The massive influx of pelagic Sargassum spp. (sargasso) into the Mexican Caribbean Sea has caused major deterioration of the coastal environment and has affected the tourism industry as well as livelihoods since 2015. Species of Sargassum have high capacity to absorb metals; thus, leachates of sargasso may contribute to contamination by potentially toxic metals when they drain into the sea and into the groundwater when dumped in inadequate land deposits. Valorization of sargasso would contribute to sustainable management; therefore, knowledge on potentially toxic metal content is necessary to define possible uses of the algae. We present concentrations of 28 elements measured using a non-destructive X-ray fluorescence analyzer (XRF) in 63 samples of sargasso collected between August 2018 and June 2019 from eight localities along ∼370 km long coastline of the Mexican Caribbean Sea. The sargasso tissues contained detectable concentrations of Al, As, Ca, Cl, Cu, Fe, K, Mg, Mn, Mo, P, Pb, Rb, S, Si, Sr, Th, U, V, and Zn. The element concentration in sargasso varied on spatial and temporal scales, which likely depended on the previous trajectory of the pelagic masses, and whether these had (or had not) passed through contaminated areas. Total arsenic concentration varied between 24-172 ppm DW, exceeding the maximum limit for seaweed intended as animal fooder (40 ppm DW) in 86% of the samples. For valorization, we recommend analyses of metal contents as a mandatory practice or avoiding uses for nutritional purposes. The high arsenic content is also of concern for environmental contamination of the sea and aquifer.

Element concentrations in pelagic Sargassum along the Mexican Caribbean coast in 2018-2019.

水表面波的傳播; Water Wave Propagation over Uneven Bottom

The discovery of dangerously high levels of mercury in the Great Lakes from industrial wastewater discharge severely shook the United States and Canada in 1970. Emergency actions covered industrial shutdowns, fishing bans and accelerated monitoring programmes. Charges against local chlor-alkali businesses, such as Dow Chemical, became the first instances of green-collar crime in the context of modern environmentalism in North America. At the same time, the legal, scientific and political management of the crisis foreshadowed the difficulties victims, prosecutors and polluters would face more generally in the field of environmental crime in the future. This contribution on Dow Chemical and the Great Lakes mercury crisis extrapolates the ambiguities inherent to ecological disaster and corporate behaviour, and encourages scholars to situate their analysis within a framework of scientific uncertainties and legal loopholes.

Corporate behaviour and ecological disaster: Dow Chemical and the Great Lakes mercury crisis, 1970–1972

https://backend.orbit.dtu.dk/ws/files/200649122/TsunamiRunupOnlyPart1_accepted.pdf

Full-scale CFD simulation of tsunamis. Part 1: Model validation and run-up

An experimental study was performed to examine multiple debris entrainment and transport in tsunami-like flow conditions. The study was performed in the Tsunami Wave Basin at Waseda University. The...

Entrainment and Transport Dynamics of Shipping Containers in Extreme Hydrodynamic Conditions

This research is to facilitate the current understanding of long wave dynamics at coasts and during on-land propagation; experimental and numerical approaches are compared against existing analytical expressions for the long wave run-up. Leading depression sinusoidal waves are chosen to model these dynamics. The experimental study was conducted using a new pump-driven wave generator and the numerical experiments were carried out with a one-dimensional discontinuous Galerkin non-linear shallow water model. The numerical model is able to accurately reproduce the run-up elevation and velocities predicted by the theoretical expressions. Depending on the surf similarity of the generated waves and due to imperfections of the experimental wave generation, riding waves are observed in the experimental results. These artifacts can also be confirmed in the numerical study when the data from the physical experiments is assimilated. Qualitatively, scale effects associated with the experimental setting are discussed. Finally, shoreline velocities, run-up and run-down are determined and shown to largely agree with analytical predictions.

Ulrike Drähne

Papers

An Experimental and Numerical Study of Long Wave Run-Up on a Plane Beach