Distribution of Redox-sensitive Elements in Bottom Waters,Porewaters and Sediments of Rogoznica Lake (Croatia) in Both Oxic and Anoxic Conditions

Geochemical, mineralogical and sedimentological analyses were carried out to contrast two different sites (respectively characterized by permanently oxic and anoxic conditions) in a small, meromictic, seawater lake. In fact, due to relatively high organic matter content, and reduced water exchange, the Rogoznica Lake has almost permanent anoxic conditions below the depth of 12 m, where sediment can be considered an anoxic–sulphidic sedimentary environment. Different water column and sediments redox conditions affect the distribution and speciation of major redox-sensitive metals (Fe, Mn, Mo), reduced sulphur species (RSS) and dissolved organic C (DOC). Trace metals, especially those that accumulate in anoxic–sulphidic environments (Fe, Mo) showed a marked enrichment in the solid phase, whereas the low solubility of sulphides leads to low porewater concentrations. The relatively high sedimentary enrichment of Mo (up to 81 mg/kg) also confirms highly anoxic conditions within the Rogoznica Lake sediments. Results clearly show that chemical species within the sediments will tend towards equilibrium between porewater and solid phase according the prevailing environment conditions such as redox, pH, salinity, DOC.     

Factorial structure of recklessness: to what extent are older drivers different?

PROBLEM: This study tests whether the original factorial structure of a recklessness questionnaire can be maintained for the current Spanish population of older drivers. JUSTIFICATION: Our recent interest in dedicating special attention to senior citizen mobility (Monterde, 2001), is due to the impending increase of the aging population in Western countries; this has led us to reinitiate the psychometric study of the construct validity, revising and including older drivers in the psychometric aspects of those evaluation instruments that will then be used in the Spanish psycho-medical check of drivers and in research. METHODS: Factorial analysis was used to determine validity. RESULTS: There was an appearance of a different psychological pattern in elderly drivers, specifically, a psychological anxiety trait related to the task of driving. Furthermore, interesting data were found about the attitude of this sector toward the "traffic society" and toward some of the measures included in Spanish legislation that affect especially older drivers (such as the psycho-medical check). IMPACT ON INDUSTRY, RESEARCH AND PRACTICE: These results suggest the possible existence of some kind of "compensation phenomenon," which could have influence over the scores obtained and their interpretation. Consequently, the evaluation instruments should be tested and, if necessary, adapted or specifically created for use with this age group.     

Soybean-Oil-Based Polyisocyanurate Rigid Foams

Polyisocyanurate foams were prepared from polymeric 4,4-diphenylmethane diisocyanate (MDI), soy polyol and polypropylene oxide polyol by varying isocyanate index from 110 to 350. The higher isocyanate index produced polyisocyanurate foams with higher thermal stability, improved flame resistance, tensile strength, higher modulus, and higher glass transition. Soy-based foams displayed better thermal stability, lower flammability, higher rigidity (modulus) and higher compression strength than those based on the propylene oxide polyols of the same molecular weight and functionality.     

Comparisons between the diets of four abundant species of elasmobranchs in a subtropical embayment: implications for resource partitioning

The diets of one ray species (Rhinobatus typus) and three shark species (Carcharhinus cautus, Negaprion acutidens, Rhizoprionodon acutus) undergo size-related changes and differ among these species in the nearshore waters of a large subtropical embayment (Shark Bay) in which these elasmobranchs are abundant, thereby reducing the potential for competition for food within and among these four species. R. typus fed almost exclusively on penaeid prawns and portunid crabs, which is reflected in its narrow dietary breadth, whereas different species of teleosts constituted a major component of the diets of each size class of the three shark species. The prey consumed by the three shark species was diverse, with representatives of 15 teleost families being consumed by C. cautus and substantial volumes of cephalopods being ingested by that species and R. acutus. The pronounced differences in the diet of the single ray species and three shark species reflect differences between a bottom-dwelling and more pelagic life, and between modes of feeding and relative mouth sizes. The relative contributions of the different species of teleost to the diets of the three shark species varied. Thus, although each of these species fed on atherinids, labrids and sillaginids, C. cautus also consumed substantial amounts of platycephalids and terapontids and R. acutus and N. acutidens also ingested considerable amounts of clupeids. Furthermore, R. acutus, which is the only one of the four species that typically occurs over seagrass, was the only species that fed on the centropomid Psammoperca waigensis, which is very abundant in seagrass meadows. However, the sparid Rhabdosargus sarba, which lives in unvegetated areas, was never ingested by R. acutus, but was consumed by C. cautus and N. acutidens. As the individuals of R. typus increased in size, they progressively consumed proportionately smaller volumes of the penaeid prawns Penaeus merguiensis and Melicertus latisulcatus and relatively greater volumes of the portunid crab Portunus pelagicus, which is slightly larger and has a harder exoskeleton. In addition to teleosts, large C. cautus ingested substantial volumes of portunid crabs and ophidian reptiles, presumably sea snakes, while large N. acutidens also fed on the ray R. typus.Communicated by G.F. Humphrey, Sydney     

Biologically induced Po emission from fresh water

Behavior of Po in fresh waters was examined in laboratory culture experiments using fresh water collected from a small pool, Xi river and Xiqing lake, showing formation of volatile Po compounds followed by emission to air. Addition of tryptone to the fresh water cultures increased the emission of Po considerably along with a growth of microorganisms, suggesting a connection of chemoheterotrophs to Po emission. Participation of photoautotrophs was also considered because Po emission was increased when NaHCO3 was added to the fresh water cultures. The emission behavior of Po and S in these experiments appeared in different ways. The quantity of Po emitted was comparable to the previous culture experiments (Momoshima, Song, Osaki & Maeda, Environ. Sci. Technol., 35, 2956-2960, 2001) in which artificial culture medium containing 3% NaCl was used and inoculated with sea sediment extract. The biological support for Po emission, thus, would be a general phenomenon in fresh water as well as a seawater environment and is possibly a source for atmospheric Po.     

