Surface runoff and transport of sulfonamide antibiotics and tracers on manured grassland

Despite their common use in animal production the environmental fate of the veterinary sulfonamide antibiotics after excretion is only poorly understood. We performed irrigation experiments to investigate the transport of these substances with surface runoff on grassland. Liquid manure from pigs treated with sulfadimidine was spiked with sulfadiazine, sulfathiazole, the herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), and the conservative tracer bromide and spread onto eight plots. Four plots received the same amounts of the spiked substances in aqueous solution (controls). Apart from the application matrix we varied the time between application and irrigation. Manure increased the runoff volume up to six times compared with the controls. It seemed that manure enhanced the runoff by sealing the soil surface. On manured plots the relative antibiotic concentrations in runoff were higher than on the controls, reaching an average of 0.3% (sulfadiazine), 0.8% (sulfathiazole), and 1.4% (sulfadimidine) of the input concentrations after a 1-d contact time. The corresponding values on the controls were 0.16% for sulfadiazine and 0.08% for sulfathiazole. After 3 d, the maximum values on the manured plots were even higher, whereas they had fallen below the limit of quantification on the controls. As a consequence, the sulfonamide losses were 10 to 40 times larger on the manured plots. The relative mobility of the sulfonamides on the control plots followed the trend expected from their chromatographic separation but the opposite was found on the manured plots. Hence it is important to consider explicitly the physical and chemical effects of manure when assessing the environmental fate of sulfonamides.     

Integrated Approaches in Urban Storm Drainage: Where Do We Stand?

Integrated approaches to urban stormwater drainage management are being increasingly advocated as necessary for advancing more sustainable and holistic management of urban water environments. In this paper, the status of integrated approaches in the management of urban stormwater discharges to receiving waterways is summarized. The starting point of the paper is with the recent scientific contributions, revealing that integration is being pursued and implemented predominantly at two conceptual levels. These include 1) integrating the technical system with the receiving waterway environment, and 2) considering the interaction and influence of the human system with the technical system through processes such as stakeholder and public participation. Additionally, it is argued that the evolving shift towards the implementation of water-quality-based strategies advances the need for further development and application of integrated models and approaches. The cases of online physically based models for predictive control and integrated source control and public participation are presented as examples of such ongoing developments in pursuit of integrated urban stormwater management.     

Ability of transgenic poplars with elevated glutathione content to tolerate zinc(2+) stress

Phytoremediation potentials of four poplar lines, Populus nigra (N-SL clone), Populus canescens, and two transgenic P. canescens clones were investigated using in vitro leaf discs cultures. The transgenic poplars overexpressed a bacterial gene encoding gamma-glutamylcysteine synthetase in the cytosol (11ggs) or in the chlopoplasts (6LgI), and therefore, they contained an elevated level of glutathione. Leaf discs of poplar clones were exposed to different concentrations of ZnSO(4) for 21 days. Zinc(2+) was phytotoxic only at high concentrations (10(-2) to 10(-1) M) at all P. canescens lines, but P. nigra was more sensitive. Transgenic poplars showed elevated heavy metal uptake as compared to the nontransformed clones. Treatments with zinc(2+) strongly induced the activity of glutathione S-transferase enzyme in untransformed poplar lines but to a lesser extent in the transgenic clones. These results suggest that transgenic poplars are more suitable for phytoremediation of soils contaminated with zinc(2+) than wild-type plants.     

High PCB residues in birds from the Sheboygan River,Wisconsin

Organochlorine residues were measured in the carcasses and, in some cases, brains and stomach contents of four species of birds collected along the Sheboygan River, Wisconsin during the years 1976 to 1980. Polychlorinated biphenyls (PCBs) were high in all samples and were the contaminants of greatest concern. Carcass residues ranged from 23 to 218 ppm PCBs on a wet weight basis; these are levels associated with reproductive impairment in laboratory studies with some birds. Food items in the stomachs of collected birds contained from 12 to 58 ppm PCBs, indicating a heavy contamination of food sources. The brain of one bird contained 220 ppm PCBs, a level that is not in the lethal range but is very high. Birds feeding in the contaminated portions of the Sheboygan River may have been harmed by high PCB levels.