Assessment of the treatment efficiency of an urban stormwater pond and its impact on the natural downstream watercourse.

During the last few decades, stormwater ponds have become an alternative management practice in order to avoid flooding and to contain rainwater and runoff in urban areas where impervious land cover has increased. A second purpose of stormwater ponds is to improve the quality of runoff water that is usually contaminated with nitrogen, phosphorus, metals and organic micropollutants. Processes used are based on natural methods such as settlement and contribute to minimize the impact of these inputs to the natural aquatic system.

Diel cycles of reduced manganese and their seasonal variability in the Marque River (northern France).

Electrolabile reduced manganese (II) has been monitored by voltammetry during two periods of one month in summer 2014 and at the end of winter 2015 in a small river (the Marque River) located in northern France and going through a suburban area with agricultural activities. Diel variations, evolution within the one-month periods and seasonal differences have been observed. Taking into consideration the multiple physical, biological and chemical reactions regulating manganese speciation in aquatic systems, it has been demonstrated that manganese speciation is probably controlled by the competition of two antagonist reactions: the photoreduction of manganese oxides (in broad sense and represented thereafter by MnOx) and the biotic oxidation of Mn(II).

Assessing the transport of PAH in the surficial sediment layer by passive sampler approach.

A new method based on passive samplers has been developed to assess the diffusive flux of fluorene, fluoranthene and pyrene in the sediment bed and across the sediment-water interface. The dissolved compound concentration gradient in the sediment in the vertical direction was measured at the outlet of a storm water pond by using polyethylene strips as passive samplers. Simultaneously, the dissipation of a set of tracer compounds preloaded in the passive samplers was measured to estimate the effective diffusion coefficients of the pollutants in the sediment.

Water quality assessment of a small peri-urban river using low and high frequency monitoring.

The biogeochemical behaviors of small rivers that pass through suburban areas are difficult to understand because of the multi-origin inputs that can modify their behavior. In this context, a monitoring strategy has been designed for the Marque River, located in Lille Metropolitan area of northern France, that includes both low-frequency monitoring over a one-year period (monthly sampling) and high frequency monitoring (measurements every 10 minutes) in spring and summer. Several environmental and chemical parameters are evaluated including rainfall events, river flow, temperature, dissolved oxygen, turbidity, conductivity, nutritive salts and dissolved organic matter.