Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 143
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 143
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 209
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 994
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3134
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
We show how concentrations of water solutes in the Vltava River (Czech Republic) and their riverine outputs from the catchment were modified by socio-economic changes, land use, and hydrology between 1960 and 2015. In the early 1960s, HCO and Ca were the dominant ions. During 1960-1989 (a period of planned economy with an over-use of synthetic fertilizers, excessive draining of agricultural land and little environmental protection), the riverine concentrations of strong acid anions (SAAs: SO, NO, and Cl) increased 2-4-fold and their leaching was accompanied for by a 1.4-1.8-fold increase in concentrations of Ca, Mg, K, and Na. SAAs mostly originated from diffuse agricultural sources (synthetic fertilizers and mineralization of organic matter in freshly drained and deeply tilled agricultural land) and their annual average concentrations (as well as those of Ca, Mg, and K) were positively correlated with discharge. During 1990-2015 (a period of a re-established market economy, reduced fertilization, ceased drainage, partial conversion of arable land to pastures, and increasing environmental protection), concentrations of SO and NO significantly decreased due to reduced agricultural production and atmospheric pollution, and their positive correlations with discharge disappeared. In contrast, Na and Cl concentrations increased due to more intensive road de-icing, and their concentrations became negatively correlated with discharge. Trends in phosphorus concentrations reflected changes in its input by both diffuse (fertilizers) and point (wastewater) sources and were discharge independent.
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Source |
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http://dx.doi.org/10.1016/j.watres.2017.08.067 | DOI Listing |
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