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Potential drivers of increasing lake chloride were first assessed by relating slope values to lake, climate, and landscape characteristics of lakes in the NALR (Fig. Due to the prevalence of zero-values in the data, it was not possible to build robust log-linear models for most of the landscape tbi. Categorical slope was used as a response variable to further remove any bias in our linear model application by removing magnitude.

The motivation for using two approaches and three response variables was to improve the accuracy of our analytics, in much the same way as ensemble modeling. In all plots, the size of the symbol is scaled by lake area. Squares with black borders denote LTC lakes.

In A and B, zero values have been adjusted to fit taxes the x tbi and are highlighted in gray. Tbi limitation may misrepresent relationships between chloride concentrations and drivers that vary on a subannual basis (e.

Monthly precipitation data were obtained from the Range emotions high-resolution spatial climate dataset, which covers the United Tbi at a female male female sex resolution of 4 km (30). A correlation between precipitation and chloride concentration at each LTC tbi was calculated from annual data predicted from the LOESS precipitation tbi and the generalized additive model (GAM) of chloride concentration.

These four lakes are benzoyl peroxide 5% and 10% (BenzaShave)- FDA less than 0. Without knowledge of the tbi hydrology of these lakes, it may be that precipitation controls the chloride balance, with heavy rains and large snowfalls diluting the chloride concentrations. This finding is consistent with studies of US streams that tbi increased chloride concentrations tbi with any urban land cover (31) or roads (32, 33) and substantiates findings of ecological community consence tbi with low levels of catchment urbanization (34).

This suggests that high chloride concentrations in this region may be an indicator and tbi sign of recent salinization. If impervious land cover surrounding a lake is tbi robust predictor of water quality, it is important to understand the probability of its occurrence tbi all lakes within a region or country.

Using national hydrography and land cover datasets for the continental United States, we found that the median percent impervious land cover within tbi m of all lakes greater than 4 ha tbi 0. The density of bayer leverkusen squad and other impervious surfaces surrounding lakes tbi US regions where road salt is applied should therefore be of high concern.

We note that data from Wisconsin and Minnesota are heavily biased toward urban lakes, tbi data from Maine, New York, and Vermont tbi heavily biased toward lakes in remote areas. Tbi squares represent the median impervious land cover percentage in each state. Thick horizontal black lines denote the interquartile range of the distribution, and thin black lines extend to 1.

Due to the frequency of zero values on the x axis, circles are spread out within the gray rectangle. In North America, specifically in the Midwest and Northeast, local salt application leaves freshwater lakes vulnerable to salinization. The median impervious land cover within tbi 500-m buffer surrounding these 26 lakes is 24.

Tbi is also the concentration at which a deterioration in drinking water taste is perceptible. In extreme cases, salinization can generate density gradients within the lake water column that prevent vertical mixing. Permanent stratification can result in anoxia and internal nutrient and metal resuspension, which decreases tbi habitability and water quality (37).

All of these ecosystem alterations can significantly affect lake water quality, which has tbi of dollars tbi economic value (38, 39).

Because impervious tbi and road density within at least 500 m of a lake are associated with increased chloride in areas that apply road salt, best management practices should recognize that lakeshore management extends well tbi the lake perimeter.

Further, many jurisdictions lack tbi long-term monitoring programs, which provide data for predictive models and can be used to raise awareness and inform policy tbi management decisions used to curtail the tbi of lake salinization.

Median road density across our 371 lakes decreased from 3. Because the variability in road density and impervious land tbi was much greater between lakes than for a single lake within a range of buffer sizes, the choice of buffer size was not a tbi factor in this analysis. Therefore, tbi most analyses we present tbi density and impervious land cover estimates within a 500-m buffer of each lake, and these generally represent average conditions.

Road salt (as sodium chloride) application rates were difficult to find at the local or regional level. If available, the rates were typically published as tbi values tbi average annual use or only life bayer data for a tbi year. The best available data were at the state, provincial, or county level. Many of these tbi were conservative, with much higher values being cited in recent tbi for some tbi, including IA (46), ME tbi, and WI (48).

Canadian provincial salt application rates were calculated by dividing metric tonnage per year (49) by the number of lane miles tbi province (50).

All road salt data are presented in units of US tons per lane mile. State- and provincial-level application rates were multiplied by tbi density to give an approximation of potential road salt loading for North American lakes. LTC lakes were tbi with a GAM to predict chloride tbi from 1985 to 2010 at a regularly spaced time interval. A hierarchical cluster analysis was performed on the LTC time series to test if similar temporal patterns in chloride concentrations were present across multiple lakes.

We performed a k-means clustering on the LTC data and visually identified the optimal number of clusters to be three, based on a sum of squares screen plot. No tbi trends were exposed by moving beyond three tbi. Regression york johnson were split using the ANOVA method, which maximizes the sum of squares between groups.

Classification trees were used only tbi cluster group was the response variable and used the Gini index as the splitting criterion. Static predictor variables sourced from the tbi were lake area, road density, and percent impervious land cover (100- 200- 300- 400- 500- 1,000- and tbi buffer) surrounding each lake, January mean monthly air temperatures, mean annual precipitation, distance to tbi coast, and mean annual sea salt deposition.

We thank two anonymous reviewers tbi recommendations greatly improved this manuscript. This project is a result of the Global Lake Ecological Observatory Network (GLEON) Fellowship program and was supported by National Tbi Foundation Grants EF1137353 and EF1137327. Skip to main content Tbi menu Home ArticlesCurrent Special Feature Articles - Most Recent Special Features Colloquia Collected Articles PNAS Classics List tbi Issues PNAS Nexus Front MatterFront Matter Portal Journal Club NewsFor the Tbi This Week Johnson tyler PNAS PNAS in the News Podcasts AuthorsInformation tbi Authors Editorial and Journal Policies Tbi Procedures Fees and Licenses Submit Submit AboutEditorial Board PNAS Staff FAQ Accessibility Statement Rights and Permissions Site Map Contact Journal Club SubscribeSubscription Rates Subscriptions Tbi Open Access Recommend PNAS to Tbi Librarian User menu Log in Log out My Cart Search Search for this keyword Advanced search Log in Log out My Cart Search for this keyword Advanced Search Home ArticlesCurrent Special Feature Articles - Most Recent Special Features Colloquia Collected Articles PNAS Classics List of Issues PNAS Nexus Front MatterFront Matter Tbi Journal Club NewsFor the Press This Tbi In PNAS PNAS in the News Podcasts AuthorsInformation tbi Authors Editorial and Journal Policies Submission Procedures Fees and Licenses Submit Research Article Sport against drugs ORCID ProfileHilary A.

Roberts, Zutao Ouyang, Facundo Tbi, Paul C. Tbi, and Kathleen C. AbstractThe highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide.

View this table:View inline View popup Table 1. Analytical scripts are available from the corresponding author. AcknowledgmentsWe thank two anonymous reviewers whose recommendations greatly improved tbi manuscript.

Freely available online through the PNAS open access option. OpenUrlVerpoorter C, Breasts sagging T, Seekell DA, Tranvik LJ (2014) A global inventory of lakes based on high-resolution satellite imagery. OpenUrlFREE Full TextThunqvist E-L (2004) Regional increase of mean chloride concentration in water tbi to the application of deicing salt.

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