Pollution of lakes and rivers. A paleoenvironmental perspective

Interpretation Theory. Abstract interpretation is a semantic theory introduced by Patrick and Radhia Cousot in 1977 in order to design static analysis of computer programs and, more in general, software systems. In [37, 1] we prove that completeness of abstract domains w.r.t. semantic operators is a property which is preserved by the operation of lowest upper bound and greatest lower bound in the lattice of abstractions, provided the semantic operators are completely additive. We also show some negative results concerning some properties of domain refinements that, although seem quite natural, do no hold in practice.

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A hybrid approach was proposed to simulate the spatial distribution of a number of heavy metals in the surface layer of the soil. The idea of the method is to simulate a nonlinear large-scale trend using an artificial neural network (ANN) and the subsequent modelling of the residuals by geostatistical methods. A comparison was made with the basic modelling methods based on ANN: generalised regression neural network (GRNN) and multilayer perceptron (MLP). The raw data for the surface layer modelling of Cuprum (Cu), Manganese (Mn) and Niccolum (Ni) were obtained as a result of the soil screening in the subarctic city Novy Urengoy, Russia. The ANN structures were selected by the computer simulation based on the root mean square error (RMSE) minimization. The predictive accuracy of each selected approach was verified by the correlation coefficient, the coefficient of determination, RMSE, Willmott's index of agreement (d), a ratio of performance to interquartile distance (RPIQ) between the prediction and raw data from the test data set. It was confirmed that the use of the hybrid approach provides an increase in prediction accuracy in comparison with the basic ANN models. The proposed hybrid approach for each element showed the best predictive accuracy in comparison with other models based on ANN.

Combining spatial autocorrelation with machine learning increases prediction accuracy of soil heavy metals

Mercury (Hg) concentration trends in top predator fish (lake trout and walleye) of the Great Lakes (GL) from 2004 to 2015 were determined by Kendall–Theil robust regression with a cluster-based age normalization method to control for the effect of changes in lake trophic status When data from the GLs (except Lake Erie) are combined, a significant decreasing trend in the lake trout Hg concentrations was found between 2004 and 2015 with an annual decrease of 41% per year, consistent with the decline in regional atmospheric Hg emissions and water Hg concentrations However, a breakpoint was detected with a significant decreasing slope (−81% per year) before the breakpoint (2010), and no trend after the breakpoint When the lakes are examined individually, Lakes Superior and Huron, which are dominated by atmospheric Hg inputs and are more likely than the lower lakes to respond to declining emissions from areas surrounding the GL, have significant decreasing trends with rates between 52 and 78% per year f

Mercury Temporal Trends in Top Predator Fish of the Laurentian Great Lakes from 2004 to 2015: Are Concentrations Still Decreasing?

Investigating urban heat island through spatial analysis of New York City streetscapes

The Laurentian Great Lakes of North America contain approximately 20% of the earth’s fresh water. Smaller lakes, rivers and channels connect the lakes to the St. Lawrence Seaway, creating an interconnected freshwater and marine ecosystem. The largest delta system in the Great Lakes is located in the northeastern portion of Lake St. Clair. This article focuses on the geovisualization of total mercury pollution from sediment samples that were collected in 1970, 1974 and 2001. To assess contamination patterns, dot maps were created and compared with surfaces that were generated using the kriging spatial interpolation technique. Bathymetry data were utilized in geovisualization procedures to develop three-dimensional representations of the contaminant surfaces. Lake St. Clair generally has higher levels of contamination in deeper parts of the lake, in the dredged shipping route through the lake and in proximity to the main outflow channels through the St. Clair delta. Mercury pollution levels were well above the Probable Effect Level in large portions of the lake in both 1970 and 1974. Lower contaminant concentrations were observed in the 2001 data. Lake-wide spatial distributions are discernable using the kriging technique; however, they are much more apparent when they are geovisualized using bathymetry data.

https://www.mdpi.com/2077-1312/4/1/19/pdf

Geovisualization of Mercury Contamination in Lake St. Clair Sediments

The Great Lakes Water Quality Agreement between Canada and the United States has identified the Buffalo River as an Area of Concern. The watershed has a long history of heavy industrial activity that contributed to its overall pollution. Sediment core data collected by the New York State Department of Environmental Conservation in 2005 were used to determine lead sediment contamination in a section of the Buffalo River. The ordinary kriging spatial interpolation technique was used to generate surface and subsurface sediment contamination estimates. Due to the meandering nature of the river, two kriging models were used to analyze surface contamination: a global kriging model and a regional kriging model, consisting of three separate sections. The results show that both the global and regional kriging models display similar interpolated surfaces and do not vary significantly. Within the sediment, lead contamination in the surface layer is lower than at the various subsurface depths. In 2011, habitat restoration efforts commenced to remediate environmental damage due to years of pollution inputs from various sources. Sediment dredging operations were initiated that are expected to be completed in 2015. The goal of these operations is to remove heavily contaminated sediments and rehabilitate the Buffalo River. The kriging results provide area-wide estimates of contamination. When compared to the dredging plan, the results indicate that additional removal of contaminated sediments may need to be considered where no dredging has occurred or is not currently planned.

