NITRATE LEVELS IN BELIZE’S RURAL DRINKING WATER

Published: 14-03-2020| Version 2 | DOI: 10.17632/xrrtwn74vj.2
Contributors:
Danladi Husaini,
2. Andrea Enriquez,
Theslyn Arzu,
Kelcia Miranda,
Denise Mossiah,
Crystal Cardinez

Description

This study examined nitrate levels in Belize’s rural water supply with the aim to providing a baseline data for monitoring the concentration of nitrates as a means to preventing public health hazards. 2 water samples were conveniently collected from reservoirs, wells, vats and standpipes from 40 villages using plastic bottles. Plastic bottles were used to collect water samples from 43 water samples from 40 villages in all the districts of the country of Belize (Figure 5). 1000ml bottles were purchased from Bowen & Bowen Limited®, thoroughly rinsed with purified water, dried and used for water samples collection. Before sample collection, the bottles were also thoroughly rinsed with the respective water samples at the site of collection. 15 water samples were collected from reservoirs, 10 from wells, 3 from standpipes (boreholes) and 15 from vats (Figure 3). Water samples were also collected from each district in the country. 9 water samples were collected each from Belize and Toledo districts; 8 from Cayo; 5 each from Corozal and Stann Creek and 7 from Orange Walk. 2 water samples were collected from either a reservoir, a vat, a standpipe, a well or both depending on what is available in the village. Collected water samples were immediately transported to the laboratory of Belize Coastal Zone Institute and analyzed for nitrates. Water samples that were not immediately analyzed were filtered and refrigerated below 4o C till analyzed. Testing and Analysis was done according to USA EP for Nitrate-Nitrite Analysis Procedures as described. For quality assurance, each sample was analyzed twice and results statistically computed and presented. The one-way analysis of variance (ANOVA) test was performed to compare the sets of data obtained from different sites. The difference among mean analyzed by one way ANOVA was further analyzed using student t-test. A value of P≤ 0.05 was considered statistically significant. Data was presented as the arithmetic mean ± S.D. Estimated nitrates levels in water samples were compared with EPA’s acceptable safe drinking water levels and presented. Except for 4 water samples from 4 different sites, all other water samples analyzed were found to contain nitrates levels below 10mg/L. Nitrate levels above 10mg/L were seen in few samples in the northern part of the country probably due to agricultural activities in these areas. Belize’s rural drinking water contains low levels of nitrates except for a few villages that the levels exceeded the acceptable 10mg/L. Higher levels of nitrates detected in those villages need regular evaluation and monitoring to avoid public health issues as well as prevent harm to livestock.

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The study started by identifying the villages that are presently using Rudimental Water Supply or other sources of portable water apart from BWSL. A total of 109 communities using RWS were identified. Out of the 109 sites, 40 representative villages were conveniently selected and visited for sample collection (Figure 5). Samples from these sites were collected over a period of 8 months (April to November 2019). Cadmium (Cd) reduction method was used to test nitrates in rural water samples. The mechanism through which cadmium reduces nitrates to nitrites is represented by the following equation: NO2- + H2O + EDTA4 + Cdo --- NO2- + 2OH + Cd (EDTA)2- Reduced nitrite is formed from nitrate when cadmium metal is added. A reaction of nitrite ion to form an immediate diazonium salt is seen in an acidic medium with sulfanilic acid. Gentisic acid then couples with the salt to form an amber colored solution that can be measured using spectrophotometer at a wavelength of 500 nm or 520 colorimeters. To reduce nitrate to nitrite, a filtered sample was passed through a column containing granulated copper cadmium. Both the original nitrate in the sample and the reduced nitrite were then determined by diazotizing with sulfanilamide to form a highly colored azo dye in combination with N-(1-naphthyl)-ethylenediamine dihydrochloride. The intensity of the highly colored azo dye was them measured using Orion™ AquaMateTM 8000 UV-Vis Spectrophotometer at 520nm. 2 water samples were conveniently collected from reservoirs, wells, vats and standpipes from 40 villages using plastic bottles. Plastic bottles were used to collect water samples from 43 water samples from 40 villages in all the districts of the country of Belize (Figure 5). 1000ml bottles were purchased from Bowen & Bowen Limited®, thoroughly rinsed with purified water, dried and used for water samples collection. Before sample collection, the bottles were also thoroughly rinsed with the respective water samples at the site of collection. 15 water samples were collected from reservoirs, 10 from wells, 3 from standpipes (boreholes) and 15 from vats (Figure 3). Water samples were also collected from each district in the country. 9 water samples were collected each from Belize and Toledo districts; 8 from Cayo; 5 each from Corozal and Stann Creek and 7 from Orange Walk. 2 water samples were collected from either a reservoir, a vat, a standpipe, a well or both depending on what is available in the village. Collected water samples were immediately transported to the laboratory of Belize Coastal Zone Institute and analysed for nitrates. Water samples that were not immediately analysed were filtered and refrigerated below 4o C till analysed. Testing and Analysis was done according to USA EP for Nitrate-Nitrite Analysis Procedures as described. For quality assurance, each sample was analysed twice and results statistically computed and presented.