Hydrologic impacts of brush management with tebuthiuron and prescribed burning on post oak savannah watersheds,Texas

Selected hydrologic variables were evaluated following conversion of heavily wooded sites to open grassland with a herbicide—prescribed burning treatment sequence in east-central Texas. Terminal infiltration rates and sediment production 3 years after aerial application of tebuthiuron pellets at 2.2 kg ha^?1 (active ingredient) for brush management differed little from values for untreated (wooded) areas. Prescribed burning in the winter (December–February) temporarily decreased infiltration rates and increased sediment production. Infiltration rates has equilibrated among brush management treatments with re-instatement of the herbaceous cover 5.5 months after burning. Sediment production was generally greater from burned than unburned plots after 5.5 months, but the absolute amount of sediment produced on the near-level (1–3% slope) fine sandy loam sites was not great, regardless of treatment. Moreover, sediment production from burned sites was not significantly different from that of untreated sites 1 year after burning. The brush management treatments had no effect on nitrate concentrations in run-off. However, in one of two experiments, total unfiltered nitrogen and phosphorus contents in run-off were greater during the growing season following burning than from unburned sites.     

Prenatal diagnosis of endocardial fibroelastosis

In a case of fetal heart failure caused by endocardial fibroelastosis, prenatal echocardiography clearly demonstrated; a thickened endocardium. We therefore suggest that an abnormal endocardium may be detected in utero by ultrasound, thus representing an important clue in the differential diagnosis of fetal nonimmune hydrops and in the evaluation of pregnancies at risk for endocardial fibroelastosis.     

Two-dimensional spectrophotometry and pseudo-color representation of chemical reaction patterns

The formation of spatio-temporal patterns in layers of chemical and biochemical media is observed and quantified by a two-dimensional spectrophotometer based on a computerized video equipment with high spatial, temporal, and intensity resolution. Images are shown, to some extent, in pseudo-colors. The use of pseudo-colors and three-dimensional perspective representations enhances the perception of the information contained in an image and the inherent order of the spatial structures.     

Anatomic correlates of ultrasonographic prenatal diagnosis

In utero sonographic diagnoses from forty-five malformed infants were correlated with their autopsy findings. Fifty-two malformations were diagnosed prenatally in 42 of the patients but 90 additional malformations were not. Nine sonographically diagnosed abnormalities were not confirmed at autopsy. Factors compromising sonographic diagnosis included: limited examinations, small fetal size, timing of examination, oligohydramnios, fetal position, nature of the malformation and unfamiliarity of the ultrasonographer with specific malformation syndromes. In vitro ultrasonography is an invaluable tool of diagnosing congenital malformations but has limitations.     

Floristics, performance and prognosis of historical trees in the urban forest of Guangzhou City (China)

Outstanding historical trees embedded in cities constitute pertinent environmental assets, yet they are widely threatened in third-world cities. Inadequate understanding of this valuable natural-cum-cultural heritage hinders proper conservation. A case study of Guangzhou in south China evaluated floristic composition, age profile and biomass structure of historical trees, assessed their performance in major habitats (institutional, park and roadside), and established a prognosis for future growth and management. The 348 historical trees examined belonged to only 25 species, vis-à -vis 254 trees in the entire urban forest, dominated by five species and native members. Roadside had more trees, followed by institutional and park, with merely the most common four species shared by all habitats. The limited commonality reflected tree-performance differentiation by habitats exerting selection pressure on species. The institutional growth-regime was more conducive to nurturing high-caliber specimens, whereas park is less capable. Individual species achievement by habitats, derived from tree-count ranking and relative-abundance indices, could inform species choice and tree conservation. Few trees exceeded 300 years of age in the millennium-old city, echoing a history of intense tree—city conflicts. Potential life-span, trunk and crown diameters indicated ample opportunities for further expansion of biomass and landscape impacts, which would be straitjacketed by the tightening urban fabric.     

Metal Pollution Assessment of Sediment and Water in the River Hindon, India

The metal pollution in water and sediment of the River Hindon in western Uttar Pradesh (India) was assessed for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The metal concentrations in water showed wide temporal variation compared with bed sediment because of variability in water discharge and variations in suspended solid loadings. Metal concentrations in bed sediments provided a better evaluation of the degree and the extent of contamination in the aquatic environment, Santagarh and Atali being the most polluted sites of the river. The ratio of heavy metals to conservative elements (Fe, Al, etc.) may reveal the geochemical imbalances due to the elevated metal concentrations normally attributed to anthropogenic sources. Metal/Al ratios for the bed sediments of the river Hindon were used to determine the relative mobility and general trend of relative mobility occurred Fe > Mn > Zn > Cr > Ni > Pb > Cu > Cd.     