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Assessing Lead Contamination in Buffalo River Sediments

Many communities depend on Lake St. Clair for drinking water and recreational uses. In addition, it is an important transport route for natural resources and manufactured products. The St. Clair River, which flows into the lake from the northeast, is a major source of sediment. The upstream area is known as “chemical valley” due to a large amount of industrial activity located along the river. Sediment sampling surveys were conducted in 1970, 1974, and 2001 by Environment Canada as part of a continuing monitoring program. Two approaches to the representation, analysis, and visualization of lead contamination were used: a two-dimensional Geographic Information System-based approach using kriging and a three-dimensional approach that utilized the interpolated kriging surfaces overlaid on bathymetry data. The results of combining this analytical method with a three-dimensional representation appear to show that Lake St. Clair generally has lower levels of sediment contamination away from the main flow and circulation patterns leading to its Detroit River outlet. Lead levels declined below the threshold effect level in 2001 compared with the higher concentrations seen in 1970 and 1974. In addition, lake-wide spatial distributions are better visualized using the kriging spatial interpolation results when they are overlaid on the bathymetry data.



L'emploi d'outils de geovisualisation pour evaluer la contamination par le plomb des sediments dans le lac Sainte-Claire

De nombreuses communautes utilisent les eaux du lac Sainte-Claire a des fins d'approvisionnement (eau potable) et recreatives. De meme, il sert d'axe principal pour le transport des ressources naturelles et des produits transformes. La riviere Sainte-Claire, qui se jette dans le lac depuis le nord-est, deverse d'importantes quantites de sediments. La zone situee en amont abonde de produits chimiques en raison des nombreuses activites industrielles en operation de part et d'autre de la riviere. Des echantillons de sediments ont ete preleves par Environnement Canada en 1970, 1974 et 2001 dans le cadre d'un programme de surveillance continue. Deux demarches ont ete mises en œuvre en vue de representer, analyser et visualiser la contamination par le plomb : une premiere s'appuie sur un systeme d'information geographique a deux dimensions utilisant une modelisation par krigeage, et une seconde a trois dimensions utilisant les surfaces d'interpolation obtenue par krigeage superposees aux donnees bathymetriques. Cette methode d'analyse conjuguee avec une representation en trois dimensions permet d'observer une diminution generale du degre de contamination sedimentaire du lac Sainte-Claire en retrait du courant du chenal principal menant a la decharge de la riviere Detroit. En 2001, les concentrations de plomb ont baisse au-dessous du niveau de l'effet de seuil par rapport aux valeurs plus elevees observees en 1970 et 1974. En outre, une meilleure visualisation des repartitions spatiales du plan d'eau est obtenue grâce aux resultats tires de l'interpolation spatiale par krigeage lorsque ceux-ci sont superposes aux donnees bathymetriques.

Using geovisualization to assess lead sediment contamination in Lake St. Clair

Thinking about GIS: Geographic Information System Planning for Managers (Third Edition) by Roger Tomlinson

The Ontario Council of University Libraries (OCUL) is a consortium of the twenty-one university libraries in Ontario, Canada. Since 1967, OCUL member institutions have worked together to share costs and workload through collective purchasing and licensing of information resources and more recently through the establishment of a shared digital infrastructure known as Scholars Portal. Under the auspices of OCUL, Ontario's university map librarians formed the OCUL Map Group in 1973 to seek opportunities to communicate and collaborate to improve the collections and services they offer their users. The opportunities provided by collaboration have ensured a greater capacity to manage evolving collections of geospatial data. The group has served as a community of practice, which has provided educational opportunities and facilitated collaborative problem solving through a listserv, conference calls, and face-to-face meetings. This collegial environment has also led to the completion of a number of projects, whic...

/pdf/collaborative-approaches-to-the-management-of-geospatial-2bihtnf8v1.pdf

Daniel J. Jakubek

Papers

Geovisualization of Mercury Contamination in Lake St. Clair Sediments

Assessing Lead Contamination in Buffalo River Sediments

Using geovisualization to assess lead sediment contamination in Lake St. Clair

Thinking about GIS: Geographic Information System Planning for Managers (Third Edition) by Roger Tomlinson

Collaborative Approaches to the Management of Geospatial Data Collections in Canadian Academic Libraries: A Historical Case Study