Evaluation of Virus Reduction by Ultrafiltration with Coagulation–Sedimentation in Water Reclamation

The evaluation of virus reduction in water reclamation processes is essential for proper assessment and management of the risk of infection by enteric viruses. Ultrafiltration (UF) with coagulation–sedimentation (CS) is potentially effective for efficient virus removal. However, its performance at removing indigenous viruses has not been evaluated. In this study, we evaluated the reduction of indigenous viruses by UF with and without CS in a pilot-scale water reclamation plant in Okinawa, Japan, by measuring the concentration of viruses using the real-time polymerase chain reaction (qPCR). Aichi virus (AiV) and pepper mild mottle virus (PMMoV) were targeted in addition to the main enteric viruses of concern for risk management, namely, norovirus (NoV) genogroups I and II (GI and GII) and rotavirus (RoV). PMMoV, which is a plant pathogenic virus and is present at high concentrations in water contaminated by human feces, has been suggested as a useful viral indicator. We also investigated the reduction of a spiked model virus (F-specific RNA bacteriophage MS2) to measure the effect of viral inactivation by both qPCR and plaque assay. Efficiencies of removal of NoV GI, NoV GII, RoV, and AiV by UF with and without CS were >0.5 to 3.7 log₁₀, although concentrations were below the detection limit in permeate water. PMMoV was the most prevalent virus in both feed and permeate water following UF, but CS pretreatment could not significantly improve its removal efficiency (mean removal efficiency: UF, 3.1 log₁₀; CS + UF, 3.4 log₁₀; t test, P > 0.05). CS increased the mean removal efficiency of spiked MS2 by only 0.3 log₁₀ by qPCR (t-test, P > 0.05), but by 2.8 log₁₀ by plaque assay (t-test, P < 0.01). This difference indicates that the virus was inactivated during CS + UF. Our results suggest that PMMoV could be used as an indicator of removal efficiency in water reclamation processes, but cultural assay is essential to understanding viral fate.     

Intramolecular Stable Isotope Ratios of N2O in the Tropical Swamp Forest in Thailand

 The dry-wet cycle is a common climatic phenomenon in the tropical regions of monsoon-affected Asia. An intermittent increase in N₂O was clearly observed in the Bang Nara River, with a tropical swamp catchment at the beginning of rainy season of November 1997. The intramolecular distribution of isotopes clearly demonstrated that nitrification is the major process for the production of N₂O. Using stable isotope data, the production mechanism of N₂O in the study areas was found to vary in time and space with changes in the redox boundary along the water flow. Received: 2 November 1999 / Accepted in revised form: 19 January 2000     

Verification of lipofuscin-based crustacean ageing: seasonality of lipofuscin accumulation in the stomatopod Oratosquilla oratoria in relation to water temperature

To verify the lipofuscin-based age estimation of crustaceans of unknown age from wild populations, we conducted a modal analysis of lipofuscin-concentration histograms in the stomatopod Oratosquilla oratoria seasonally collected from Tokyo Bay, Japan. Confocal microscopy and subsequent image analysis were used to quantify lipofuscin concentrations in the protocerebral bridge cell mass in the brain. Conventional body length frequency analysis failed to detect modes corresponding to ≥1 year old. In contrast, four or five distinct modes were found in the lipofuscin-concentration histograms, in which modes could be readily traced across months, suggesting that each mode represented an independent age group. The lipofuscin accumulation rate fluctuated seasonally: it was high in summer (June–July) and low in winter (December–January). Cross-correlation analysis showed that the highest instantaneous lipofuscin accumulation rate was achieved in early summer before maximum bottom temperatures were reached and when the temperature was increasing most rapidly. Our findings support the usefulness of lipofuscin concentration analysis in age estimation in wild crustacean populations.     

