In Karst, inventories of soil organic carbon should be reviewed

In Karst, inventories of soil organic carbon should be reviewed

Living almost 15 years in karst has allowed me to know the particularities of its soils, its diversity. For that reason, when I see the maps of soil organic carbon content I am horrified to see such great mistakes made by my colleagues, the same feeling causes me to hear or read that the Yucatan peninsula, is the largest store of organic carbon in the soil in Mexico.
The organic carbon inventories in the soil in karst areas should be done in a very different way to the way they are being carried out. Discontinuity and spatial heterogeneity should be taken into account at short distances of meters. Soil bulk Density data must be generated and the soil depth not to be used beyond the real depth.

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The summary of the paper is:

The organic carbon stock in Leptosls with discontinuous distribution in the Peninsula  of Yucatan

The SOC estimation requires quantifying the coarse fraction(stones and gravels), bulk density and depth. The soils inventory realized for INEGI didn´t reports the first two parameters, then, the generated SOC maps have considerable doubt SOC.

The objective was to evaluate the spatial variability of soil organic carbon over short distances, as well as to report the contents of organic carbon per unit area in Leptosols from northern of Yucatan Peninsula.

102 samples were taken; organic carbon was analyzed by technique of potassium dichromate; and coarse fragments (coarse gravel, medium and fine gravel) were separated from the fine earth. The Color was recorded dry and wet, bulk density was measured using the amount of fine earth in a volume of 10×10 cm surface by a depth to find the rock.

Leptosols presented SOC values below 100 t ha-1 reported for this area, with mean values of 32.85, 37.57, 43.72, and 61.93 t ha-1, for dark brown soils, very dark brown, blacks and very dark grays respectively. Coarse fragments ranging from 6.7% to 96.4% with an average of71.15%.

The amount of edaphic organic carbon is in agreement with the values reported in percentage but lower than those reported in unit of surfaces, which is why it is being overestimated.

The spatial analysis of the soils at short distances reveals a high discontinuity and variability in the percentage of carbon, as well as in the depth and quantity of coarse fragments.

The comparison in the COS content between soils should consider the spatial discontinuity and the amount of COS in kilograms per hectare.
In the soil organic carbon inventories in the north of the Yucatán Peninsula, there has been an overestimation of the organic carbon of the soil that must be corrected considering the discontinuity of the soil and its shallow depth.

Delgado C, Bautista F, Calvo-Irabien LM, Aguilar-Duarte Y y Martínez-Tellez J. 2017. El carbono orgánico en Leptosols con distribución discontinua  en la península de Yucatán. Ecosistemas y Recursos Agropecuarios. 4(10):  31-38.

Spatial distribution and integration of heavy metals using SIG

Spatial distribution and integration of heavy metals using SIG

In Ensenada Baja California, ships and vehicles produce particles with heavy metals. These particles are blown by the wind and deposited on the soil becoming urban dust. Heavy metals may affect the health of the population, so a quick diagnosis is required to find a solution to this problem.

The aim of this study is to identify those areas of higher pollution within the city.

A total of 86 urban dust samples were sampled on diferent substrates (soil, cement and asphalt). Heavy metals were analyzed by X-ray fluorescence. Differences among substrates were identified by analysis of variance. The analysis of ordinary Kriging interpolation (KO) was performed to estimate the spatial distribution of heavy metals.

figura-1-ingles

Asphalt contains higher concentration of Cr, Ni, Pb and Zn; cement contains  higher concentrations of Cu and V; and soil contains higher concentrations of Rb. A total of thirty six sites exceed the concentration of vanadium established by the NOM-147-SEMARNAT/SSA1-2004.

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The map which includes the classes with higher concentration of heavy metals shows that the southwest area of the city is the most polluted area due to port and transpeninsular highway.

Cortés J.L*.; F. Bautista; P. Quintana; y A. Gogichaishvili. 2017. Distribución espacial de los metales pesados en polvos urbanos de la ciudad de Ensenada, Baja California, México. Revista Chapingo Serie Ciencias Forestales y del Ambiente.

Density of karst depressions in Yucatán state, México

Density of karst depressions in Yucatán state, México

The abundance of karst depressions in Yucatán has been widely recognized, but they have not been classified or quantified despite their importance in land planning and use.

Our objective was to study the types and areas of the sinkholes, uvalas, and poljes and identify their patterns of spatial distribution.

We used 58 topographic maps (1:50,000) from INEGI, from which we extracted the depressions and bodies of water. For typology, we used a circularity index and the shape and area of the depressions. For single-density analysis, we extracted the centroids and added an inventory of karst features (cenotes, caves).

We counted 6717 depressions with a total area of 454 km2 and 750 karst features. We identified 4620 dolines (34 km2), mainly in plateaus below 30 masl. In number, they are followed by uvalas (2021) and poljes (76), occupying together a similar area (210 km2) and dominating in elevations higher than 30 masl. Eighty percent of the dolines were automatically labeled.

Depressions

Density maps of karst depressions have a wide range of applications.

