Study of the uncertainty in NO<Subscript>2</Subscript> chemiluminescence measurements due to the NO–O<Subscript>3</Subscript> reaction in sampling lines

Introduction  

The change in light intensity that takes place when an ambient air sample is drawn into the detection chamber of a chemiluminescence monitor generates changes in the concentrations of several species, such as NO₂, NO and O₃. Although this phenomenon has been known for several decades, there is still no commonly accepted approach on when or how to correct for it in NO₂ and O₃ readings.     

Limitation of the concentration of organic pollutants in sewage sludge for agricultural purposes: A case study in South Spain

In 2000, the EU published the third draft of a future sludge directive entitled “Working document on sludge” where limit values for some organic compounds, including di-(2-ethyhexyl)phthalate (DEHP), sum of nonylphenol (NP), nonyphenol mono-(NP1EO) and diethoxylates (NP2EO), seven polychlorinated biphenyl congeners (PCB), polycyclic aromatic hydrocarbons (PAH) and linear alkylbenzene sulphonates (LAS), are fixed. In the present work, the monitoring of these organic compounds in sludge samples from four wastewater treatment plants (WWTPs) is reported. All WWTPs use anaerobic biological stabilization of sludge. The highest concentration levels were found for LAS, NPE and DEHP, in this order, with, in general, anaerobically-digested dehydrated sludge and compost samples being the most contaminated samples. DEHP, NPE, LAS and PAH were found at concentration levels above the limit values fixed in the third draft of the future EU sludge directive in the 44%, 88%, 13% and 6% of the analyzed anaerobically-digested dehydrated sludge and compost samples.     

Influence of particle location on the number of charges per charged nanoparticle at the outlet of a needle charger

This study has investigated numerically the influence of particle location on the number of charges per charged particle in the 10-40 nm size range at the outlet of a needle charger by simulating flow field, electric field, particle charging, and particle trajectory at various conditions. The results show that the total (i.e., diffusion + field charging) number of charges per particle increase with decreasing ratio values of radial location at the outlet of the charger due to the particle position close to the needle tip. It has also been shown that in the outlet region of the charger there is a critical radial location at which the number of charges per particle is a maximum; this critical radial location represents the point at which the charged particle trajectory becomes closest to the needle electrode. The maximum value of number of charges increases with increasing Reynolds number and slightly increases with decreasing applied voltage for particle diameter larger than 20 nm. The maximum number of charges per charged nanoparticle increases with increasing particle diameter. In addition, the minimum ratio value of radial particle location decreases with increasing Reynolds number for various particle diameters.     

Population characteristics of young African women influencing prenatal exposure to DDT (Manhiça, Mozambique)

The concentrations of dichlorodiphenyltrichloroethane (DDT) compounds in cord blood of 214 children born between 2003 and 2006 in Manhiça (Mozambique) have been determined. In this time interval, corresponding to the period before DDT reintroduction for indoor residual spraying, the observed values averaged 0.8 and 0.4 ng/ml for 4,4′-dichlorodiphenyldichloroethylene (4,4′-DDE) and 4,4′-DDT, respectively, and were similar to those found in western countries. However, the 4,4′-DDT/4,4′-DDE ratio was high indicating that the inputs of these compounds arriving to children in utero originated from recent uses of the insecticide. The strongest factor affecting DDT concentration was parity. A well-defined decreasing concentration trend was observed for the cord blood concentrations in the period of study. The trend was also observed for multiparae and primiparae mothers independently. Children from multiparae women showed much lower concentrations than primiparae women. Children from mothers with secondary school level exhibited lower concentrations of these pesticides than mothers with lower degree of education.     

Occurrence and risk assessment of pharmaceutically active compounds in wastewater treatment plants. A case study: Seville city (Spain)

The occurrence of four anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen and naproxen), an antiepileptic drug (carbamazepine) and a nervous stimulant (caffeine) in influent and effluent samples from four wastewater treatment plants (WWTPs) in Seville was evaluated. Removal rates in the WWTPs and risk assessment of the pharmaceutically active compounds have been studied. Analytical determination was carried out by high performance liquid chromatography (HPLC) with diode array (DAD) and fluorescence (Fl) detectors after sample clean up and concentration by solid phase extraction. All pharmaceutically active compounds, except diclofenac, were detected not only in wastewater influents but also in wastewater effluents. Mean concentrations of caffeine, carbamazepine, ketoprofen and naproxen ranged between 0.28-11.44 microg l(-1) and 0.21-2.62 microg l(-1) in influent and effluent wastewater, respectively. Ibuprofen was present in the highest concentrations in the range 12.13-373.11 microg l(-1) and 0.78-48.24 microg l(-1) in influent and effluent wastewater, respectively. Removal rates of the pharmaceuticals ranged between 6 and 98%. Risk quotients, expressed as ratios between the measured environmental concentration (MEC) and the predicted no effect concentrations (PNEC) were higher than 1 for ibuprofen and naproxen in influent wastewater and for ibuprofen in effluent wastewater.     

