Aerating grassland before manure application reduces runoff nutrient loads in a high rainfall environment

The effect of mechanically aerating grassland before liquid manure application in the fall on surface runoff and transport of nutrients and solids was studied in a high rainfall area. The two treatments were control and aeration, the latter receiving one pass with an aerator perpendicular to the slope before fall application of liquid manure (dairy in Years 1-3 and swine in Year 4). Treatments were randomly assigned on 3 to 5% sloping land with a silt loam surface soil (Aquic Dystroxerept) planted in orchardgrass (Dactylis glomerata L.). Runoff from natural rainfall events was sampled for nutrient and solids analysis. Aeration significantly reduced runoff and loads of suspended solids, total Kjeldahl N (TKN), and dissolved reactive P in all years. Annual runoff amounts were reduced by 47 to 81%, suspended and volatile solid loads by 48 to 69% and 42 to 83%, respectively, TKN loads by 56 to 81%, and total P (TP) loads by 25 to 75%. Loads of the soluble nutrient NH4-N, dissolved reactive P, and K were reduced by 41 to 83%. The first three runoff events after manure application accounted for approximately one-third of the annual total runoff and solid and nutrient loads when averaged across treatments, with loads of TKN, K, and NH4-N totaling 4.4, 3.3, and 1.9 kg ha-1, respectively. Aeration slightly increased downward movement of NO3-N, but not other nutrients in the soil. Thus mechanical aeration can be an effective tool for reducing runoff and loads of solids and nutrients after surface application of liquid manure on sloping grassland.     

Application of automated mass spectrometry deconvolution and identification software for pesticide analysis in surface waters

A new approach to surface water analysis has been investigated in order to enhance the detection of different organic contaminants in Nathan Creek, British Columbia. Water samples from Nathan Creek were prepared by liquid/liquid extraction using dichloromethane (DCM) as an extraction solvent and analyzed by gas chromatography mass spectrometry method in scan mode (GC-MS scan). To increase sensitivity for pesticides detection, acquired scan data were further analyzed by Automated Mass Spectrometry Deconvolution and Identification Software (AMDIS) incorporated into the Agilent Deconvolution Reporting Software (DRS), which also includes mass spectral libraries for 567 pesticides. Extracts were reanalyzed by gas chromatography mass spectrometry single ion monitoring (GC-MS-SIM) to confirm and quantitate detected pesticides. Pesticides: atrazine, dimethoate, diazinone, metalaxyl, myclobutanil, napropamide, oxadiazon, propazine and simazine were detected at three sampling sites on the mainstream of the Nathan Creek. Results of the study are further discussed in terms of detectivity and identification level for each pesticide found. The proposed approach of monitoring pesticides in surface waters enables their detection and identification at trace levels.     

Heavy metals in seaducks and mussels from misty fjords national monument in Southeast Alaska

Quartz Hill, in Misty Fjords National Monument near Ketchikan, Alaska, is the site of a proposed molybdenum-producing mine. To provide baseline data for use in post-development comparisons, we analyzed tissues of Barrow's goldeneyes (Bucephala islandica), common mergansers (Mergus merganser), and blue mussels (Mytilus edulis) for seven heavy metals that could potentially be released into the environment as a result of mining operations. Specimens were collected in 1980, 1981, and 1982 from two fjords likely to be used for discharge of tailings from the proposed mine and from two control fjords. Concentrations of arsenic, cadmium, copper, chromium, molybdenum, lead, and zinc were measured in soft tissues of mussels and in kidney, liver, and muscle of birds. The highest mean concentrations of metals found in bird tissues were 55.7 ppm dry weight cadmium in kidneys and 154 ppm dry weight zinc in livers of Barrow's goldeneyes. Concentrations of several metals in blue mussels differed among seasons and locations, but the most significant finding in mussels was a maximum mean cadmium concentration of 9.6 ppm dry weight, a level higher than normally found in undisturbed areas. With the exception of 104 ppm dry weight cadmium in the kidney of one common merganser and 12.7 ppm dry weight lead in the kidney of another, concentrations of other metals in seaduck and mussel tissues were low, consistent with what would be expected for a pre-development environment. Molybdenum was found in low concentrations (<10 ppm dry weight) in all avian kidney samples and most liver samples, but was not detected in blue mussels.THE U.S. GOVERNMENT RIGHT TO RETAIN A NON-EXCLUSIVE, ROYALTY FREE LICENCE IN AND TO ANY COPYRIGHT IS ACKNOWLEDGED.     

