Real-time, high-resolution quantitative measurement of multiple soil gas emissions: selected ion flow tube mass spectrometry

A new technique is presented for the rapid, high-resolution identification and quantification of multiple trace gases above soils, at concentrations down to 0.01 microL L(-1) (10 ppb). The technique, selected ion flow tube mass spectrometry (SIFT-MS), utilizes chemical ionization reagent ions that react with trace gases but not with the major air components (N2, O2, Ar, CO2). This allows the real-time measurement of multiple trace gases without the need for preconcentration, trapping, or chromatographic separation. The technique is demonstrated by monitoring the emission of ammonia and nitric oxide, and the search for volatile organics, above containerized soil samples treated with synthetic cattle urine. In this model system, NH3 emissions peaked after 24 h at 2000 nmol m(-2) s(-1) and integrated to approximately 7% of the urea N applied, while NO emissions peaked about 25 d after urine addition at approximately 140 nmol m(-2) s(-1) and integrated to approximately 10% of the applied urea N. The monitoring of organics along with NH3 and NO was demonstrated in soils treated with synthetic urine, pyridine, and dimethylamine. No emission of volatile nitrogen organics from the urine treatments was observed at levels >0.01% of the applied nitrogen. The SIFT method allows the simultaneous in situ measurement of multiple gas components with a high spatial resolution of < 10 cm and time resolution <20 s. These capabilities allow, for example, identification of emission hotspots, and measurement of localized and rapid variations above agricultural and contaminated soils, as well as integrated emissions over longer periods.     

Isolation of fetal cells from transcervical samples by micromanipulation: Molecular confirmation of their fetal origin and diagnosis of fetal aneuploidy

Transcervical cell (TCC) samples have been shown to contain fetal cells amenable to molecular analysis. However, the presence of ‘contaminating’ maternal cells limits their use for prenatal diagnoses. In this report we show that clumps of fetal cells can be isolated from transcervical samples by micromanipulation and tested by fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR). Out of 129 clumps, isolated from mucus aspirates and transcervical lavages from 29 patients, 29 clumps from 11 patients were found to be exclusively of fetal origin as judged by the detection of chromosome 21-specific polymorphic DNA markers and Y-derived DNA sequences by PCR and FISH. One case of a male triploid fetus, diagnosed by the analysis of TCC samples obtained by mucus aspiration and lavage, was confirmed by testing clumps of cells isolated by micromanipulation.     

Intensive cattle grazing affects pasture litter-fall: an unrecognized nitrous oxide source

The rationale for this study came from observing grazing dairy cattle dropping freshly harvested plant material onto the soil surface, hereafter called litter-fall. The Intergovernmental Panel on Climate Change (IPCC) guidelines include NO emissions during pasture renewal but do not consider NO emissions that may result from litter-fall. The objectives of this study were to determine litter-fall rates and to assess indicative NO emission factors (EFs) for the dominant pasture species (perennial ryegrass [ L.] and white clover [ L.]). Herbage was vacuumed from intensively managed dairy pastures before and after 30 different grazing events when cows (84 cows ha) grazed for 24 h according to a rotational system; the interval between grazing events ranged from 21 to 30 d. A laboratory incubation study was performed to assess potential EF values for the pasture species at two soil moisture contents. Finely ground pasture material was incubated under controlled laboratory conditions with soil, and the NO emissions were measured until rates returned to control levels. On average, pre- and postgrazing dry matter yields per grazing event were 2516 ± 636 and 1167 ± 265 kg DM ha (±SD), respectively. Pregrazing litter was absent, whereas postgrazing fresh and senesced litter-fall rates were 53 ± 24 and 19 ± 18 kg DM ha, respectively. Annually, the rotational grazing system resulted in 12 grazing events where fresh litter-fall equaed to 16 kg N ha yr to the soil. Emission factors in the laboratory experiment indicated that the EF for perennial ryegrass and white clover ranged from 0.7 to 3.1%. If such EF values should also occur under field conditions, then we estimate that litter-fall induces an NO emission rate of 0.3 kg NO ha yr. Litter-fall as a source of NO in grazed pastures requires further assessment.     

Ammonia,methane, and nitrous oxide emission from pig slurry applied to a pasture in New Zealand

Much animal manure is being applied to small land areas close to animal confinements, resulting in environmental degradation. This paper reports a study on the emissions of ammonia (NH3), methane (CH4), and nitrous oxide (N2O) from a pasture during a 90-d period after pig slurry application (60 m3 ha-1) to the soil surface. The pig slurry contained 6.1 kg total N m-3, 4.2 kg of total ammoniacal nitrogen (TAN = NH3 + NH4) m-3, and 22.1 kg C m-3, and had a pH of 8.14. Ammonia was lost at a fast rate immediately after slurry application (4.7 kg N ha-1 h-1), when the pH and TAN concentration of the surface soil were high, but the loss rate declined quickly thereafter. Total NH3 losses from the treated pasture were 57 kg N ha-1 (22.5% of the TAN applied). Methane emission was highest (39.6 g C ha-1 h-1) immediately after application, as dissolved CH4 was released from the slurry. Emissions then continued at a low rate for approximately 7 d, presumably due to metabolism of volatile fatty acids in the anaerobic slurry-treated soil. The net CH4 emission was 1052 g C ha-1 (0.08% of the carbon applied). Nitrous oxide emission was low for the first 14 d after slurry application, then showed emission peaks of 7.5 g N ha-1 h-1 on Day 25 and 15.8 g N ha-1 h-1 on Day 67, and decline depending on rainfall and nitrate (NO3) concentrations. Emission finally reached background levels after approximately 90 d. Nitrous oxide emission was 7.6 kg N ha-1 (2.1% of the N applied). It is apparent that of the two major greenhouse gases measured in this study, N2O is by far the more important tropospheric pollutant.     

