Microphytoplankton in the Strait of Otranto (eastern Mediterranean)

The Strait of Otranto is the connection between the Adriatic and Ionian Seas. Low nutrient concentrations, high transparency, and low phytoplankton cell density and biomass reflect the oligotrophic character of the area. Enrichment of the euphotic layer with nutrients is mainly due to discharge of Albanian and Greek rivers, as well as mixing and upwelling in winter/early spring. Following phytoplankton bloom in April, a progressive decrease of phytoplankton cell density is due to the consumption of nutrients throughout the proceeding summer and autumn. Nitrogen was a strong limiting factor for phytoplankton growth in summer. Deep biomass maxima were detected in the 50 to 100 m layer and corresponded mostly to cells smaller than 20 m. The eastern part of the strait is mostly influenced by the northerly inflowing current from the Ionian Sea, and the western part by the southerly outflowing current from the Adriatic Sea. This typical circulation could be disturbed by inertial oscillations in the current field, generated by the strong oscillating winds and cyclonic eddies. The type of circulation determined the distribution of thermohaline characteristics, abundance, biomass, as well as taxonomic composition of phytoplankton, across the strait. Ecological characteristics of the water masses on two sides of the strait were significantly different during the formation of a longitudinal thermohaline front in May 1990.     

Effects of Selenium Supplementation on Arsenism: An Intervention Trial in Inner Mongolia

This paper reports the effects of a placebo-controlled Se-enriched yeast supplementation trial, conducted for 14 months, on arsenism in adult farmers living in a rural community in Inner Mongolia, China. The farmers had been naturally exposed to elevated concentrations of As in drinking water from tube-wells since 1983 but changed to arsenic-free drinking water when the trial began in June 1996. Blood and hair Se and As concentrations were analysed pre-intervention and at the end of the 3rd, 9th and 14th month, while skin lesions were assessed pre-intervention, as well as at the end of the 14th month, using the Arsenism Clinical Criteria established by the Ministry of Health, China. As the trial was a voluntary one, a number of farmers did not routinely have their blood and hair samples taken for analysis. Consequently, the data have been analysed in two categories. Fifty-four farmers from the Se-group and 29 from the placebo-group who were sampled on each occasion were considered as one group, which has been compared with the second group comprising up to a total of 100 farmers in the Se-group and 86 in the placebo-group. Results calculated for those farmers who were sampled on each occasion, showed that at the end of the trial, blood and hair Se concentrations of the Se-group increased from 0.130 to 0.186 µg ml^–1 and from 0.431 to 0.502 µg g^–1, respectively, while those of the placebo-groups remained constant. Blood and hair As concentrations of the Se-group decreased from 0.051 to 0.015 µg ml^–1 and from 2.57 to 0.680 µg g^–1, respectively, a greater reduction than those in the placebo-group that went from 0.064 to 0.024 µg ml^–1 and from 2.62 to 1.25 µg g^–1, respectively. When the data from all patients were examined, the analytical trends were similar. An evaluation of skin lesions in the category who were sampled for hair and blood on each occasion showed that 41.2% of hyperkeratosis, 50.0% of depigmentation and 44.7% of pigmentation in the Se-group improved one or more degrees, while those in the placebo-group improved by only 7.1, 12.0 and 6.7%, respectively. A total of 61.1% of the adults in Se-group improved in one or more type of skin lesion, but only 17.2% improved in the placebo-group. Comparable results were obtained when all the data from both categories of farmers were examined. Results from the trial showed that Se supplementation was more effective for the improvement of adults who were affected by double or triple skin lesions. In the placebo-group, most of the severely affected adults improved in only one kind of skin lesion, but in the Se-group, more adults improved in two or three kinds of skin lesions. Although the trial was limited by its relatively small size, the results have provided some evidence of the usefulness of Se supplementation for people affected by arsenism.     

Arsenism Clinical Stages and their Relation with Hair Arsenic Concentration of Residents of Bayinmaodao Rural District, Inner Mongolia, China

The clinical skin lesions of arsenism in men and women in Bayinmaodao rural district in Inner Mongolia, Peoples Republic of China, have been examined by doctors, and their hair and drinking water samples analysed for arsenic by hydride generation and ICP-AES. Altogether 311 arsenism patients with a 15.53% prevalence rate for the district were recorded. The disease prevalence rate was positively related to population, age, and their exposure to elevated arsenic concentrations in the drinking water from 1983 when new wells were dug and drinking of surface water was abandoned. Hyperkeratosis was the most serious skin lesion with the highest occurrence rate, then depigmentation and pigmentation in decreasing order. With increasing severity of the disease, ranging from skin lesion with single hyperkeratosis 1° to hyperkeratosis 3° with depigmentation 3° and pigmentation 3°, the results showed that arsenic concentrations in head hair had increased. Arsenic concentrations in hair were positively correlated with the arsenic concentrations in drinking water obtained from local wells.     

