Influence of sample manipulation on contaminant flux and toxicity at the sediment-water interface

Toxicities of sediments from San Diego and San Francisco Bays were compared in laboratory experiments using sea urchin (Strongylocentrotus purpuratus) embryos exposed to pore water and at the sediment-water interface (SWI). Toxicity was consistently greater to embryos exposed at the SWI to intact (unhomogenized) sediment samples relative to homogenized samples. Measurement of selected trace metals indicated considerably greater fluxes of copper, zinc, and cadmium into overlying waters of intact sediment samples. Inhibition of sea urchin embryo development was generally greater in sediment pore waters relative to SWI exposures. Pore water toxicity may have been due to elevated unionized ammonia concentrations in some samples. The results indicate that invertebrate embryos are amenable to SWI exposures, a more ecologically relevant exposure system, and that sediment homogenization may create artifacts in laboratory toxicity experiments.     

Model of Reflection Spectra of Rock Surface in 2π Space

This paper deals with reflection spectra and polarized reflection spectra of 20 sorts of rock in 2π space, and then creates a model of reflection spectra of rock surface in 2π space. We measured the change of reflection and polarized reflection spectra as altering the incidence angle, vertex angle, azimuth angle, band and polarization. The results show that influence of the incidence angle on spectral curves is very strong. And when the vertex angle is constant, the horizontal azimuth polarizes rock spectra, and distorts the circular spectrum to become elliptic. The polarization influences the reflection intensity of rock spectra, but has no evident influence on the characteristics of wave forms of rock in 2π space. Therefore, we can describe the whole reflection spectral characteristics, including polarization, of rock surface in 2π space by measuring and calculating the e and p values in several key directions.     

航空图像与卫星图像大气圈校正的算法

本文描述了进行快速大气圈校正的一种算法。所需辐射参数储存在一个检查表格中。基本程序是把所测辐射率、波长、观察方向和照射方向、观察面高度及烟、大气微粒和气吸收的光学厚度输入一个检查表内。然后计算面辐射率、面瞬时辐照度及面反射率。同时,该程序还可以计算给定反射率,观察和照射方向、烟、大气微粒与气吸收的光学厚度等参数情况下特定高度处的上方的辐射率。     

碰撞造山带的P—T—t轨迹

压力—温度—时间(P—T—t)轨迹综合了造山作用期间变质岩石遭受的压力与温度的变化。它们为解释复杂的变质历史提供了一种简便的骨架,也提供了深入探讨碰撞造山带中控制变质作用的热因素与大地构造因素的条件。P—T—t资料是由结构观察、地质温度计、地质热时测定综合获得的,并组合构成适于地质条件的P—T—t轨迹曲线。假设瞬间变形及传导热松驰的一维P—T—t模式易于构制且对于检验大地构造模式是常用的,特别是在地质年代数据可以利用时更是如此。二维模式适于更复杂的变形几何,且容许多有对流效应的介入。根据经典楔状体理论对碰撞造山带进行的分析,可以出现反映加厚、抬升、剥离和会聚间的偶合现象的P—T—t轨迹。在剥蚀速率达到构造抬升速率时,就象目前新西兰南阿尔卑斯带中所出现的情况,那么高级变质岩可以迅速由很深处剥露出来。另一方面,迅速剥露可能反映了过陡或热软化的造山带中受重力作用出现的伸展。     

斜长石的碎裂流与半脆性变形

在温度为25～700℃、压力为500～1500MPa和应变率10~(-5)S~(-1)的条件下,对布什维尔德斜长石(An_(75),粒度350μm,5％其它物质)展开了一系列实验。在所施加的P—T范围内布什维尔德杂岩的强度都保持对压力敏感,而弱化则出现在给定压力条件下增温的情况。由粘滑向稳定滑移的转变出现在200～300℃和≥500MPa条件下。在200～300℃时强度的降低,局部出现的碎裂流及缺少晶内塑性变形的微观证据都有利地说明一种可能性,即这种转变对应于一定量随机分布的热破裂的扩展。均匀韧性流动仅出现在600℃和700℃温度,1000～1500MPa压力条件下,它与机械双晶,不均匀和带状波状消光的发育对应,这可能是由半脆性变形引起的。在这些条件下,变形持续至应变高达44％。     

