Risk Of Water Contamination Research Articles

A longitudinal study of the association between domestic contact with livestock and contamination of household point-of-use stored drinking water in rural Siaya County (Kenya)

BackgroundEmerging evidence suggests close domestic proximity of livestock and humans may lead to microbiological contamination of hands, objects, food and water supplies within domestic environments, adversely impacting public health. However, evidence quantifying the relationship between livestock, domestic animals, humans and microbiological contamination of household stored water remains limited.AimThis longitudinal study aimed to examine the relationship between domestic contact with livestock and domestic animals on microbiological contamination of household Point-of-Use (POU) stored drinking water in rural Kenya and assess the influence of choice of faecal indicator on such associations.MethodologyA survey was performed in 234 households in Siaya county, Kenya, to observe presence of livestock (cattle, goats, poultry) and domestic animals (cats, dogs) in household compounds, alongside other risk factors for contamination of POU stored drinking water such as sanitation, storage conditions and hygiene practices. Samples from water sources (e.g. piped, spring/wells, boreholes, surface and rainwater) and from POU storage containers were tested for E. coli and intestinal enterococci. Livestock-related risk factors for water contamination were examined through multinomial regression, controlling for confounders.ResultsRainwater was the main POU water source and was found to be highly susceptible to contamination. Multivariate analysis showed greater risk of gross (>100 CFU/100 mL) water contamination (with E. coli) for households where goats were observed, and/or where poultry roosted in proximity to stored household water (relative risk RR = 2.71; p = 0.001 and RR = 2.02; p = 0.012 respectively). Presence of a poultry coop was also associated with elevated intestinal enterococci densities (RR = 4.46; p = 0.001). Associations between contamination and livestock risk factors were thus similar for both bacteria groups, but E. coli counts declined more rapidly following collection from surface waters than enterococci counts (p = 0.024).ConclusionThe presence of livestock (particularly goats) and poultry within household compounds increases POU water contamination risk, suggesting the need for improved interventions to address cross-contamination within rural domestic settings. Within Siaya county, more effective community education is needed to raise awareness of POU water quality protection, particularly of rainwater.

Coping with water insecurity at the household level: A synthesis of qualitative evidence.

Water insecurity is a key public health and developmental challenge for many communities across the world. Using a meta-ethnographic synthesis, this study examines how households cope with water insecurity, as well as the socio-economic consequences and determinants of water insecurity coping strategies. A systematized keyword search was conducted in various electronic databases (PubMed, CINAHL EBSCOHost, Embase Ovid, Science Direct, Medline, Global Health, SCOPUS, Google and Google scholar). Out of 1352 potential articles, 21 studies were selected for review. Households employed nine key coping strategies. These strategies include water storage, construction of alternative water source, water sharing and borrowing from social networks, buying water from private vendors, water management and reuse, illegal connections to public water networks, water harvesting, fetching water from distant sources, and water treatment to improve the quality. Some of these coping strategies had far-reaching health and economic consequences, including the risk of water contamination, adverse psychosocial health, and impacts on household savings. We found that poor households, due to their over-reliance on short term labour-intensive and time-consuming coping strategies, are further economically disadvantaged by water insecurity. From a policy perspective, we recommend that investments in effective and efficient water supply infrastructure are needed to help alleviate the day-to-day hassles of water users. While policymakers are looking for long term solutions to these problems, some of the coping strategies identified in this synthesis, such as water conservation, water reuse, and purification of water before consumption, could be encouraged as supplementary strategies to meet households' immediate water needs.

Dairy Calves in Uruguay Are Reservoirs of Zoonotic Subtypes of Cryptosporidium parvum and Pose a Potential Risk of Surface Water Contamination.

