福建一次大暴雨过程的多尺度分析

利用常规气象资料、自动气象站降水资料和NCEP再分析1°×1°等资料,对福建2017年6月初一次强降水过程进行多尺度分析。结果表明:(1)冷空气与暖湿气流相互作用形成持续性暴雨,中尺度系统的活动导致短时暴雨。(2)较大的风暴相对螺旋度,低层的正涡度和中低层的上升运动有利于中尺度对流系统(MCS)的发展和维持;强烈的热力不稳定和较强的垂直风切变是中尺度对流发展的环境特征。(3)强的整层水汽通量和水汽辐合为暴雨区提供水汽来源和水汽条件。(4)锋生的大小和位置对降水的强度和落区有很好的指示作用;低层以水平锋生为主,中层以垂直锋生为主,有利于成片暴雨的发生。(5)中尺度系统对天气尺度的水汽辐合和边界层对流不稳定条件有增幅作用;上下两支次级环流的上升支叠加,有利于低层不稳定能量的释放,促进中尺度系统的发展。     

The dust distribution within the inner coma of comet P/Halley 1982i: encounter by Giotto's impact detectors

Analysis of the data from Giotto's Dust Impact Detection System experiment (DIDSY) is presented. These data represent measurement of the size of dust grains incident on the Giotto dust shield along its trajectory through the coma of comet P/Halley on 1986 March 13/14. First detection occurred at some 287000 km distance from the nucleus on the inbound leg; the majority of the DIDSY subsystems remained operational after closest approach (604 km) yielding the last detection at about 202000 km from the nucleus. In order to improve the data coverage (and especially for the smallest grains, to approximately 10(-19) kg particle mass), data from the PIA instrument has been combined with DIDSY data. Flux profiles are presented for the various mass channels showing, to a first approximation, a 1/R2 flux dependence, where R is the distance of the detection point from the cometary nucleus, although significant differences are noted. Deviations from this dependence are observed, particularly close to the nucleus. From the flux profiles, mass and geometrical area distributions for the dust grains are derived for the trajectory through the coma. Groundbased CCD imaging of the dust continuum in the inner coma at the time of encounter is also used to derive the area of grains intercepted by Giotto. The results are consistent with the area functions derived by Giotto data and the low albedo of the grains deduced from infrared emission. For the close encounter period (-5 min to +5 min), the cumulative mass distribution function has been investigated, initially in 20 second periods; there is strong evidence from the data for a steepening of the index of the mass distribution for masses greater than 10(-13) kg during passage through dust jets which is not within the error limits of statistical uncertainty. The fluences for dust grains along the entire trajectory is calculated; it is found that extrapolation of the spectrum determined at intermediate masses (cumulative mass index alpha = 0.85) is not able to account for the spacecraft deceleration as observed by the Giotto Radio Science Experiment and by ESOC tracking operations. Data at large masses (>10(-8) kg) recently analysed from the DIDSY data set show clear evidence of a decrease in the mass distribution index at these masses within the coma, and it is shown that such a value of the mass index can provide sufficient mass for consistency with the observed deceleration. The total particulate mass output from the nucleus of comet P/Halley at the time of encounter would be dependent on the maximum mass emitted if this change in slope observed in the coma were also applicable to the emission from the nucleus; this matter is discussed in the text. The flux time profiles have been converted through a simple approach to modeling of the particle trajectories to yield an indication of nucleus surface activity. There is indication of an enhancement in flux at t approximately -29 s corresponding to crossing of the dawn terminator, but the flux detected prior to crossing of the dawn terminator is shown to be higher than predicted by simple modelling. Further enhancements corresponding to jet activity are detected around +190 s and +270 s.     

Sublethal impact of short term exposure to the organophosphate pesticide azamethiphos in the marine mollusc Mytilus edulis

Concern has been raised that the increased use of pesticides in intensive aquaculture practices may cause adverse sublethal effects to non-target aquatic species. Azamethiphos is an organophosphate (OP) pesticide used to combat sea lice infestations in farmed salmonids. Here, the sublethal impact on the blue mussel, Mytilus edulis, of short term exposure to azamethiphos was determined. The testing regime included biomarkers of exposure (acetylcholinesterase activity), cytotoxicity (neutral red retention), immune function (phagocytic index) and physiological condition (feeding rate). The distribution and sensitivity of M. edulis acetylcholinesterase to inhibition by azamethiphos was first determined, yielding IC(50) values of 0.736 and 1.30 mg l(-1) for gill and haemolymph, respectively. Exposure of mussels to 0.1 mg l(-1) azamethiphos for periods of up to 24h caused a significant reduction in acetylcholinesterase activity in both the haemolymph (P<0.0002) and the gill (P<0.002), alteration in cell viability (P<0.02) and decrease in phagocytic index (P<0.03). The feeding rate remained unaffected. The results support the hypothesis that, in addition to its neurotoxic effects, azamethiphos can modulate haemocyte function and immune defence in M. edulis at environmentally relevant concentrations after only a few hours.     

Influence of salinity and fish species on PAH uptake from dispersed crude oil

The use of chemical oil dispersants to minimize spill impacts causes a transient increase in hydrocarbon concentrations in water, which increases the risk to aquatic species if toxic components become more bioavailable. The risk of effects depends on the extent to which dispersants enhance the exposure to toxic components, such as polycyclic aromatic hydrocarbons (PAH). Increased salinities can reduce the solubility of PAH and the efficiency of oil dispersants. This study measured changes in the induction of CYP1A enzymes of fish to demonstrate the effect of salinity on PAH availability. Freshwater rainbow trout and euryhaline mummichog were exposed to water accommodated fractions (WAF), and chemically-enhanced water accommodated fractions (CEWAF) at 0 per thousand, 15 per thousand, and 30 per thousand salinity. For both species, PAH exposure decreased as salinity increased whereas dispersant effectiveness decreased only at the highest salinity. Hence, risks to fish of PAH from dispersed oil will be greatest in coastal waters where salinities are low.     

Short-term effects of the prestige oil spill on the peregrine falcon (Falco peregrinus)

We have monitored the distribution, population status, breeding success, turnover rate and diet of a Peregrine Falcon population in Bizkaia (North of Spain) since 1997. On the 13th November 2002, the tanker Prestige sunk off La Coruña (NW Spain) causing an oil spill that affected the whole of the Cantabrian Coast and the Southwest of France. The total number of birds affected by the Prestige oil spill was expected to be between 115,000 and 230,000, some of them raptors. The loss of clutches during the incubation period increased significantly and was correlated with the loss of females. Moreover, the turnover rate of the population increased from 21% to 30%. The polycyclic aromatic hydrocarbon concentrations in the eggs, collected from five nests after they were deserted, ranged from 21.20 ng/g to 461.08 ng/g, values which are high enough to cause the death of the embryos and poisoning of adult birds. The effects of pollution reached inland since some inland-breeding falcons prey on shorebirds that use rivers during their migratory flights. As the Prestige oil spill has clearly resulted in increased rates of adult mortality and reduced fertility, we suggest that the environmental authorities urgently undertake measures aimed at protecting the Peregrine Falcon in Bizkaia.     

明光一带渐新世明光组的发现

明先城北地区出露不整合于定远组之上的碎屑岩，通过ESR年龄测定，认为属于渐新世的沉积。建立明先组填补了该区渐新世沉积的空白。