Net ecosystem CO2 exchange over a larch forest in Hokkaido, Japan

Larch forests are distributed extensively in the east Eurasian continent and are expected to play a significant role in the terrestrial ecosystem carbon cycling process. In view of the fact that studies on carbon exchange for this important biome have been very limited, we have initiated a long-term flux observation in a larch forest ecosystem in Hokkaido in northern Japan since 2000. The net ecosystem CO₂ exchange (NEE) showed large seasonal and diurnal variation. Generally, the larch forest ecosystem released CO₂ in nighttime and assimilated CO₂ in daytime during the growing season from May to October. The ecosystem started to become a net carbon sink in May, reaching a maximum carbon uptake as high as 186 g C m⁻² month⁻¹ in June. With the yellowing, senescing and leaf fall, the ecosystem turned into a carbon source in November. During the non-growing season, the larch forest ecosystem became a net source of CO₂, releasing an average of 16.7 g C m⁻² month⁻¹. Overall, the ecosystem sequestered 141–240 g C m⁻² yr⁻¹ in 2001. The NEE was significantly influenced by environmental factors. Respiration of the ecosystem, for example, was exponentially dependent on air temperature, while photosynthesis was related to the incident PAR in a manner consistent with the Michaelis–Menten model. Although the vapor pressure deficit (VPD) was scarcely higher than 15 hPa, the CO₂ uptake rate was also depressed when VPD surpassed 10 hPa.     

Carcinogenic tryptophan pyrolysis products in cigarette smoke condensate and cigarette smoke-polluted indoor air

The carcinogenic tryptophan pyrolysis products, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido-[4,3-b]indole (Trp-P-2), have been measured in condensate of cigarette mainstream smoke by high-performance liquid chromatography. These carcinogens have been detected in indoor air as well as in the air of the outdoor environment. Levels of these carcinogens in indoor air were much higher than those in outdoor air. The source of these carcinogens in indoor air was determined to be cigarette smoke by the application of smoking machine studies. Concentrations of these carcinogens in indoor air increased markedly with an increase in cigarettes smoked. The results in this investigation suggest that cigarette smoking is a source of carcinogenic tryptophan pyrolysis products in the indoor environment. Our data also suggest that smokers are persistently exposed to the carcinogenic heterocyclic amines together with potent carcinogens such as polynuclear aromatic hydrocarbons and N-nitroso compounds.     

Characterizing and Contextualizing the Water Challenges of Megacities

We characterize and compare water challenges confronting the 28 megacities of the world in 2014. Relying on existing literature and diverse primary data sources, we present a unique portrait at a global scale of the water implications of the rapid growth in megacities. We find that differentiating and analyzing the complexity of megacities' water problems based on geographic contexts, historical development trajectories, urban population growth rates, and forms of urban expansion helps explain the nature of the various water management problems they confront. Two governance features also shed light on megacity water challenges: fragmentation resulting from forms of megacity urban expansion; and, urban dualism resulting from contradictions between historical and cultural legacies and the rise of global engineering and technological norms for water management. The increasing vulnerability of megacities to climate change poses risks as well as opportunities for a more collective response to address this global phenomenon. Our analysis raises important questions and offers guidance about the future trajectories of many more large cities around the world that are on their way to becoming megacities.     

Fate estimation of estrogenic substances in an urban river by flux calculation.

This study investigated the fate of estrogenic substances in an urban river receiving discharge from wastewater treatment plants (WTPs) by flux calculation, focusing on the middle reaches of the Tama River in Tokyo, which is one of the most urbanized rivers in Japan. The level of estrogenic activity flux was almost negligibly small at the upstream station. The level was considerably raised after inflows from the WTPs and then the level declined in the lower reaches of the river. When contributions of estrogenic substances to estrogenic activity were estimated, estrone (E1) was the primary contributor to the total estrogenic activity in all the sampling stations, followed by estradiol (E2). The contribution of nonylphenol to estrogenic activity was small. The E1 and E2 accounted for approximately 90% or more of estrogenic activity in the Tama River. As for the total fluxes of the estrogenic substances in the study area in the Tama River, the proportion of flux associated with WTP discharge was approximately 100% of the total fluxes, and the effects of the tributaries flowing into the river were almost negligible. When the reduction ratios of estrogenic activity were calculated by the flux, the ratios were found to increase toward the lower reaches of the river. Similar changes were observed for E1. Meanwhile, the change of reduction ratios for E2 was different from that observed for estrogenic activity.