No abstract

No abstract

Abstract. The field-scale transport of natural organic matter (NOM) was examined in a two-well forced gradient injection experiment in a sandy, coastal plain aquifer in Georgetown, South Carolina. Spatial moments described the migration of the center of mass of NOM and conservative tracer. Temporal moments were used to estimate mass loss and retardation of the NOM along a transect of six sampling locations at two depths and at the withdrawal well. Large differences were observed in transport behavior of different subcomponents of NOM. Larger and more strongly binding NOM components in the injection solution are postulated to adsorb and displace weakly binding, low-molecular weight NOM in groundwater. Conversely, NOM components that were similar to the groundwater NOM were transported almost conservatively, presumably due to ''passivation'' of the aquifer by previously adsorbed components of the groundwater NOM. NOM may thus exhibit two types of effects on contaminant dynamics in the subsurface. When the equilibria between solution and solid phase NOM is disrupted by introduction of a novel source of NOM, descriptions of the multicomponent transport process are complex and predictive modeling is problematic. Because of the differences in transport behavior of NOM subcomponents, the chemical properties and, more importantly, the functional behavior of NOM with respect to contaminant migration will vary with time and distance along a flow path. However, when groundwater NOM exists at a steady state with respect to adsorption on aquifer surfaces, the migration of NOM, and the contaminant-NOM complex, may be approximated as the transport of a conservative solute.

No abstract

To evaluate the impact of land-based contaminants on benthic faunas, as part of the Land-Ocean Contamination Study (LOCS), a study transect was established in Jakarta Bay, Indonesia during the 1996 southeasterly monsoon. The transect extended 72 km between the city's main port, Tanjung Priok, and the Pilau Seribu Island chain in the Java Sea. The dissolved concentrations of Pb, Cu, Zn, Cr and Ni in seawater, in suspended particulate matter (SPM) and surficial sea bed sediments were measured along the transect at nine sites. In addition, metal concentrations were measured in tissues of the corals Goniopora lobata and Lobophyllia hemprichii at five sites, and of the green mussel, Perna viridis at six sites. An assessment of the impact of contaminants on the faunas was made using a biomarker approach, employing coral community analysis and lysosomal stability with Perna viridis. The results of the study showed two main trends. The distributions of metals dissolved in seawater, in SPM, and in the coral and mussel tissues were similar, and failed to show a consistent graded response from inshore to offshore sites. This suggests that the concentration of metals in waters is the primary route for metal uptake by the coral and mussel tissues. By way of contrast, a clear offshore increase in coral generic diversity, coral cover, coral colony numbers and neutral-red retention time (lysosomal stability) was observed, suggesting increasing nearshore stress. Whilst the coral community stucture may reflect the seasonally-averaged metal distributions in the bay (shown by the metal content of sea bed sediments which increase shorewards), it is more likely that the coral community structure and lysosomal biomarker are responding principally to other nearshore stresses, such as sediment and nutrient loading of water (sewage) or, more likely, organic contaminants such as oils and other hydrocarbons. 0 1999 Ifremer / CNRS / IRD / fiditions scientifiques et medicales Elsevier SAS Jakarta / contamination I biomarker I coral-community RCsumC-l&aluation de l'impact de contaminants terrestres sur la faune benthiique du golfe de Djakarta, IndonCsie. Dans le cadre du programme Contamination Continent-Ocean (LOU, Land-Ocean Contamination Study), l'impact des contaminants terrestres sur la faune benthique du golfe de Djakarta (Indonesie) a 6te #&al& en 1996, pendant la mousson du sud-est, sur une radiale de 72 km entre le port principal Tanjung Priok et la chaine insulaire Pulau Seribu, dans la mer de Java. Les concentrations de Pb, Cu, Zn, Cr et Ni dissous ont Cte mesurees : 1) dans l'eau de mer, dans les particules en suspension et dans les sediments superficiels (9 stations) ; 2) dans les tissus des coraux Goniopora lobata et Lobophyllia hemprichii (5 stations) ; 3) dans les tissus de la moule verte Perna viridis (6 stations). L'impact des contaminants sur la faune a CtC CvaluC a l'aide d'un marqueur biologique, par analyse de la communaute corallienne et stabilite lysosomiale avec Perna viridis. Deux tendances principales ressortent de c...