V Gopal

Le transport des m taux l' tat de traces de la terre vers l'oc an emprunte diff rentes voies et pr sente diff rentes efficacit s. Les l ments toxiques qui p n trent dans les rivi res pour tre d bouch s dans la mer par les estuaires proviennent soit de l'alt ration naturelle des sols et des roches, soit de l'introduction anthropique de sources ponctuelles ou diffuses, sous forme labile ou particulaire. Cependant, des tudes r centes indiquent que le transport des l ments traces vers le milieu aquatique est beaucoup plus complexe que ce que l'on pensait. La chimie et l' cologie d'un syst me estuarien sont enti rement diff rentes du syst me fluvial et du syst me marin. L'environnement estuarien est caract ris par un m lange d'eau sal e et d'eau douce qui change constamment. Dans la pr sente zone d' tude, l'estuaire de Manakudy est situ environ 8 kilom tres au nord-ouest de Kanyakumari (Latitude N 08 05' 21.8''et Longitude E 077 29' 03.7''). Afin de mieux comprendre le comportement g ochimique des param tres physico-chimiques et des l ments traces dans l'estuaire et d'examiner les variations des flux chimiques associ s, 20 chantillons d'eau ont t collect s dans tout l'estuaire de Manakudy, une rivi re mineure du sud-ouest de l'Inde.

Der Transport von Spurenmetallen vom Land ins Meer erfolgt auf verschiedenen Wegen und mit unterschiedlicher Effizienz. Die Quellen toxischer Elemente in den Fl ssen, die ber die M ndungsgebiete ins Meer gelangen, sind entweder nat rlich aus den B den und Gesteinen verwittert oder anthropogen aus Punkt- oder Nichtpunktquellen in labiler oder partikul rer Form eingebracht. J ngste Studien zeigen jedoch, dass der Transport von Spurenelementen in die aquatische Umwelt viel komplexer ist als bisher angenommen. Die Chemie und kologie eines stuarsystems unterscheidet sich v llig von der eines Flusssystems oder eines Meeressystems. Die stuarumwelt ist durch eine sich st ndig ver ndernde Mischung aus Salz- und S wasser gekennzeichnet. Das M ndungsgebiet von Manakudy liegt etwa 8 Kilometer nordwestlich von Kanyakumari (Breitengrad N 08 05' 21.8'' und L ngengrad E 077 29' 03.7''). Um ein besseres Verst ndnis des geochemischen Verhaltens der physikalisch-chemischen Parameter und Spurenelemente im stuar zu erlangen und die Schwankungen der damit verbundenen chemischen Fl sse zu untersuchen, wurden 20 Wasserproben im gesamten stuar von Manakudy, einem kleineren Fluss im S dwesten Indiens, gesammelt.

O transporte de metais vestigiais da terra para o oceano tem uma s rie de rotas e efici ncias diferentes. As fontes de elementos t xicos nos rios a serem rebocados para o mar atrav s de estu rios ou s o desgastadas naturalmente pelos solos e rochas ou introduzidas antropogenicamente a partir de fontes pontuais ou n o pontuais, na forma de l bil ou de part culas. No entanto, estudos recentes indicam que o transporte de elementos vestigiais para o ambiente aqu tico muito mais complexo do que o que se tem pensado. A qu mica e a ecologia de um sistema estuarino s o totalmente diferentes do sistema fluvial, bem como do sistema marinho. O ambiente estuarino caracterizado por uma mistura de sal e gua doce em constante mudan a. Na actual rea de estudo, o estu rio de Manakudy situa-se a cerca de 8 quil metros a noroeste de Kanyakumari (Latitude N 08 05' 21,8''e Longitude E 077 29' 03,7''). Para melhor compreens o do comportamento geoqu mico dos par metros f sico-qu micos e dos elementos vestigiais no estu rio e para examinar varia es na qu mica associada fluxes, foram recolhidas 20 amostras de gua em todo o estu rio do Manakudy, um rio menor no sudoeste da ndia.

Il trasporto di metalli in traccia dalla terraferma all'oceano ha una serie di percorsi ed efficienze diverse. Le fonti di elementi tossici che entrano nei fiumi per essere riversati in mare attraverso gli estuari sono costituite da agenti atmosferici naturali provenienti da suoli e rocce o introdotti antropogenicamente da fonti puntuali o non puntuali, in forma labile o in forma di particolato. Tuttavia, studi recenti indicano che il trasporto di elementi in traccia nell'ambiente acquatico molto pi complesso di quanto si pensasse. La chimica e l'ecologia di un sistema estuarino sono completamente diverse da quelle di un sistema fluviale e marino. L'ambiente estuarino caratterizzato da una miscela di acqua dolce e salata in costante cambiamento. Nella presente area di studio l'estuario di Manakudy situato a circa 8 chilometri a nord-ovest di Kanyakumari (latitudine N 08 05 21,8 e longitudine E 077 29 03,7 ). Per comprendere meglio il comportamento geochimico dei parametri fisico-chimici e degli elementi in traccia nell'estuario ed esaminare le variazioni dei flussi chimici associati, sono stati raccolti 20 campioni d'acqua nell'estuario di Manakudy, un fiume minore dell'India sud-occidentale.

To gain a better understanding the sedimentological behaviour in the estuarine, coastal environment and their distribution patterns in trace elements in the estuary and to examine variations in associated sediment fluxes, 20 surface samples were collected throughout the Manakudy estuary, a minor Pazhayar river in south-western India. These samples, collected in typical dry season during Premonsoon 2012, were analyzed for Sedimentological, Textural and Trace Elements (HOAc). Our results show that estuary is dominated by sand fraction of the sediments (72.68%), the conservative behavior of trace metals with salinity has been strongly has been affected by the introduction of these metals by external sources and they are due to the higher organic activity in soils as well as faster rates of chemical weathering reaction in the source region. Even though the trace metals in the contaminated sediments have been removed and incorporated in sediments due to flocculation, the concentration of these metals did not decrease. The present study provides a history of accumulation of trace metals and their present level, and the data can be used as a baseline to monitor the estuaries environments.

Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental management issues (including policy-making, planning, and enforcement of statutory regulations). They usually involve a set of procedures and techniques for delimitation, characterization and classification of terrain units. However, terrain assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas. Bhavani basin (Study area) is the fourth largest (about 6,500 km2) sub-basin in the Cauvery basin (81,000 km2). The western part (Western Ghats) is hilly terrain with an altitude ranging from 300 to 2,400 metres. The northern and north-eastern (Eastern Ghats), the southern and south-eastern sides of the basin are dominated by rugged discontinuous hills, with altitudes ranging from 300 to 1,000 metres. LANDSAT ETM+ data is one of the best River Basin models that can be used for understanding the geology, geomorphology, hydrology as well as agricultural productivity. It is also proved that the model can be employed under different climate change as well as management scenarios for developing adaptation.