7种海洋微藻对UV-B辐射的敏感性差异分析

在实验室条件下研究了UV B辐射对 7种海洋微藻生长的影响 .结果表明 :7种微藻的相对增长率随着UV B辐射剂量的增强呈明显的下降趋势 (P <0 0 5 ) .实验微藻对UV B辐射的敏感性符合绿藻 >硅藻 >金藻的分类学规律 ,其中金藻 870 1是最敏感的一种 .叶绿素a和类胡萝卜素的 48h半数有效抑制浓度EC50 远远大于相对增长率的EC50 .分光光度法测定微藻在UV波段的吸收峰集中在UV C波段 .在UV B波段 ,每 10 4 个细胞的最大吸收度的顺序为 :绿藻 >硅藻 >金藻 .微藻对UV B辐射的敏感性可能与其在该波段的吸收度之间存在一致性关系     

Assessing the toxicity and teratogenicity of pond water in north-central minnesota to amphibians

BACKGROUND: Incidence of amphibian deformities have increased in recent years, especially in the northern region of the United States. While many factors have been proposed as being responsible for generating deformities (e.g., contaminants, ultraviolet radiation [UV], parasites), no single cause has been definitively established. METHODS: To determine whether waterborne chemicals are responsible for amphibian deformities in ponds in north-central Minnesota, we deployed semipermeable membrane devices (SPMDs) in an impacted and a reference site to accumulate lipophilic contaminants. We then exposed native tadpoles (northern leopard frogs; Rana pipiens) to the SPMD extracts combined with two agricultural pesticides (atrazine, carbaryl) at two levels of UV radiation. RESULTS AND DISCUSSION: UV radiation alone caused a slight increase in hatching success and tadpole growth rate. Deformity rate among hatchlings was high following exposure to SPMD extracts from the reference site in the absence of UV, suggesting that chemicals present at this site are broken down by UV to less harmful forms, or become less bioavailable. Conversely, impacted site SPMD extracts caused hatchling deformities only in the presence of UV, suggesting that UV potentiates the teratogenicity of the compounds present there. Impacted site SPMD extracts significantly increased the number of bony triangles among metamorphs, a common deformity observed at this site. The incidence of skin webbings increased significantly with SPMD extracts from both sites as well as with our pesticide control containing atrazine and carbaryl alone. CONCLUSIONS: Higher deformity rates among tadpoles reared in the presence of UV radiation and SPMD extracts from sites where deformities are common indicates a chemical compound (or compounds) in the water at this site may be causing the deformities. RECOMMENDATIONS AND OUTLOOK: It is important to examine the effects of chemical stressors in the presence of other natural stressors (e.g., UV radiation) to gain a better understanding of how multiple stressors work to impact amphibians and amphibian populations.     

Effects of ultraviolet radiation on toad early life stages

Background  Exposure to harmful levels of ultraviolet-B radiation (UVB), a component of solar radiation, has been suggested as a potential cause of amphibian declines. Methods  We measured solar radiation (UVB, ultraviolet-A, and visible) wavebands in breeding ponds of Bufo boreas (boreal toad, a montane species that has undergone severe population declines) and Bufo woodhousii (Woodhouse’s toad, a plains toad that has not experienced declines) and examined tolerances of these species to simulated solar UVB exposures in the laboratory. Results  We found larvae of both species to be tolerant of simulated solar UVB in excess of solar UVB levels observed in their breeding ponds. B. boreas tadpoles were more tolerant of simulated solar UVB exposure than B. woodhousii tadpoles, possibly because of greater amounts of photoprotective melanin in B. boreas skin. Conclusions  UVB levels observed in B. boreas habitats do not currently appear to constitute a threat to the survival of these animals; however, long-term (>1 month) exposure to UVB levels comparable to levels associated with the water interface appears to reduce survival in B. woodhousii tadpoles. Therefore, future increases in surface and water column UVB radiation in bufonid habitats might pose significant survival risks to B. boreas or B. woodhousii populations.     

The role of the egg jelly coat in protecting<Emphasis Type="Italic">Hyla regilla</Emphasis> and<Emphasis Type="Italic">Bufo canorus</Emphasis> embryos from ultraviolet B radiation during development

BACKGROUND: Previous studies have suggested that Ultraviolet B (UVB) radiation may play a role in amphibian population declines. Some of these studies also indicate that egg hatching success is unaltered in some species of anurans as a result of UVB exposure. It has been proposed that the egg mass jelly provides photoprotection to the developing embryos. METHODS: Direct spectrophotometric scans of egg jelly, scans of egg jelly methanol extracts, and experimental manipulation in a solar simulator during development were all used to assess the role of egg mass jelly as a photoprotective agent. RESULTS/DISCUSSION: For Hyla regilla, scans of egg jelly and methanolic extracts (for mycosporine-like amino acid content) both displayed no absorption in the UV range. Experimental manipulation (removal of egg mass jelly) with both Hyla regilla and Bufo canorus egg masses in a solar simulator demonstrated that egg mass jelly played no apparent role in photoprotection of either of these species. CONCLUSIONS: Based on the results in this study it seems unlikely that the egg jelly coat is playing a crucial role in protecting developing embryos from the impact of UVB radiation.     