Cryptosporidium parvum, a major cause of diarrhea in calves, is of concern given its zoonotic potential. Numerous outbreaks of human cryptosporidiosis caused by C. parvum genetic subtypes are reported yearly worldwide, with livestock or water being frequently identified sources of infection. Although cryptosporidiosis has been reported from human patients in Uruguay, particularly children, epidemiologic information is scant and the role of cattle as reservoirs of zoonotic subtypes of C. parvum has not been explored. In this study, we aimed to (a)-identify C. parvum subtypes infecting dairy calves in Uruguay (including potentially zoonotic subtypes), (b)-assess their association with calf diarrhea, (c)-evaluate their spatial clustering, and (d)-assess the distance of infected calves to surface watercourses draining the farmlands and determine whether these watercourses flow into public water treatment plants. Feces of 255 calves that had tested positive for Cryptosporidium spp. by antigen ELISA were selected. Samples had been collected from 29 dairy farms in seven Uruguayan departments where dairy farming is concentrated and represented 170 diarrheic and 85 non-diarrheic calves. Selected samples were processed by nested PCRs targeting the 18S rRNA and gp60 genes followed by sequencing to identify C. parvum subtypes. Of seven C. parvum subtypes detected in 166 calves, five (identified in 143 calves on 28/29 farms) had been identified in humans elsewhere and have zoonotic potential. Subtype IIaA15G2R1 was the most frequent (53.6%; 89/166), followed by IIaA20G1R1 (24.1%; 40/166), IIaA22G1R1 (11.4%; 19/166), IIaA23G1R1 (3.6%; 6/166), IIaA17G2R1 (3%; 5/166), IIaA21G1R1 (2.4%; 4/166), and IIaA16G1R1 (1.8%; 3/166). There were no significant differences in the proportions of diarrheic and non-diarrheic calves infected with any of the C. parvum subtypes. Two spatial clusters were detected, one of which overlapped with Uruguay's capital city and its main water treatment plant (Aguas Corrientes), harvesting surface water to supply ~1,700,000 people. Infected calves on all farms were within 20–900 m of a natural surface watercourse draining the farmland, 10 of which flowed into six water treatment plants located 9–108 km downstream. Four watercourses flowed downstream into Aguas Corrientes. Calves are reservoirs of zoonotic C. parvum subtypes in Uruguay and pose a public health risk.

A web-based spatial decision support system for monitoring the risk of water contamination in private wells

ABSTRACT Long-term exposure to contaminated water can cause health effects, such as cancer. Accurate spatial prediction of inorganic compounds (e.g. arsenic) and pathogens in groundwater is critical for water supply management. Ideally, environmental health agencies would have access to an early warning system to alert well owners of risks of such contamination. The estimation and dissemination of these risks can be facilitated by the combination of Geographic Information Systems and spatial analysis capabilities – i.e., spatial decision support system (SDSS). However, the use of SDSS, especially web-based SDSS, is rare for spatially explicit studies of drinking water quality of private wells. In this study, we introduce the interactive Well Water Risk Estimation(iWWRE), a web-based SDSS to facilitate the monitoring of water contamination in private wells across Gaston County, North Carolina (US). Our system implements geoprocessing web services and generates dynamic spatial analysis results based on a database of private wells. Environmental health scientists using our system can conduct fine-grained spatial interpolation on 1) a particular type of contaminant such as arsenic, 2) on various subsets through a temporal query. Visuals consist of an estimation map, cross validation information, Kriging variance and contour lines that delineate areas with maximum contaminant levels (MCL), as set by the US Environmental Protection Agency (EPA). Our web-based SDSS was developed jointly with environmental health specialists who found it particularly critical for the monitoring of local contamination trends, and a useful tool to reach out to private well users in highly elevated contaminated areas.

Water contaminants detection using sensor placement approach in smart water networks

Incidents of water pollution or contamination have occurred repeatedly in recent years, causing significant disasters and negative health impacts. Water quality sensors need to be installed in the water distribution system (WDS) to allow real-time water contamination detection to reduce the risk of water contamination. Deploying sensors in WDS is essential to monitor and detect any pollution incident at the appropriate time. However, it is impossible to place sensors on all nodes of the network due to the relatively large structure of WDS and the high cost of water quality sensors. For that, it is necessary to reduce the cost of deployment and guarantee the reliability of the sensing, such as detection time and coverage of the whole water network. In this paper, a dynamic approach of sensor placement that uses an evolutionary algorithm (EA) is proposed and implemented. The proposed method generates a multiple set of water contamination scenarios in several locations selected randomly in the WDS. Each contamination scenario spreads in the water networks for several hours, and then the proposed approach simulates the various effect of each contamination scenario on the water networks. On the other hand, the multiple objectives of the sensor placement optimization problem, which aim to find the optimal locations of the deployed sensors, have been formulated. The sensor placement optimization solver, which uses the EA, is operated to find the optimal sensor placements. The effectiveness of the proposed method has been evaluated using two different case studies on the example of water networks: Battle of the water sensor network (BWSN) and another real case study from Madrid (Spain). The results have shown the capability of the proposed method to adapt the location of the sensors based on the numbers and the locations of contaminant sources. Moreover, the results also have demonstrated the ability of the proposed approach for maximising the coverage of deployed sensors and reducing the time to detect all the water contaminants using a few numbers of water quality sensors.

