Evaluating ground water-sea water interactions via resistivity and seepage meters

We investigated submarine ground water discharge and salt water-fresh water interactions at two locations along the shoreline of the Upper Gulf of Thailand to evaluate mechanisms of water and material transport into the coastal zone. Our data set illustrates the value of using a combined approach consisting of automatic seepage meters to monitor flow rates while assessing the conductivity (salinity) of the subterranean fluids via remote resistivity measurements. Negative correlations between electric conductivities of fluids measured directly inside seepage meter chambers and the remotely assessed resistivities of subsurface pore water show that such measurements may evaluate the spatial distribution of flow rates as well as the subterranean water quality in the coastal zone. Combined seepage and resistivity measurements may thus provide a more complete understanding of coastal ground water dynamics.     

来自海洋地壳深处的甲烷

在许多语气表明，在地球的更深化部位存在着来自地幔的巨厚甲烷储层。这种成因类型的甲烷在Ｃ，Ｏ，Ｈ同位素上与有机质正常裂解所形成的甲烷气明显不同。Ｋｅｌｌｅｙ认为该类ＣＨ４的形成至少有两个阶段；第一阶段涉及到岩浆挥发分，形成的温度较高，ＣＨＲ被捕获在包体中，并在其中继续发生ＣＯ２转化为ＣＨ４的反应，使ＣＨ４聚集较轻的碳同位素，即残留的ＣＯ２比原始地幔气更重；第二阶段发生于４００℃左右，由于冷却作用，在     

Startle response of captive North Sea fish species to underwater tones between 0.1 and 64 kHz

World-wide, underwater background noise levels are increasing due to anthropogenic activities. Little is known about the effects of anthropogenic noise on marine fish, and information is needed to predict any negative effects. Behavioural startle response thresholds were determined for eight marine fish species, held in a large tank, to tones of 0.1-64 kHz. Response threshold levels varied per frequency within and between species. For sea bass, the 50% reaction threshold occurred for signals of 0.1-0.7 kHz, for thicklip mullet 0.4-0.7 kHz, for pout 0.1-0.25 kHz, for horse mackerel 0.1-2 kHz and for Atlantic herring 4 kHz. For cod, pollack and eel, no 50% reaction thresholds were reached. Reaction threshold levels increased from approximately 100 dB (re 1 microPa, rms) at 0.1 kHz to approximately 160 dB at 0.7 kHz. The 50% reaction thresholds did not run parallel to the hearing curves. This shows that fish species react very differently to sound, and that generalisations about the effects of sound on fish should be made with care. As well as on the spectrum and level of anthropogenic sounds, the reactions of fish probably depend on the context (e.g. location, temperature, physiological state, age, body size, and school size).     

DEPOSITIONAL SEQUENCES AROUND J/K BOUNDARY IN THE QOMOLONGMA AREA, SOUTH TIBET

DEPOSITIONAL SEQUENCES AROUND J/K BOUNDARY IN THE QOMOLONGMA AREA, SOUTH TIBET1　ShiX ,YinJ ,JiaC ,MesozoicandCenozoicsequencestratigraphyandsea levelchangesintheNorthernHimalayas,SouthTibet,China[J].NewslStratigr ,1996 ,33(1) :15～ 6 1. 2　LiuG ,WangS ,AdvancesintheUpperJurassictoLowerCretaceousstudyoftheTebetanHimalayas.PapStratigrPale ontol[M ].Beijing :GeologicalPress ,1987,17:143～ 16 6 .theNationalNaturalScienceFoundationofChina (No ..4982 5 …     

The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina)

To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use sound of a similar frequency (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the acoustic transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour seal (Phoca vitulina). No information is available on the effects of ACME-like sounds on harbour seals, so this study was carried out as part of an environmental impact assessment program. Nine captive harbour seals were subjected to four sound types, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' location in a pool during test periods to that during baseline periods, during which no sound was produced. Each of the four sounds could be made into a deterrent by increasing its amplitude. The seals reacted by swimming away from the sound source. The sound pressure level (SPL) at the acoustic discomfort threshold was established for each of the four sounds. The acoustic discomfort threshold is defined as the boundary between the areas that the animals generally occupied during the transmission of the sounds and the areas that they generally did not enter during transmission. The SPLs at the acoustic discomfort thresholds were similar for each of the sounds (107 dB re 1 microPa). Based on this discomfort threshold SPL, discomfort zones at sea for several source levels (130-180 dB re 1 microPa) of the sounds were calculated, using a guideline sound propagation model for shallow water. The discomfort zone is defined as the area around a sound source that harbour seals are expected to avoid. The definition of the discomfort zone is based on behavioural discomfort, and does not necessarily coincide with the physical discomfort zone. Based on these results, source levels can be selected that have an acceptable effect on harbour seals in particular areas. The discomfort zone of a communication sound depends on the sound, the source level, and the propagation characteristics of the area in which the sound system is operational. The source level of the communication system should be adapted to each area (taking into account the width of a sea arm, the local sound propagation, and the importance of an area to the affected species). The discomfort zone should not coincide with ecologically important areas (for instance resting, breeding, suckling, and feeding areas), or routes between these areas.