## 5 Conclusions  
The goal of this work is to improve data management and visualization, especially for various environmental parameters with spatial and temporal components. Although some of these principles are well-known and self-explanatory, they have not been implemented into practical everyday use. Despite tremendous improvements in informatics and measurement techniques, environmental data are still not fully utilized. That is why, in this paper we identified gaps of common data visualization and management tools and proposed the solutions. Let us summarize the main advantages of our approach:  
* Web application as a universal and easy to use tool for data validation and analysis;
* Same tool for visualization and submission of validation and other results in a one-step process;
* Alignment of our system to INSPIRE directive and easy integration with web GIS and spatial services;
* Intuitive way of data presentation used without any training by experts and non expert persons, providing them quick and easy insight into an environmental dataset. From data feeds and validation to so-called information for decision makers, large amounts of environmental data are lost or not properly used. Collecting data can be very expensive, but an even higher price is paid when poor decisions are made to protect the environment due to a lack of knowledge and understanding. The use of relational databases and interactive, bidirectionally linked charts and maps can improve the quality and accessibility of data. The visualization of environmental data on the Internet is also important because it can make data more accessible to the general public. Public interest in environmental data is increasing, and many organizations outside of environmental science institutions are looking for reliable and easy-to-understand information. The amount of information available today is huge, and to distinguish high quality data from \"information noise\" we need good presentation and visualization of data. There are many initiatives to improve data discovery and reuse, but there are few initiatives to  
Figure 12: Example of marine litter categories visualization. improve data presentation. We are trying to contribute to a clear and consistent presentation of environmental data. The proposed approach is demonstrated on two case study datasets--the HarmoNIA project dataset and the Croatian national monitoring dataset. In the future, we will continue to work on the usability of the user interface by integrating other information via web GIS with WMS and WFS services, especially, instead of Google Map API for the cartographic part. This will improve spatial analysis and the real challenge will be integrating with graphics and identifying the various spatial elements that are interactive with user actions. Committing changes to the database and improving upload quality is another area for future improvement. By fusing the results of multiple user data validation we will be able to make both data and validation quality assessments. Using similar principles for visualising raster data, such as the results of numerical models with regular spatial grid and time intervals and comparing model results with real measurements, will also be a next challenge. Conceptualization, D.I. ; methodology, Li,S. ; software, D.I. ; validation, D.I. ; writing--original draft preparation, D.I. ; writing--review and editing, Lj.S., V.D. and A.I. All authors have read and agreed to the published version of the manuscript. This research was supported by the project \"The European Marine Observation and Data Network (EMODnet) Chemistry\" funded by EU Blue Growth strategy, Marine Knowledge 2020. Not applicable. Data Availability Statement: Data used for HarmoNIA visualisations can be found and downloaded at: [[http://harmonia.maris2.nl/search](http://harmonia.maris2.nl/search)]([http://harmonia.maris2.nl/search](http://harmonia.maris2.nl/search)) (accessed on 22 May 2022). Only 6% of data have some restrictions as is noticed in section \"Description of data\".