Compartmentalisation and groundwater–surface water interactions in a prospective shale gas basin: Assessment using variance analysis and multivariate statistics on water quality data

AbstractAn environmental concern with hydraulic fracturing for shale gas is the risk of groundwater and surface water contamination. Assessing this risk partly involves the identification and understanding of groundwater–surface water interactions because potentially contaminating fluids could move from one water body to the other along hydraulic pathways. In this study, we use water quality data from a prospective shale gas basin to determine: if surface water sampling could identify groundwater compartmentalisation by low‐permeability faults; and if surface waters interact with groundwater in underlying bedrock formations, thereby indicating hydraulic pathways. Variance analysis showed that bedrock geology was a significant factor influencing surface water quality, indicating regional‐scale groundwater–surface water interactions despite the presence of an overlying region‐wide layer of superficial deposits averaging 30–40 m thickness. We propose that surface waters interact with a weathered bedrock layer through the complex distribution of glaciofluvial sands and gravels. Principal component analysis showed that surface water compositions were constrained within groundwater end‐member compositions. Surface water quality data showed no relationship with groundwater compartmentalisation known to be caused by a major basin fault. Therefore, there was no chemical evidence to suggest that deeper groundwater in this particular area of the prospective basin was reaching the surface in response to compartmentalisation. Consequently, in this case compartmentalisation does not appear to increase the risk of fracking‐related contaminants reaching surface waters, although this may differ under different hydrogeological scenarios.

Potential water pollution from recycled concrete aggregate material

Recycled concrete aggregates (RCA) are a widely used recycled building material. RCA materials have many uses such as a road base or backfilling trenches. Our study investigated the potential water-contamination risks of water exposed to RCA materials. We recirculated water for 60min through four different treatments. Two treatments were a PVC gutter filled with different size grades of RCA material (20mm and 45mm), the third treatment was a clean PVC gutter and the fourth and final treatment was an unused concrete water pipe. Results showed that RCA material exposed to water released a suite of contaminants that could be ecologically hazardous to aquatic species. RCA leached metals over the 60-min recirculation (aluminium, arsenic, barium, chromium, lead, manganese, molybdenum, titanium, lithium and strontium). Water exposed to RCA material exceeded aquatic ecosystem guidelines for aluminium by 50 times and lead by up to 12 times. RCA materials increased pH by up to 4.35 pH units and electrical conductivity (EC) by up to 11 times the starting EC (mean 27.9 µs cm–1). We suggest that RCA materials need to be used with caution in settings that could be exposed to water and flow to waterways of conservation value.

Pesticide residues in agricultural topsoil from the Hainan tropical riverside basin: Determination, distribution, and relationships with planting patterns and surface water

Pesticide residues were assessed in rice-vegetable rotation topsoil from tropical riverside basin. The 256 tropical topsoil samples from the Nandu River Basin (NRB) and Wanquan River Basin (WRB) in Hainan (China) were taken from 2018 to 2019. A total of 32 current-use pesticides (CUPs) and nine legacy pesticides (LPs) were detected using a method based on a QuEChERS technique. The highest residues were from the fungicide carbendazim (257.2 μg/kg) and the insecticide imidacloprid (139.4 μg/kg). The nine LPs (8 organochlorine pesticides and chlorpyrifos) were detected in 84.4% of the samples with mean concentrations ranging from 0.02 to 675.4 μg/kg. The two most commonly detected pesticides were imidacloprid and emamectin benzoate with detection rates of 96.8% and 91.8%, respectively. The highest total concentration of pesticides from the NRB and WRB was detected in July. The highest average number of multi-residues (16) was recorded in January, compared to 14 and 12 in July and November, respectively. There was a significant correlation between the multiple pesticide residues in soil and vegetable planting types (p < 0.01). There was a significant positive correlation between the pesticide number in topsoil and the pesticide number in water (p < 0.01). The multiple pesticide residues found in surface water were consistent with those in topsoil, suggesting a potential risk of water contamination in the rice-vegetable rotation.

