Fluoride occurrence in publicly supplied drinking water in Estonia

A study was undertaken to examine the content and spatial distribution of fluoride in drinking water. Water samples (735) from public water systems covering all Estonian territory were analysed using SPADNS method. In order to specify the natural source of fluoride, the chemistry data from five aquifer systems utilised for water supply were included into the study. Fluoride concentrations in tap water, to a great extent, ranged from 0.01 to 6.95 mg/l. Drinking water in southern Estonia, where terrigenous Middle-Devonian aquifer system is exploited, has a fluoride concentration lower than recommended level (0.5 mg/l), thus promoting susceptibility to dental caries. The western part of the country is supplied by water with excess fluoride content (1.5–6.9 mg/l). Groundwater abstracted for drinking purposes originates from Ordovician and Silurian carbonate rocks. The content of fluoride in Silurian–Ordovician aquifer system is associated with the groundwater abstraction depth and the main controlling factors of dissolved fluoride are the pH value and the chemical type of water.     

A geostatistical model for estimating edge effects and cumulative human disturbance in wetlands and coastal waters

ABSTRACT

The modification of landscapes for agriculture, residential housing, and other human uses has the potential to alter ecosystem function, reduce native biodiversity, and to diminish the capacity of natural systems to provide essential goods and services. Resultantly, methods aimed at quantifying disturbance intensity at the intersection of anthropogenic and natural lands are important to applied aspects of landscape planning and natural resource management, as well as theoretical facets of spatial ecology. Tools to appraise human disturbance in wetlands and coastal waters are especially needed because the topographic settings of surface waters make them particularly susceptible to pollutant accumulation, hydrologic alteration, and other influences from the surrounding landscape. Assuming a water resources focus, we developed a novel geostatistical method to quantify and visualize edge effects and cumulative human disturbance for all wetlands and coastal waters in the State of Florida (USA). Model validation revealed that estimated disturbance intensity was strongly correlated to species richness, levels of heavy metal contamination, and persistent organic pollutant concentration. The presented modeling framework offers a flexible means to assess human disturbance across spatial scales and could be readily applied to prioritize conservation land acquisition and to anticipate future impacts from the proposed development.     

Mapping multi‐year ground water salinity patterns in irrigation areas using time‐series analysis of ground water salinity maps

In irrigation areas, ground water salinity (GWS) levels may vary depending on the amount and quality of irrigation water applied and on the activity of the drainage system. GWS plays a vital role in irrigation systems by influencing whether the environment is suitable for plant growth. Hence, it is necessary to monitor changes in GWS both temporally and spatially. Maps are generally used to visualize this information. However, evaluation of temporal and spatial variations of GWS can be difficult because of the necessity of assessing many maps together to understand both temporal and spatial changes. In this study, a data assessment method that can be used for multi‐year ground water salinity evaluations is presented. The method looks at the spatial and temporal relationships between the main salinity classes present in the study area, their typical locations (i.e. areas where the salinity classes are most frequently located), and the alternate salinity classes in those locations in any of the years of the time series. As a case study, the method was applied to multi‐year (1990–2000) GWS observations in the Mustafakemalpasa irrigation project (19 370 ha) in the Marmara region of north‐western Turkey. Copyright © 2007 John Wiley & Sons, Ltd.     

Study of the Kuroshio/Ryukyu Current system based on satellite-altimeter and <Emphasis Type="Italic">in situ</Emphasis> measurements

Data from satellite altimeters and from a 13-month deployment of in situ instruments are used to determine an empirical relationship between sea-level anomaly difference (SLA) across the Kuroshio in the East China Sea (ECS-Kuroshio) and net transport near 28°N. Applying this relationship to the altimeter data, we obtain a 12-year time series of ECS-Kuroshio transport crossing the C-line (KT). The resulting mean transport is 18.7 ± 0.2 Sv with 1.8 Sv standard deviation. This KT is compared with a similarly-determined time series of net Ryukyu Current transport crossing the O-line near 26°N southeast of Okinawa (RT). Their mean sum (24 Sv) is less than the mean predicted Sverdrup transport. These KT and RT mean-flow estimates form a consistent pattern with historical estimates of other mean flows in the East China Sea/Philippine Basin region. While mean KT is larger than mean RT by a factor of 3.5, the amplitude of the KT annual cycle is only half that of RT. At the 95% confidence level the transports are coherent at periods of about 2 years and 100–200 days, with RT leading KT by about 60 days in each case. At the annual period, the transports are coherent at the 90% confidence level with KT leading RT by 4–5 months. While the bulk of the Kuroshio enters the ECS through the channel between Taiwan and Yonaguni-jima, analysis of satellite altimetry maps, together with the transport time series, indicates that the effect of mesoscale eddies is transmitted to the ECS via the Kerama Gap southwest of Okinawa. Once the effect of these eddies is felt by the ECS-Kuroshio at 28°N, it is advected rapidly to the Tokara Strait.     

Impacts of landscape fragmentation on simulated precipitation fields in the Amazonian sub-basin of Ji-Paraná using the Eta model

Numerical studies on impacts of landscape fragmentation due to land use and land cover change (LUCC) on precipitation fields over the Ji-Paraná basin in the Amazon region are carried out using atmospheric Eta model. Experiments consider historical data about LUCC over the basin from 1978 to 2000 and compare simulations under LUCC conditions with simulations under pristine conditions. In agreement with previous observational studies, model results do not show statistically significant impacts on precipitation in the region. Results indicate that variability in precipitation in this region is mainly controlled by large-scale atmospheric characteristics and soil moisture conditions. However, some limitations are identified in the model simulations, mainly associated to the diurnal cycle of precipitation.     

APOD mission status and preliminary results

On September 20 th, 2015, twenty satellites were successfully deployed into a near-polar circular orbit at 520 km altitude by the Chinese CZ-6 test rocket, which was launched from the Tai Yuan Satellite Launch Center. Among these satellites, a set of 4 Cube Sats conform the atmospheric density detection and precise orbit determination(APOD) mission, which is projected for atmospheric density estimation from in-situ detection and precise orbit products. The APOD satellites are manufactured by China Spacesat Co. Ltd. and the payload instruments include an atmospheric density detector(ADD), a dual-frequency dualmode global navigation satellite system(GNSS) receiver(GPS and Beidou), a satellite laser ranging(SLR) reflector, and an S/Xband very long baseline interferometry(VLBI) beacon. In this paper, we compare the GNSS precise orbit products with colocated SLR observations, and the 3 D orbit accuracy shows better than 10 cm RMS. These results reveal the great potential of the onboard micro-electro-mechanical system(MEMS) GNSS receiver. After calibrating ADD density estimates with precise orbit products, the accuracy of our density products can reach about 10% with respect to the background density. Density estimates from APOD are of a great importance for scientific studies on upper atmosphere variations and useful for model data assimilation.