Water Turbidity and Suspended Particulate Matter Concentration at Dredged Material Dumping Sites in the Southern Baltic

Analysing the accessibility of a selected southern Baltic Sea location with relevance to conducting surveys

The article presents the accessibility conditions for carrying out research work for an exemplary site in the southern Baltic Sea region. The basic parameter of the state of the marine environment was the significant wave height determined at a frequency of one hour based on the ERA 5 model data covering the period between 1940 and 2022. A statistical analysis of the variability of this height on a monthly basis, taking into account its conversion into the time of potential availability in conditions enabling research, showed its strong seasonal variability in the form of differences in the number of hours that can be used for operating purposes. This number, depending on the research vessel capabilities, may even be an order of magnitude higher in the summer months than in winter. Additionally, it was found that the variability of the significant wave height has not changed substantially over the last 82 years.

Modelling the upwelling radiance detected in a seawater column for oil-in-water emulsion tracking

This study concerns changes in the solar light transfer in seawater as a result of the appearance of oil substances in the form of oil-in-water emulsions. The expected effect of the studies is to gather knowledge that would be useful in designing an optical sensor for monitoring oil substances penetrating the seawater column. The paper presents the process of the Monte Carlo modelling of the upwelling radiance detected by a virtual underwater sensor. Moreover, this article discusses the predicted difference between the intensity of the signal from the upwelling radiance meter and the signal from the downwelling radiance meter. The modelling results suggest that in order to obtain a strong signal indicating the presence of oil substances, the radiance meter should receive light running upwards in the sea depth.

Comparison of high turbidity events: Sand nourishments and storm events on sandy beaches at the Baltic Sea, Germany

Coastal zones are permanently under stress by storms, cliff breaks, waves and currents. These events can cause the retreat of the coastline and are currently compensated by beach nourishments. The commonality of these sediment eroding and accumulating processes are turbidity plumes created in coastal waters, increasing the resuspension of particles and possibly nutrient concentrations. To compare sand nourishments and storm events, total suspended solids (TSS) and nutrient measurements were performed during winter season at the German Baltic Sea Coast. A pre-experiment showed that the TSS was homogenous through the water column. There were significant differences between both events, with sand nourishments exceeding the TSS of storms with the factor two. Due to the nourishment mechanism, the relative organic content was lower than during storm events. The nutrient uptake was unsteady. Therefore, sand nourishment can be considered to have more influence on the ecology of sand shores than storm events.

Light Penetrating the Seawater Column as the Indicator of Oil Suspension-Monte Carlo Modelling for the Case of the Southern Baltic Sea

The strong need to control investments related to oil extraction and the growing demand for offshore deep-water exploration are the reasons for looking for tools to make up a global underwater monitoring system. Therefore, the current study analyses the possibility of revealing the existence of oil-in-water emulsions in the water column, based on the modelling of the downwelling radiance detected by a virtual underwater sensor. Based on the Monte Carlo simulation for the large numbers of solar photons in the water, the analyses were carried out for eight wavelengths ranging from 412 to 676 nm using dispersed oil with a concentration of 10 ppm. The optical properties of the seawater were defined as typical for the southern Baltic Sea, while the oil emulsion model was based on the optical properties of crude oil extracted in this area. Based on the above-mentioned assumptions and modelling, a spectral index was obtained, with the most favourable combination of 555/412 nm, whose value is indicative of the presence of an oil emulsion in the water.