Historical trends of metals and metalloids into lake and coastal sediments of Halong Bay (Vietnam).

Halong Bay (northern Vietnam) is heavily affected by human activities. Metals and metalloids (e.g.

Assessing fluvial organic carbon flux and its response to short climate variability and damming on a large-scale tropical Asian river basin.

Fluvial organic carbon (OC) transfer is an essential resource for downstream ecosystems. Multiple factors affect its transfer process, e.g.

GLORIA - A globally representative hyperspectral in situ dataset for optical sensing of water quality.

The development of algorithms for remote sensing of water quality (RSWQ) requires a large amount of in situ data to account for the bio-geo-optical diversity of inland and coastal waters. The GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments (GLORIA) includes 7,572 curated hyperspectral remote sensing reflectance measurements at 1 nm intervals within the 350 to 900 nm wavelength range. In addition, at least one co-located water quality measurement of chlorophyll a, total suspended solids, absorption by dissolved substances, and Secchi depth, is provided.

Soil erodibility mapping using the RUSLE model to prioritize erosion control in the Wadi Sahouat basin, North-West of Algeria.

Soil losses must be quantified over watersheds in order to set up protection measures against erosion. The main objective of this paper is to quantify and to map soil losses in the Wadi Sahouat basin (2140 km) in the north-west of Algeria, using the Revised Universal Soil Loss Equation (RUSLE) model assisted by a Geographic Information System (GIS) and remote sensing. The Model Builder of the GIS allowed the automation of the different operations for establishing thematic layers of the model parameters: the erosivity factor (R), the erodibility factor (K), the topographic factor (LS), the crop management factor (C), and the conservation support practice factor (P).

Change detection of Bunaken Island coral reefs using 15years of very high resolution satellite images: A kaleidoscope of habitat trajectories.

In Bunaken Island (Indonesia), a time-series of very high resolution (2-4m) satellite imagery was used to draw the long-term dynamics of shallow reef flat habitats from 2001 to 2015. Lack of historical georeferenced ground-truth data oriented the analysis towards a scenario-approach based on the monitoring of selected unambiguously-changing habitat polygons characterized in situ in 2014 and 2015. Eight representative scenarios (coral colonization, coral loss, coral stability, and sand colonization by seagrass) were identified.

Challenges in rendering Coral Triangle habitat richness in remotely sensed habitat maps: The case of Bunaken Island (Indonesia).

The Coral Triangle is the epicenter of marine biodiversity, yet the numbers of habitats that can be found on coral reefs remain poorly described. First surveys for habitat mapping in Indonesia revealed a high number of habitats (>150) even for structurally simple reefs. To be able to represent all these habitats, typical habitat mapping procedures and performances are poorly effective even using very high resolution satellite images.

Variability of apparent and inherent optical properties of sediment-laden waters in large river basins - lessons from in situ measurements and bio-optical modeling.

We investigated the relationships between inherent and apparent optical properties (IOP and AOP, respectively) and suspended sediment concentrations (SSC) in the main Amazonian river waters. In situ measurements of SSC, remote sensing reflectance (R), the diffuse light attenuation coefficient (K) and the total and non-algal particle (NAP) absorption coefficients (a and a, respectively) were conducted during three sampling trips along different streams of the Amazon River catchment (104 stations). The size distribution and chemical characteristics of the suspended sediment were also determined for 85 stations.

CDOM-DOC relationship in contrasted coastal waters: implication for DOC retrieval from ocean color remote sensing observation.

Increasing our knowledge on dissolved organic carbon (DOC) spatio-temporal distribution in the coastal ocean represents a crucial challenge for better understanding the role of these ecosystems in the global oceanic carbon cycle. The assessment of DOC concentration from the absorption properties of the colored part of the dissolved organic matter (a(cdom)) was investigated from an extensive data set covering a variety of coastal environments. Our results confirmed that variation in the a(cdom)(412) to DOC ratio (a*(cdom)(412)) can be depicted from the CDOM spectral slope in the UV domain (S(275-295)).

Fate and tidal transport of butyltin and mercury compounds in the waters of the tropical Bach Dang Estuary (Haiphong, Vietnam).

In this work, two field campaigns were performed in July 2008 (wet season) and March 2009 (dry season) to produce original data on the concentration, partition and distribution of mercury and butyltin compounds along the tropical Bach Dang Estuary located in North Vietnam (Haiphong, Red River Delta). The results demonstrate that mercury and butyltin speciation in the surface waters of this type of tropical estuary is greatly affected by the drastic changes in the seasonal conditions. During high river discharge in the wet season, there was a large estuarine input of total Hg and tributyltin, while the longer residence time of the waters during the dry season promotes increasing MMHg formation and TBT degradation.

Inherent optical properties and satellite retrieval of chlorophyll concentration in the lagoon and open ocean waters of New Caledonia.

The retrieval of chlorophyll-a concentration from remote sensing reflectance (Rrs) data was tested with the NASA OC4v4 algorithm on the inner New Caledonian lagoon (Case 2) and adjacent open ocean (Case 1) waters. The input to OC4v4 was Rrs measured in situ or modeled from water's inherent optical properties (2001-2007). At open ocean stations, backscattering and absorption coefficients were correlated with chlorophyll (R(2)=0.

Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters.

Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji.

A combined modelling and geochemical study of the fate of terrigenous inputs from mixed natural and mining sources in a coral reef lagoon (New Caledonia).

Open-cast mining for Ni, Cr and Co was conducted in the south-west part of New Caledonia during the 20th century. Abandoned mining and prospecting sites were severely affected by erosion, resulting in an increase in the load of terrigenous particles transported to the coral reef lagoon. This article assesses the impact of a typical small catchment area (La Coulée River, 85 km2 watershed) on two bays (Boulari and Sainte Marie) located near Noumea, New Caledonia's main city.

Above-water measurements of reflectance and chlorophyll-a algorithms in the Gulf of Lions, NW Mediterranean Sea.

Above-water reflectance and surface chlorophyll a concentrations (Chl a) were measured in the Gulf of Lions, northwestern Mediterranean Sea in 2000 and 2001 in order to test Chl a inversion algorithms. Surface waters were separated in Case 2 waters in the Rhône River plume and proximal Region of Freshwater Influence (ROFI) stations, and Case 1 waters at all the other stations. Case 2 waters were characterized by R443/R555 < R443/R510 < R490/R555 < R490/R510 < 1.

Introducing a mini-catamaran to perform reflectance measurements above and below the water surface.

An innovative platform is tested to perform reflectance measurements at sea. This platform is a mini-catamaran with two hulls 1m long and set 0.7m apart, fitted with optical sensors.