The pollution status and the toxicity of surface sediments in Izmit Bay (Marmara Sea), Turkey

Izmit Bay is one of the most polluted and populated enclosed sea in Turkey. It has been the centre of industrial activities for the last 30 years. Seven major sources enter the bay waters along the north coastline of the bay. This investigation forms part of continuing ecotoxicology studies in the Izmit Bay designed to constrain and minimise the pollution caused by flourishing industry and a growing population. Sediments sampled from the mouths of the major discharges of Izmit Bay were analysed for their organic carbon, total polycyclic aromatic hydrocarbon (t-PAH) and trace inorganic element (Cd, Al, As, Pb, Hg and Cu) contents and compared with those found in the sediments from the reference station in the outer bay (in the Marmara Sea). The toxicity of sediments was determined in the bulk and elutriate samples by using algal (Phaeodactylum tricornutum) batch bioassays. Chemical data showed that the sediments collected from the inner sites of the bay have been contaminated with Cd, Hg, As and PAHs. Organic carbon contents were also found higher. All the major industrial discharges into the bay are now biologically treated but bioassays performed with bulk sediments revealed that the recent sediments are toxic to the microalgae throughout the bay. The results are consistent with the previous toxicity studies performed with the industrial discharges.     

两种生态下粳稻近等基因系形态性状与糙米元素间的关联性

昆明自然和阿子营冷水下鉴定了亲本及其十和田×NIL回交的BC5F5群体264个材料12个性状及ICP-AES测定了昆明自然下糙米17种矿质元素,并研究了该群体两点12个性状间及其17种矿质元素间的相关,结果表明:(1)阿子营冷水条件下该群体9个形态性状的平均值及其变异系数与昆明常温条件下相近,但穗实粒数、秕粒数及结实率3个耐冷性指标性状的平均值及其变异系数差异较大.(2)冷水条件下十和田 NIL群体形态性状间的相关比常温条件下吏密切,冷水条件下有42对呈显著或极显著相关(-0.823**～0.954**)而常温条件下仅有1 9对呈显著或极显著相关(-0.206**～0.432**).(3)在昆明常温和阿子营冷水下BC5F5群体及其亲本12个形态性状与糙米17种矿质元素组成的408对性状中仅有糙米9种矿质元素(S、Fe、Na、P、Zn、Ca、K、Mg和Mn)与孕穗期耐冷指标性状密切相关.     

云南稻种磷高效特性相关性状的生态差异

云南不仅是世界稻种(Oryza sativa L.)最大的遗传和生态多样性中心之一,也是中国土壤类型最丰富的地区;中国南方和云南耕地65%以上缺乏有效磷,土壤缺磷已成为稻作生产的主要限制因子.该文中,缺磷(速效磷6.26 mg·kg-1)与适磷(速效磷40 mg·kg-1)酸性红壤进行比较,以相对茎蘖数(RTA)、相对总质量(RTB)、相对地上质量(RDWU)和相对地下质量(RDWG)为参数,研究了来自云南省16个州市5个稻作区577份水稻核心种质的磷高效基因型及其生态差异,结果表明:低磷胁迫下云南稻核心种质的相对茎蘖数、相对总质量、相对地上质量和相对地下质量密切相关,这4个性状是水稻磷高效鉴定较可靠和方便的指标,并筛选出10个磷高效品种;磷高效基因型在籼粳间存在较大差异,但丁颖分类性状中的水陆、粘糯间差异较小;水稻磷高效品种广泛分布于5个稻作区和绝大多数州市,特别是磷高效极强品种主要来自云南稻种的遗传多样性中心(思茅、临沧、西双版纳、德宏和文山州)和基因多样性中心(南部边缘水陆兼作区).这些结果有力地支持了水稻磷高效特性与酸性红壤和遗传多样性中心有关,更好地理解水稻磷高效特性的地理生态和遗传多样性机制.     

云南稻核心种质苗期与孕穗期耐冷性特点及关系分析

以544份云南地方稻核心种质为材料,在昆明自然低温(苗期平均5.5～12.3℃,孕穗期平均17.8℃)冷害下,按籼粳、稻作区进行云南稻核心种质苗期耐冷性与孕穗期耐冷性的特点及关系研究.结果表明:(1)苗期耐冷性与孕穗期耐冷性密切相关,苗期耐冷性强的材料表现为孕穗期株高、剑叶长和宽、穗颈长、穗下节长、1～2节长、穗长较长、穗粒数较多,耐冷性较强.通过对苗期耐冷性的严格选择,可以间接获得孕穗期耐冷性较强的材料.(2)苗期和孕穗期耐冷性在籼粳间、稻作区间差异明显.籼粳间均表现为粳稻强于籼稻;稻作区间苗期耐冷性为滇中一季籼粳稻区和滇南单双季籼稻区最强,滇中一季籼粳稻区和滇西北高寒粳稻区孕穗期耐冷性较强,揭示了水稻苗期与穗期耐冷性的形成演化机制存在一致性和差异性.