The objectives of this study were to determine field‐scale pesticide and nutrient losses to subsurface tile drains over a 3‐yr period on a low organic matter and poorly structured silt loam soil under typical agricultural management practices. A subsurface drain spacing study was instrumented to measure drain discharge rates and to collect drainflow samples continuously on a flow‐proportional basis. Two replicates of three drain spacings (5, 10, and 20 m) were included in the study. Water samples were analyzed for all applied pesticides (atrazine, cyanazine, alachlor, carbofuran, terbufos, and chlorpyrifos)1 as well as major nutrients (N, P, K) and sediment. Small amounts of carbofuran, atrazine, cyanazine, and alachlor were detected in subsurface drainflow within 3 wk of pesticide application and after less than 2 cm net subsurface drainflow from the soil. This early arrival of pesticides at the drain is consistent with preferential flow concepts. Annual carbofuran losses in subsurface drainflow ranged from 0.8 to 14.1 g ha−1, or 0.05 to 0.94% of the amount applied to the soil. Losses of all other pesticides were ≤0.06% of the amount applied. The rank‐order of pesticide mass losses corresponded with the rank‐order of sorption coefficients of the pesticides. Total mass of pesticides, nutrients, sediment, and water removed by subsurface drains on a per‐area basis was greatest for the 5 m spacing and least for the 20‐m spacing. Annual nitrate‐N losses to subsurface drainflow ranged from 18 to 70 kg ha−1 and averaged 41.7 kg ha−1. Annual average ammonium‐N, soluble P, and K losses were 0.5, 0.04, and 2.6 kg ha−1, respectively.

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Mucus glycoproteins (mucins) were obtained from human cervical and pig gastric mucus as well as from chronic-bronchitic sputum after low-shear extraction. The mucus gel was solubilized in guanidinium chloride supplemented with proteinase inhibitors, and the macromolecules were purified by using isopycnic density-gradient centrifugation. The macromolecules were spread in monolayers of benzyldimethylalkyl-ammonium chloride and studied with electron microscopy after staining with uranyl acetate and/or shadowing with platinum/carbon. The mucins appeared as flexible linear threads with lengths varying from approx. 200 nm to about 400 nm. No regularly branched or star-shaped structures were observed. The macromolecular architecture of cervical, respiratory and gastric mucins is thus similar.

We have carried out experiments to study the incorporation and movement of HCl within the structure of ice. These involved freezing HCl solutions, and observing them in a scanning electron microscope fitted with an X‐ray microanalysis system. We are able to show that HCl is not easily incorporated into ice crystals, but is strongly partitioned towards the grain boundaries. Furthermore, the diffusion of HCl through ice crystals is slow. These results contradict the interpretation of earlier experiments. They mean that if HCl is to be available for reaction on polar stratospheric cloud particles, as required by current theories of Antarctic ozone depletion, then it must be present in some form other than a solid solution.

A procedure is described for forming a flat face on a frozen piece of plant tissue, which may then be observed fully-hydrated or lightly etched, and coated or uncoated with a metal film, in scanning electron microscopy (SEM). The frozen sample was planed with a glass knife at -80 degrees C in a cryo-ultramicrotome. The sections were discarded, and the planed block face placed on the cold stage in the microscope column, either for observation uncoated at low kV, or for light etching (-90 degrees C) to reveal the cell outlines. If a higher accelerating voltage was needed, the face was given an evaporative coating of Al in the cryo-preparation chamber and returned to the column. The advantages of the planed face over the usual fracture face are illustrated: imaging at a chosen rather than a chance position; clearer cellular and subcellular detail; preservation of hydrated gels like mucilage and swollen cell walls; the possibility of making serial parallel sections through the same piece of tissue; opportunities for accurate morphometric analyses on the planed face; capacity to produce longitudinal sections; preservation of very delicate structures that are destroyed by fixation and drying. A major advantage of the Al-coated planed face is the increased accuracy of energy-dispersive X-ray (EDX) microanalyses on a smooth rather than a rough surface. Tests are included which show that neither the light etching employed, nor successive planing, interferes with the analyses of elements in the frozen face.