Biochar incorporation into pasture soil suppresses in situ nitrous oxide emissions from ruminant urine patches

Nitrous oxide (N2O) emissions from grazing animal excreta are estimated to be responsible for 1.5 Tg of the total 6.7 Tg of anthropogenic N2O emissions. This study was conducted to determine the in situ effect of incorporating biochar, into soil, on N2O emissions from bovine urine patches and associated pasture uptake of N. The effects of biochar rate (0-30 t ha(-1)), following soil incorporation, were investigated on ruminant urine-derived N2O fluxes, N uptake by pasture, and pasture yield. During an 86-d spring-summer period, where irrigation and rainfall occurred, the N2O fluxes from 15N labeled ruminant urine patches were reduced by >50%, after incorporating 30 t ha(-1) of biochar. Taking into account the N2O emissions from the control plots, 30 t ha(-1) ofbiochar reduced the N2O emission factor from urine by 70%. The atom% 15N enrichment of the N2O emitted was lower in the 30 t ha(-1) biochar treatment, indicating less urine-N contributed to the N2O flux. Soil NO3- -N concentrations were lower with increasing biochar rate during the first 30 d following urine deposition. No differences occurred, due to biochar addition, with respect to dry matter yields, herbage N content, or recovery of 15N applied in herbage. Incorporating biochar into the soil can significantly diminish ruminant urine-derived N2O emissions. Further work is required to determine the persistence of the observed effect and to fully understand the mechanism(s) of the observed reduction in N2O fluxes.     

Detection of fetal cells in transcervical samples and prenatal diagnosis of chromosomal abnormalities

Transcervical samples collected by lavage, aspiration, and cytobrush from women between 6 and 13 weeks of gestation were tested for the presence of fetal cells using fluorescence in situ hybridization (FISH) with probes for chromosomes X, Y, 1, and 21, and by polymerase chain reaction (PCR) amplification of DNA sequences derived from chromosomes X, Y, and 21. With a few exceptions, a good correlation was observed between the results of sexing the fetuses using FISH or PCR on transcervical cell (TCC) samples retrieved by lavage and those obtained by testing fetal (placental) tissue. In a comparative study between TCC samples collected by lavage or cytobrush, the sex of the fetus was correctly diagnosed by PCR amplification of a Y-derived DNA sequence. Variable results were observed with samples obtained by aspiration, mainly because this procedure was found to be more prone to failure to remove thick mucus without previous injection of physiological saline. Chromosome 21-derived small tandem repeats (STRs) of fetal origin were successfully detected in about 40 per cent of TCC samples recovered by lavage. Two cases of chromosomal abnormalities, one of trisomy 21 and one of triploidy, were detected in TCC samples in the course of our investigations.     

Molecular evidence of fetal-derived chromosome 21 markers (STRs) in transcervical samples

Transcervical cells (TCCs), collected by flushing or aspiration at 8–13 weeks of gestation, were analysed for the presence of fetal-derived DNA sequences. DNA extracted from maternal peripheral blood, TCC samples, and placental tissue was amplified by the polymerase chain reaction (PCR) to detect small tandem repeat (STR) markers specific to chromosome 21. STR products of fetal origin could be clearly observed in four TCC samples. TCC samples collected by flushing or aspiration were also analysed by fluorescent in situ hybridization (FISH) using X and Y probes simultaneously: 46,XY cells could be detected in all TCC samples obtained from mothers with male fetuses.     

Methods for the transcervical collection of fetal cells during the first trimester of pregnancy

Before termination of pregnancy, four techniques for retrieving fetal cells transcervically were investigated: uterine lavage, endocervical lavage, cytobrush and mucus aspiration. The yield of fetal cells in these samples was studied and found to be somewhat better after uterine lavage. A preliminary assessment of the safety of mucus aspiration was carried out before transcervical chorionic villus sampling (CVS) in continuing pregnancies. No difference in outcome to a control group having only CVS was found.     

Expect Déjà vu all over again

It is difficult to define “property damage,” but one knows it when one sees it. Groundwater and soil impacts are readily discernible. However, owners of property that has been adversely affected by environmental conditions caused by others have recently sought recovery for the stigma which may attach to property which has in the past been affected by hazardous substances, even after remediation. These cases are particularly interesting in light of the traditional causes of action for negligence, trespass, and nuisance, and the statutes of limitations which may affect both rights to sue and damages. This article addresses “stigma” as an emerging area and an element of damages in environmental cases.