XVIth INTERNATIONAL CONGRESS OF PHOTOGRAMMETRY AND REMOTE SENSING

The XVIth International Congress of Photogrammetry and Remote Sensing, organised by the International Society for Photogrammetry and Remote Sensing, was held in the Kyoto International Conference Hall from 1st to 10th July, 1988. The activities of the seven technical commissions of ISPRS were described at a meeting of the Photogrammetric Society on 18th October, 1988. The meeting also heard about the Congress Exhibition and the deliberations of the General Assembly during the Congress. Papers from the Congress were published in the International Archives of Photogrammetry and Remote Sensing 27.     

Distributional patterns of blue crabs (Callinectes sp.) in a tropical estuarine lagoon

A two-year trawl study of Laguna Joyuda, Puerto Rico, a small, polyhaline lagoon with restricted oceanic exchange, yielded 803 crabs belonging to sixCallinectes species.Callinectes danae was the most abundant (35.7%), followed byC. sapidus (21%),C. ornatus (12.6%),C. bocourti (12.1%),C. exasperatus (1.2%), andC. larvatus (0.4%). Abundances of different species differed more spatially than temporally despite very homogeneous salinities.Callinectes bocourti andC. sapidus were most abundant furthest from the lagoon’s inlet, whileC. danae andC. ornatus were most abundant near the inlet and in the center of lagoon. Juveniles were least abundant in the center of the lagoon. Size frequencies of most species showed common trends with high percentages of small crabs furthest from the inlet, and high percentages of larger crabs near the inlet and central parts of the lagoon. Distributional patterns appear to be a result of complex interactions of habitat preferences and intra- and interspecific interactions among the crabs.     

Lateral textural grading in overwash sediments

Overwash deposits are characterized by horizontally layered laminations. Vertical sequences could be interpreted in terms of individual storm deposits by recognizing time breaks or discontinuities in the stratigraphic section. Results from comparison of channel deposit data for textural grading across the washover fan were inconclusive. Samples taken from individual laminations revealed the true textural grading when traced along a 61 m trench and sampled at designated localities. The overwash deposit was found to become finer in grain size from the apex to the margins of sedimentation in the direction of transport.     

Vibration of beams on non-homogeneous elastic foundations

The natural response of a beam or pile supported by an elastic foundation is investigated for the case when the coefficient of subgrade reaction varies linearly along the span of the member.     

Heavy metals in bottom sediments of great slave lake (Canada): A reconnaissance

Near the shores of Great Slave Lake, natural sources of heavy metals include gold and base metal deposits, mineralized greenstone belts and sedimentary bedrock, and uraniferous granites. Potential anthropogenic sources of heavy metals (As, Zn, Pb) include large gold and base metal extraction -processing facilities on the shores of the lake. Six sediment cores were collected on a traverse of the lake. Heavy metal concentrations and distributions are related to the regional bedrock geochemistry in the drainage basin. Higher uranium concentrations in the northernmost core are attributed to extensive uraniferous areas north of the lake. More subtle variations of concentration are related to sedimentologic characteristics and processes in the lake. The west basin is a natural sink for most of the heavy metals determined. Two centrally located west basin cores had mean zinc concentrations of 145 ppm, whereas cores closer to the north and south shores had mean concentrations of 80–110 ppm. Mn, Ni, and Pb were enriched in some of the cores from the area of shallower water near the MacKenzie River outlet, rather than in the central west basin. The enrichment is related to Mn-, Ni-, and Pb-rich amorphous coatings on quartz grains. Elevated zinc or lead levels from anthropogenic activities were not detected but elevated levels are suspected for arsenic. In the two cores from the center of the west basin, surface sediment contains up to 12 ppm arsenic, not high in comparison with noncontaminated freshwater lakes elsewhere in Canada but considerably elevated relative to concentrations of 1 ppm found deeper in the same cores. Contribution from the National Water Research Institute, Western and Northern Region. Presented at the 10th International Sedimentological Congress, Jerusalem, Israel, 1978.