Loss of pendimethalin in runoff and leaching from turfgrass land under simulated rainfall

A field study was undertaken to investigate runoff and leaching loss of the herbicide pendimethalin in turfgrass land of loamy sand soil. A series of plots constructed in a golf course fairway were surface-applied with pendimethalin SC formulation at the rate of 2. 25 or 4.50 kg a.i./ha and subjected to simulated rainfall at 2.0 cm/day for 10 consecutive days. Runoff losses of pendimethalin were the highest at the first rainfall and then gradually decreased with time. The first runoff event contained pendimethalin in its highest concentration, and in subsequent runoff samples the concentration decreased exponentially. The ranges of pendimethalin concentration were 80.9-18.2 and 177.4-48.6 microgram/L in the standard and double doses, respectively. Total losses by 20 cm of rainfall for 10 days reached 0.81 and 1.22% of the initial deposits at 2.25 and 4.50 kg a. i./ha, respectively. Pendimethalin concentration in the leachate collected at 30-cm soil depth was quite lower than that in the runoff, and the concentration rapidly decreased from 4.3-4.7 to 0. 2-0.4 microgram/L during the 10 days of rainfall treatment. Soil residue analysis at 45 and 90 days after pendimethalin treatment showed that more than 90% of the residue remained at the top 10 cm of soil depth. Low runoff and leaching confirmed that lateral and downward movement of the herbicide should be limited in turf soil. The half-life of pendimethalin under field conditions was 23-30 days and was not affected by application dose and rainfall treatment, but longer persistence was observed under laboratory conditions. Considering low runoff and leaching, as well as relatively short persistence in soil, it is concluded that little environmental carryover of pendimethalin would be expected in turfgrass land.     

Infant mortality and soil type: a case study in south-central England (with discussion)

We have analysed the differences in infant mortality for 1981 to 1990 in areas of contrasting soil types in south-central England. The soils overlie rocks of varied lithology and hydrology, ranging from porous and permeable Chalk and limestones, to the generally wet and impermeable Oxford and Lower Jurassic Clays. The study area comprises 504 administrative wards, for each of which the soil has been classified as being predominantly‘Wet’, ‘ Intermediate’ or ‘Dry’, depending on the degree of seasonal or periodic waterlogging. The soil classes used are those mapped by the Soil Survey of England and Wales and relate closely to the underlying geology. We find proportionately more infant deaths on the‘Wet’ soils, and a gradation towards lower infant mortality rates on the drier soils. Overall, infant mortality on the‘Wet’ soils is 31·9 percent greater than on the‘Dry’ soils, for reasons that remain unexplained. This relation between infant mortality and soil moisture remains after the effect of social class has been removed.     

Activated carbon amendments to soil alters nitrification rates in Scots pine forests

The influence of charcoal on biotic processes in soils remains poorly understood. Charcoal is a natural product of wildfires that burned on a historic return interval of ∼100 years in Scots pine (Pinus sylvestris L.) forests of northern Sweden. Fire suppression and changes in forest stand management have resulted in a lack of charcoal production in these ecosystems. It is thought that charcoal may alter N mineralization and nitrification rates, however, previous studies have not been conclusive. Replicated field studies were conducted at three late-succession field sites in northern Sweden and supporting laboratory incubations were conducted using soil humus collected from these sites. We used activated carbon (AC), as a surrogate for natural-occurring fire-produced charcoal. Two rates of AC (0 and 2000 kg ha⁻¹), and glycine (0 and 100 kg N as glycine ha⁻¹) were applied in factorial combination to field microplots in a randomized complete block pattern. Net nitrification, N mineralization, and free phenol concentrations were measured using ionic and non-ionic resin capsules, respectively. These same treatments and also two rates of birch leaf litter (0 and 1000 kg ha⁻¹) were applied in a laboratory incubation and soils from this incubation were extracted with KCl and analyzed for NH₄⁺ and NO₃⁻. Nitrification rates increased with AC amendments in laboratory incubations, but this was not supported by field studies. Ammonification rates, as measured by NH₄⁺ accumulation on ionic resins, were increased considerably by glycine applications, but some NH₄⁺ was apparently lost to surface sorption to the AC. Phenolic accumulation on non-ionic resin capsules was significantly reduced by AC amendments. We conclude that charcoal exhibits important characteristics that affect regulating steps in the transformation and cycling of N.     

Design,Evaluation and Application of a Continuously Stirred Tank Reactor System for Use in Nitric Acid Air Pollutant Studies

Nitric acid (HNO₃) vapor is a significant component of air pollution. Dry deposition of HNO₃ is thought to be a major contributor to terrestrial loading of anthropogenically-derived nitrogen (N), but many questions remain regarding the physico-chemical process of deposition and the biological responses to accumulation of dry-deposited HNO₃ on surfaces. To examine these processes experimentally, a continuously stirred tank reactor (CSTR) fumigation system has been constructed. This system enables simultaneous fumigation at several concentrations in working volumes 1.3 m dia by 1.3 m ht, allowing for simultaneous fumigation of many experimental units. Evaluation of the system indicates that it is appropriate for long-term exposures of several months duration and capable of mimicking patterns of diurnal atmospheric HNO₃ concentrations representative of areas with different levels of pollution.     

