pu et al.,2003; Gu et al., 2004; Yu and Liu, 2004). Lin and Mo(2004), Mo and Lin (2004) and Mo et al. (2004) alsostudied a s…  相似文献   
997.
A detailed marine survey made to the South West of Mount Eratosthenes is described. The results show the existence of a narrow zone of WNW trending deformed sediment west of the mount surrounded by an evaporite sequence in different stages of deformation.This work was intended to settle the conflict between the results of three previous interpretations of the tectonic structure of this area. We see the area being characterised by five areas with different degrees of tectonic deformation yet showing little causal relationship to overburden of Nile Cone sediments. A fault controlled cliff coincides with the previously described salt wall and strike slip fault yet we see no evidence for its diapiric origin nor positive evidence for strike slip motion along it. We concur with the previously observed area of higher free-air gravity anomalies termed the Eratosthenes tectonic zone, although it is traversed by several boundaries between areas of different deformation. Our results thus show some agreements and some re-interpretations of the observations. This complicated region is not yet fully understood however.  相似文献   
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