Slowest of the slow: latitudinal insensitivity of burrowing capacity in the bivalve <Emphasis Type="Italic">Laternula</Emphasis>

Low temperature limits the rate of biochemical reactions and aerobic scopes of cold water ectotherms. To compensate for this limiting effect, animals living in cold environments often possess physiological or morphological adaptations to maintain vital functions. Cross-latitudinal comparison of aerobic capacities is one method to test which factors constrain activity in thermally distinct environments particularly when congeneric studies are carried out on related species with conservative ecology and habitat. Burrowing is a major aerobic activity of bivalve molluscs that is described here for the first time for the tropical mangrove species Laternula truncata and Laternula boschasina and then compared with their Antarctic congener Laternula elliptica. About 80% of L. truncata (16.3–46.1 mm shell length) and 63% of L. boschasina (11.3–27.7 mm shell length) buried within 24 h at 28°C. The burrowing rate index (BRI = [³√wet weight/time to bury]×10⁴) ranged between 1.1 and 20.2 for L. boschasina and 1.1–32.9 for L. truncata. These values are 2–3 orders of magnitude less than other tropical bivalve molluscs and are amongst the lowest recorded for any bivalve. Comparisons with the Antarctic L. elliptica showed little or no differences in BRI (Q ₁₀ of 1.0–1.2 for specimens of the same size). This is contrary to the general pattern over a wide range of bivalves, where BRI increases with a Q ₁₀ of between 2.9 and 6.4 between high latitudes and the equator. L. elliptica has 25–30% longer relative foot length than tropical congeners of the same size, which could be a morphological adaptation compensating for reduced burrowing speeds in a colder environment. Burrowing rates within the genus Laternula could, however, also be maintained by differing habitat, ecological and physiological constraints on burrowing capability.     

Conservation genetics of <Emphasis Type="Italic">Lumnitzera littorea</Emphasis> (Combretaceae), an endangered mangrove,from the Indo-West Pacific

Mangrove forests, with their ecological significance and economic benefits, are vital inter-tidal wetland ecosystems. Lumnitzera littorea (Combreataceae) is a non-viviparous mangrove distributed in tropical Asia and North Australia. Due to natural and human impacts, populations of this species have been isolated, fragmented, and highly disturbed. In China, L. littorea is an endangered species, restricted to small regions of Hainan Island. The genetic composition of five populations of this species from the Indo-West Pacific (South China, Malay Peninsula, Sri Lanka, North Australia) was assessed using inter simple sequence repeat (ISSR) makers. At the species level, expected mean heterozygosity (He) was 0.240 with 75.6% of loci polymorphic (P). However, genetic variation was much lower at the population level (P = 37.1%, He = 0.118). A high coefficient of gene differentiation (Gst = 0.515) and low level of gene flow (Nm = 0.470) indicated significant genetic differentiation among populations. AMOVA also indicated that more than half the total variation (58.4%) was partitioned among populations. The high degree of differentiation observed among populations emphasizes the need for appropriate conservation measures that incorporate additional populations into protected areas, and achieve the restoration of separate, degraded populations.     

湘南第四纪红壤吸附SO_4~(2-)的机理研究

本文研究了湖南第四纪红粘土及其发育的旱地和水田表层土壤对SO_4~2的吸附.结果表明这三种土壤吸附SO_4~2的顺序为;红粘土>旱地红壤>红壤性水稻土.而且随介质pH的升高,SO_4~2吸附量减少,吸附机理也发生改变:当介质pH6.5以后,解吸占优势.     

The Relationship Between Exposure to Arsenic Concentrations in Drinking Water and the Development of Skin Lesions in Farmers from Inner Mongolia, China

Associations between the concentration of arsenic naturally occurring in drinking water and the development of skin lesions in people have been documented for some years at various locations around the world. Data on the exposure-response relationship between concentrations of arsenic in drinking water and prevalence of skin lesions in farmers from five locations in Inner Mongolia, China have been collected from the original publications and re-analysed together as a meta-study. The calculated data show a positive linear exposure-response relationship without a threshold. The reasons for this linear correlation are discussed and compared with the data from Xinjiang, another arsenism area located in a different geographical area of China. Here a different relationship was recorded that involved a threshold concentration before skin lesions developed. The significance of these two different exposure-response scenarios is discussed.     