Field validation, in Scotland and Iceland, of the artificial mussel for monitoring trace metals in temperate seas

The artificial mussel (AM), a novel chemical sampling device, has been developed for monitoring dissolved trace metals in marine environments. The AM consists of Chelex-100 suspended in artificial seawater within Perspex tubing and enclosed with semi-permeable polyacrylamide gel at both ends. To validate the field performance of the AM in temperate waters, we deployed AMs alongside transplanted blue mussels Mytilus edulis in coastal environments in Scotland (Holy Loch, Loch Fyne, Loch Striven and Millport) and Iceland (Reykjavikurh?fn, Gufunes, South of thornerney, Hofsvik, Hvalfj?rethur and Sandgerethi) for monitoring trace metals. While uptake patterns of Cd between the AM and M. edulis were highly comparable, discrepancies were found in the accumulation profiles of the other metals (Cu, Cr, Pb and Zn), in particular Zn. Nonetheless, the AMs gave a better resolution to accurately reveal the spatial difference in dissolved metal contamination when compared with M. edulis. AMs complement the use of mussels since AMs indicate dissolved metals in seawater, whereas uptake by mussels indicates a mixture of dissolved and particulate metals. Our results also indicated that historical metal exposure of the transplanted M. edulis could significantly confound their metal concentrations especially when the deployment period was short (i.e. <34d). This study suggested that the AM can overcome problems associated with variable biological attributes and pre-exposure history in the mussel, and provides a standardized and representative time-integrated estimate of dissolved metal concentrations in different marine environments.     

Spatio-temporal changes of marine macrobenthic community in sub-tropical waters upon recovery from eutrophication. II. Life-history traits and feeding guilds of polychaete community

A two-year study was conducted in the vicinity of a harbour in sub-tropical Hong Kong, to examine the progress of recovery of macrobenthic community, based on analyses of both life-history traits and trophic guilds of polychaetes, upon cessation of organic pollution caused by sewage discharge. Seventy seven out of 83 species collected were classified under four ecological groups based on the life-history traits and sensitivity to organic gradients. The mean ATZI marine biotic index (AMBI) derived from these ecological groups showed spatial difference among the five sampling locations. In particular, the presence of different percentages of polychaete species from Groups III (unbalanced community) and IV (polluted community) suggested the presence of pollution stress in certain degree at all sampling locations. However, no significant temporal changes were noted over the study period. From all polychaete species identified, they were classified into 13 feeding guilds. The mean diversity of these feeding guilds at most of the sampling locations was significantly higher than that at one of the inside-harbour locations. The composition of feeding guilds was also significantly different spatially. At one of the inside-harbour locations, the dominant feeding guilds were motile/discretely motile surface deposit feeders with tentaculates or unarmed pharynx, and motile omnivores with jawed pharynx in the first year of study, but were replaced by motile, jawed carnivores in the second year of study. The increased proportion of carnivores over the study period can be seen as a sign of recovery in the community structure since abundance of predators is commonly higher in habitats with better environmental quality. The implications of using life-history traits and feeding guild analyses for benthic community are discussed.     

Okadaic acid, a causative toxin of diarrhetic shellfish poisoning, in green-lipped mussels Perna viridis from Hong Kong fish culture zones: method development and monitoring

Green-lipped mussels (Perna viridis) were collected from seven fish culture zones (FCZs) in Hong Kong and analyzed for okadaic acid (OA). A conventional HPLC method was modified by incorporating a proteinase K digestion step. Results suggest that a higher recovery (2.5 times higher) of OA was obtained from spiked samples after the addition of 1.08 mg proteinase K in comparison with samples incubated without the proteolytic enzyme. For the hepatopancreas (HP) of individual field-collected mussels, the additional digestion step can enhance OA extraction by 3.1 times. Spatial and temporal variations in OA concentrations in the mussels from various FCZs were investigated. The highest concentration of OA in mussel HP samples was 1164.9 ng/g HP wet wt. With respect to OA concentrations in whole mussel tissues from seven sites and four seasonal samplings, the concentrations were between 70.0 and 131.0 ng/g wet wt., which did not exceed the generally recognized international regulatory criteria (>200 ng/g) for OA.