Nitrification, the chemoautotrophic process by which NH4-N is converted to NO,-N, is an integral biogeochemical transformation in stream ecosystems. Previous research has shown that experimental addition of dissolved organic C inhibits rates of nitrification, and that NH4-N addition stimulates rates of nitrification. In many streams, large amounts of C and N may be present in particulate and so...

~ Organic matter from aquatic and terrestrial sources provides the carbon energy that 'drives' aquatic food webs. Most streams and rivers are heterotrophic — that is, more carbon is consumed (e.g. by animals and bacteria) than is produced within the system by aquatic plants. However, despite the presence of vast amounts of carbon in streams and rivers, only a small proportion of the total is tr...

The atmospheric and deep sea reservoirs of carbon dioxide are linked via physical, chemical, and biological processes. The last of these include photosynthesis, particle settling, and organic matter remineralization, and are collectively termed the "biological carbon pump." Herein, we present results from a 13-y (1992-2004) sediment trap experiment conducted in the permanently oligotrophic Nort...

The relationship between light extinction coefficient (kT) and Secchi depth (ZSD), as well as that between these variables and chlorophyll-a concentration (chl-a) and suspended material (SST) was studied in the Sau reservoir between 1995 and 2001. The results show that kT and ZSD are correlated by the equation kT = 1.36 ZSD, although this relationship exhibits a high inter-annual variability. A...

Exposure to particulate matter air pollution causes inflammatory responses and is associated with the progression of atherosclerosis and increased cardiovascular mortality. Macrophages play a key role in atherogenesis by releasing proinflammatory cytokines and forming foam cells in subendothelial lesions. The present study quantified the inflammatory response in a human macrophage cell line (U9...

Trace element distribution was monitored for Uluabat lake water polluted with point and non-point sources in Bursa. An examination of Zn, Cr, Ni, Cu, Pb, As, B concentrations during the study period indicated that the particulate phase at the bottom of the water column were high in regard to dissolved phase. The source of trace elements in the deeper parts of the water column was derived from t...

Soil organic matter is critical to sustainable agriculture because it provides nutrients to crops as it decomposes and increases nutrient- and water-holding capacity when built up. Fast- and slow-cycling fractions of soil organic matter can have different impacts on crop production because fast-cycling fractions rapidly release nutrients for short-term plant growth and slow-cycling fractions bi...

Bacterial biomarkers (D-amino acids and muramic acid) were measured in various organic matter size fractions collected in the North Pacific and North Atlantic, and they were used to quantitatively estimate bacterial contributions to particulate and dissolved organic carbon and nitrogen reservoirs. The origins and yields of biomarkers were determined in cultured marine bacteria, and the results ...

Polycyclic aromatic hydrocarbons (PAH) are components of complex organic mixtures featuring liquid and solid fossil fuels as well as tars derived from combustion and/or pyrolysis of coal and hydrocarbon fuels. PAH can also be detected at the exhaust of combustion systems, often associated to carbon particulate matter emissions. Due to their high toxicological potential the concentration levels ...

INTRODUCTION On January 2, 2011, the Spanish government passed a new smoking law that banned smoking in hospital campuses. The objective of this study was to evaluate the implementation of smoke-free campuses in the hospitals of Catalonia based on both airborne particulate matter and observational data. METHODS This cross-sectional study included the hospitals registered in the Catalan Networ...