Recording the Response of Plants to Various Air Pollutants

A discussion of the methods used to determine the most economic design of chimney for a new thermal power station or large industrial plant is presented, with the objective that ground level concentration of pollutants will be kept at a minimum. Attention is paid to the geography and climatology of the site, with special reference to the frequency and height of inversions and the prevailing wind direction and speed.

A method is illustrated in using a large thermal power station as an example. The maximum sulfur dioxide concentrations at ground level are computed for several chimney heights and gas exit velocities. The values of these sulfur dioxide concentrations, the capital cost of the chimney, the pumping costs, and the gas pressures within the chimney are considered in selecting a suitable chimney height and a gas exit velocity which will meet most economically the stated objective.

The paper deals primarily with chimneys for industrial or power boiler plant of maximum continuous rating greater than 450 million Btu/hr (about 450,000 lbs of steam/hr), or to chimneys serving furnaces burning fuel at a maximum rate greater than 50,000 lbs/hr of coal, or 80,000 lbs/hr of oil. For chimneys serving plant with smaller heat inputs, chimney selection by reference to Clean Air Act 1956, Memorandum on Chimney Heights is suggested.     

Farmers,Streams, Information,and Money: Does Informing Farmers About Riparian Management Have Any Effect?

We assessed relationships between the extent to which farmers reported exposure to relevant information and their attitudes towards, knowledge about, and degree of adoption of riparian management strategies. We also examined associations between knowledge of, or receipt of, financial assistance for riparian fencing/planting and intentions for and extent of adoption of this strategy. A mail survey of 718 pastoral farmers in Otago and Southland in New Zealand [294 surveys returned (41%)] yielded 279 usable questionnaires. Indices were developed to reflect range and frequency of information use and range of practices adopted. Attitudes were measured using Likert-type responses to 11 statements, and knowledge as a score on a ten-question true/false test. Positive relationships between information and the three main response variables (attitude, knowledge, and adoption) were weak but significant and systematic. These associations remained significant when important demographic and farm characteristics were taken into account. Informed farmers were more likely to report intentions to carry out riparian fencing or planting within the next year. Farmers who were aware that funding was available were also more likely to state this intention, independent of information level. The reported extent to which waterways had been fenced to exclude stock was related to receipt of funding, but not to information level. Financial factors were the most influential barrier preventing adoption of permanent fencing. Our research shows a positive correlation between the receipt of information and funding and the adoption of specific riparian management measures.     

Recovery Trajectories After In Situ Burning of an Oiled Wetland in Coastal Louisiana,USA

The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate in a brackish marsh at Rockefeller Wildlife Refuge in southwestern Louisiana was remediated through the use of in situ burning. An assessment of vegetation recovery was initiated in three treatment marshes: (1) oil-impacted and burned, (2) oil impacted and unburned, and (3) a nonoiled unburned reference. We compared percent cover, stem density, and biomass in the treatment marshes to define ecological recovery of the marsh vegetation and soil hydrocarbon content to determine the efficacy of in situ burning as a cleanup technique. Burning led to a rapid decrease in soil hydrocarbon concentrations in the impacted-and-burned marsh to background levels by the end of the first growing season. Although a management fire accidentally burned the oil-impacted-and-unburned and reference marshes in December 1995, stem density, live biomass, and total percent cover values in the oil-impacted-and-burned marsh were equivalent to those in the other treatment marshes after three years. In addition, plant community composition within the oil-impacted-and-burned marsh was similar to the codominant mix of the grasses Distichlis spicata (salt grass) and Spartina patens (wire grass) characteristic of the surrounding marsh after the same time period. Rapid recovery of the oil-impacted-and-unburned marsh was likely due to lower initial hydrocarbon exposure. Water levels inundating the soil surface of this grass-dominated marsh and the timing of the in situ burn early in the growing season were important factors contributing to the rapid recovery of this wetland. The results of this in situ burn evaluation support the conclusion that burning, under the proper conditions, can be relied upon as an effective cleanup response to hydrocarbon spills in herbaceous wetlands.     

Second-trimester levels of maternal urinary gonadotropin peptide in down syndrome pregnancy

Urinary gonadotropin peptide (UGP; β-core fragment), a major metabolite of human chorionic gonadotropin (hCG), was shown recently to be markedly elevated in Down syndrome pregnancy between 19 and 22 weeks of gestation. To confirm and extend this finding, we obtained maternal urine and matching maternal serum samples from 14 cases of Down syndrome and six other aneuploidies between 17 and 21 weeks of gestation. UGP was measured in all these samples and in 91 singleton control urines. Results were corrected for urinary creatinine level and expressed as multiples of the control median (MOM). hCG levels were assayed in all serum samples from the cases and compared with previously established reference values. The median UGP level in Down syndrome cases was 5.34 MOM (range 2.71–12.57); 88 per cent of the values were above the 95th centile of control levels after modelling. The median maternal serum hCG level for the same cases was 2.20 MOM (range 0.84–3.40); 36 per cent of the values were above the 95th centile. The level of UGP in every case including all other aneuploidies was higher than the comparable maternal serum hCG level. Elevated UGP measurements are strongly associated with fetal Down syndrome during the second trimester and could contribute to improved Down syndrome screening protocols that are more accessible and less expensive than are currently available.     

Trisomy 16 fetus surviving into the second trimester

A 27-year-old gravida 4, para 3 was found to have anhydramnios at 14 weeks' gestation following a size/date discrepancy noted at her routine prenatal visit. A detailed ultrasound revealed multiple fetal anomalies including congenital heart defect, chest hypoplasia, and bilateral dysplastic kidneys. Karyotype revealed trisomy 16 in 15/15 cells from a tissue specimen obtained from the fetal cord insertion site following elective pregnancy termination.     

Long-Term Landscape Change and Bird Abundance in Amazonian Rainforest Fragments

Abstract:  The rainforests of the Amazon basin are being cut by humans at a rate >20,000 km²/year, leading to smaller and more isolated patches of forest, with remaining fragments often in the range of 1–100 ha. We analyzed samples of understory birds collected over 20 years from a standardized mist-netting program in 1– to 100-ha rainforest fragments in a dynamic Amazonian landscape near Manaus, Brazil. Across bird guilds, the condition of second growth immediately surrounding fragments was often as important as fragment size or local forest cover in explaining variation in abundance. Some fragments surrounded by 100 m of open pasture showed reductions in insectivorous bird abundance of over 95%, even in landscapes dominated by continuous forest and old second growth. These extreme reductions may be typical throughout Amazonia in small (≤10 ha), isolated fragments of rainforest. Abundance for some guilds returned to preisolation levels in 10- and 100-ha fragments connected to continuous forest by 20-year-old second growth. Our results show that the consequences of Amazonian forest loss cannot be accurately described without explicit consideration of vegetation dynamics in matrix habitat. Any dichotomous classification of the landscape into "forest" and "nonforest" misses essential information about the matrix.