Diving Protection Against Nuclear Contaminants

Abstract The risks of radioactive water contamination are high today and divers can make a decisive contribution to removing these risks. The equipment used and the diving procedures are specific. The specialists of the Research Laboratory, in collaboration with those of the Hyperbaric Laboratory of the Diving Center from Constanta, have contributed to the development of this equipment and the diving procedures in the radioactive contaminated environment.

Análise da presença de micropoluentes de origem antrópica em nascente do Lajeado Erval Novo, Bom Progresso/RS

Considering the risks of water contamination by anthropic activities in general, objectified aimed to analyze the impacts of activities installed in the contribution basin of one of the main springs of Lajeado Erval Novo, rural area of the municipality of Bom Progresso/RS. Bordering the source, after the riparian forest, there is agricultural occupation with management of annual crops.. Far 280 m upstream from the source operates a landfill. The evaluation of contamination by micro pollutants was performed through the analysis of physical, chemical and microbiological indicators, as well as the search for pesticides. Four analytical campaigns were conducted during 2018, with sampling in January, April, July and October. Among the findings of the study it is noteworthy that the landfill has negligible potential for contamination to spring water and that no characteristic elements of landfill leachate were found. The high concentration of aluminum and the slightly acidic pH of the waters may be of natural origin. Sulphate and nitrate contents, as well as the high total and thermotolerant coliforms count may indicate agricultural contamination. No pesticide molecules were quantified. It was also concluded by the classification of the source as Class 3.

Leachate production estimation for a landfill in south of Brazil using Hydrus-1D

The disposal of municipal solid waste (MSW) is currently a great challenge to society mainly due to the threat posed by leachate and gases released from the decomposition sites. Landfills have been widely used for this purpose because their waterproofing, drainage and treatment systems have reduced the risks of soil, water and air contamination. Estimating the amount of leachate and gases generated is extremely important for the control and operation of these systems. In this context, this study was developed in the landfill of Timbó, State of Santa Catarina, Brazil, in order to estimate the generation of leachate and to evaluate the effect of profile composition. HYDRUS-1D was used to simulate unsaturated fluid flow through layers. Data on soil matrix such as characteristic curve and unsaturated hydraulic permeability were obtained from previous studies and pedotransfer functions and the respective curves for MSW were obtained from literature. Thirteen layers were simulated by attributing an atmospheric variably boundary condition on top cover and free drainage on the bottom of the profile for two hydrologic years (2017-2019). HYDRUS-1D overestimated the leachate volume by 33.67% when compared with field data. Layers distribution showed an attenuation effect on leachate production which is consistent with design.

Phosphorus accumulation in Canadian agricultural soils over 30 yr

Phosphorus (P) loss to freshwater is a key driver of eutrophication, and understanding the scale and spatial distribution of potential P sources is a key pre-requisite for implementing policies for P management to minimize environmental impacts. Soil test P (STP) is a useful indicator of the accumulation of P in soils, but these data are not readily available for most agricultural land in Canada, so the cumulative P balance (P inputs as manure or fertilizer minus removal of P in crops) is calculated as a proxy for this value. Cumulative P balance is an important calculation within the indicator of risk of water contamination by P, so allocations of manure and fertilizer P to cropland were updated within the calculation of P balance, and for Ontario, data from 1961 to 1980 were added to account for P applications during that period. The STP concentrations were calculated from the resulting cumulative P balances. When compared with reported STP concentrations, the predicted concentrations showed a statistically significant regression at the national (R2 = 78%) and provincial scale (Ontario, R2 = 36%; Prince Edward Island, R2 = 36%; Manitoba, R2 = 72%; British Columbia, R2 = 40%). There was significant variation in the cumulative P balance across Canada, with the highest values corresponding with areas of high livestock density, whereas large zones of P deficit were detected across the Prairies.

