Vulnerability of biological resources to potential oil spills in the Lower Amazon River, Amapá, Brazil.

Ships that transport oil or derivatives on the Lower Amazon River waterway are at a considerably high risk of suffering spills, with severe environmental and socioeconomic consequences. The present study is aimed at modeling and simulating the oil dispersion and magnitude of these accidents in terms of the vulnerability of biological resources, considering two oil types most often transported by medium-sized tankers in the region (S500 and S10). The study method was as follows: (a) secondary data were collected from local species, and the coastal sensitivity index (CSI) was calculated, obtained from Brazil's Letters of Environmental Sensitivity to Oil Spill (Cartas de Sensibilidade Ambiental ao Derramamento de Óleo (SAO)); (b) ship traffic information was obtained from Brazil's Statistical Yearbook of Waterway (Anuário Estatístico Aquaviário (ANTAQ)); (c) modeling and numerical simulation of oil spills in water were performed, in order to investigate dispersion scenarios (SisBaHia); (d) three numerical scenarios of oil plume dispersion (in May and November) were integrated to assess species vulnerability in three zones of environmental interest (I, II, and III). Some species identified in zone II were considered to be the most vulnerable (fish, plankton, aquatic mammals, amphibians, aquatic invertebrates, trees, and plants), with the mammal Sotalia fluviatilis being at risk of extinction (Gervais & Deville, 1853). The simulated scenarios showed that contingency plans should have a minimum response time of 3 h and a maximum response time of 72 h to prevent the oil plumes from dispersing as far as 170 km longitudinally, depending on the zone, season, and tidal phase. Thus, a total of 62 sites of biological resources were identified in the literature recorded from 2016. Considering them, 324 species of flora and fauna were recorded, distributed in the following seven groups: (i) 49 tree and plant species, (ii) 37 amphibian species, (iii) 2 aquatic invertebrate species, (iv) 23 invertebrate species, (v) 1 aquatic mammal species, (vi) 95 fish species, and (vii) 117 planktonic species. A failure to respond to these accidents would impact immense intact aquatic areas and ecosystems, with unpredictable consequences for local biodiversity conservation.

Modeling pollutant dispersion scenarios in high vessel-traffic areas of the Lower Amazon River.

Large ships are efficient in transporting oil and its derivatives. However, they can cause spills in the event of accidents. The aim of the study is to simulate oil dispersion processes in scenarios of likely accidents with ships traveling on sea routes interconnected with Amazonian ports and with the Atlantic Ocean. Navigation routes were based on traffic data to identify risk areas, as well as to compare them to data from the environmental (oil) sensitivity index and to results of numerical simulations of plumes dispersion. These three approaches were integrated to each other in order to assess potential environmental impacts of plumes on coastal biota and human populations. Scenarios results have indicated that the rainy season is the most critical period for plumes dispersion. But, depending on the emission point, plumes tend to remain close to the coast, extend up to 132 km within 72 h, affecting the biodiversity, protected areas and water supply systems from the urban areas.

Experimental and numerical studies of sediment removal in double bottom ballast tanks.

The sediments inside the ballast tanks might compromise the effectiveness of the ballast water exchange procedure. In the present study, the sediment removal from double bottom ballast tanks due to flow-through ballast water exchange is investigated by simplified experimental and numerical models. Two flow rates and two sediment densities were considered to verify their influence on the process. Besides, the effectiveness of two tank configuration modifications to improve the sediments removal was investigated. The first is the introduction of a flow deflector inside the tank and the second is the water inflow from the bottom. A fully Lagrangian particle-based method is adopted to simulate the sediment removal process with complex tank geometry. A new boundary condition is proposed to model the mesh of the bottom inlet in the bottom inflow configuration. Despite the simplifications of the numerical model, the computational results are in good agreement with the experimental ones. The results show that the flow-through ballast water exchange method might not be effective to remove the sediments entrapped between the bottom stiffeners, and the proposed modifications, despite challenging implementation, improve the sediment removal.

Ballast water: a threat to the Amazon Basin.

Ballast water exchange (BWE) is the most efficient measure to control the invasion of exotic species from ships. This procedure is being used for merchant ships in national and international voyages. The ballast water (BW) salinity is the main parameter to evaluate the efficacy of the mid-ocean ballast water exchange. The vessels must report to the Port State Control (PSC), via ballast water report (BWR), where and how the mid-ocean BWE was performed. This measure allows the PSC to analyze this information before the ship arrives at the port, and to decide whether or not it should berth. Ship BW reporting forms were collected from the Captaincy of Santana and some ships were visited near the Port of Santana, located in Macapá (Amazon River), to evaluate the BW quality onboard. We evaluated data submitted in these BWR forms and concluded that the BWE efficacy might be compromised, because data contained in these BWR indicate that some ships did not change their BW. We found mistakes in filling the BWR forms and lack of information. Moreover, these ships had discharged BW with high level of salinity, Escherichia coli and total coliforms into the Amazon River. We concluded that the authorities of the Amazon Region need to develop more efficient proceedings to evaluate the ballast water reporting forms and BW quality, as there is potential risk of future invasion of exotic species in Brazilian ports.

Onshore ballast water treatment: a viable option for major ports.

Ballast water treatment consists of the elimination of exotic species. Currently, the development of alternative methods for this process is directed toward treatment onboard ships. However, we present onshore treatment as a viable alternative for ballast water treatment. We investigated onshore treatment in two iron ore ports with movement capacities of 25 and 90 million tons annually (Mta) that receive 7.5 and 25 million cubic meters annually (Mm(3)) of ballast water, respectively. Discrete event simulation was used as the method of analysis, considering the processes of arrival, berthing, ship loading and capture and treatment of ballast water. We analyzed data from 71 ships operating in these ports to validate our simulation model. We were able to demonstrate that onshore treatment does not impact the cargo capacity, occupation rate or average queuing time of ships at these ports. We concluded that implementation of onshore ballast water treatment may be practicable in ports that receive high volumes of ballast water.