Investigating the Provenance and Seasonal Variations in Sulphate Sulphur and Oxygen Isotopes of Central Roztocze River Water,SE Poland

The isotope composition of sulphur and oxygen were measured in water collected from the Central Roztocze (SE of Poland) rivers. The research focused mainly on the upper section of the Wieprz River, its confluences and springs and on two confluences of the Tanew River. The results proved that there are two sources of sulphate dissolved in water: the Cretaceous aquifer and soil within the catchment's area. Seasonal variation of the sulphate concentration together with sulphur and oxygen isotope composition was observed. The isotope composition of sulphate varied in water collected at the different locations of the same river. They are similar for sulphates in springs and rivers. The isotope composition of sulphate varied in water collected at the different locations of the same river. The δ³⁴S values of sulphates in the Wieprz River are the lowest (negative) in lower part of the river. It shows that the contribution of sulphate from spring water increases downstream. The low sulphate content and high δ³⁴S and δ¹⁸O value in sulphates was found downstream from dams. It may be the result of deficiency of oxygen in mud and the reduction in bacteria activity. The seasonal variations of the oxygen isotope composition in sulphate are significant in sulphates collected from rivers and from springs. They are caused by seasonal variations of the δ¹⁸O in water stored in the soil. The narrow range of the δ¹⁸O values for the sulphates extracted from springs at the same time means that the main source of sulphate in spring water are oxidising processes using the same source of oxygen in every location. The high sulphate content combined with the high δ³⁴S values of the sulphates in springs suggest, that the sulphates from Cretaceous aquifer were mixed with sulphates dissolved from the soil.     

A subsoil compaction database: its development, structure and content

A database which holds results of field and laboratory experiments on the impact of subsoil compaction on physical and mechanical soil parameters and on crop yields and environmental impact is being developed within the EU sponsored concerted action (CA) project “Experiences with the impact of subsoil compaction on soil, crop growth and environment and ways to prevent subsoil compaction”. The database accumulates and can provide all available data from the participants of the European Union countries, and is compatible with the European Soil Database and other related databases.

More than 600 sets of data (Excel workbooks) from participants from the European Union, plus Poland, Switzerland and Norway are included in the database. Through a similar EU sponsored CA, Eastern European countries are expected to deliver 260 sets of data thus bringing the total number of Excel workbooks to approximately 860. In total, the database will contain approximately 13,500 data spreadsheets.

The objective of the database is to collect data on subsoil compaction, to store it in a structured format and to make it available for analysis and use. Thereby it will enable elucidation of the impact of subsoil compaction on soil properties, crop yields and environment and evaluate the vulnerability of soils to compaction.     

2-Dodecylcyclobutanone does not induce mutations in the Escherichia coli tryptophan reverse mutation assay

Like thermal processing, ionizing radiation can break molecular bonds and induce the formation of chemicals not found in the unprocessed product. Irradiation of foods containing palmitic acid can lead to the formation of 2-dodecylcyclobutanone (2-DCB). In this study, the Escherichia coli tryptophan reverse mutation assay was used to evaluate the capacity of 2-DCB to induce mutations. E. coli tester strains WP2 (pkM101) and WP2 uvrA (pKM101), with and without exogenous metabolic activation, were exposed to 0, 0.05, 0.1, 0.5, and 1 mg/well 2-DCB using the Miniscreen version of the assay. 2-DCB did not induce mutations in the E. coli tryptophan reverse mutation assay. These results are in agreement with negative results obtained in short-term and long-term genetic toxicology tests of irradiated food products.     

Influence of temperature on the motility of Pseudomonas oryzihabitans and control of Globodera rostochiensis

The motility and efficacy of Pseudomonas oryzihabitans as a biocontrol agent against the potato cyst nematode Globodera rostochiensis were studied with respect to temperature. The influence of soil moisture on bacterial movement was also tested. In a closed container trial, P. oryzihabitans significantly reduced invasion of second stage juveniles (J2) of G. rostochiensis in potato roots, its effect being more marked at 25 and 21 °C than at 17 °C. P. oryzihabitans motility in vitro was optimal at 26 °C and inhibited at temperatures below 18 °C. In soil, both temperature and matric potential affected bacterial movement. At 16 °C its movement and survival were suppressed, but they were unaffected at 25 °C. At both temperatures the biocontrol agent moved faster in the wetter (−0.03 MPa) than in the drier soil (−0.1 MPa). These results suggest that temperature is a key factor in determining the potential of P. oryzihabitans as a biocontrol agent.     

alpha- and beta-Thujones (herbal medicines and food additives): synthesis and analysis of hydroxy and dehydro metabolites

Essential oils containing alpha- and beta-thujones are important herbal medicines and food additives. The thujone diastereomers are rapidly metabolized convulsants acting as noncompetitive blockers of the gamma-aminobutyric acid-gated chloride channel. Synthesis and analysis of the metabolites are essential steps in understanding their health effects. Oxidation of alpha- and beta-thujones as their 2,3-enolates with oxodiperoxymolybdenum(pyridine)(hexamethylphosphoric triamide) gave the corresponding (2R)-2-hydroxythujones assigned by (1)H and (13)C NMR and X-ray crystallography. alpha-Thujone was converted to 4-hydroxy-alpha- and -beta-thujones via the 3,4-enol acetate on oxidation with peracid and osmium tetroxide, respectively. Ozonation provided 7-hydroxy-alpha- and -beta-thujones, and by dehydration provided the 7,8-dehydro compounds. 4,10-Dehydrothujone was prepared from sabinene via sabinol. The hydroxy and dehydro derivatives are readily identified and analyzed by GC/MS as the parent compounds and trimethylsilyl and methyloxime derivatives. A separate study established that all of these compounds are metabolites of alpha- and beta-thujones.