Safe Limits For Drinking Water Research Articles

Investigation into the physico-chemical properties and hydrochemical processes of groundwater from commercial boreholes In Yenagoa, Bayelsa State, Nigeria

The physico-chemical and hydrochemical study of commercial borehole waters in Yenagoa, Bayelsa State have been carried out. Eight commercial borehole water samples were analyze for various physico-chemical parameters using standard methods. The results obtained shows that the water samples quality examined compared favourably with WHO (1998) standard for drinking water. Although the values for pH (5.20±0.14, 6.10±0.10, 6.20±0.10, 6.20±0.20 in well 2, 5, 6, and 7 respectively), electrical conductivity (EC) of 520.00±5.50 mS/cm in well 7, biochemical oxygen demand (BOD) of 9.55±0.26 mg/L in well 3, Ca (9.25±0.10, 8.25±0.03 and 7.90±0.10 mg/L in well 2, 3, and 7 respectively) and all values obtained for Fe exceeded the WHO permissible limits for safe drinking water. The concentration of heavy metals; lead, copper, chromium, cadmium and arsenic (major sources of ground water pollution) were below detectable limit except at well 5, 6, and 7 where lead values of 0.03±0.001, 0.008±0.00, 0.04±0.00 mg/L respectively were obtained. The hydrochemical analysis shows that ion exchange and silicate weathering are the major prevailing hydrochemical processes in the groundwater. All the results obtained were however not significantly different from other reported values within the Niger Delta region. The higher concentrations of some of the parameters (pH, Ec, BOD, Fe, Ca 2+ ) and the present of lead in some samples is an indication of some levels of pollution in the boreholes/ground water. This therefore calls for appropriate treatment measures before the consumption of these waters by the populace to avoid long term accumulative health problems of these pollutants. Recommendations on the strategies to reduce/eliminate some of these pollutants were made. Key words: Physico-chemical properties, hydrochemical processes, groundwater, boreholes, Yenagoa.

Monitoring the pollution risk and water use in orchard terraces with mango and cherimoya trees by drainage lysimeters

Agricultural nonpoint-source pollution is the leading cause of water-quality degeneration of rivers and groundwater. In this context, the coast of Granada province (SE Spain) is economically an important area for the subtropical fruit cultivation. This intensively irrigated agriculture often uses excessive fertilizers, resulting to water pollution. Therefore, a 2-year experiment was conducted using drainage lysimeters to determine the potential risk of nutrient pollution in mango (Mangifera indica L. cv. Osteen) and cherimoya (Annona cherimola Mill. cv. Fino de Jete) orchards. These lysimeters were used to estimate the nutrient budgeting for each crop. NO3-N, NH4-N, PO4-P and K losses according to lysimeters were, respectively, 55.1, 12.4, 3.7, and 0.6 for mango and 61.8, 17.8, 4.9, and 0.5 kg ha−1 yr−1, for cherimoya. NO3, concentrations in the leachates ranged from 1.8 to 44.3 mg L−1, and from 23.0 to 51.0 mg L−1, for mango and cherimoya, respectively, in some cases exceeding the limits for safe drinking water. PO4 also exceeded the permitted concentrations related to eutrophication of water, ranging from 0.07 to 0.5 mg L−1 and from 0.12 to 0.68 mg L−1 from mango and cherimoya lysimeters, respectively. With respect to the nutrient balance, N, P, and K removed by cherimoya fruits was 76.4, 5.5, and 22.6 kg ha−1 yr−1, and for mango fruits 30.2, 3.3 and 27.8 kg ha−1 yr−1, respectively. Nutrient losses in the leachates were surprisingly low, considering total N, P, and K applied during the year, in mango lysimeters 3.8, 0.11, and 12.6%, and in cherimoya lysimeters 7.7, 0.23 and 16.0%, respectively, indicating a potential soil accumulation and eventual loss risk, especially during torrential rains. Crop coefficient (Kc) values of mango trees varied within ranges of 0.35–0.67, 0.55–0.89, and 0.39–0.80 at flowering, fruit set, and fruit growth, respectively. Kc values for cherimoya trees had ranges of 0.58–0.67, 0.61–0.68, and 0.43–0.62 at flowering, fruit set and fruit growth, respectively. In this study, the Kc values of mango and cherimoya were significantly correlated to julian days. Therefore, the estimated WUE in the mango and cherimoya orchards reached 21.2 and 14.0 kg ha−1 mm−1, respectively. Thus, this study highlights the urgency to establish the optimal use of fertilizers and irrigation water with respect to crop requirements, to preserve surface-water and groundwater quality, thereby achieving more sustainable agriculture in orchard terraces.

