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Autonominio povandeninio garso įrašymo įtaiso sukonstravimas ir tobulinimas.
No full textAn underwater noise is the most pervasive type of physical energy that spreads in underwater marine environment. The concerns regarding man-made underwater noise effects on the aquatic animals became prominent within scientific com-munities. The determination of underwater noise levels became very actual either for environmental monitoring or scientific research purposes. Various tools for acquisition of the underwater sound as well, modelling became available, although some techniques are costly and requires special considerations. One of the examples are the sound recording devices containing hydrophones along with digital sound acquisition systems used for recording of ambient (continuous) underwater sounds. By the date there are already developed the international and European standards for monitoring the long term (yearly) underwater continuous noise levels. However, the techniques known to be able to record the short and mid-term noise levels can serve for the research purposes greatly. In this research the cost efficient autonomous underwater sound recorder was developed, with the purpose to record an ambient underwater noise continuously and autonomously for the periods of up to 15 days, following the already known methods. In this paper we present the steps of the development of the autonomous recorder, its features and capabilities as well, calibration results of the underwater sound recording system
Worms and submersed macrophytes reduce methane release and increase nutrient removal in organic sediments /
No full textOrganic sediments are greenhouse gas and nutrient hotspots. They may display lower methane (CH4) emissions and increase nutrient retention when macrophytes and macrofauna are present, due to oxygen leakage from roots and bioirrigation. We tested this hypothesis via incubations of microcosms reproducing four treatments: bare sediment, sediment with oligochaetes, sediment with macrophytes, and sediment with both organisms. Along a 12-d experiment, CH4 ebullition in bare sediment (470 ± 13 mmol m−2) decreased by 67%, 88%, and 97% in the presence of plants, oligochaetes, and both organisms, respectively. Oligochaetes increased N2 production by ~ 200 mmol N m−2 and nitrate consumption by a factor of 4, whereas macrophytes reduced nitrogen losses by ~ 65 mmol N m−2. All treatments acted as phosphate sink. Results suggest that the maintenance of vegetation and associated macrofauna in organic sediments promotes their combined ecosystem services, resulting in significant reduction of greenhouse gas emission and nutrient release to the water column
Emission, transport, and deposition of visible plastics in an estuary and the Baltic Sea – a monitoring and modeling approach /
No full textAim: was to assess whether a comprehensive approach linking existing knowledge with monitoring and modeling can provide an improved insight into coastal and marine plastics pollution. We focused on large micro- and mesoplastic (1-25 mm) and selected macroplastic items. Emission calculations, samplings in the Warnow river and estuary (water body and bottom sediments) and a flood accumulation zone monitoring served as basis for model simulations on transport and behavior in the entire Baltic Sea. Considered were the most important pathways, sewage overflow and stormwater. The coastline monitoring together with calculations allowed estimating plastics emissions for Rostock city and the Warnow catchment. Average concentrations at the Warnow river mouth were 0.016 particles/m³ and in the estuary 0.14 particles/m³ (300 µm net). The estuary and nearby Baltic Sea beaches were hot-spots for plastic accumulation with 6-31 particles/m². With increasing distance from the estuary, the concentrations dropped to 0.3 particles/m². This spatial pattern, the plastic pollution gradients and the observed annual accumulation values were consistent with the model results. Indicator items for sewer overflow and stormwater emissions exist, but were only found at low numbers in the environment. The considered visible plastics alone can hardly serve as indicator for microplastic pollution (<1 mm). The use of up-scaled emission data as input for Baltic Sea model simulations provided information on large scale emission, transport and deposition patterns of visible plastics. The results underline the importance of plastic retention in rivers and estuaries
Geochemistry of the dust Collected by passive samplers as a tool for search of pollution sources: the case of Klaipėda port, Lithuania /
