The Jordan River, which cuts through Israel and Jordan, largely reflects the scarcity of water in the region. The above picture shows a rare flooding event in the Jordan River in the winter of 2003 at the Baptist site (well-known in Christianity). Just several months later, during the summer of 2003, the river was dry again, as shown below at a site close to Abdalla Bridge. Courtesy of Avner Vengosh.
Data collected from more than 6,000 selected sampling points reveal that more than 10 percent of the water resources in the Mediterranean basin have boron levels exceeding 1 milligram per liter, the new E.U. drinking water standard. We found that the highest values of boron are in areas associated with geothermal activity, such as in Tuscany, Italy, and Chalkidiki, Greece. In addition, we discovered high boron levels in the groundwater basins in the central part of Cyprus and in the southern coastal aquifer that is shared between Israel and the Gaza Strip. In order to delineate the origin of boron and salinity in these groundwater basins, we investigated the chemical and isotopic compositions of the boron-contaminated groundwater.
Boron has two stable isotopes that are distributed unevenly among different geological materials and natural water resources. Because different sources of water pollution have unique isotopic fingerprints, we were able to use the boron isotopes to identify clearly the source of the water contamination. For example, the boron isotopic ratios in seawater, wastewater and rocks vary significantly. Thus, when groundwater is contaminated, the imprinted isotopic signature of these different sources is preserved, serving as a tracer for delineating their origin. Similarly, the application of other isotopes such as oxygen, hydrogen and strontium provide a clue to the origin of the polluted water. By integrating these chemical tools, we discovered that the boron contamination in the Mediterranean groundwater basins is derived primarily from natural processes.
In the Cornia basin in Tuscany, we found that boron leaching from sediments into local groundwater is associated with seawater intrusion, reflecting a complex history of boron uptake and release by clay minerals. In western Chalkidiki, the mixing of groundwater with underlying thermal water rich in boron caused the boron contamination. In Cyprus, water-rock interaction is the main mechanism for the boron enrichment in the water. In the southern coastal aquifer of Israel and the Gaza Strip, we discovered that boron pollution is associated with the migration of saline groundwater from Israel into the Gaza Strip.
The chemical and isotopic compositions of the groundwater in these studies clearly indicate that the boron problem in the Mediterranean water resources, on the whole, is derived from natural (geogenic) sources rather than anthropogenic ones.
Our results have several implications for the management of national and transboundary groundwater resources in the Mediterranean basin and for the remediation of boron.
Perhaps most importantly, we are challenging the conventional perception that the boron contamination in these countries is a source of human pollution. For years, companies added boron to detergents because it is an excellent bleaching agent thus resulting in the formation of boron-rich sewage. Moreover, similar to other inorganic ions, boron is not removed during standard sewage treatment processes and even treated wastewater typically has high boron concentrations.
Thus, as a precautionary measure, environmental regulators in both Cyprus and Israel have chosen a particular strategy to reduce boron contamination: mandating regulations that restrict the amount of boron that can be added to detergents. Although the reduction in boron in treated sewage may prove to be beneficial for agriculture because there will be less boron contamination in the irrigation water, these regulations will have negligible effects for improving drinking water.
For a country that soon will join the European Union, such as Cyprus, it will only be able meet its obligation to abide by E.U. standards for drinking water by pursuing an alternative strategy that calls for technological intervention to remove boron. To date, Israel has yet to adopt an official drinking water standard for boron, despite the new proposals for desalination calling for 0.5 milligrams per liter boron in desalinated water. Thus, Israel already faces a similar challenge to Cyprus.
In short, because boron contamination in all our investigated cases comes from natural geochemical background pollution and hence cannot be prevented, the only way to address the boron problem is through treatment of the drinking water.
At present in Italy and Israel, water authorities mix the boron-rich water with high-quality water to reduce the level of boron in the water supplied for both drinking and agricultural purposes. However, the longevity of dilution as a solution is limited, primarily due to the diminishing amount of high-quality water that is available. As a result, our research has focused on the creation of alternative water resources, through the application of technological solutions such as improved desalination and the introduction of new techniques for boron removal from the water.
Reverse osmosis desalination has tremendous potential for a supply of new water for the 21st century, especially in areas of the world where water is scarce or the quality is inadequate. Its widespread application, however, is hampered by the fact that reverse osmosis desalination does not remove boron sufficiently (only 60 percent). As a result, desalination of seawater does not reduce the boron level below the new standard for drinking water in the European Union (and will be also problematic for the non-European Mediterranean countries adopting a similar drinking water standard for boron). Therefore, additional removal techniques must be introduced in order to bring boron levels down to drinking standards.
