No abstract

The aim of this study was to determine parameters of dissolved oxygen, temperature and nitrogen in the coastal basin of the Jamapa River as indicators of eutrophication. Six sampling sites were selected in the lower basin, where samples were collected in triplicate in each site, during three seasons; north winds, dry and rainy. Results of the research, analyzed using the Minitab statistical program, were: site 2 showing the maximum value of dissolved oxygen with 5.83 mg/L; site 5 with the maximum temperature value of 30.3 ºC, during the dry season. Whereas, maximum mean values of total nitrogen were at site 2 (4.596 mg/L) and site 5 (4.281 mg/L). Coastal basins can change markedly the nitrogen concentration with respect to weather and environmental conditions. As well as, reduced forms of nitrogen cause alterations in dissolved oxygen and the increase in water temperature, along with high concentrations of nutrients.

Total suspended solids are an indicator of material constituted by sedimentable solids, suspended solids, and colloidal, whose origin is erosion, wastewater discharges, and agricultural waste. The objective of this research was to determine territorial water erosion, its relation with total suspended solids, and the water quality in the lower basin of the Usumacinta River in Tabasco. Three sampling points were established, located in the municipalities of Tenosique, Emiliano Zapata, and Jonuta, in the state of Tabasco. Water samples were collected during 12 monthly sampling campaigns in an annual cycle, and the total suspended solids were determined according to the provisions of the NMX-AA-034-SCFI-2015 standard. Water erosion was calculated based on the Universal Soil Loss Equation (USLE) and with the use of geographic information systems (GIS). The results obtained were statistically analyzed, finding that the measured maximum TSS concentrations are 130.92 mg.L-1 in Boca del Cerro, 165.28 mg.L-1 in Chablé, and 113.91 mg.L-1 in Jonuta which are within the permissible concentrations for protection of freshwater aquatic life and agricultural irrigation according to ecological criteria of water quality (CE-CCA-001/89), in Mexico. The lower basin of the Usumacinta River has areas with extreme erosion (990 tons.ha-1yr-1), with conditions that accelerate the erosion process, such as annual rainfall between 1805 mm and 2250 mm, clay soils located on slopes greater than 16%, and agricultural soils. These events cause loss of the soil fertile layer where agriculture is developed, also giving rise to the accelerated transport of suspended solids; which negatively alter the quality of the water of the Usumacinta River.

Farming aquatic plants can be used as an alternative in the treatment of effluents from aquaculture production units and in turn, in the production of biomass plant for feeding terrestrial and aquatic organisms. This research aims to evaluate the efficiency of duckweeds Spirodela sp. and Lemna sp. in the treatment of tilapia effluents (Oreochromis niloticus). The experiment was performed in triplicate and was conducted under natural environmental conditions within the facilities of the Laboratory of Applied Aquaculture Research (LAAR) of the Technological Institute of Boca del Río (ITBOCA). Each treatment contained 230 liters of effluent in each tube, with a water column of 40 cm and a seeding density of 400 g/m 2 of vegetative biomass. The evaluation of the efficiency of Spirodela sp. and Lemna sp., in the removal of dissolved nutrients, was performed in 7 monitoring times; 12, 24, 36, 48, 72, 96 and 120 h. The results showed an efficiency in nutrient removal at 120 h of 75, 74 and 66% of N-NH 3 ; 96, 92 and 75% N-NO 2 ; 93, 88 and 75% N-NO 3 ; 75, 72 and 64% N-NTK; 73, 60 and 58% of N-org., and 73, 63 and 68% of P. On the other hand, the removal of TSS and BOD5, during the first 24 h, was 83, 54, 58% and 65, 59, 33%, in the treatments. The efficiency in nutrient removal of both duckweeds, showed that both plants can be used in the treatment of effluents, being a sustainable and economical alternative for the aquaculture industry.

This article aims to show the dimensioning and evaluation of a Distributed Generation system based on renewable energies for its application in a rural area in the state of Veracruz, Mexico. The main motivation of this work arises from the shortage of energy or a deficient supply in numerous localities located in the state of Veracruz, derived from different reasons. A methodology based on the application of HOMER Pro software is proposed for the sizing and optimization of a renewable hybrid system, considering it as an isolated set from the supply network, achieving the optimization and evaluation from technical and economic aspects. Initially, the meteorological data of the site were obtained, from its geographical coordinates; subsequently, the demand profile of one of the households in the community is determined to extrapolate it to the total number of dwellings. The results obtained in this research can serve as a basis for its implementation and, therefore, improve the conditions in which the population of rural communities or isolated from supply networks usually live.