Employing indicator-based geostatistics and quantitative microbial risk analysis to assess the health risks of groundwater use for household demands on the Pingtung Plain, Taiwan.

Because of the limited surface water on the Pingtung Plain, Taiwan, the plain's residents frequently extract groundwater to meet their daily household water demands. The residents may experience gastrointestinal infections due to incidental ingestion of groundwater with fecal pollution. This study used indicator kriging (IK) and quantitative microbial risk analysis (QMRA) to assess the health risks of using groundwater for household cleaning and horticultural irrigation on the Pingtung Plain. First, IK was employed to determine the conditional cumulative distribution function (CCDF) of groundwater Escherichia coli (E. coli). Nonparametric Monte Carlo simulation based on established CCDF was then adopted to characterize the distributions and uncertainty of groundwater E. coli. Finally, QMRA was employed to determine health risks of groundwater use for household cleaning and horticultural irrigation, and the 95th percentiles of the risk distributions were calculated to obtain a representative risk. The study results indicated that the health risks of groundwater use ranged from 3.95 × 10-5 to 2.49 × 10-2 infections/user/year and exceeded the acceptable level, 1 × 10-4 infections/user/year, in most of the aquifers. Accordingly, residents of this plain should not directly extract groundwater for use in daily life.

Assessment of spatiotemporal variations in river water quality for sustainable environmental and recreational management in the highly urbanized Danshui River basin.

Rivers are an important urban resource, and water quality influences the use of river water. Thus, analyzing spatiotemporal variations in river water quality is crucial for sustainable use and management of water resources in a highly urbanized region. This study employed river pollution index (RPI) data obtained in 2013 to assess spatiotemporal variations in river water quality for sustainable environmental and recreational management in the highly urbanized Danshui River basin. First, ordinary kriging was adopted to analyze monthly RPI distributions. Subsequently, different percentiles of monthly estimated RPI distributions were probabilistically determined at a river segment. Finally, three measurement methods of local uncertainty, namely-conditional variance, local entropy, and interquartile range-were used to characterize spatiotemporal variations in river water quality in the Danshui River basin. Assessment results revealed that more highly polluted river water quality resulted in higher seasonal variations. Moreover, high and very high seasonal variations were mainly concentrated in urban river segments, whereas low and very low seasonal variations were primarily located in upstream river segments. Thus, to achieve sustainable development goals, artificial wetlands should be established at downstream and midstream urban riverbanks and urban recreational activities should be developed in upstream riverbank parks in the Danshui River basin before the comprehensive improvement of river water quality.

Spatial dynamic assessment of health risks for urban river cruises.

River cruising ships move along river courses, and thus health risks to passengers may vary spatially due to the accidental exposure of river fecal pollution. This study performed a spatial dynamic assessment of health risks for river cruises in the highly urbanized Tamsui River Basin. First, the spatial distributions of river Escherichia coli (E. coli) were probabilistically characterized using indicator kriging (IK). Moreover, the current river cruise information was surveyed to obtain cruise routes and transit times. Then, to explore the parametric uncertainty of quantitative microbial risk assessment (QMRA), the ingestion rate (IR) for boating was determined using Monte Carlo simulation (MCS). Moreover, river E. coli distributions were estimated using nonparametric MCS according to multi-threshold IK estimates. Eventually, after combining the distribution of the joint probability of the IR and E. coli in QMRA, the ß-Poisson dose-response function was adopted to analyze risks to river cruise passengers at discretized segments of cruise routes. Health risks to river cruise passengers were integrated at the discretized segments to explore suitable recreational strategies for river cruises. The research results indicate that all health risks do not exceed a daily target level of 8 illnesses per 1000 exposures for single-trip cruise routes. However, health risks to passengers can exceed this level for round-trip cruise routes along highly polluted urban river courses.

Electrochemical analysis of naproxen in water using poly(l-serine)-modified glassy carbon electrode.

A poly(l-serine)-modified glassy carbon electrode (PLS/GCE) was fabricated by electropolymerization and used to study the detection of naproxen (NPX), a representative non-steroidal anti-inflammatory drug, in phosphate buffer supporting electrolyte at pH 5.0. Results indicated that the PLS/GCE was capable of determination of NPX at a working potential of 0.92 (vs. Ag/AgCl) in voltammetry mode. Experimental factors such as scan rate, accumulation time, solution pH, initial NPX concentration, and interferences were optimized for NPX determination efficiency. The morphology and elemental distribution of the electrode surface were characterized by ESEM, TEM, PSD, XRD, FTIR, TGA, XPS, and zeta potential. NPX oxidation current increased with increasing analyte concentration and scan rate but decreased with increasing pH. Linear sweep voltammetry calibration curve was established in the NPX concentration range of 4.3-65 µM, with detection limit and average recovery of 0.69 µM (n = 3) and 104 ± 2.5%, respectively. PLS/GCE is simple, accurate, reproducible, and easy for operation, therefore would be cost-effective for the determination of NPX.