Surface solar ultraviolet radiation: A theoretical approach of the SUVR reaching the ground in Athens, Greece

Daily total ozone observations made during 1985–1993 by both the Total Ozone Mapping Spectrometer (TOMS) flown on the Satellite Nimbus-7 and the Dobson Spectrophotometer have been used in order to investigate the fluctuations of the daily broad-band and spectral solar ultraviolet radiation reaching the ground. This investigation has been performed by employing a recently developed parametric algorithm for the estimation of the spectral and broad-band solar ultraviolet radiation which takes the total ozone variations into consideration. Total ozone reductions during the summertime from 1985 to 1993 over Athens, Greece (37.6° N, 23.4° E), cause an increase in the ultraviolet irradiance which reaches the ground of 0.54 %, 0.98 %, 2.60 % and 0.79 % per decade for the months of July at 300 nm, 312 nm, 320 nm and UVB (280-320 nm), respectively.     

Effects of the Interaction between Genetic Diversity and UV-B Radiation on Wood Frog Fitness

Abstract:  Genetic diversity may buffer amphibian populations against environmental vicissitudes. We hypothesized that wood frogs (  Rana sylvatica ) from populations with lower genetic diversity are more susceptible to ultraviolet-B (UV-B) radiation than those from populations with higher diversity. We used RAPD markers to obtain genetic diversity estimates for 12 wood frog populations. We reared larval wood frogs from these populations and exposed experimental groups of eggs and larvae to one of three treatments: unfiltered sunlight, sunlight filtered through a UV-B-blocking filter (Mylar), and sunlight filtered through a UV-B-transmitting filter (acetate). In groups exposed to UV-B, larval mortality and deformity rates increased significantly, but egg mortality did not. We found a significant negative relationship between genetic diversity and egg mortality, larval mortality, and deformity rates. Furthermore, the interaction between UV-B treatment and genetic diversity significantly affected larval mortality. Populations with low genetic diversity experienced higher larval mortality rates when exposed to UV-B than did populations with high genetic diversity. This is the first time an interaction between genetic diversity and an environmental stressor has been documented in amphibians. Differences in genetic diversity among populations, coupled with environmental stressors, may help explain patterns of amphibian decline.     

ALGAL BLOOM PROBABILITY IN A LARGE SUBTROPICAL LAKE1

ABSTRACT: Algal blooms, defined as chlorophyll α concentrations greater than 40 μg l^?1, are common in Lake Okeechobee, Florida. Using logistic regression techniques, we have developed equations that relate limnological variables to algal bloom occurrence in four distinct open-water regions of this large shallow lake: central pelagic, northwest, southwest, and a transition region between the western and pelagic regions. Wind velocity and total phosphorus, which are closely related to resuspended material in the central region, are negatively related to algal bloom occurrence there. In the transition region, algal bloom occurrence is positively related to total nitrogen and wind velocity. Algal bloom occurrence is strongly and positively related to total nitrogen and total phosphorus concentrations in the western regions. The logistic regression model predicts an algal bloom probability greater than 95 percent in the northwest region when total phosphorus exceeds 0.10 mg l^?1 and total nitrogen exceeds 2.5 mg l^?1. In the southwest region the model predicts algal bloom probability of 100 percent when total phosphorus exceeds 0.10 mg l^?1 and total nitrogen exceeds 2.8 mg l^?1. Given 1994 mean total phosphorus concentrations of 0.05 and 0.04 mg l^?1 in the northwest and southwest regions, respectively, total nitrogen would have to remain below 1.32 and 1.43 mg l^?1, respectively, to keep the algal bloom probability below 10 percent. Because the lake is heterogenous, such nutrient standards should be considered on an in-lake regional basis for Lake Okeechobee.     

重庆雾的声雷达回波与大气SO2浓度的对比分析

本文分析了重庆１９８９年１２月３０日雾的声雷达回波特征与浓雾天气的关系，讨论了雾日大气ＳＯ２地面浓度状况。结果表明，声雷达回波与雾的定变有较好的对应；地面污染物浓度与声雷达回波所反应的大气层结状况关系密切，３００－４００米高度上的逆温层维持较长时间是加重当日大气ＳＯ２地面浓度的重要原因。     

关于不同海拔高度宇宙射线吸收剂量率测量方法的探讨

本文报道了使用FT—620型照射量率仪和高压电离室对四川省不同海拔高度宇宙射线电离成份所致空气吸收剂量率的测量结果。测量水面是四川省的三岔湖(海拨461米);邛海(海拔1510米);泸沽湖(海拔2690米)。根据测量结果经过换算,得出了在一定的地理纬度下,宇宙射线电离成份所致空气吸收剂量率随海拔高度的变化曲线。由此可评价不同海拨高度地区,宇宙射线电离成份所致居民受照剂量和计算陆地r辐射剂量率     

济南市电磁辐射环境污染状况评价与分析

本文通过对济南市电磁辐射污染源、电磁辐射环境的调查、评价与分析 ,基本查清电磁辐射污染源的污染状况、布局以及对大环境的影响情况 ,初步得出济南市的电磁辐射环境基本是清洁的结论。