Nutrient and particle load estimates to Lake Tahoe (CA-NV, USA) for Total Maximum Daily Load establishment.

The Lake Tahoe Total Maximum Daily Load (TMDL) requires detailed methodologies to identify sources of flows and pollutants (particles and nutrients) for estimating time-variant loads as input data for the Lake Tahoe clarity model. Based on field data and a modeling study, the major sources of pollutant loads include streams (three subdivisions of this category are urban, nonurban, and stream channel erosion), intervening zones (IZs) (two subdivisions of this category are urban and nonurban), atmosphere (wet and dry), groundwater and shoreline erosion. As Lake Tahoe remains well oxygenated year-round, the contribution of internal loading from the bottom sediments was considered minor. A comprehensive quantitative estimate for fine particle number (< 16 µm diameter) and nutrient (nitrogen and phosphorus) loading is presented. Uncertainties in the estimation of fine particle numbers and nutrients for different sources are discussed. Biologically available phosphorus and nitrogen were also evaluated. Urban runoff accounted for 67% of the total fine particle load for all sources making it the most significant contributor although total urban runoff was only 6%. Non-urban flows accounted for 94% of total upland runoff, but the nitrogen, phosphorus and fine sediment loadings were 18%, 47% and 12%, respectively of the total loadings. Atmospheric nitrogen, phosphorus, and fine particle loadings were approximately 57%, 20%, and 16%, respectively of the total loading. Among streams and IZs, IZ 8000, Upper Truckee River, Trout Creek, Blackwood Creek, and Ward Creek are the top fine particle, nitrogen and phosphorus contributors. The relative percentage contribution of inorganic fine particles from all sources based on annual average for the period 1994-2008 on size classes 0.5-1, 1-2, 2-4, 4-8, and 8-16 µm are 73%, 19%, 5%, 2%, and 1%, respectively. These results suggest clear priorities for resource managers to establish TMDL on sources and incoming pollutants and preserving lake clarity.

Coal workers' pneumoconiosis: a study of prevalence in coal mines of eastern Madhya Pradesh and Orissa states of India.

With objective to find out prevalence of Coal Worker's Pneumoconiosis and variation among readers in reading x-ray plates for pneumoconiosis, a retrospective epidemiological survey of Coal Worker's Pneumoconiosis was undertaken in 72 collieries of Madhya Pradesh and Orissa by re-reading of x-ray plates taken during the Periodical Medical Examination at the Occupational Health Units over a period of 5 years. Six readers, trained abroad in reading pneumoconiosis x-ray plates, were involved for the study. Each reader reported approximately one sixth of the available x-ray plates of all the collieries and classified on the 12 point scale of I.L.O. (International Labour Organisation) 1980 in special format. Total 43,504 chest x-rays were reviewed. The overall prevalence was found to be 3.03%, ranging from 1.52% to 4.76% between 10 areas (group of mines). Major category of profusion was category-I (81.09%), followed by category-II (17.84%). Only 3 cases of Progressive Massive Fibrosis (PMF) were detected. Round shaped opacities are predominant (89.59%) in Coal Worker's Pneumoconiosis. Among the opacities, 'p' type is more prevalent (48.29%) followed by 'q' type (40.62%). There was variation amongst the different readers and ranged from 1.14% to 6.76% for reporting the prevalence of Coal Worker's Pneumoconiosis. However, when analysis of six readers for inter reader variation was conducted, that shows no abnormal deviation in the reading of any of the readers.