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment

We provide a global assessment, with detailed multi-scale data, of the ecological and toxicological effects generated by inorganic nitrogen pollution in aquatic ecosystems. Our synthesis of the published scientific literature shows three major environmental problems: (1) it can increase the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems; (2) it can stimulate or enhance the development, maintenance and proliferation of primary producers, resulting in eutrophication of aquatic ecosystems; (3) it can reach toxic levels that impair the ability of aquatic animals to survive, grow and reproduce. Inorganic nitrogen pollution of ground and surface waters can also induce adverse effects on human health and economy. Because reductions in SO2 emissions have reduced the atmospheric deposition of H2SO4 across large portions of North America and Europe, while emissions of NOx have gone unchecked, HNO3 is now playing an increasing role in the acidification of freshwater ecosystems. This acidification process has caused several adverse effects on primary and secondary producers, with significant biotic impoverishments, particularly concerning invertebrates and fishes, in many atmospherically acidified lakes and streams. The cultural eutrophication of freshwater, estuarine, and coastal marine ecosystems can cause ecological and toxicological effects that are either directly or indirectly related to the proliferation of primary producers. Extensive kills of both invertebrates and fishes are probably the most dramatic manifestation of hypoxia (or anoxia) in eutrophic and hypereutrophic aquatic ecosystems with low water turnover rates. The decline in dissolved oxygen concentrations can also promote the formation of reduced compounds, such as hydrogen sulphide, resulting in higher adverse (toxic) effects on aquatic animals. Additionally, the occurrence of toxic algae can significantly contribute to the extensive kills of aquatic animals. Cyanobacteria, dinoflagellates and diatoms appear to be major responsible that may be stimulated by inorganic nitrogen pollution. Among the different inorganic nitrogenous compounds (NH4+, NH3, NO2-, HNO2NO3-) that aquatic animals can take up directly from the ambient water, unionized ammonia is the most toxic, while ammonium and nitrate ions are the least toxic. In general, seawater animals seem to be more tolerant to the toxicity of inorganic nitrogenous compounds than freshwater animals, probably because of the ameliorating effect of water salinity (sodium, chloride, calcium and other ions) on the tolerance of aquatic animals. Ingested nitrites and nitrates from polluted drinking waters can induce methemoglobinemia in humans, particularly in young infants, by blocking the oxygen-carrying capacity of hemoglobin. Ingested nitrites and nitrates also have a potential role in developing cancers of the digestive tract through their contribution to the formation of nitrosamines. In addition, some scientific evidences suggest that ingested nitrites and nitrates might result in mutagenicity, teratogenicity and birth defects, contribute to the risks of non-Hodgkin's lymphoma and bladder and ovarian cancers, play a role in the etiology of insulin-dependent diabetes mellitus and in the development of thyroid hypertrophy, or cause spontaneous abortions and respiratory tract infections. Indirect health hazards can occur as a consequence of algal toxins, causing nausea, vomiting, diarrhoea, pneumonia, gastroenteritis, hepatoenteritis, muscular cramps, and several poisoning syndromes (paralytic shellfish poisoning, neurotoxic shellfish poisoning, amnesic shellfish poisoning). Other indirect health hazards can also come from the potential relationship between inorganic nitrogen pollution and human infectious diseases (malaria, cholera). Human sickness and death, extensive kills of aquatic animals, and other negative effects, can have elevated costs on human economy, with the recreation and tourism industry suffering the most important economic impacts, at least locally. It is concluded that levels of total nitrogen lower than 0.5-1.0 mg TN/L could prevent aquatic ecosystems (excluding those ecosystems with naturally high N levels) from developing acidification and eutrophication, at least by inorganic nitrogen pollution. Those relatively low TN levels could also protect aquatic animals against the toxicity of inorganic nitrogenous compounds since, in the absence of eutrophication, surface waters usually present relatively high concentrations of dissolved oxygen, most inorganic reactive nitrogen being in the form of nitrate. Additionally, human health and economy would be safer from the adverse effects of inorganic nitrogen pollution.     

Temporal evolution of polycyclic aromatic hydrocarbons (PAHs) in sludge from wastewater treatment plants: comparison between PAHs and heavy metals

This paper presents results on the presence and temporal variability of the 16 PAHs recommended by the EPA in primary, secondary and digested sewage sludge over a year. The sewage sludges originated from the Guadalete wastewater treatment plant (WWTP) site in Jerez de la Frontera (Cádiz, Spain). These organic pollutants have been extracted from the sewage sludge by microwave energy. High performance liquid chromatography coupled with diode array (HPLC-DAD) or fluorescence (HPLC-FL) detectors have been used. The results showed that total PAHs concentration varied between 1,945 ng g(-1) dry matter (DM) for primary sludges collected in March and 10,100 ng g(-1) DM for primary sludge collected in June. Generally, concentrations of PAHs were higher in compost and digested sludge than in fresh one. On the other hand, the highest concentration of PAHs were found on summer. This thing is associated to the traffic increase from inland zones to the coast (Jerez de la Frontera is very near to beaches). Finally, this paper present a comparative study of the American an European legislation concluding that the limits of concentrations established are not exceeded. In addition heavy metals were analysed. The origin of PAHs and heavy metals seems to be different.     

Evaluation of heavy metal contents in co-composts of poultry manure with barley wastes or chestnut burr/leaf litter

The presence of heavy metals in composts is a main cause of adverse effects on animal and human health, transmitted through the food chain from the soil, groundwater and plants. In this study, the contents of Zn, Cd, Pb and Cu present in co-composts of poultry manure (liquid or solid) with a co-composting material (barley wastes or chestnut burr/leaf litter) were assessed. A compost of solid manure was used as control because a compost cannot be obtained from the liquid manure. The original solid poultry manure showed a Zn content of 2134+/-75 mg/kg, exceeding the current legal limit in Spain of 1100 mg/kg. In the solid poultry manure co-compost with chestnut burr/leaf litter and barley wastes, Zn content decreased to 813+/-25 mg/kg and 883+/-37 mg/kg, respectively. The contents in heavy metals (Zn, Cd, Pb and Cu) of the co-composts were under the maximum limit permitted under the Spanish legislation, excepting for the Zn level in liquid poultry manure co-composted with chestnut burr/leaf litter.