In utero diagnosis and treatment of fetal goitrous hypothyroidism,caused by maternal use of propylthiouracil

A fetal goitre is a potentially dangerous phenomenon because of mechanical obstruction and possible fetal thyroid function disorders. In this report we describe a patient with Graves' disease diagnosed in early pregnancy and treated with propylthiouracil, which resulted in a large fetal goitre and fetal hypothyroidism. The diagnostic problems are discussed and we focus on the need for fetal thyroid hormone serum evaluation. The only reliable way to obtain information about the fetal thyroid status is percutaneous fetal umbilical cord blood sampling, since amniotic fluid levels do not properly represent the fetal thyroid function. Fetal hypothyroidism can thus be diagnosed in utero and treated with intra-amniotic injections of thyroxine. The recommended dose and frequency of injections are only based on a few case reports and for that reason we performed a second fetal blood sampling 1 week later to evaluate our therapy. Weekly intra-amniotic injections of 250 μg of thyroxine seem to be sufficient to reduce a fetal goitre and give a normal thyroid hormone level.     

Oxidative stress induced by copper: defense and damage in the marine planktonic diatom Ditylum brightwellii,grown in continuous cultures with high and low zinc levels

Light-limited cultures of the planktonic diatom Ditylum brightwellii (West) Grunow were grown at 14 salinity. Cells were subjected to oxidative stress induced by copper, in the presence of zinc. In two continuous cultures with total Zn levels of 40 and 140 nM, respectively, dissolved Cu levels were increased from 3 to 126 nM. This resulted in an increased Cu adsorption capacity of the cell walls, probably due to an increase of surface area and roughness. Sexual reproduction (auxospore formation) was accelerated but was considered as a non-specific stress response. Cu-induced oxidative stress was indicated by a decrease of reduced glutathione (GSH), and a removal of superoxide anions monitored as an increasing activity of superoxide dismutase (SOD). Although Zn has no oxidative potential per se, cell division rates and chlorophyll c contents were lower in the culture with high Zn levels. In both cultures, the pro-oxidant Cu caused a decrease of chlorophyll a, decreasing photosynthetic O₂ evolution and cell devision rates, and a growing number of deformed and broken cells.     

Validated sampling strategy for assessing contaminants in soil stockpiles

Dutch legislation on the reuse of soil requires a sampling strategy to determine the degree of contamination. This sampling strategy was developed in three stages. Its main aim is to obtain a single analytical result, representative of the true mean concentration of the soil stockpile. The development process started with an investigation into how sample pre-treatment could be used to obtain representative results from composite samples of heterogeneous soil stockpiles. Combining a large number of random increments allows stockpile heterogeneity to be fully represented in the sample. The resulting pre-treatment method was then combined with a theoretical approach to determine the necessary number of increments per composite sample. At the second stage, the sampling strategy was evaluated using computerised models of contaminant heterogeneity in soil stockpiles. The now theoretically based sampling strategy was implemented by the Netherlands Centre for Soil Treatment in 1995. It was applied to all types of soil stockpiles, ranging from clean to heavily contaminated, over a period of four years. This resulted in a database containing the analytical results of 2570 soil stockpiles. At the final stage these results were used for a thorough validation of the sampling strategy. It was concluded that the model approach has indeed resulted in a sampling strategy that achieves analytical results representative of the mean concentration of soil stockpiles.