Transport of chlordecone and two of its derivatives through a saturated nitisol column (Martinique, France)

Soils, surface and groundwater in Martinique (French West Indies) are contaminated by chlordecone (CLD), a highly persistent organochlorine pesticide. In Situ Chemical Reduction (ISCR) using zero valent iron has been tested as a remediation technique to lower CLD levels in soils but it produces derivatives whose fate in environment may differ from the parent molecule. Here, the transfer of CLD and two of its main derivatives resulting from ISCR, CLD5aH and a CLD-3Cl, have been investigated in untreated and treated nitisol from a banana plantation using column experiments (20 cm long and 2.5 cm in diameter) under saturated conditions. The circulation of CaCl2 10-2M solution, simulating the ionic strength of soil water, in untreated nitisol results in CLD concentrations in solutions that remain for decades above the threshold limit for drinking water. ISCR treatment lowers the CLD concentration by ~50% in soil and by a factor 3 in waters but they remain above the threshold values. CLD derivatives, CLD5aH and a CLD-3Cl and, to a lesser extent, a CLD-2Cl and a CLD-5Cl, are found in waters after treatment. Dechlorination increases the mobility of the derivatives with respect to the parent molecule, which is likely to induce their transfer to deeper soil layers than those treated by ISCR: CLD-3Cl is more mobile than CLD5aH which is more mobile than CLD. When the water is in contact with the contaminated soil, a period of fast desorption kinetic of CLD and its derivatives, followed by a period of slow kinetics are found. This attests the high risk for water contamination and the potential influence of rainfall events on the concentrations likely to be encountered in soil waters or in waters accumulated on the soil surface.

Assessment of water contamination and health risk of endocrine disrupting chemicals in outdoor and indoor swimming pools

The occurrence of endocrine disrupting chemicals (EDCs) in swimming pool waters has been scarcely investigated. In this study, the concentrations of 20 EDCs (4 phenols, 6 estrogens, 4 progestogens, 5 androgens, and 1 pharmaceutical) in 40 outdoor and indoor swimming pools in Changsha, China were investigated. Out of them, two phenols (bisphenol A and 4-tert-octylphenol), three estrogens (17β-estradiol, 17ɑ-ethinlestradiol (EE2), and hexestrol), one pharmaceutical (caffeine), and two progestogens (progesterone and levonorgestrel) were detected in the collected samples. The androgens were not detected. Bisphenol A and caffeine were the dominant EDCs at concentrations of ND-23.22 ng/L and ND-39.08 ng/L, respectively. The levels of caffeine were significantly higher in indoor swimming pools (11.15 ng/L in average) than those in outdoor pools (1.90 ng/L in average) (p < 0.05), owing to the less sun’s UV radiation and less use of sunscreens containing caffeine. The progestogens (progesterone and levonorgestrel) and estrogens (17β-estradiol and hexestrol) were only detected in outdoor swimming pools. The detection frequencies and concentrations of bisphenol A and caffeine in downtown pools were significantly higher than those in outskirt pools. Besides, the correlations between the concentrations of EDCs and water quality parameters evaluated by the Spearman correlation analysis implied that residual chlorine had strong oxidant capable to bisphenol A and suggested that caffeine could be a potential indicator of organic contamination in swimming pool water. Finally, a quantitative risk assessment revealed that non-athletic child and athletic adult female were vulnerable subpopulations. The EDItotal of EE2 for athletic child, non-athletic female, non-athletic male, and non-athletic child were higher than ADIEE2 adopted by Australia and the EDItotal of EE2 for athletic female and athletic male were higher than ADIEE2 adopted by the United States.

