Underwater sounds near a fuel receiving facility in western Hong Kong: relevance to dolphins

Western Hong Kong is home to two species of marine mammals: Indo-Pacific humpbacked dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides). Both are threatened in many parts of their range in southeast Asia [for example, International Biological Research Institute Reports 9 (1997), 41; Asian Marine Biology 14 (1997) 111]. In 1998, when the new Hong Kong International Airport opened in western Hong Kong, small tankers (about 100 m long, cargo capacity about 6300 metric tons) began delivering fuel to the Aviation Fuel Receiving Facility (AFRF) just off Sha Chau Island, north of the airport. Calibrated sound recordings were taken over a 4-day period from a quiet, anchored boat at distances 80-2000 m from aviation fuel delivery activities at the AFRF. From the recordings, 143 sections were selected for analysis. Narrowband spectral densities on the sound pressures were computed, and one-third octave band levels were derived for center frequencies from 10 to 16,000 Hz. Broadband levels, viz. 10-20,000 Hz. were also computed. The results showed that the Sha Chau area is normally noisy underwater, with the lowest broadband levels measured corresponding to those expected during a storm at sea (sea state 6). This background noise is believed to come largely from heavy vessel traffic in the Urmston Road to the north and east of Sha Chau and from vessels in the Pearl River Estuary to the West. The sound levels from the AFRF tankers are comparable to the levels measured from similar- and smaller-sized supply vessels supporting offshore oil exploration. The strongest sounds recorded were from a tanker leaving the AFRF at distance 100 m from the hydrophone, for which the one-third octave band level at 100 Hz was 141 dB re 1 microPa (spectrum level 127 dB re 1 microPa2/Hz) and the 10-20,000 Hz broadband level was 146 dB. At distances of 100 m or more and frequencies above 300 Hz, the one-third octave band levels were less than 130 dB (spectrum level 111 dB re 1 microPa2/Hz) and decreased with increasing frequency and distance. At distances greater than about 500 m, AFRF-associated sounds were negligible, masked by the generally high noise level of the area and attenuated by poor transmission in the very shallow water (<10 m). Because it is believed that humpbacked dolphins and finless porpoises are not very sensitive to sounds below 300 Hz, the Airport Authority Hong Kong (AA) stipulated that dedicated terminal vessels not radiate underwater sounds at spectrum levels greater than 110 dB re 1 microPa2/Hz at frequencies above 300 Hz and distances greater than 300 m. The spectrum levels at 300 Hz and higher frequencies of sounds from the tankers arriving, departing, or off-loading at AFRF were less than 110 dB re 1 microPa2/Hz even at distances of 200 m or less. The AA stipulation was met. However, it is presently unknown whether the generally strong noise levels of western Hong Kong inhibit acoustically based feeding and communication, or result in increased stress or permanent shifts in hearing thresholds.     

白垩纪温度较冷的估价

白垩纪温度较冷的估价Ｂ．ｗ．Ｓｅｌｌｗｏｏｄ等有关白垩纪气候的概念部分基于详尽的地质证据，如不耐寒冷的古生物（如：珊瑚的分布比现在偏极地５－１５℃）和特殊气候条件的沉积相的广泛分布。这些资料的解释反映２１℃的等温线在纬度上至少向两极移动５°，全球的平...     

Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions

Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical Observatory. The difference in the magnetic field strength between the two layers seems reasonable. The solar radio maps of active regions obtained with the Nobeyama radioheliograph, both in total intensity (I-map) and in circular polarizations (V-map), are compared with the optical magnetograms obtained with the SMFT. The comparison between the radio map in circular polarization and the longitudinal photospheric magnetogram of a plage region suggest that the radio map in circular polarization is a kind of magnetogram of the upper chromosphere. The comparison of the radio map in total intensity with the photospheric vector magnetogram of an AR shows that the radio map in total intensity gives indications of magnetic loops in the corona, thus we have a method of defining the coronal magnetic structure from the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified three components: (a) a compact bright source; (b) a narrow elongated structure connecting two main magnetic islands of opposite polarities (observed in both the optical and radio magnetograms); (c) a wide, diffuse, weak component that corresponds to a wide structure in the solar active region which shows in most cases an S or a reversed S contour, which is probably due to the differential rotation of the Sun. The last two components suggest coronal loops on different spatial scales above the neutral line of the longitudinal photospheric magnetic field.     