Different partners in the BOREMED project have developed several independent methodologies for removing boron from water. In Cyprus, BOREMED partners have utilized boron-specific resins combined with a small-scale reverse osmosis to reduce the amount of boron in the groundwater for local users. In Israel, BOREMED partners have succeeded in removing boron by optimization of reverse osmosis processes such as multi-step desalination. Other partners from the Netherlands have established a new method of boron removal through co-precipitation with hydroxides. In addition, a joint Israeli-Turkish team invented a new technique for boron removal through reacting seawater with fly ash and coal materials. This method is particularly useful in Mediterranean countries such as Turkey, where fly ash is abundant and cheap.
Each of the new different methodologies has its own benefits and costs. Ultimately, the E.U. countries that face a boron problem will have to adopt one of these new technologies in order to be in compliance with the new drinking water standard for boron.
Through an integration of geochemistry, hydrogeology, numerical modeling and policy analysis, we also have devised a potential management solution to the water crisis in the Gaza Strip. The local aquifer underlying the Gaza Strip is perhaps one of the most stressed resources in the Mediterranean basin in terms of water quantity and quality: Chloride concentrations reach 1,500 milligrams per liter (six times the E.U. standard); nitrate concentrations reach 400 milligrams per liter (eight times the E.U. standard); and boron concentrations reach 3.5 milligrams per liter (more than three times the E.U. standard).
Over the past five decades, the amount of water pumped from the Gaza aquifer has far exceeded the natural water replenishment. As the water level has declined, the water quality has become unsuitable for human consumption, owing to the high levels of salinity, boron and nitrate pollution. Nevertheless, more than 1 million people depend entirely upon this aquifer for drinking and irrigation water.
The BOREMED project has mapped boron distribution in groundwater from the southern Mediterranean coastal aquifer and the Gaza Strip. The different colors represent boron concentration in milligrams per liter. In most parts of the aquifer and the Gaza Strip, the boron concentration exceeds the drinking standard of 1 milligram per liter for the European Union. Courtesy of Avner Vengosh.
Our chemical and isotopic data show that most of the salinity phenomenon in the Gaza Strip is derived from flow of natural saline groundwater from Israel towards the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic upstream-downstream dispute over a transboundary aquifer: Israels upstream pumping of the saline groundwater can potentially reduce the salinization rates of groundwater in the Gaza Strip rather than cause downstream harm.
Numerical simulation of different pumping scenarios confirms our hypothesis that increasing pumping along the Gaza Strip border combined with desalination and supply to the Gaza Strip, as well as moderate reduction of pumping within the Gaza Strip, would improve the water quality of groundwater there. Moreover, our finding that the salinity problem in the Gaza Strip is partially natural de-politicizes the water issue and offers a practical solution for the water crisis in the Gaza Strip that has win-win benefits for both the Palestinian Territory and Israel.
Clearing the way
The promulgation of a new drinking water standard for boron in the European Union has forced both E.U. member and non-member states to address boron contamination in drinking water even before a strong causal link has been found between boron contamination and health effects. Yet, while new technologies now exist for boron removal, the adoption of this new drinking water standard is complicated by the fact that each country faces different institutional constraints.
In Italy, the boron problem is a local problem rather than a national one, and as a result, the end-user in conjunction with the regional water authority is responsible for developing its own program for boron removal. In contrast, in the coastal aquifer that is shared between Israel and the Palestinian Authority, the boron and salinity problem will only be resolved through the development of institutions for international cooperation. Finally, in Cyprus, the boron problem is a national problem, thus requiring a national solution instead of a local or international solution.
In the end, the ability to address the boron problem at the local, national and international levels in the Mediterranean basin will depend entirely on an integration of science, technology and policy.
At the surface,
northern Africa is one of the driest places on the planet. But underneath
the desert, ancient water lies in a complex groundwater system composed
of the Nubian aquifer. Radiocarbon dating techniques have indicated that
most Nubian aquifer water is at least 50,000 years old, but a newly developed
technique shows that some of the water is 1 million years old adding
further complexity to the Nubian aquifer system, which waters the region.
Boron is only one of many geologic materials that occur naturally in the environment
and can pose health risks to people. Geoscientists are actively involved in
studying such substances by monitoring groundwater, surface water and soils,
and by mapping their distributions. The findings may help policy-makers devise
new strategies for regulation and mitigation. Online sources for asbestos, radon,
mercury, arsenic, crystalline silica and boron are listed below; also see link
to past Geotimes coverage. See this month's print issue for more