The concentrations of carbon monoxide (CO) and other gases were measured in the emissions from solid waste degradation under aerobic and anaerobic conditions during laboratory and field investigations. The emissions were measured as room temperature headspace gas concentrations in reactors of 1, 30, and 150 L, as well as sucked gas concentrations from windrow composting piles and a biocell, under field conditions. The aerobic composting laboratory experiments consisted of treatments with and without lime. The CO concentrations measured during anaerobic conditions varied from 0 to 3000 ppm, the average being 23 ppm, increasing to 133 ppm when methane (CH 4 ) concentrations were low. The mean/maximum CO concentrations during the aerobic degradation in the 2-L reactor were 101/194 ppm without lime, 486/2022 ppm with lime, and 275/980 ppm in the 150-L reactors. The presence of CO during the aerobic composting followed a rapid decline in O 2 concentrations Significantly higher CO concentrations were obtained when the aerobic degradation was amended with lime, probably because of a more extreme depletion of oxygen. The mean/maximum CO concentrations under field conditions during aerobic composting were 95/1000 ppm. The CO concentrations from the anaerobic biocell varied from 20 to 160 ppm. The hydrogen sulfide concentrations reached almost 1200 ppm during the anaerobic degradation and 67 ppm during the composting experiments.There is a positive correlation between the CO and hydrogen sulfide concentrations measured during the anaerobic degradation experiments.

When pesticides are used in arable watersheds, residues are usually found in the recipients. However, small constructed wetlands (CWs) in first and second order streams can reduce the loss of pesticides, since water purification processes are stimulated. This paper presents the results of adding 13 pesticides to a CW in Norway. The relative retention increased between 0 and 67% for the pesticides fluroxypyr, bentazone, dicamba, mecoprop, propiconazole, MCPA, dichlorprop, linuron, fenpropimorph, metalaxyl, metribuzin, metamitron and propachlor. In many cases, the CW reduced the peak concentrations to values regarded as non-toxic for aquatic life, even though the wetland covered less than 0.4% of the watershed surface area, and the average hydraulic load often was above 0.8 m d(-1). Possible retention factors were adsorption to soil particles and organic matter, sedimentation of particles, low or high redox-potential, and biodegradation of nitrogen-rich pesticides. However, the retention processes are complex, and are not fully understood.

A literature review shows that more than 500 compounds occur in wetlands, and also that wetlands are suitable for removing these compounds. There are, however, obvious pitfalls for treatment wetlands, the most important being the maintenance of the hydraulic capacity and the detention time. Treatment wetlands should have an adapted design to target specific compounds. Aquatic plants and soils are suitable for wastewater treatment with a high capacity of removing nutrients and other substances through uptake, sorption and microbiological degradation. The heavy metals Cd, Cu, Fe, Ni and Pb were found to exceed limit values. The studies revealed high values of phenol and SO(4). No samples showed concentrations in sediments exceeding limit values, but fish samples showed concentrations of Hg exceeding the limit for fish sold in the European Union (EU). The main route of metal uptake in aquatic plants was through the roots in emergent and surface floating plants, whereas in submerged plants roots and leaves take part in removing heavy metals and nutrients. Submerged rooted plants have metal uptake potential from water as well as sediments, whereas rootless plants extracted metals rapidly only from water. Caution is needed about the use of SSF CWs (subsurface flow constructed wetlands) for the treatment of metal-contaminated industrial wastewater as metals are shifted to another environmental compartment, and stable redox conditions are required to ensure long-term efficiency. Mercury is one of the most toxic heavy metals and wetlands have been shown to be a source of methylmercury. Methyl Hg concentrations are typically approximately 15% of Hgt (total mercury). In wetlands polycyclic aromatic hydrocarbons (PAH), bisphenol A, BTEX, hydrocarbons including diesel range organics, glycol, dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCB), cyanide, benzene, chlorophenols and formaldehyde were found to exceed limit values. In sediments only PAH and PCB were found exceeding limit values. The pesticides found above limit values were atrazine, simazine, terbutylazine, metolachlor, mecoprop, endosulfan, chlorfenvinphos and diuron. There are few water quality limit values of these compounds, except for some well-known endocrine disrupters such as nonylphenol, phtalates, etc.

Restrictions on the use of long-chain per- and polyfluoralkyl substances (PFASs) has led to substitutions with short-chain PFASs.

Pesticides in Norwegian ground water have been monitored since 1995. Here, we report data including 2004. The monitoring has focused on shallow ground water near agricultural fields (4 locations), on farm wells (22 locations), and on public waterworks (38 locations) 450 samples were analyzed for a total of 62 pesticide compounds and metabolites, and the result was 514 detections of single compounds. Altogether 27 pesticides and metabolites were detected: 2 insecticides, 9 fungicides, and 16 herbicides. Herbicides were most frequently detected (in 79% of the samples), followed by fungicides (20%) and insecticides (1%). Pesticide concentration was generally low, although high concentrations also occurred, for example, 33 μg/L of metribuzine in shallow ground water near agricultural fields and 20 μg/L of bentazon in a farm well. Some water soluble pesticides occurred both frequently and with relatively high concentrations in shallow ground water near agricultural fields. The results show that local ground water near farms is vulnerable for contamination of pesticides and needs further monitoring. Efforts should be made to minimize contamination of wells in farming areas through education on pesticide use, monitoring, and well positioning. Few pesticides were detected in ground water from waterworks and the concentrations were low. Monitoring of waterworks ended in 2002. The data show that there is a continuous need to monitor pesticides as well as selected metabolites in shallow ground water and wells near agricultural fields in Norway.

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Loss of pesticides is likely from watersheds where pesticides are used. The herbicides propachlor, linuron and metamitron, and the fungicides propiconazole, fenpropimorph and metribuzin and metalaxyl, were applied on an arable soil plot. A mass balance study showed that approximately 96% of the applied pesticides disappeared within the watershed. Three pesticides remained as residuals in the soil profile one year after the application. The 4% of the pesticides that were lost from the watershed gave peak concentrations, appearing immediately after spraying, reaching levels that can be hazardous to aquatic life. The constructed wetland situated in the first-order stream generally managed to lower the peak concentrations significantly. For the summer season, retention varied from 12 to 67% the first year. The second year, we observed both loss and retention. Increasing the wetland surface from 0.2% to 0.4% of the watershed area increased the average retention with 21% units the first year and 9% units the second year. Chemical properties of the pesticides could explain some of the behaviour in the watershed and in the wetland.

No abstract