Questionable Water Solutions

Questionable Water Solutions

By West Marrin, Ph.D.

Conventional seawater desalination, wastewater recycling, geoengineering, and transcontinental water importation are a few of the solutions that have been proposed to address the shortage of available freshwater.  While useful for a limited timeframe or in certain locations, these technologies have drawbacks related to energy requirements, environmental effects and long-term sustainability.


Contributors to atmospheric carbon dioxide are recommending the “sequestering” of carbon in the oceans or underground in saline aquifers that frequently involves capturing greenhouse gases and relocating them to environments that are not in direct contact with the atmosphere. Ocean sequestration can have devastating effects on marine chemistry and biodiversity, whereas underground sequestration can pollute potable groundwater aquifers.

Technologies such as cloud seeding have long been hyped as a potential means of increasing local rainfall and, although potential side effects are often minimal, their reliability is still in question. Fertilizing the oceans with soluble iron and creating tropical tree plantations have been proposed to limit the rise in atmospheric carbon dioxide levels, but their effects on soil productivity, ecosystem stability and critical water quality parameters are unknown. Those who recommend geoengineering techniques often believe that the immediate consequences of climate change are more of a concern than are the potential longer-term negative effects.

Water Reuse.

The reuse of wastewater can produce potable water, although treatment to drinking water standards is both energy- and water-intensive. Constructed wetlands, or living machines (wetland-like systems), and various types of treatment lagoons that utilize aquatic plants or microalgae to remove pollutants from wastewater streams are significantly more efficient than are conventional treatment facilities. Conventional or and centralized treatment facilities utilize chemicals and electrical energy to clean wastewater, while wetlands and lagoons primarily utilize plants and microorganisms. Although constructed wetlands cannot produce potable water, they can produce water suitable for irrigation, cooling, and other household purposes.

Water reuse and conventional seawater desalination may eventually become expensive necessities for providing potable water to drought-stricken regions; however, exploring more energy-efficient alternatives that produce fewer wastes may be prudent in the interim.20141106_173902

Figure 1. Seawater desalanization is a non sustainable solution

Alternative Energy Sources.

Conventional energy sources (e.g., fossil fuels, nuclear, hydroelectric) are major users and/or polluters of water, but a number of supposedly “green” energy sources are nearly as water inefficient. Hydrogen gas is often touted as a substitute fuel, but most hydrogen gas is produced by reacting steam with natural gas, a process that is both water consumptive and polluting.

Bioethanol is even more water unfriendly as a result of its dependence on cultivating starchy plants that have the same irrigation demands as food crops and that pollute waters with pesticides, fertilizers and processing wastes. Moreover, the global production of bioethanol has been linked to regional food shortages. Alternatively, the combined actions aquatic algae and bacteria can produce hydrogen gas in a complex process that generates a renewable fuel.

Bulk Water Imports.

A common response to drought is moving water from where it is to where it is not. Much of the U.S. Southwest was developed (or overdeveloped) using this tactic, and now the hunt is on for water from more distant sources. Beyond the enormous energy demands of transporting water through pipelines or canals and the staggering costs of building the required infrastructure, importing entire water supplies is neither sustainable nor secure.

Transport of water

Figure 2. Import water is a non sustainable solution

Similarly energy inefficient and unsustainable is the proposed shipping of bulk water (via large tankers) between continents or towing of icebergs from Polar Regions. Questions remain as to whether shipping a more limited volume of bottled drinking water is even energy efficient.

Healthy soils results in clean water: soil as a natural reactor

Healthy soils results in clean water: soil as a natural reactor

The diversity of soil also called pedodiversity and edafodiversity is a basic concept in soil science, it is the recognition of differences between soils using some taxonomic scheme as Soil Taxonomy (USDA) or the World Reference Bases of Soil Resource (WRB) (Figure 1).pedo-diversity

Figure 1. An example of the diversity of soils in Latin America

Along with the identification of soil profile (taxon, name), recognizing the occupied surfaces is required, this activity is called soil geography. The product is a soil map.

What follows is the recognition of the potential use of soils and recognizing the environmental and ecological functions performed by each soil, each soil area. The product is the map of soil functions.

One of the environmental functions of soils is water purification, its function as a natural reactor as plant wastewater treatment.

