A legal framework with scientific basis for applying the ‘polluter pays principle’ to soil conservation in rural watersheds in Brazil

Riparian vegetation represents a protective barrier between human activities installed in catchments and capable of generating and exporting large amounts of contaminants, and stream water that is expected to keep quality overtime. This study explored the combined effect of landscape composition and buffer strip width (L) on stream water quality. The landscape composition was assessed by the forest (F) to agriculture (A) ratio (F/A), and the water quality by an index (IWQ) expressed as a function of physico-chemical parameters. The combined effect (F/A × L) was quantified by a multiple regression model with an interaction term. The study was carried out in eight catchments of Uberaba River Basin Environmental Protection Area, located in the state of Minas Gerais, Brazil, and characterized by very different F/A and L values. The results related to improved water quality (larger IWQ values) with increasing values of F/A and L, which were not surprising given the abundant similar reports widespread in the scientific literature. But the effect of F/A × L on IWQ was enlightening. The interaction between F/A and L reduced the range of L values required to sustain IWQ at a fair level by some 40%, which is remarkable. The interaction was related to the spatial distribution of infiltration capacity within the studied catchments. The high F/A catchments should comprise a larger number of infiltration patches, allowing a dominance of subsurface flow widespread within the soil layer, a condition that improves the probability of soil water to cross and interact with a buffer strip before reaching the stream. Conversely, the low F/A catchments are prone to the generation of an overland flow network, because the absence of permanent vegetation substantially reduces the number of infiltration patches. The overland flow network channelizes runoff and conveys the surface water into specific confluence points within the stream, reducing or even hampering an interaction with a buffer strip. Notwithstanding the interaction, the calculated L ranges (45–175 m) are much larger than the maximum width imposed by the Brazilian Forest Code (30 m), a result that deserves reflection.

Section: Study Areamentioning

confidence: 99%

A Regression Model of Stream Water Quality Based on Interactions between Landscape Composition and Riparian Buffer Width in Small Catchments

Pissarra

Valera

Costa

et al. 2019

“…The Geographic data are represented as figures embedded along with the current text. They were prepared using ArcMap [85], a computer package increasingly used in many hydrologic and environmental studies [86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101]. The complete summary dataset with information sources is depicted in Table 1 and Figures 5a-g.…”

Section: Dataset Preparationmentioning

confidence: 99%

An Assessment of Groundwater Contamination Risk with Radon Based on Clustering and Structural Models

Martins

Pereira

Oliveira

et al. 2019

There is currently some controversy in the scientific community regarding the efficiency of the water–rock interaction process in the contamination of radon in groundwater. In this study, some difficulties were found in the sampling phase. Many of the water collection points are used for human consumption. As such, some municipalities did not want to collaborate. When this natural contaminant is undetectable to the human sense and may cause pulmonary neoplasms in the long term, it is difficult to obtain collaboration from the municipalities concerned. To overcome this controversy, it is important to understand that geogenic, climatic, hydrological, and topographic features may contribute to the effective transfer of radon from rocks to groundwater. In brief, this new approach combines the radon transfer from the geological substrate to the groundwater circulation through hierarchic agglomerative clustering (HAC) and partial least squares-path modeling (PLS-PM) methods. The results show that some lithologies with higher radon production may not always contribute to noticeable groundwater contamination. In this group, the high-fracturing density confirms the recharge efficiency, and the physical-chemical properties of the hydraulic environment (electric conductivity) plays the main role of radon unavailability in the water intended for human consumption. Besides, the hydraulic turnover time of the springs can be considered an excellent radiological indicator in groundwater. In the absence of an anomalous radioactive source near the surface, it means that the high-turnover time of the springs leads to a low-radon concentration in the water. Besides linking high-risk areas with a short period required to free local flow discharges, this study exposes the virtues of a new perspective of a groundwater contamination risk modeling.

“…The summary of the total dataset used for the PCV plot is depicted in Table S2 in the Supplementary Material. The complete dataset from the Excel worksheet was prepared in the ArcMap [45] computer package, which is increasingly used in many hydrologic and environmental studies (e.g., [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]). The PCV plot is a graphical user interface tool (available in Excel using the XLSTAT statistical software) that analyzes the dissimilarities between grouped objects, resulting in a dendrogram, which shows the following data grouping within the suitable number of geological groups.…”

Section: Resultsmentioning

confidence: 99%

A New Framework for the Management and Radiological Protection of Groundwater Resources: The Implementation of a Portuguese Action Plan for Radon in Drinking Water and Impacts on Human Health

Martins

Pereira

Oliveira

et al. 2019

In general, this study was developed to assess the radon contamination in groundwater intended for human consumption, to raise awareness among policy-makers to implement a legal framework for drinking water management and the radiological protection of groundwater resources. Thus, we analyzed with parallel coordinate visualization (PCV) plots what features may influence the water–rock interaction and promote high-radon concentrations in water intended for human consumption. The results show that in granitic areas composed by biotite granites (Group V), although there is a higher radon production in the rocks, the radon transfer to groundwater was not effective, mainly due to the physical and chemical properties of the water. The main conclusions show that in all springs sampled (n = 69) for the entire study area, there are only four springs that must have an immediate intervention, and 22 of them are above the limit imposed by the Portuguese legislation. These results are intended to promote a Portuguese Action Plan for Radon that can be framed in the guidelines on the management and protection of groundwater resources.