Field and laboratory studies were conducted to evaluate the use of bacterial growth on aquatic
insects as a metric for determining the existence of nutrient impacts in wetlands. Results from field investigations
indicated that elevated concentrations of nitrate and phosphate...
Our current level of long-term and comparative information on estuaries in many cases prohibits objective
determination of the status and trends among these ecosystems. The way to resolve this situation is to
develop and evaluate estuarine environmental indicators that will permit objective and meaningful
evaluation of estuaries. However, this effort far exceeds the ability of one or a few well-intentioned
Defi ning, gathering, and disseminating international statistics is a collective effort of many people and
organizations. The indicators presented in World Development Indicators are the fruit of decades of work
at many levels, from the fi eld workers who administer censuses and household surveys to the committees
and working parties of the national and international statistical agencies that develop the nomenclature,
classifi cations, and standards fundamental to an international statistical system.
The different sources of potential confounding in time series studies of air pollution and
mortality can be broadly classiﬁed as either measured or unmeasured. Important measured
confounders include weather variables such as temperature and dewpoint temperature. Daily
temperature measurements are readily available for metropolitan areas in the USA and numer-
ous studies have demonstrated a relationship between temperature and mortality which is gen-
erally positive for warm summer days and negative for cold winter days (e.g. Curriero et al.