豆科树种刺槐、黄檀、合欢根瘤菌的数值分类及16S rDNA-PCR RFLP研究

测定了从豆科树种刺槐、黄檀、合欢根瘤中分离获得的51个菌株与18株参比菌株的唯一碳源、氮源利用，抗生素抗性，耐逆性和酶活性等132个表型性状，并用MINTS软件进行聚类分析，结果表明，全部供试菌株在59％的相似性水平上分为两大群：一个各为慢生菌群，另一群为快生和中慢生菌群，在85.1%的相似性水平上分为5个亚群，其中亚群4不与任何已知参比菌株聚在一起，可能为新种。同时，表型性状测定结果发现某些菌株对抗生素（300μg／mL）、温度（40℃）有较强抗性，大多数菌株能在较宽的pH值范围内生长（pH5-12），这些具有抗逆特性的菌株为我国西部大中种植豆科植物接种适宜的根瘤菌提供了宝贵的种质资源，在数值分类的基础上，又对47株菌进行了16S rD-NA-PCR RFLP分析，经SPSS软件聚类后，划分为7个亚群，在较大类群的划分上，与数值分类的结果有较好的一致性，16S rDNA-PCR RFLP遗传图谱共有30种类型。表型及遗传型分析结果表明，豆科树种根瘤菌具有极大的多样性，图2表2参14。     

湘南红壤对NO_3~-和SO_4~(2-)的吸附机理研究

本文研究了湘南第四纪红粘土发育的红壤对NO_3和SO_4~(2-)的吸附等温线。结果表明红壤对NO_3~-的吸附在浓度低时为负吸附,浓度高时为正吸附,吸附机理为非专性吸附,红壤对SO_4~(2-)的吸附等温式以Freundlich方程最好,在达到最大吸量(X_m)之前,SO_4~(2-)以置换羟基(—OH)的配位吸附为主;而在达到最大吸附量以后,以非专性物理吸附为主。     

城市公共安全规划理论与方法的探讨

分析了进行城市公共安全规划研究的意义和理论基础,并对了城市公共安全规划的方法进行了探讨。     

A Study of Plant Species Extinction in Singapore: Lessons for the Conservation of Tropical Biodiversity

The native vascular plant flora of the Republic of Singapore has suffered the extinction of 594 out of a total 2277 species. These represent local, not global, species extinctions. Coastal habitats, including mangroves, have lost 39% of their species, while inland forests have last 29%. Epiphytic species (62% loss) appear particularly prone to extinction, which is reflected in a similar disposition exhibited by the Orchidaceae. Deforestation and disturbance have been the main cause of plant species extinction in Singapore. The rich mangrove epiphyte flora has been totally exterminated, and a number of tree species are reduced to populations of a few mature individuals. Many more species continue to survive than the species-area relationship would predict given the 99.8% loss of primary forest. This is interpreted as a result of the failure of equilibrium to be achieved yet in the remnant forest fragments, even after more than a century of isolation. Singapore's secondary forests appear to accrete plant diversity very slowly, even if contiguous with primary forest areas. We conclude that remnant fragments of primary tropical forest, even of very small size, can play a major role in the conservation of tropical biodiversity. The patterns of extinction observed in Singapore indicate that coastal and estuarine sites are in greatest demand for development and therefore must be given high priority for conservation despite their somewhat lower biodiversity. Epiphyte and orchid diversity appear to be very good indicators of the degree of disturbance suffered by a habitat in the humid tropics.     

天津市土壤风沙尘元素的分布特征和来源研究

通过与土壤标准和背景值的比较分析了天津市土壤风沙尘元素的质量分数分布特征，通过富集因子法分析了天津市风沙尘元素的富集特征，进而说明天津市风沙尘元素的来源及其变化。结果表明，（1）Cr、Ni、Cu、Zn和As质量分数均有超过土壤标准的现象。（2）Ni、Cu、Pb、Zn和Ag超过背景值10倍以上，受到了人为污染。（3）粗颗粒中西青区的Pb元素，津南区的Ni元素和Pb元素以及细颗粒中东丽区的Ca元素和Zn元素，西青区的Cu、Pb，津南区的Cr、Ni、Pb等元素达到显著污染级别；各区粗细颗粒中的Ag元素污染级别最高，有的为极强烈污染；这些元素是典型的人为污染元素。（4）粗颗粒中只有Ca和Ni污染级别有所增加，细颗粒中只有Na、Ni、As等3种元素的富集因子略有增加。所以，天津市土壤风沙尘的治理重在控制人为来源的Ni、Cu、Pb、Zn、Ag、Cr和Ca等高污染元素。     

γ-辐照对水中腐殖酸去除的研究

以腐殖酸作为消毒副产物前驱物的代表,研究了γ-辐照对其去除效果.结果表明,γ-辐照对水中腐殖酸具有较好的去除作用.腐殖酸初始浓度为10mg·l-1时,在1.0kGy的辐照剂量下,腐殖酸去除率为88.6%,总有机碳减少62.8%,色度去除率为76%.随着辐照剂量的增加,氧化还原电位先增大后减小,而电导率则相反.在相同的辐照剂量下,初始浓度较低的腐殖酸去除率较高.碳酸盐对辐照去除腐殖酸具有抑制作用,中性条件有利于γ-辐照对腐殖酸的去除.辐照去除腐殖酸的过程可用一级动力学描述.