活性炭吸附水中铅离子的动态研究

本文采用两种煤质活性炭，研究了其对不同浓度二价铅离子溶液的吸附，应用固定床吸附动力学模型，Ｍａｒｑａｄｔ方法非线性回归固定床吸附流出曲线，获得了铅离子在活性炭上的扩散传质系数。结果发现，孔扩散系数Ｄｐ强裂地依赖于铅离子入口浓度，随着入口浓度的升高，孔扩散系数变小，随后用上述扩攻系数理论预测了其它操作条件下的流出曲线，结果表明实验曲线与理论预测曲线能很好地相符，动态法能可靠地获取固吸附过程的吸附及扩     

拓扑指数在定量结构生物降解性关系中的应用

本文采用二氧化碳生成量实验，对训练组有机物，利用逐步回归分析程序，从计算和十四种分子连接性指数中筛选出与生物降解性最为相关的分子结构描述参数，建立定量结构－生物降解性关系模型，其相关系数为０．９３１，利用该模型对预测组质的预测结果表明，此模型对芳香化合物的好氧生物降解性具有良好的预测能力，其正确预测率达８３．３％。     

Bioleaching of spent Ni-Cd batteries and phylogenetic analysis of an acidophilic strain in acidified sludge

Biohydrometallurgy is a novel method to recycle discarded batteries, in which sewage sludge is used as microorganisms and culture due to the presence of indigenous Thiobacilli. A two-step continuous flow leaching system consisting of an acidifying reactor and a leaching reactor was introduced to achieve the bioleaching of spent nickel-cadmium (Ni-Cd) batteries. The acid supernatant produced in the acidifying reactor by the microorganisms with ferrous ions as the substrate was conducted into the leaching reactor to dissolve electrode materials. The efficiency of a batch treatment of batteries was examined. The results showed that the complete dissolution of two AA-sized Ni-Cd batteries with 0.6 L/d acid supernatant took about 30, 20, and 35 days for Ni, Cd, and Co, respectively. But the dissolution ability of the three metals was different. Cd and Co can be leached mostly for pH below 4.0 while the complete dissolution of Ni can be achieved for pH below 2.5. Meanwhile, a strain (named Thiooxidans. WL) accounting for the reduction of pH in the acidified sludge was isolated and sequenced. It was identified to be 100% similar to Acidithiobacillus ferrooxidans strain Tf-49 based on 16S rDNA sequence analysis. The relevant phylogenetic tree constructed indicates that the strain should be classified into genus Acidithiobacillus ferrooxidans.     

Estimating the complexity of bird song by using capture-recapture approaches from community ecology

Repertoire size, the number of unique song or syllable types in the repertoire, is a widely used measure of song complexity in birds, but it is difficult to calculate this exactly in species with large repertoires. A new method of repertoire size estimation applies species richness estimation procedures from community ecology, but such capture-recapture approaches have not been much tested. Here, we establish standardized sampling schemes and estimation procedures using capture-recapture models for syllable repertoires from 18 bird species, and suggest how these may be used to tackle problems of repertoire estimation. Different models, with different assumptions regarding the heterogeneity of the use of syllable types, performed best for different species with different song organizations. For most species, models assuming heterogeneous probability of occurrence of syllables (so-called detection probability) were selected due to the presence of both rare and frequent syllables. Capture-recapture estimates of syllable repertoire size from our small sample did not differ significantly from previous estimates using larger samples of count data. However, the enumeration of syllables in 15 songs yielded significantly lower estimates than previous reports. Hence, heterogeneity in detection probability of syllables should be addressed when estimating repertoire size. This is neglected using simple enumeration procedures, but is taken into account when repertoire size is estimated by appropriate capture-recapture models adjusted for species-specific song organization characteristics. We suggest that such approaches, in combination with standardized sampling, should be applied in species with potentially large repertoire size. On the other hand, in species with small repertoire size and homogenous syllable usage, enumerations may be satisfactory. Although researchers often use repertoire size as a measure of song complexity, listeners to songs are unlikely to count entire repertoires and they may rely on other cues, such as syllable detection probability.Communicated by A. Cockburn     

西太平洋海域海水和雨水的化学特征

本工作测定了西太平洋海域中海水、海水悬浮物和海面上雨水的元素组成和浓度。通过富集因子的计算,探讨海面上雨水中微量元素的富集程度及其来源,讨论了海面上气溶胶粒子大小与洗出因子的关系,结果表明不同质量粒径大小的微量元素在公海上具有相似的洗出因子。     

汽车尾气净化非贵金属催化剂SO2中毒机理研究

用TPD,IR,XPS等方法研究了汽车尾气净化的复合氧化物催化剂SO_2中毒机理。结果表明,催化剂SO_2中毒失(?),首先是SO_2在催化剂活性中心上进行化学吸附,然后部分SO_2与活性组分生成相应的亚硫酸盐和硫盐酸,从而使催化剂失活。SO_2的化学吸附及部分生成相应的亚硫酸盐,与生成硫酸盐相比,对催化剂失活的影响,前者更为明显。     

Biology of penaeid prawns in the Suez Canal lakes

A study was made from January 1988 to March 1989 of the penaid prawns in the Great Bitter Lake and Lake Timsah located in the central part of the Suez Canal. Two species of Red Sea origin were investigated,Metapenaeus stebbingi andTrachypenaeus curvirostris; the former is by far the commoner. Both species displayed seasonal breeding over the period April to October, with peaks in the early and late parts of the season.M. stebbingi had two main cohorts each year. A spring-spawned cohort survived 16 mo, and attained modal sizes of 23 mm carapare length (CL) for females and 16 to 17 mm CL for males. The autumn-spawned cohort survived 13 mo, and reached modal sizes of 20 mm and 15 mm CL for males and females, respectively. The reasons for the success ofM. stebbingi in the Canal lakes, in contrast to other Lessepsian penaeids which have flourished in the Mediterranean Sea, have been considered. The main factors are that it is essentially a shallow-water species, with excellent tolerance of salinity variations and adverse environments. However, the Canal lake populations have smaller maximum sizes, and mature earlier, than those in open seas.