Limited information is available on the prevalence of waterborne pathogens in aquatic environments in developing countries. In this study, water samples were collected from nine shallow wells and a river in the Kathmandu Valley, Nepal, during the rainy season in 2009 and were subjected to detection of waterborne protozoa, viruses and coliphages using a recently developed method for simultaneous concentration of protozoa and viruses in water. Escherichia coli and total coliforms were also tested as indicator bacteria. At least one type of the five pathogens tested (Cryptosporidium, Giardia, human adenoviruses, and noroviruses of genogroups I and II) was detected in five groundwater samples (56%) (1000 ml each) from shallow wells. Compared with groundwater samples, the pathogens were more abundant in the river water sample (100ml); the concentrations of Cryptosporidium and Giardia were 140 oocysts/l and 8500 cysts/l, respectively, and the mean threshold cycle (Ct) values in real-time RT-PCR were 34.3, 36.8 and 34.0 for human adenoviruses and noroviruses of genogroups I and II, respectively. Genotyping of F-RNA coliphages by real-time RT-PCR was successfully used to differentiate human and animal faecal contamination in the samples. Moreover, for the groundwater samples, protozoa and viruses were detected only in E. coli-positive samples, suggesting that E. coli may be an appropriate indicator of pathogen contamination of valley groundwater.
Here, we discuss the effects of individuality and the distribution pattern of riparian wetlands on longitudinal changes in dissolved organic carbon (DOC) concentration in a headwater stream using model simulations. The model, which was composed of the catchment area, the flow distance of tributary channels, the DOC concentration of spring water and the DOC supply capacity of tributaries, well reproduced a longitudinal change in stream DOC concentration during a nonstorm period. This model calculation showed that the roles of riparian wetlands as DOC sources varied greatly among riparian wetlands, even though such wetlands were predominant sources of stream DOC. When we simulated for the longitudinal changes using three representative values (average, minimum and maximum) of the DOC supply capacity, the simulation results could not explain the features of the longitudinal changes, implying that the individuality of riparian wetlands strongly affects longitudinal changes. In addition, when we simulated the features under the different distribution patterns of riparian wetlands, i.e., wide, one-point and dispersed (two-point) distributions, there was a major difference between each simulation result, suggesting that the distribution pattern of riparian wetlands control longitudinal changes. Owing to the individuality and the distribution pattern of riparian wetlands, features of longitudinal changes in stream DOC concentration can vary largely even in the same region.
Multi-stable isotope analysis is effective for exposing the mislabeling of food production areas. However, in the case of rice, grain dry weight can influence the fractionation of stable carbon (δ13C) and nitrogen (δ15N) isotopes of grains within a production area. The relationship between these isotope fractionations and grain weight remains unclear; thus, the reason for the fractionation has not yet been elucidated. We collected Koshihikari rice grains from four production areas in Japan (Niigata, Aichi, Kagawa and Miyazaki prefecture) and analysed the effect of grain weight on the fractionation of δ13C and δ15N. δ13C was positively fractionated, depending on grain weight by translocation (grain-weight dependency) in all areas, whereas δ15N was not. The statistical analysis of δ13C adjusted by grain weight was able to distinguish between Aichi and Miyazaki, which was not the case for unadjusted δ13C. Our findings suggest that the applicability of δ13C for discrimination can be expanded by considering its grain-weight dependency.
This study investigates the contribution ratios of different groundwater recharge sources and influence of a dual monsoon system in Kofu basin, central Japan, through the hydrogen and oxygen isotopic analysis of precipitation, river water, and groundwater. The study is focused on the area of the Kamanashigawa and Midaigawa alluvial fans, which are formed by two main rivers. Precipitation isotopic content exhibits significant seasonal variability. Also, river water presents d-excess values higher than annual precipitation at plain areas (9 and 10‰), suggesting that two different air-masses contribute to precipitation, corresponding to the monsoon and pre-monsoon periods. The results of this study allow estimation of relative contributions of different sources to groundwater and influence of a dual monsoon system. The mass-balance analysis of the δ18O to identify the groundwater source indicates the river water contributes 38–100% of the recharge, while precipitation contributes 29–62% in Kamanashigawa alluvial fan. In the case of Midaigawa alluvial fan, river water contributes 77–99% in the northern part; in the southern side, 30–93% of contribution comes from precipitation. The mass-balance analysis of the d-excess indicates pre-monsoon precipitation contributes 46–68% and 39–65% to groundwater of the Kamanashigawa and Midaigawa alluvial fans, respectively.
Water security is one of the central global issues today. This study aimed to describe and test the validity and reliability of a household water insecurity scale, and to assess the impact of household water insecurity on psychological distress among 371 women living in urban Nepal. A household interview survey was conducted using a structured questionnaire. Approximately 70% of the participants experienced collecting less water than they needed. Four domains of household water insecurity emerged from the principal components factor analysis: (i) difficulties in house-work related to water, (ii) lost opportunity costs and social interactions related to water, (iii) an insufficient safe water supply, and (iv) difficulties in basic activities related to water. Multivariate regression analysis showed that the domains of ‘lost opportunity costs and social interactions’, ‘difficulties in house-work’ and ‘difficulties in basic activities’ were associated with psychological distress among women. The impact of household water insecurity on psychological distress differed by water supply service levels. The current household water insecurity scale is a simple instrument which can be used to prioritise the target population for water interventions. Further research should be conducted towards the development of a universally applicable measurement tool.