As it can be seen in Fig. 2 Soils best filter and purify water are Vertisols. However, Luvisoles work best in the decomposition of the soluble organic matter.

soil reactor

Figure 2. Application of wastewater to different soil columns. In flasks below, you can see the differences in water quality after passing through the soil column. ARP = swine wastewater

Vertisols absorb the soluble organic matter; however, the decomposition of organica matter is slow. On the other hand, Luvisols absorb soluble organic matter in mean quantities; but the organic matter decompose faster.

Now you know one environmental function of soils: water purification capacity you use and drinking.

More information,



  • Bautista F., A.J. Zinck.y S. Cram. 2010. Los suelos de Latinoamérica: retos y oportunidades de uso y estudio. Boletín del Sistema Nacional de Información Estadística y Geográfica. 2: 93-142.
  • Aguilar Y. y Bautista F.. 2011. Extrapolating the suitability of soils as natural reactors using an existing soil map: application of pedotransfer functions, spatial integration and validation procedures. Tropical and subtropical agroecosystems. 13: 221- 232.
  • Aguilar Y., Bautista F., and E. Díaz-Pereira.2011.Soils as natural reactors for swine wastewater treatment. Tropical and subtropical agroecosystems. 13: 199- 210.
Indicators of Climate change (ICC); a software that can analyze millions of data in seconds

Indicators of Climate change (ICC); a software that can analyze millions of data in seconds

The intergovernmental panel on climate change defined the indicators that allow to identify or find the evidences of climate change.  Some indicators are related to temperature and others to rainfall.

Before entering the subject, it is necessary to define two terms: indicator and indexes.

  • An Index (from Latin index) is a sign or signal something. It can be the numerical expression of the relationship between two quantities or indicators.
  • An Indicator is a procedure that allows to quantify or associate a phenomenon; it serves to “indicate” or suggest the existence of certain characteristics in the phenomenon under study, often to record its changes

 Climate change indicators are intended to be mathematical elements (indexes) used to identify, register, meet and make clear climate change later relate these changes to the responses of organisms, with crops, livestock and forestry with aspects of health and environmental risks

Some are related to extreme high or low temperatures: Consecutive dry days (CDD); Ice days (ID); Cold spell duration index (CSDI); Summer days (SU); Diurnal temperature range (DTR); Cold nights (TN10p); Frost days FD; Warm nights (TN90p); Growing season length (GSL); Lowest minimum temperature (TNn); Highest minimum temperature (TNx); Cool days (TX10p); Hot days (TX90p); Lowest maximum temperature (TXn); Highest maximum temperature (TXx); Warm spell durationi ndex (WSDI); Tropical nights (TR); and Consecutive days over 40 °C (DC40).


Other indices are related to extreme rainfall events:
5-day maximum rainfall (RX5Day); Simple daily intensity index (SDII); Consecutive wet days (CWD); Total annual rainfall (PRCPTOT); Heavy precipitation days index (R10mm); Very heavy precipitation days (R20mm); Very wet days (R95p); Extremely wet days (R99p); Days with more than nn of rainfall (Rnnmm); and 1-day maximum rainfall (RX1Day).Slide2

The “Indicators of climate change” software is a tool for climatology experts and non-experts interested in the climate such as geographers, agricultural and forestry biologists, zootechnicians, environmental consultants, engineers, architects and a long etcetera. It is an intuitive software, using colors to guide the user in the interpretation of the changing trends.


Using daily data, this software provides the same results as the analysis of trends in weather elements, but it also suggests the harm or benefit that that would be caused by specific changes in climate, e.g., changes in cold nights, warm nights, cool days, hot days, the simple daily intensity index and very humid days, among others.

In this way, the CCI software is an informatic tool that, using daily local data, can be useful to detect the direction, magnitude and significance of climate change. After detecting a change, the software attempts to correlate it with agricultural production, the migration of wildlife species, livestock productivity, possible changes in the phenology of plants, aspects of human health, disaster risk forecast, the spread of pests, the presence of invasive species and other processes associated with climate change.


Análisis de las tendencias de cambio climático: resultados generados con Clic-MD Más información: Pagina oficial: Facebook: …

Soil & Environment (S&E)

Software to evaluate the environmental functions of the soils with the profile data. S&E is possible: • To shape stages of conservation and degradation for soil …

Correlation between heavy metals and magnetic properties in soils of Mexico City

Correlation between heavy metals and magnetic properties in soils of Mexico City

By Rubén Cejudo, Francisco Bautista, Patricia Quintana, Carmen Delgado, Daniel Aguilar, Avto Goguichaishvili y Juan Morales.

