Underwater Outfall Research Articles

Use of survival rates of the barnacle Chthamalus stellatus as a bioindicator of pollution.

Concentrations of heavy metals and trace elements in marine environments have increasingly become a problem for several ocean ecosystems, due to increments in pollution. Habitats daily exposed to extreme conditions, such as the intertidal rocky platforms and pools, are more vulnerable to pollution effects. In the coast of Punta del Hidalgo (Tenerife, Spain), we have located a water-treatment plant that could be pouring periodically pollutants to the near shore. We studied coverage and survival rates of the cirriped Chthamalus stellatus inhabiting the intertidal near the sewage pipe of the water plant of ​Punta del Hidalgo and in a control area in a proximate location. Concurrently, water samples from intertidal pools were obtained from both affected and control areas in order to corroborate the presence of pollutants, analyzing the concentrations of metals and trace elements. The results obtained clarified that the area near the underwater outfall presented higher percentage of coverage and mortality of C. stellatus than the control zone. The analysis of metal content in water samples also showed higher concentrations of metals for the affected area compared to the control one. We therefore propose the use of survival rates of populations of C. stellatus in the intertidal as bioindicators of metal pollution.

Impact of vertical shift of current velocity on propagation of contaminated water from an underwater outfall in stratified environment

Impact of vertical shift of current velocity on propagation of contaminated water from an underwater outfall in stratified environment

Influence of a Vertical Shift in the Current Velocity during Propagation of Contaminated Water from an Underwater Outfall under Stratified Conditions

The features of the spatial structure of coastal water caused by the impact of a nonstationary deep source of waste under stratified conditions is studied using a numerical hydrothermal model. The task is solved for the case of contaminated water outfall in Golubaya Bay of the city of Sevastopol. It is found that the activity of the source is accompanied by a jet and a stream of contaminated water. The pycnocline layer is mostly polluted with the contaminated area reaching 0.3–0.5 km2. The increase in the vertical shift of the velocity of background current leads to the increase in the existing period of contaminated zones and displacement of the stream of waste water toward the free surface (the stream becomes more localized vertically). The fields of contamination, temperature, and salinity of water have a complex spatial structure.

New data on Aplidium tabarquense (Tunicata: Ascidiacea)distribution in the Adriatic Sea

The colonial ascidian Aplidium tabarquense Ramos-Espla 1991 was recorded in Montenegro during a monitory survey carried out by scuba divers on an underwater outfall of the wastewater discharge system in Traste Bay. Several colonies were present on artificial substrata at a depth of 27 m. This is the first record of the species in the South Adriatic Sea. Further observations are recommended both to delineate the effective distribution and population density of A. tabarquense in the Mediterranean Sea and to widen the knowledge on ascidian diversity along Montenegro's coasts.

Quantifying the efficiency of a mono-port diffuser in the dispersion of brine discharges

Reverse-osmosis seawater desalination processes produce a hypersaline effluent waste (brine) which is usually discharged back into the sea via an underwater outfall. Brine discharges can cause environmental problems due to their high salt concentration, but the effects can be minimised by installing a diffuser structure at the end of the pipeline. In May 2010, a mono-port diffuser was installed at the Nuevo Canal de Cartagena desalination plant pipeline (located in Murcia, Spain) in order to increase effluent dispersion.The aim of this paper was to characterise the brine-plume dispersion throughout a series of oceanographic surveys that were carried out before and after the diffuser installation (2006–2011), and to quantify the effects of the diffuser on the behaviour and dilution rate of the effluent. The results of six years of operational monitoring were also compared with simulations predicted by a numerical mixing model simulation (CORMIX 1), obtaining high concordance with field data. After the diffuser installation, both field data results and model simulations showed a strong increase in the dilution rate of the brine plume, and a significant reduction in the size of the affected area.

Dispersion of desalination plant brine discharge under varied hydrodynamic conditions in the south of Gran Canaria

Brine discharged directly into the sea from desalination processes, forms a very dense plume that spreads out over the sea floor following the steepest slope due to its greater density than ambient sea water. Because the large difference in density slows down brine dilution processes in ambient sea water, hypersaline plumes spread out over broad areas and affect the benthic communities in their path. The Maspalomas II desalination plant, in the south of the island of Gran Canaria (Canary Islands-Spain), discharges brine through an underwater outfall over a wide sandy bottom with a mild slope. The behavior of this brine discharge was characterized under various hydrodynamic conditions. A higher degree of hydrodynamic exposure favored dilution of the outer edges of the plume, helping to reduce the area of influence.

Detection and Control of Pollution at Alicante Beaches (Spain): Applications of a Two Dimensional Model to the Pollution Distribution around an Underwater Outfall

Detection and Control of Pollution at Alicante Beaches (Spain): Applications of a Two Dimensional Model to the Pollution Distribution around an Underwater Outfall

Contaminants on the sea surface around an underwater outfall

The distribution of contaminants surrounding the boil of an underwater outfall has been studied. Over a 1-year period coliforms, enterococci, nitrogen and phosphorus were determined at 12 sampling stations located along the cardinal directions, at different distances from the boil, situated at Albufereta beach, Alicante, southeastern Spain. The plume was followed using Rhodamine B as a tracer. Although the major proportion of the pollution was transported by the plume, high levels were detected at a distance of about 200 m from the boil in all directions, regardless of the plume. A gaussian equation has been applied to the data, to approximately predict the pollution levels, at different distances from the boil.