Assessment of groundwater quality in shallow wells within the southern districts of Malawi

Lack of safe drinking water is a major problem in developing countries. Within Africa most people rely mainly on local groundwater sources for their water needs. These can be deep boreholes or shallow wells, the latter are normally found in poorer communities as they are the least expensive to construct. Over time water from these sources can be contaminated leading to fatal consequences. Previous monitoring of the quality of water from boreholes and shallow wells have been irregular, with the focus being mainly on boreholes. Information on seasonal water quality changes in shallow wells used by rural communities in Malawi has generally been lacking. A study was conducted from 2006 to 2007 to determine the quality of water from shallow wells in three districts in southern Malawi namely, Balaka, Chikwawa and Zomba districts. Water samples from 21 covered and five open shallow wells were analysed for chemical, microbiological and physical parameters using a portable water testing kit. Sampling was carried out at four different times of the year i.e. in August and October 2006 (dry season) and February and April 2007 (wet season). Microbiological data indicated that around 80% of the samples, obtained from the covered wells, failed to meet safe drinking water limits, set by World Health Organisation guidelines and Malawi Bureau of Standards, of zero total and faecal colony forming units (cfu)/100 ml. Values in excess of 1000 cfu/100 ml were noted in 10% of the samples, indicating gross contamination and the probability of pathogens being present. Contamination levels were higher during the wet season than the dry season in all three districts. Arsenic, ammonia, nitrate, nitrite and sulphate were all within the acceptable limits. Elevated levels of hardness, turbidity were noted in certain wells.

Physico-Chemical Characteristics of Some Waters Used for Drinking and Domestic Purposes in the Niger Delta, Nigeria

Physico-chemical characteristics of some river and hand-dug well waters used for drinking and domestic purposes in the oil rich Niger Delta area of Nigeria were assessed using standard methods. The concentrations of the parameters in the river water samples ranged in the following order: pH (5.6-6.9), temperature (26.90-28.60 degrees C), turbidity (23-63 NTU), electrical conductivity (52-184 mus/cm), DO (5.4-7.2 mg/l), BOD (21-57 mg/l), TDS (6.0-217 mg/l), PO4 (3-) (0.19-1.72 mg/l), SO4 (2-) (25-36.8 mg/l), NO3 (-) (20.3-28 mg/l), Fe (6.07-15.71 mg/l), Zn (0.04-0.24 mg/l), Pb (0.01-0.17 mg/l), Ni (0.01-0.13 mg/l), Vn (0.01-0.20 mg/l) and Hg (0.001-0.002 mg/l). The concentrations of these parameters in the hand-dug well water ranged in the following order: pH (5.7-6.8) temperature (26-30 degrees C), turbidity (134-171 NTU), electrical conductivity (160-340 mus/cm), DO (5.4-6.4 mg/l), BOD (13-34 mg/l), TDS (110-190 mg/l), PO(4) (3-) (0.84-1.84 mg/l), SO4 (2-) (10.6-28.1 mg/l), NO3 (-) (11.3-23 mg/l), Fe (13.17-16.31 mg/l), Ni (0.01-0.02 mg/l), Vn (0.01-0.04 mg/l) and Hg (0.001-0.004 mg/l). The concentrations of BOD, turbidity, NO3 (-) and Fe in the water samples were above WHO and FMENV permissible limits for safe drinking water. The results suggest that the use of such waters for drinking and domestic purposes pose a serious threat to the health of the users and calls for the intervention of government agencies.

