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I recently read a pop-science article about sea-water infilitration into (sweet) groundwater. One specific instance mentioned was the gaza strip: Exzessive well building and drawing of groundwater lowers the groundwater level, this leads to sea water infiltration. Then the article states the the nitrate content in the groundwater is higher, leading to blue baby sysndrome.

Now, I assume that an elevated nitrate content in the groundwater is due to fertilizer runoff, damaged sewer systems or similiar and unrelated to the saltwater problem, the author of the article simply mixed those problems up. But I'm not sure, hence this question: Is there any causal link between sea-water inflitration and groundwater nitrate?

An answer not specific to Gaza would be ok as I want to understand possible mechanisms.

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While the context and specifics would likely vary from site to site, the situation along the Gaza strip may be due to contamination of the Mediterranean Sea. I am unsure of natural levels of Nitrate in ocean water, but I know that it is possible to contaminate water, independent of it's salinity.

Nitrate, like other water-soluble ions, ultimately is transported from the land to the oceans via the hydrologic cycle. Waste from marine organisms also likely contributes nitrate. This paper talks on the content of nitrate in ocean water. For more information on the various major constituents of sea water, check out this site.

There has been reported incidence of sewage draining into the Mediterranean, which would explain nitrate contamination in conjunction with sea-water intrusion.

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  • $\begingroup$ the first link does not work (I think there's one paranthesis too much + soest.hawai.edu is not found by my browser) $\endgroup$ – mart Jun 17 '14 at 20:35
  • $\begingroup$ Also I want to check wether nitrate concentrations in contaminated seawater can be so high that the nitrate is a bigger problem than the saltyness. $\endgroup$ – mart Jun 17 '14 at 20:36
  • $\begingroup$ Rather than just linking to papers, it's probably a good idea to summarise the relevant information that they provide, and then cite them. $\endgroup$ – naught101 Jan 27 '15 at 5:18
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One of several pages would seem to indicate there are other constituents that make up a much larger percentage of seawater than nitrate, At least on average. Not to say that some areas may have higher concentrations of nitrate - though this is typically associated with anthropogenic causes. I don't think nitrates are as conservative as chloride, and given a lack of dissolved oxygen and the right mix of bacteria (http://pubs.usgs.gov/fs/fs05300/), substantial denitrification can occur - so in areas of high nitrates, one might first look for rapid pathways for the entry of water from land that would contain such constituents rather than from seawater.

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    $\begingroup$ Rather than just linking to papers, it's probably a good idea to summarise the relevant information that they provide, and then cite them. $\endgroup$ – naught101 Jan 27 '15 at 5:19

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