The Mexico City has not system of environment monitoring that evaluate fast and reliable the quality of soil in term of pollution by potentially toxic elements. Diverse researches in soil showed a correlation between potentially toxic elements and magnetic parameters however none have expressed a threshold value that determinate a contaminated soil.

The aim of this work was to identify those magnetic parameters that express a strong correlation statistical with the concentration of potentially toxic elements and stabilizing a threshold value for this magnetic parameter that will allow the identification of contaminated soil of form fast and reliable.

The use of magnetic parameters will be tested as alternative method of monitoring to evaluate the soil quality. 88 samples of topsoil were collected in Mexico City since the city is built on two type of geological environments, the samples were separated in two groups (37 soils of volcanic zone and 51 soils of lacustrine zone). The correlations between magnetic parameter and potentially toxic elements were determined for the two groups. The magnetic parameter that showed a significant statistical correlation in the two geological environments were selected to identified the threshold value for to decide whether a sample is contaminated or not.

The magnetic parameters used in this work were the mass magnetic susceptibility (c), percentage frequency dependent susceptibility (cfd%), the value of isothermal remanent magnetization to 0.7 T (SIRM), ration SIRM/c. The identification of type of magnetic mineralogy, concentration and magnetic coercivity was determined by variation of volume magnetic susceptibility (κ) versus temperature (T), the curves of isothermal remanent magnetization (IRM) and ratio S-200.


Figura 1. a) Valores de susceptibilidad magnética másica vs porcentaje de la susceptibilidad magnética dependiente de la frecuencia con límites de concentración de granos superparamagnéticos (Dearing, 1999). b) Curvas representativas de magnetización remanente isotermal obtenida de suelos superficiales.

The determination of concentration of potentially toxic elements (Cr, Cu, Ni, Pb, V y Zn) and oxides (Fe2O3 y TiO2) in soil was obtained by energy disperse X-ray fluorescence (ED-XRF) spectroscopy. In addition were determined the pollution load index (PLI) to compare the levels of pollution of each site. The SIRM was the magnetic parameter that showed a statistically significant correlation between the concentration of Cr (0.54), V (0.36), TiO2 (0.41) y Fe2O3 (0.50) in both geological zones. The mean value of PLI was of 1.85 this suggested that many soils in Mexico City showed a moderate pollution by potentially toxic elements. The statistically determined threshold value of SIRM for polluted sites was of 46 mAm2 kg-1, this threshold value is valid for soils of volcanic zone and lacustrine zone.


 Tabla 3.  Correlaciones Pearson para las muestras de suelo superficial de zona volcánica entre parámetros magnéticos, metales tóxicos y ICC
N = 51 c MRIS MRIS/c Cr Cu Ni Pb V Zn TiO2 Fe2O3 ICC
c 1
MRIS 0.36 1
MRIS/c -0.32 0.75 1
Cr 0.06 0.54 0.48 1
Cu 0.09 -0.04 -0.12 0.14 1
Ni -0.20 -0.28 -0.15 -0.09 0.12 1
Pb 0.15 -0.08 -0.23 0.17 0.55 0.22 1
V 0.00 0.33 0.29 0.42 -0.13 -0.32 -0.17 1
Zn -0.10 -0.19 -0.14 0.07 0.80 0.68 0.55 -0.27 1
TiO2 0.03 0.40 0.37 0.58 -0.17 -0.34 -0.21 0.79 -0.30 1
Fe2O3 0.07 0.45 0.37 0.57 -0.11 -0.33 -0.19 0.85 -0.25 0.93 1
ICC -0.02 -0.10 -0.13 0.26 0.69 0.63 0.74 -0.15 0.90 -0.17 -0.14 1

Significancia estadística con valores P < 0.05 marcadas en negro.

The conclusion of this work shows the feasibility of utilize magnetic parameters as alternative of monitoring for to determine or to estimate the concentration of potentially toxic elements in soils of Mexico City.



Cejudo et al., 2015. Correlación entre elementos potencialmente tóxicos y propiedades magnéticas en suelos de la Ciudad de México para la identificación de sitios contaminados: definición de umbrales magnéticos, 32:50-61.