Land Use Change And Nitrogen Enrichment Of A Rocky Mountain Watershed

Headwater ecosystems may have a limited threshold for retaining and removing nutrients delivered by certain types of land use. Nitrogen enrichment was studied in a Rocky Mountain watershed undergoing rapid expansion of population and residential development. Study sites were located along a 30-km transect from the headwaters of the Blue River to Lake Dillon, a major source of drinking water for Denver, Colorado. Ground water in residential areas with septic systems showed high concentrations of nitrate-N (4.96 +/- 1.22 mg/L, mean +/- SE), and approximately 40% of wells contained nitrate with delta15N values in the range of wastewater. Concentrations of dissolved inorganic nitrogen (DIN) in tributaries with residential development peaked during spring snowmelt as concentrations of DIN declined to below detection limits in undeveloped tributaries. Annual export of dissolved organic nitrogen (DON) was considerably lower in residential streams, suggesting a change in forms of N with development. The seasonal delta15N of algae in residential streams was intermediate between baseline values from undeveloped streams and stream algae grown on wastewater. Between 19% and 23% of the annual N export from developed tributaries was derived from septic systems, as estimated from the delta15N of algae. This range was similar to the amount of N export above background determined independently from mass-balance estimates. From a watershed perspective, total loading of N to the Blue River catchment from septic and municipal wastewater (2 kg x ha(-1) x yr(-1)) is currently less than the amount from background atmospheric sources (3 kg x ha(-1) x yr(-1)). Nonetheless, nitrate-N concentrations exceeded limits for safe drinking water in some groundwater wells (10 mg/L), residential streams showed elevated seasonal patterns of nitrate-N concentration and ratios of DIN to total dissolved phosphorus, and seasonal minimum concentrations of nitrate-N in Lake Dillon have increased exponentially to 80 microg/L over the last decade from an initial value near zero. Results suggest that isotopic ratios in autotrophs can be used to detect and quantify increases in N enrichment associated with land use change. The biotic capacity of headwater ecosystems to assimilate increases in inorganic N from residential development may be insufficient to prevent nitrogen enrichment over considerable distances and multiple aquatic ecosystems downstream.

Holding effects on coliform enumeration in drinking water samples.

Standard procedures for analyzing drinking water stress the need to adhere to the time and temperature conditions recommended for holding samples collected for microbiological testing. The National Drinking Water Laboratory Certification Program requires compliance with these holding limits, but some investigators have reported difficulties in meeting them. Research was conducted by standard analytical methods to determine if changes occurred when samples were held at 5 and 22 degrees C and analyzed at 0, 24, 30, and 48 h. Samples were analyzed for coliforms by the membrane filter and fermentation-tube procedures and for heterotrophs by the pour plate method. A total of 17 treated water samples were collected from a large municipal distribution system from August to December 1981, and 12 samples were collected from January to May 1983. The samples were dosed with coliforms previously isolated from the water system, Enterobacter cloacae in 1981 and Citrobacter freundii in 1983. The coliform counts declined linearly over time, and the rates of decline were significant at both 5 and 22 degrees C. Within 24 h at 22 degrees C, levels of E. cloacae and C. freundii decreased by 47 and 26%, respectively, and at 5 degrees C, E. cloacae numbers declined by 23%. Results from these representative laboratory-grown coliforms reinforced those previously obtained with naturally occurring coliforms under the same experimental conditions. Significantly, some samples with initially unacceptable counts (greater than 4/100 ml) met the safe drinking water limits after storage at 24 h at 5 and 22 degrees C and would have been classified as satisfactory.(ABSTRACT TRUNCATED AT 250 WORDS)

Heavy metal inputs to Mississippi Delta sediments

Heavy metal concentrations were determined in suspended particulates, filtered water and sediment collected in the Mississippi River and from its marine delta. More than 90% of the metal load of the river is associated with particulate matter, which is relatively constant in chemical composition with time and place. The Mississippi River suspended material is similar to average crystal rocks in Fe, Al, V, Cr, Cu, Co, Mn, and Ni concentration but is generally enriched in Zn, Cd and Pb. Sediment cores dated by the Pb 210 method show that the Cd and Pb enrichments are recent phenomenon and are most likely due to the activities of man. About 6000 tonne of Pb and 300 tonne of Cd are being added to the delta sediments by man each year, more than 30 times the amount added to the Southern California Bight. River particulate matter is essentially identical to deltaic sediments in Al, Fe, Cr, V, Cd and Pb concentration, but the sediments are depleted in Co, Cu, Mn, Ni and Zn by 20 to 40%. Chemical leaching of the solids show the metal losses to be primarily from the oxide phase, suggesting diagenetic reduction and mobilization as a mechanism. Trace metal concentrations in filtered Mississippi River water were below the limits for safe drinking water and were similar to world average river values. The abundant river suspended matter and high pH combine to keep dissolved trace metal concentrations low.