The application of rapid handheld FTIR petroleum hydrocarbon-contaminant measurement with transport models for site assessment: A case study

Conventional contaminated site assessment requires sophisticated sampling and laboratory analyses, which are costly and time consuming. There is a trend for soil analyses to shift from complex laboratory procedures to rapid, simple and non-destructive spectroscopic methods that can be used in the field. Handheld Fourier Transform Infrared (FTIR) spectroscopy has the advantage of providing information for rapid in situ site characterisation. To apply the infrared (IR) spectral application for petroleum hydrocarbon (PH) contamination site investigation, the coherent bands at locations from 3000 to 2800 cm−1 represent carbon (C) – hydrogen (H) bonding for long-chain alkanes due to –C–H stretching vibrations. The areas of the coherent bands at these locations can be used to quantify the total petroleum hydrocarbon (TPH) concentrations in soils. With additional spectral data from IR spectroscopy there is potential for predicting soil texture and water content, which are the basic inputs for modelling the migration of PH at contaminated sites. This study demonstrates the innovative coupling of spectral analytical models and a handheld FTIR instrument, with a soil erosion model, the Revised Universal Soil Loss Equation (RUSLE), and the Hydrus hydrological model. The integration of these models were used to investigate the potential downstream water and groundwater contamination risks from the migration of PH at a PH-contaminated site.

1227. Replacement and Rerouting of Pipes to Remediate Intractable Contamination of Potable Water Fixtures in a Pair of ICU Rooms

Background“Green” construction approaches may place hospitals at risk for long-term contamination of potable water, presenting hazards for immunosuppressed patients. Remediation may be needed to manage these unanticipated consequences. An indolent, 11-year cluster of Sphingomonas koreensis infections at the NIH Clinical Center was traced to potable water. During the investigation, 4 sinks in 2 ICU rooms were found to have intractable contamination. Despite replacement of sink fixtures, faucet swabs and water continued to grow S. koreensis, and mean free chlorine residual (FCR) from the sinks was 0.27 mg/L (goal > 0.5). We undertook a major project to replace and reroute sections of pipes leading to the sinks (Figures 1 and 2).MethodsHot and cold water pipes were removed from the sinks to the supply pipes and replaced. Pipes were rerouted so that hot and cold water supplying the sinks returned in a loop to the domestic hot water heater to eliminate 10-meter drop-down sections of dead-leg pipe. Automatic faucets were replaced with manual faucets. Faucet biofilm was swabbed and cultured monthly for S. koreensis. Environmental samples were cultured on sheep blood agar for 5 days. Yellow colonies were subcultured and identified by MALDI-TOF MS (Bruker).ResultsDemolition of the wall behind the sinks revealed hot and cold water piping containing stagnant water. Water pooled in cold water pipe had heavy growth of S. koreensis; water from the hot water pipe could not be collected. Hot and cold water FCR for the sinks after piping changes averaged 0.74 and 1.07 mg/L, respectively, compared with 0.27 mg/L simultaneously from automated faucets in unmodified ICU rooms. Faucet cultures were negative for S. koreensis after replumbing, and have remained negative for >6 months.ConclusionNew hospital construction strategies appear to increase potable water contamination risks; novel remediation approaches are needed. Replacing contaminated water pipes and rerouting pipes to minimize stagnation eradicated longstanding contamination of 2 ICU sinks. Although the experiment was conducted on a small scale, it demonstrates that plumbing flaws that jeopardize patient safety can be corrected through multidisciplinary collaboration and creative plumbing strategies. Disclosures All authors: No reported disclosures.

Agrotóxicos no Semiárido de Alagoas: agricultura químico-dependente e suas contradições

RESUMO: Os agrotóxicos integram o modelo químico-dependente vigente na agricultura brasileira e é parte da complexa totalidade capitalista em que as megacorporações agroquímicas gozam de enorme centralidade. As linhas que seguem têm como objetivo analisar as contradições subjacentes à agricultura dependente de agrotóxicos no Semiárido de Alagoas, oferecendo um aporte reflexivo a partir de dados e informações de destacada relevância. O fenômeno dos agrotóxicos se materializa de maneira desigual no Semiárido de Alagoas e tem resultado em agudas contradições socioambientais. A pesquisa conseguiu identificar uma expressiva incidência de intoxicação humana e riscos de contaminação das águas e dossolos com os ingredientes químicos usados nas plantações. Ademais, constatou-se a sujeição da renda da terra camponesa ao capital por meio da compra/venda regular de variados agrotóxicos. No texto são veiculados dados primários e secundários levantados ao longo da investigação, através de visita de campo a algumas das comunidades situadas às margens do Canal do Sertão e do rio Moxotó, Mesorregião do Sertão, porção oeste do Semiárido, e coletados por meio de consultas a diversos órgãos do Estado.PALAVRAS-CHAVE: pesticidas, capital, renda da terra