Flow-injection analysis with fluorescence detection for the determination of trace levels of ammonium in seawater

A method using flow-injection, gas-diffusion, derivatisation and then fluorescent detection has been established for ammonium ion determination in seawater. The fluorescent derivative formed by reacting ortho-phthaldialdehyde (OPA) and sulfite with ammonia gives high sensitivity while removing potential interferences. This is required to measure the low concentrations of ammonium often seen in the open ocean. The experimental conditions (flow-rate, reagent concentrations, membrane configurations, etc.) were manipulated to improve performance. For a sample throughput of 30 samples h(-1), the limit of detection was 7 nM, the coefficient of variation was 5.7% at 800 nM, and the calibration curve was linear to at least 4 micromol L(-1). Interferences were minimised by a gaseous diffusion step. Volatile small molecular-weight amines as interferents were discriminated against by this method. They neither passed through the membrane as efficiently as ammonia, nor reacted as readily with OPA when sulfite was the reductant. Contamination by ammonia from laboratory and shipboard sources complicates application of the method to natural waters, especially measurement of low concentrations (<100 nM) in open-ocean waters. Steps to overcome contamination are described in detail. Some results are presented for ammonium determination in Southern Ocean and Huon Estuary (Tasmania) waters.     

An assessment of the bioavailability of persistent organic pollutants from contaminated soil

A procedure to assess the bioavailability of persistent organic pollutants (POPs) from soil samples has been developed. The procedure is based on the use of simulated in vitro gastrointestinal extraction to remove POPs from soil matrices. The level of recovery, using this approach, is assessed following liquid-liquid extraction (LLE) and analysis by gas chromatography-mass selective detection (GC-MSD). The remaining soil residue is then extracted using pressurised fluid extraction (PFE) followed by GC-MSD analysis to assess the residual fraction. The residual fraction is monitored to determine the unavailable fraction i.e. not available for absorption in the gastrointestinal tract of humans. The procedure was applied to four soil samples i.e. an aged, spiked soil and three certified reference materials (CRMs) contaminated with POPs. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II), phenols (cresol, TCP and PCP), and base neutral compounds (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from aged, spiked soil following extraction with gastric fluid ranged from 0.8 to 8.3% while following intestinal extraction ranged from 5.5 to 13.5%, irrespective of POP. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II) from CRM 805-050 following extraction with gastric fluid were below the limit of detection while following intestinal extraction ranged from 5.3 to 12.8%. Recoveries of phenols (cresol, TCP and PCP) from CRM 401-225 following extraction with gastric fluid ranged from 1.6 to 2.0% while following intestinal extraction ranged from 4.1 to 5.4%. Recoveries of base neutral acid analytes (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from CRM 107-100 following extraction with gastric fluid ranged from 1.4 to 4.0% while following intestinal extraction ranged from 6.6 to 12.7%. It has been found that the majority of POPs present i.e. >75%, would be excreted if consumed and not be absorbed in the gastrointestinal tract of humans.     

The organic composition of diesel particulate matter, diesel fuel and engine oil of a non-road diesel generator

Diesel-powered equipment is known to emit significant quantities of fine particulate matter to the atmosphere. Numerous organic compounds can be adsorbed onto the surfaces of these inhalable particles, among which polycyclic aromatic hydrocarbons (PAHs) are considered potential occupational carcinogens. Guidelines have been established by various agencies regarding diesel emissions and various control technologies are under development. The purpose of this study is to identify, quantify and compare the organic compounds in diesel particulate matter (DPM) with the diesel fuel and engine oil used in a non-road diesel generator. Approximately 90 organic compounds were quantified (with molecular weight ranging from 120 to 350), which include alkanes, PAHs, alkylated PAHs, alkylbenzenes and alkanoic acids. The low sulfur diesel fuel contains 61% alkanes and 7.1% of PAHs. The identifiable portion of the engine oil contains mainly the alkanoic and benzoic acids. The composition of DPM suggests that they may be originated from unburned diesel fuel, engine oil evaporation and combustion generated products. Compared with diesel fuel, DPM contains fewer fractions of alkanes and more PAH compounds, with the shift toward higher molecular weight ones. The enrichment of compounds with higher molecular weight in DPM may be combustion related (pyrogenic).