No full textGeochemical investigations of total suspended particulates (TSP) help detect hotspots and emission sources in port cities with stevedoring operations. The aim was to reveal these sources via geochemical indices (gI). TSP were collected in Klaipėda using original passive samplers in ten sites during four periods, during one of them, in ten additional sites near iron ore stevedoring (IOS). The contents of 22 elements (PHEs, crustal, Br, Cl) were determined by EDXRF in TSP and characteristic dust (CD) of stevedored iron ore, apatite, phosphorite, potassium fertilizers, and in waste incineration ash. Median Fe content in TSP near IOS was ~29%. The significant anthropogenic origin of clusters Fe–Cr, Sr–P, V–Ni–Zn–Cu, Pb–As, and Mg–Ca, Br–S–Cl was confirmed by gI mapping and analysis of CD. Significant temporal variability of Cl, S, Sr, Ni, Br, V, and Zn due to weather changes was revealed. Near IOS, significantly higher values of gI were found for Fe and Cr, while far from IOS, for K, Sr, Ti, Rb, Cu, Al, Si, Zr, Ca, Mg. Significantly higher values of normalized enrichment factor near IOS were not only for Fe and Cr, but also for As, Pb, S, Mn, Br, and Cl
Automated quantification of brittle stars in seabed imagery using computer vision techniques /
No full textUnderwater video surveys play a significant role in marine benthic research. Usually, surveys are filmed in transects, which are stitched into 2D mosaic maps for further analysis. Due to the massive amount of video data and time-consuming analysis, the need for automatic image segmentation and quantitative evaluation arises. This paper investigates such techniques on annotated mosaic maps containing hundreds of instances of brittle stars. By harnessing a deep convolutional neural network with pre-trained weights and post-processing results with a common blob detection technique, we investigate the effectiveness and potential of such segment-and-count approach by assessing the segmentation and counting success. Discs could be recommended instead of full shape masks for brittle stars due to faster annotation among marker variants tested. Underwater image enhancement techniques could not improve segmentation results noticeably, but some might be useful for augmentation purposes
Tiesinė diskriminantinė gausinių erdvės-laiko duomenų analizė.
No full textIn this article we focus on the problem of supervised classifying of the spatio-temporal Gaussian random field observation into one of two classes, specified by different mean parameters. The main distinctive feature of the proposed approach is allowing the class label to depend on spatial location as well as on time moment. It is assumed that the spatio-temporal covariance structure factors into a purely spatial component and a purely temporal component following AR(p) model. In numerical illustrations with simulated data, the influence of the values of spatial and temporal covariance parameters to the derived error rates for several prior probabilities models are studied
Erdvinių auto-beta modelių taikymas statistiniame klasifikavime.
No full textIn this paper, spatial data specified by auto-beta models is analysed by considering a supervised classification problem of classifying feature observation into one of two populations. Two classification rules based on conditional Bayes discriminant function (BDF) and linear discriminant function (LDF) are proposed. These classification rules are critically compared by the values of the actual error rates through the simulation study
Can’t tell a book by its cover: disjointed groundwater contamination and land use in an alluvial aquifer of Northern Italy /
No full textIn the Po plain, intensive agriculture is supported by large irrigation volumes and use of fertilizers. We analysed the effects of different land uses in a sector of the Mincio River on groundwater hydrochemical characteristics and hypothesized local regulation of NO3- contamination. In the unconfined coarse-grained alluvial aquifer, hydraulic heads were measured monthly in 17 wells from May 2019 to December 2019, to trace how the aquifer recharge and manure spreading influence groundwater physico-chemical parameters and quantity. The experimental site was divided into two different zones on the left and right bank characterized by different land use. Although these dissimilarities concern different irrigation and fertilization practices, we measured in both areas nitrate (NO3-) contamination in groundwater, with concentrations exceeding legislative limits by a factor of 2. Our results suggest that NO3- contamination in this area is not only driven by specific land use and related agricultural practice; rather, other local factors intrinsic to the local aquifer and groundwater characteristics play an important role. Presented results on groundwater quality and quantity provide useful information to increase knowledge on local N dynamics and to the administrations regulating fertilizer use in this area, already reported as Nitrate Vulnerable Zones (NVZ)