The study was carried out to assess the concentration of heavy metals in water and Tengra fish (Mystus vittatus) of the Surma River, the largest water basin ecosystem covering the northeastern parts of Bangladesh. Water and Tengra fish (M. vittatus) samples were collected from a total of six sampling stations in which three sampling stations were in Sylhet district and the rest three were in Sunamganj district. Samples were collected from February 2017 to June 2017 on a monthly basis. Water and Tengra fish (M. vittatus) samples were analyzed for the detection of heavy metals viz., lead (Pb), chromium (Cr) and cadmium (Cd) concentrations.Atomic absorption spectrophotometry was used for the detection of heavy metals after digestion of the samples. Pb and Cr were detected from both water and Tengra fish (M. vittatus) samples collected from all the six sampling stations of Sylhet and Sunamganj district. But, Cd was not found both in water and Tengra fish (M. vittatus) during the study period. This study concluded that the detected concentrations of metals (Pb and Cr) in the studied Tengra fish (M. vittatus) muscles were accepted by the international legislation limits and are safe for human consumption. But in water, Pb is the only metal that potentially poses the ecological risk to the water body as it exceeds the acceptance level recommended by World Health Organization (WHO). Consequently, close monitoring of metals pollution of the Surma River is recommended with a view to minimizing the health risk of the population that depend on the river for their water and fish supply.

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This paper is concerned with a new technique (the terrestrial/photogrammetric (TP) technique) for the detection and compensation of systematic height errors in block aerial triangulation. The technique improves the height accuracy of such triangulation by reducing the original bridging distance, using new bands of corrected photogrammetric tie points as height control together with the original bands of the terrestrial (or ground) height control. A number of photogrammetric blocks with different characteristics and configurations have been tested in a comprehensive manner. The tests show that the TP technique gives consistent results over a wide range of circumstances and that it is a most effective, simple and inexpensive method for the compensation of systematic errors. Résumé Cet article relate une technique nouvelle permettant de détecter et de compenser les erreurs altimétriques systématiques dans l'aérotriangulation par blocs: la technique terrestre/photogrammétrique (TP). Cette technique améliore la précision altimétrique de l'aérotriangulation en réduisant la distance de l'aérocheminement original, grâce à l'utilisation d'un canevas de points d'appuis altimétriques composés de points de liaison photogrammétriques corrigés, en supplément du canevas original de points d'appui altimétriques déterminés sur le terrain. On a essayé de manière approfondie un grand nombre de blocs dotés de caractéristiques et de configurations diverses. Les essais montrent que la technique TP fournit des résultats fiables dans un large éventail de circonstances et que c'est une méthode de compensation des erreurs systématiques efficace, simple et peu coûteuse. Zusammenfassung Im Artikel wird ein neues Verfahren behandelt (das terrestrisch‐photogrammetrische Verfahren (TP)), das zur Aufdeckung und Kompensation system‐atischer Höhenfehler in der Block triangulation dient. Es wird die Höhengenauigkeit durch Verkürzung der ursprünglichen Überbrückungsdistanz verbessert, indem neue Streifen korrigierter Verbindungspunkte als Höhenpasspunkte zusammen mit den ursprünglichen Reihen der terrestrischen Höhenpasspunkte verwendet werden. Eine Anzahl photogrammetrischer Blöcke unterschiedlicher Figur und Charakteristik wurde umfassend getestet. Die Tests zeigen, dass die TP‐Methode konstante Ergebnisse für einen grossen Bereich van Möglichkeiten ergibt und dass es ein höchst effektives, einfaches und billiges Verfahren zur Eliminierung systematischer Fehler ist.