千里山花岗岩体地质地球化学及与成矿关系

千里山花岗岩由似斑状黑云母花岗岩、等粒黑云母花岗岩和花岗斑岩组成。前两期岩体分别与两期钨多金属矿化有关，后一期与铅锌银成矿密切相联。两套花岗岩虽然均来自地壳，但取于不同源地。该岩体既为富Ｆ、Ｌｉ，Ｒｂ，Ｂｅ，Ｇａ的ＢＥＬＩＦ花岗岩，又是富Ｕ，Ｔｈ的高热花岗岩。     

太古宙陆壳的地质和地球化学演化

引言因为现代大陆壳的大部分(可能大于50％)看来是在太古宙(>25亿年)期间形成的,所以试图认识导致太古宙地壳发展的岩浆和构造作用是重要的。但还存在许多问题。为什么在大约38亿年以前没有形成地壳?或是它再循环回到地幔系统,以致没有残留物吗?太古宙高级片麻岩、麻粒岩区和低级花岗岩一绿岩区之间的主要差别是什么?它们是否代表太古宙不同的构造环境?这种环境是太古宙独有的,或已发现了现代的相     

Butterfly-plant interactions and body size patterns along an elevational gradient in the Manang region of central Nepal

Butterflies are widely studied due to their key ecosystem functions.For this reason,they are used in ecosystem assessment,formulating conservation plans and in raising the environmental awareness.Quantification of different factors affecting diversity of butterflies is important for their effective conservation.In this study,we investigated abiotic and biotic factors affecting species richness and community composition of butterflies along an elevational gradient in Manang region,central Nepal.We also tested if butterfly species follow the Bergmann’s rule.A total of 57 butterfly species belonging to 39 genera and 8 families were recorded in the study area.Out of a total of 127 plant species identified in the study region,only 67 plant species were visited by butterflies as nectar sources.Species richness of butterflies increased with increasing elevation.Species richness was significantly higher in places with shrubs compared to other places and also in autumn than in summer.Species richness of butterflies also depended on composition of plant species occurring at the localities.Butterfly species composition varied among sampling localities.It was also determined by habitat type,elevation,sampling time,plant species and interactions of elevation×time.The relationship between butterfly size and elevation was in the opposite direction than expected according to the Bergmann’s rule.In conclusion,protection of butterfly diversity can only be achieved by protecting different habitats across the diverse physiography of the region and different plant species,in particular herbs and shrubs.Our results do not support the Bergmann’s rule for butterflies along an elevational gradient in our region.     

两株琼胶酶高产细菌的筛选和鉴定

从海洋环境中筛选得到两株琼胶酶的高产菌株，通过形态观察和生理生化反应，确定它们属于弧菌属，通过BIOLOG细菌鉴定系统鉴定，并同弧菌属标准菌株分析比较，确定上方宝剑两株菌都是塔式弧菌（Vibrio tubiashii)，这两株菌在碳源利用方面存在差别。     

大地震远程触发小地震的首次证据

就在去年6月28日破晓以前,位于洛杉矶以东200km的莫哈维沙漠发生了7.3级地震。这次地震以距震中最近的小城的名字命名为兰德斯地震。该地震虽然比三年前旧金山发生的地震强烈,但由于这一地区人口稀少,没有引起人们太大的注意。但是,这次地震却对地震学史有贡献。80年代期间,在美国极西部地区建立的高密度、分布广的地震台网提供了令人信服的证据:兰德斯地震引发了一系列的继发性地震。最远的在其东北1250km处的黄石国家公园。     

SEDIMENT YIELD AND HYDROLOGY IN NORTHWESTERN RANGELANDS

lINTRODUCTIONRangeandforestlandsofnorthwesternNorthAmericahavebeenutilizedforres0urceextracti0nandproductionsinceinitialhuman0ccupationofthecontinent.Intensive"managed"utilizati0nofec0systemsforspecificbenefitsincludingcattle,sheep,t1sh,w00dandagriculturalpr0ductshasbeenong0ingfornearly0ne-and-haIfcenturies.Intensiveresourceproducti0nhasto0oftenbeenacc0mpaniedbyunwanted"sideeffects"includingacceleratederosion,s0illossandsedimentdeliveredoffsitetod0wnstreamlocati0ns,estuariesandoceanicsin…     

关于估量河流供水量变化的問題

关于河流供水量的多年变化問題,很多研究者都做过研究。而且,由于沒有估量年徑流量变化的成因分析方法,而几乎迫使所有研究者不得不应用概率理論来解决这一問題。但是这个理論只可能估算徑流量变化范圍及不同数值的流量出现的概率,而并沒有提供定出被研究现象在年序中的情况的可能性。为了对于河流年徑流量变化的特点,这种变化按年代次序演变的情况以及几条河流供水量变化过程同时发生的情况等等問題,获得比較明确的概念,到目