Measuring ammonia emissions from land applied manure: an intercomparison of commonly used samplers and techniques

A number of techniques have been developed to quantify ammonia (NH(3)) emissions following land application of manure or fertiliser. In this study, coefficients of variation were determined for three commonly used field techniques (mass balance integrated horizontal flux, wind tunnels and the equilibrium concentration technique) for measuring emissions from a range of manure types. Coefficients of variation (CV) for absorption flasks, passive flux samplers and passive diffusion samplers were 21, 10 and 14%, respectively. In comparative measurements, concentrations measured using passive flux samplers and absorption flasks did not differ significantly, but those measured using passive diffusion samplers were on average 1.8 times greater. The mass balance technique and wind tunnels gave broadly similar results in two out of four field tests. Overexposure of passive diffusion samplers for some sampling periods meant that estimation of cumulative NH(3) emission using the equilibrium concentration technique in the field tests could not be made. For cumulative NH(3) emissions, CVs were in the range of 23-52, 46-74 and 21-39% for the mass balance, wind tunnel and equilibrium concentration techniques, respectively. Lower CVs were associated with measurements following slurry compared with solid manure applications. Our conclusions from this study are that for the measurement of absolute emissions the mass balance technique is to be preferred, and for small-plot comparative measurements the wind tunnel system is preferred to the equilibrium concentration technique.     

Prenatal sonographic diagnosis of metastatic neuroblastoma: Report of a case and review of the literature

Congenital malignant tumours are rare. Neuroblastoma is the most common solid tumour, accounting for about 30–50 per cent of tumours evident during the neonatal period. A case of metastatic, rapidly growing neuroblastoma, diagnosed prenatally by ultrasound at 32 weeks' gestation, is presented.     

Tibial hemimelia syndrome: Prenatal diagnosis by real-time ultrasound

The tibial hemimelia syndrome is a rare autosomal dominant condition associated with limb deficiencies. We recently diagnosed this condition in a pregnancy at 16·5 weeks' gestation by ultrasound and a positive family history. To our knowledge, this represents the first case to be detected prenatally.     

Three-dimensional ultrasound in prenatal diagnosis of skeletal dysplasia

A lethal form of bone dysplasia, platylospondylic lethal chondrodysplasia, was diagnosed prenatally using three-dimensional ultrasound. The various types of three-dimensional imaging mode provided diagnostic details not available by conventional two-dimensional ultrasound. The diagnosis was made after referral in the 23rd week of gestation, allowing termination of pregnancy due to the poor prognosis. Prenatal sonograms were compared with postnatal radiographs.     

Maternal serum biochemical markers in pregnancies with fetal parvovirus B19 infection

Hydrops fetalis and fetal death caused by fetal parovirus B19 infection have been reported to be associated with elevated maternal serum alpha-fetoprotein (AFP), based on a total of six cases. It has been suggested that the absence of AFP elevation may be reassuring. Maternal serum levels of the Down syndrome screening markers unconjugated oestriol and human chorionic gonadotropin in cases of fetal parvovirus infection have not been previously reported. We report four cases of hydrops fetalis and fetal death caused by fetal parvovirus infection, each with unremarkable second-trimester levels of AFP, unconjugated oestriol, and human chorionic gonadotropin.     

‘False-negative’ and ‘false-positive’ prenatal cytogenetic results due to ‘true’ mosaicism

A 37-year-old gravida was referred for CVS because of advanced maternal age. A trisomy 21 was present in all cells after short-term incubation (direct processing (DP)) and long-term culture. According to our policy, a retap was offered for confirmation of the result during the legally required 3-day waiting period between communication of the result and termination of pregnancy. Unexpectedly all cells after DP showed a normal male chromosome complement. Further investigations revealed mosaicism in trophoblast tissue and a normal karyotype in amniotic fluid cells and fetal blood (50 mitoses each). The parents elected to continue the pregnancy after extensive ultrasound examinations did not show suspicious findings. After the birth of a healthy child, cell cultures from ten different placental sites confirmed mosaicism. Four out of 100 mitoses from a lymphocyte culture showed an additional chromosome 21. The child had no dysmorphic features and the development was normal at the age of 10 weeks. This case demonstrates the restricted validity of prenatal cytogenetic analysis in the presence of true fetal mosaicism. It also stresses the benefit of our policy to offer a retap in cases with abnormal cytogenetic results prior to termination of pregnancy which is considered unnecessary by many cytogeneticists.     

Measuring impacts on species with models and metrics of varying ecological and computational complexity

Approaches to assess the impacts of landscape disturbance scenarios on species range from metrics based on patterns of occurrence or habitat to comprehensive models that explicitly include ecological processes. The choice of metrics and models affects how impacts are interpreted and conservation decisions. We explored the impacts of 3 realistic disturbance scenarios on 4 species with different ecological and taxonomic traits. We used progressively more complex models and metrics to evaluate relative impact and rank of scenarios on the species. Models ranged from species distribution models that relied on implicit assumptions about environmental factors and species presence to highly parameterized spatially explicit population models that explicitly included ecological processes and stochasticity. Metrics performed consistently in ranking different scenarios in order of severity primarily when variation in impact was driven by habitat amount. However, they differed in rank for cases where dispersal dynamics were critical in influencing metapopulation persistence. Impacts of scenarios on species with low dispersal ability were better characterized using models that explicitly captured these processes. Metapopulation capacity provided rank orders that most consistently correlated with those from highly parameterized and data-rich models and incorporated information about dispersal with little additional computational and data cost. Our results highlight the importance of explicitly considering species’ ecology, spatial configuration of habitat, and disturbance when choosing indicators of species persistence. We suggest using hybrid approaches that are a mixture of simple and complex models to improve multispecies assessments.     

Effects of sublethal exposure to a pesticide on levels of energetic compounds in Anguilla anguilla.

Abstract

The effect of two sublethal fenitrothion concentrations (0.02 and 0.04 mg/L) on the energy metabolism of the european eel Anguilla anguilla and its recovery from intoxication was investigated. Analysis of various parameters such as glycogen, proteins and total lipids was made on liver and muscle eel tissues after 2, 8, 12, 24, 32, 48, 56, 72 and 96 hr of fenitrothion (0,0‐dimethyl 0–3‐methyl‐4‐nitrophenyl phosphorothioate) exposure. Subsequently, the fish were allowed recovery periods of 8, 12, 24, 48, 72, 96, 144 and 192 hr in clean water, and the same parameters were again evaluated. The results obtained during the exposure to the pesticide as well as during the recovery phase were used to calculate the caloric content in both tissues of A. anguilla. A reduction in energy reserves in the selected tissues was observed after exposure to both fenitrothion concentrations and the caloric content in those animals was lower than in the controls. Most of the metabolic disorders did not persist after allowing recovery in clean water during a week.