Road Dust as a Significant Radiocesium Transporter from Land to River.

This study made it clear that road dust plays an important role for Cs-137 dynamics emitted by the Fukushima Daiichi nuclear power plant accident. It was proved from the Cs-137 and heavy metals determination in road dust, drainage gutter sediment beside pavement, and riverbed sediment around the inflow point of the gutter. Road dust and drainage gutter sediment contained significantly higher concentrations of Cs-137 and Cr, Ni, Cu, Zn, Mo, Cd, Sn, Sb, and Pb than riverbed sediment. These heavy metals are typically enriched in road dust in general and originate in anthropogenic sources. Concentrations of Cs-137 and the heavy metals were higher in riverbed sediments at the inflow point of drainage than in non-inflow points. Drainage gutter sediments exhibited Cs-137 and heavy metal accumulation at the downmost of the gutter, which is the inflow point into the river. Accordingly, distribution of Cs-137 and the heavy metals concentrations were consistent with each other. Moreover, the concentrations of Cs-137 and heavy metals were correlated positively and significantly, with different proportions between sampling sites but similar between sample type and survey date. This indicates that the discharge of Cs-137 and heavy metals is characteristic of the features of the locations, such as Cs-137 and heavy metals concentrations, (micro-) topography, structure of the road and gutter, pavement area, traffic density, and so on. We conclude that road dust is a major medium of Cs-137 transport from land into aquatic ecosystems.

Has irrigated water from Mahaweli River contributed to the kidney disease of uncertain etiology in the dry zone of Sri Lanka?

The Mahaweli is the largest river basin in Sri Lanka that provides water to the dry zone region through multipurpose irrigation schemes . Selenium, arsenic, cadmium, and other bioimportant trace elements in surface waters of the upper Mahaweli River were measured using ICP-MS. Trace element levels were then compared with water from two other rivers (Maha Oya, Kalu Ganga) and from six dry zone irrigation reservoirs. Results showed that the trace metal concentrations in the Mahaweli upper catchment were detected in the order of Fe > Cu > Zn > Se > Cr > Mn > As > Ni > Co > Mo. Remarkably high levels of Ca, Cr, Co, Ni, Cu, As, and Se were observed in the Mahaweli Basin compared to other study rivers. Considerably high levels of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, and Se were found in upstream tributaries of the Mahaweli River. Such metals possibly originated from phosphate and organic fertilizers that are heavily applied for tea and vegetable cultivations within the drainage basin. Cadmium that is often attributed to the etiology of unknown chronic kidney diseases in certain parts of the dry zone is much lower than previously reported levels. Decrease in these metals in the lower part of the Mahaweli River could be due to adsorption of trace metals onto sediment and consequent deposition in reservoirs.