  1. The different densities are indicative of the types of groundwater flow. These characteristics should be included in models of groundwater flow 
  2. In addition, these density maps can also be used as precursors to tracer studies to identify preferential water flows in order to locate aquifer limits
  3. Depression-density maps are also useful in determining areas with hazard of subsidence and collapse

Aguilar, Y*., F. Bautista, M. Mendoza, O. Frausto, T. Ihl. 2016. Density of karst depressions in Yucatan state, México. Journal of Studies of Cave and Karst. 78(2): 51-60.  DOI: 10. 4311/2015ES01.24.

https://caves.org/pub/journal/PDF/v78/cave-78-02-51.pdf

Software for land evaluation (Soil, Water and Climate)

Software for land evaluation (Soil, Water and Climate)

Given the global environmental crisis and its association with soil degradation, climate change and water scarcity, there is a need for better decision making processes regarding agricultural land management. This in turn creates the need for systems that are able to manage, process and analyze large amounts of information. The aim of this study was to describe the creation and use of three different softwares.

They were designed and developed using Eclipse as programming interface, Derby as database management system and Java as programming language.

The Soils and Environment (S&E) software uses a few soil properties to perform environmental assessments of soil profiles. These assessments are performed qualitatively, considering Human life, Flora and fauna, Natural Archive and Cultural Archive, and quantitatively, considering Water Cycle (associated with field capacity and hydraulic capacity), Nutrient Cycle (cation exchange capacity), Heavy Metals (pH, CEC, texture and structure), Means of Transformation (organic pollutants), Food and Biomass (field capacity, aeration capacity and effective cation exchange capacity), Filtration and Infiltration, and Organic carbon Stock.

Diapositiva3

The software for evaluation of water quality for agriculture (Agriwater) was designed to evaluate the quality of irrigation water (salinity, sodicity, chlorine toxicity) and to identify water families. The transformation of units is done automatically.Diapositiva2

The Climate Change with Monthly Data (Clic-MD) software was designed to analyze climate change trends at the local level using monthly data; with Click-MD, we can make up to 432 graphs of indicators of climate change per weather station.Diapositiva1

S&E, Agriwater and Clic-MD facilitate the management of large databases, which in turn improves staff productivity and related data management, and reduces the time of analysis by more than 90%.

Mor information: www.actswithsciencce.com

 

Quality of groundwater for irrigation in Yucatán, México

Quality of groundwater for irrigation in Yucatán, México

In the state of Yucatán, studies focused on the distribution of groundwater quality from an agricultural perspective are scarce. Furthermore, spatial analyses of these resources have not yet been conducted although this could lead to a better use of water and to a decrease of soil degradation hazard.

In order to foresee and achieve the modernization process of agricultural activities in the state of Yucatán, which would necessarily involve an irrigation alternative, it is essential to evaluate the current state of water quality. Seasonal agriculture is characterized by a very low productivity and in several regions it barely provides enough produce for subsistence. The evaluation of water quality is a fundamental requirement for implementation of rural developments projects at state level (some of which are already beginning to develope). The present study considers chemical parameters related to variations in water salinity and hardness because both conditions are important limiting factors for commonly grown crops in the region, such as maize, beans, grasslands, fruit trees (mainly citruses) and other produce for human consumption.

The main purpose is to identify and characterize zones in the state of Yucatán by distinctive groundwater qualities as regards agricultural use, based on the geostatistical validation of agricultural parameters.

Water samples were collected at 113 supply wells. The concentrations of Ca2+, Mg2+, Na+, K+, HCO3, SO42-, NO3, Cland the electric conductivity (EC) were determined. Sodium adsorption ratio (SAR), potential salinity (PS) and effective salinity (ES) were also calculated. A geostatistical analysis by kriging interpolation was performed. ES, PS and SAR as well as Na+, EC, Cl, SO42-, and Ca2+ were selected to make maps, in accordance with the values of semivariogram and values of cross validation. The map of the ES was taken as the base to make the map of zones of agricultural quality groundwater.

The quality of karstic groundwater in the state of Yucatán cannot be recommended for agriculture in Zones I (EC and ES), II (EC, Chlorides, PS and ES) and III (EC, sulfates and ES); in Zones IV and V the water is of medium quality and in the Zone VI, water is considered good for agricultural use.

Zonas

In Zone VI, the water quality was classified as good quality due to low values of chlorides, PS and ES. Zone VI covers 1056.8 km2 and corresponds to 28.7% of the state of Yucatán.

The water in this zone is classified as good for agricultural uses. However, soil salinity monitoring is recommended.

Zone VI has the best agricultural groundwater but it is also the zone with most urban population, industrial development and pig farming, so it is the zone with greater pollution with lead, chromium, cadmium, arsenic, copper, zinc, nitrates, pesticides and fecal pathogens that hazard human health.

This information will be relevant in decision-making for government’s agricultural and environmental planning.

Now we have a software for the evaluation of agricultural irrigation water quality (Agriwater), with this software analysis time is less and increases the efficiency of the evaluation. https://www.actswithscience.com/agriaqua/

The paper reference is: Delgado C. C., Pacheco A. J., Cabrera S. A., Batllori S. E., Orellana R. and Bautista F. 2010. Quality of groundwater for irrigation in tropical karst environment: the case of Yucatán, México. Agricultural water management. 97, 1423-1433. Factor de impacto 2.016. SCI. http://www.sciencedirect.com/science/journal/03783774