Conversion to drip irrigated agriculture may offset historic anthropogenic and wildfire contributions to sediment production

This study is an investigation into the roles of wildfire and changing agricultural practices in controlling the inter-decadal scale trends of suspended sediment production from semi-arid mountainous rivers. In the test case, a decreasing trend in suspended sediment concentrations was found in the lower Salinas River, California between 1967 and 2011. Event to decadal scale patterns in sediment production in the Salinas River have been found to be largely controlled by antecedent hydrologic conditions. Decreasing suspended sediment concentrations over the last 15years of the record departed from those expected from climatic/hydrologic forcing. Sediment production from the mountainous headwaters of the central California Coast Ranges is known to be dominated by the interaction of wildfire and large rainfall/runoff events, including the Arroyo Seco, an ~700km(2) subbasin of the Salinas River. However, the decreasing trend in Salinas River suspended sediment concentrations run contrary to increases in the watershed's effective burn area over time. The sediment source area of the Salinas River is an order of magnitude larger than that of the Arroyo Seco, and includes a more complicated mosaic of land cover and land use. The departure from hydrologic forcings on suspended sediment concentration patterns was found to coincide with a rapid conversion of irrigation practices from sprinkler and furrow to subsurface drip irrigation. Changes in agricultural operations appear to have decreased sediment supply to the Salinas River over the late 20th to early 21st centuries, obscuring the influence of wildfire on suspended sediment production

A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5-22.7) and 16.5 cm (13.3-19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8-144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries

Structure-properties changes in ZnO-PbO-GeO 2 glasses

We have studied the structure of ZnO-PbO-GeO2 glasses by Fourier transform infrared spectroscopy and showed that the analysis of the vibrational spectra can lead to a quantitative description of the network structure in terms of the fraction of the local germanate polyhedra. The presence of GeO4, GeO6 and GeO4 with NBOs units was evidenced in the studied glass network. The initial additions of ZnO would introduce modifier Zn2+ ions at the expense of the former PbO4 units. With increasing ZnO content, ZnO4 tetrahedra would mainly replace modifier PbO. The decrease in density when introducing ZnO at the expense of PbO content is not only due to the vast difference in molecular mass between PbO and ZnO, but also due to the formation of Q2 and Q3 units. The glass network of the investigated glasses posseses a more covalent character upon replacing ZnO for PbO. This is the reason for increasing the microhardness and the glass transformation temperature of the glasses investigated with increasing zinc oxide content. The change in the conductivity at certain temperature not only attributed to the change in the covalency of the glass matrix upon replacing PbO by ZnO but also due to a change in the strain energy because of the change in Vm