Climatic Factors in Relation to Diarrhoea Hospital Admissions in Rural Limpopo, South Africa

Diarrheal disease is one of the leading causes of morbidity and mortality globally, particularly in children under 5 years of age. Factors related to diarrheal disease incidence include infection, malnutrition, and exposure to contaminated water and food. Climate factors also contribute to diarrheal disease. We aimed to explore the relationship between temperature, precipitation and diarrhoea case counts of hospital admissions among vulnerable communities living in a rural setting in South Africa. We applied ‘contour analysis’ to visually examine simultaneous observations in frequencies of anomalously high and low diarrhoea case counts occurring in a season, and assigning colours to differences that were statistically significant based on chi-squared test results. Children under 5 years of age were especially vulnerable to diarrhoea during very dry, hot conditions as well as when conditions were wetter than usual. We saw an anomalously higher number of diarrhoea cases during ‘warmer than usual’ conditions in the dry winter season, with average winter temperatures in Limpopo being from about 5 to 10 °C. As for ‘wetter than usual’ conditions, we saw an anomalously higher number of diarrhoea cases during ‘drier than usual’ conditions for the winter and spring. The lagged association seen in cumulative rainfall could not be distinguished in the same way for temperature-related variables (indicating rainfall had a larger impact on higher cases of diarrhoea), nor for the older age group of 5 years and older. Dry conditions were associated with diarrhoea in children under 5 years of age; such conditions may lead to increased water storage, raising the risks of water contamination. Reduced use of water for personal hygiene and cleaning of outdoor pit latrines also affect sanitation quality. Rural communities require adequate and uninterrupted water provision, and healthcare providers should raise awareness about potential diarrhoeal risks, especially during the dry season as well as during wintertime when conditions are warmer than usual.

Water quality of five rural Caribbean towns in Colombia

The water quality in drinking water or raw water supplies in the Colombian Caribbean region was evaluated using the risk index for water quality (IRCA) and the water quality index (IAP) proposed by CETESB, Brazil. The following towns were selected: Mahates, supplied with surface water from the Canal del Dique, San Joaquin, Malagana and San Basilio de Palenque, which use groundwater, and Mandinga, supplied by an artisanal dam. Physical and chemical parameters, heavy metals, microbiological parameters (total coliforms and Escherichia coli) and pesticides (organochlorine and organophosphorus compounds) used in the region for agriculture and livestock were determined. Groundwater showed a high hardness and surface water a high turbidity. Critical concentrations of pesticides were not detected, but microbiological contamination was found in water supplies and aqueducts, as well as Fe, Cr and Ni levels in water supplies, and Pb and Ni in aqueducts, higher than those allowed by both quality indices. The water supplies of the towns presented unsafe IRCA and IAP in the majority cases. This investigation studied the contamination in water supplies and aqueducts in the Colombian Caribbean region to provide environmental authorities with the necessary information to establish strategies and regulations to reduce the risks of water contamination.

Addressing Imbalances in Phosphorus Accumulation in Canadian Agricultural Soils

Adequate phosphorus (P) is needed for crop production, but excessive P poses a potential risk to water quality. Results from the cumulative P balance calculations within the indicator of risk of water contamination by phosphorus (IROWC-P) developed in Canada were assessed to determine the spatial and temporal trends in P accumulation at a regional scale and to consider the implications of these trends. Regional cumulative P balances were calculated from census data as a proxy for soil test P (STP) values, including the contribution of fertilizer or manure P to these balances. Ideally, over time we would see a convergence of soil test values at the low end of the critical response range for crop growth, where agronomic and environmental considerations are balanced, but this does not appear to be the case for many regions in Canada. Nationally, about 61% of agricultural land was predicted to be low in STP, and over half of this land is failing to replace the P that is removed each year. While only about 10% of the agricultural land has accumulated significantly more P than is needed for crop growth, almost all of this land is continuing to accumulate P rather than drawing it down. Manure is the dominant P source for continuing accumulation in regions with high or very high estimated STP; reducing this input will be difficult because of the nature of manure and the investment in buildings and infrastructure tied to specific locations, but it is clear that current Canadian policies need strengthened.