Prenatal diagnosis of congenital gastric outlet obstruction

A case of gastric outlet obstruction diagnosed prenatally at 22 weeks' gestation is described. The differential diagnosis and the clinical management of this rare condition are discussed, and an updated literature review is presented.     

Toxicity persistence in runoff and soil from experimental soybean plots following insecticide applications

Persistence of toxicity in runoff water and soil was investigated in experimental soybean plots subjected to successive runoff events following pesticide application. Runoff events were produced by irrigation using a sprinkler system. The pesticides applied were cypermethrin and endosulfan, which are widely used in soy production in Argentina. Toxicity tests were performed on two abundant components of the regional fauna, the amphipod Hyalella curvispina and the fish Cnesterodon decemmaculatus. Runoffs from two pesticide applications were assayed at different stages of the growing season: an early application when the soil was almost bare and a late one close to harvest, when the ground was covered by vegetation and just before soy leaves fell. Toxicity to H. curvispina in runoff ceased almost one month after the early application of the two pesticides, while it persisted for over three months after the late application. Soil toxicity to H. curvispina and runoff toxicity to C. decemmaculatus followed the same pattern. Higher temperatures and solar radiation are likely to have enhanced insecticide degradation after the early application. Lower temperatures and solar radiation in combination with increased organic matter from litter probably contributed to the longer persistence of toxicity recorded after the late application, as compared with the early application. Cypermethrin caused no mortality to C. decemmaculatus after the early application, while endosulfan toxicity persisted for almost four months after the late one.     

ECONOMIC POLICIES FOR REGULATING AGRICULTURAL DRAINAGE WATER1

ABSTRACT: Agricultural drainage water is a major source of environmental pollution in many areas. This paper reviews the literature on the economics of nonpoint-source pollution and applies it to the regulation of agricultural drainage water. Four types of regulatory policies are considered. The empirical analysis is carried out for cotton production in the San Joaquin Valley of California. Variable inputs are the quantity of water applied and the type of irrigation system. All four policies can achieve economic efficiency under the conditions assumed here, but the policies differ in terms of the distributional impacts and administrative requirements.     

Denitrification in constructed wetlands used for treatment of swine wastewater

Constructed wetland treatment of swine wastewater probably involves substantial denitrification. Our objective was to assess denitrification and denitrification enzyme activity (DEA) in such wetlands in relation to plant communities, N loading, carbon or nitrogen limitations, and water depth. Two wetland cells each 3.6 m wide and 33.5 m long were connected in series. One set of cells was planted with rushes and bulrushes, including soft rush (Juncus effusus L.), softstem bulrush [Schoenoplectus tabernaemontani (K.C. Gmel.) Pallal, American bulrush [Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller], and woolgrass bulrush [Scirpus cyperinus (L.) Kunth]. Another set was planted with bur-reeds and cattails, including American bur-reed (Sparganium americanum Nutt.), broadleaf cattail (Typha latifolia L.), and narrowleaf cattail (Typha angustifolia L.). The sets will be referred to herein as bulrush and cattail wetlands, respectively. Denitrification and DEA were measured via the acetylene inhibition method in intact soil cores and disturbed soil samples that were taken during four years (1994-1997). Although DEA in the disturbed samples was greater than denitrification in the core samples, the measurements were highly correlated (r2 > or = 0.82). The DEA was greater in the bulrush wetlands than the cattail wetlands, 0.516 and 0.210 mg N kg(-1) soil h(-1), respectively; and it increased with the cumulative applied N. The DEA mean was equivalent to 9.55 kg N ha(-1) d(-1) in the bulrush wetlands. We hypothesized and confirmed that DEA was generally limited by nitrate rather than carbon. Moreover, we determined that one of the most influential factors in DEA was wetland water depth. In bulrush wetlands, the slope and r2 values of the control treatment were -0.013 mg N kg(-1) soil h(-1) mm(-1) depth and r2 = 0.89, respectively. Results of this investigation indicate that DEA can be very significant in constructed wetlands used to treat swine wastewater.     

Partial relaxation of enzyme-product binding by refolding of the growing chain in autocatalytic RNA replication

Helpful advice and discussions with Prof. M. Eigen are gratefully acknowledged. A conversation with Dr. Chr. Biebricher proved most useful.     

Biofiltration of the antibacterial drug sulfamethazine by the species Chenopodium quinoa and its further biodegradation through anaerobic digestion

The biofiltering capacity, distribution patterns and degradation of the antimicrobial sulfamethazine(SMT) by halophyte Chenopodium quinoa under hydroponic conditions and its further biodegradation through anaerobic digestion were evaluated. C. quinoa was cultivated for a complete life cycle under different concentrations of SMT(0, 2 and 5 mg/L) and sodium chloride(0 and 15 g/L). C. quinoa is able to uptake and partially degrade SMT. The higher the SMT concentration in the culture medium, the higher the SMT content in the plant tissue. SMT has different distribution patterns within the plant organs, and no SMT is found in the seeds.Dry crop residues containing SMT have a great potential to produce methane through anaerobic digestion and, in addition, SMT is further biodegraded. The highest specific methane yields are obtained using crop residues of the plants cultivated in the presence of salt and SMT with concentrations between 0 and 2 mg/L.     

Promotion of residential water conservation measures in South Africa: the role of water-saving equipment

Environmental Economics and Policy Studies - In many urban settings around the world the severity of water scarcity has induced changes in household behavior, leading to reduction in the volume of...