Trace metal loading on water-borne soil and dust particles characterized through the use of split-flow thin-cell fractionation.

The fate and transport of metallic pollutants through a watershed are related to the characteristics of undissolved solid particles to which they are bound. Removal of these particles and their associated pollutants via engineered structures such as settling ponds is one goal of stormwater management. Because the particles most often implicated in metal pollution have nominal diameters of <50 microm, Split-flow thin-cell (SPLITT) fractionation was investigated to study the metal loading as a function of particle settling rate. Several diverse particle samples--soil, urban dust, and parking deck sweepings--were fractionated using this technique, and the metal loadings were quantified with inductively coupled plasma-atomic emission spectrometry. Implications for stormwater management are discussed.

Adverse male reproductive effects following subchronic exposure of rats to sodium dichloroacetate.

Dichloroacetate (DCA) activates the pyruvate dehydrogenase complex enhancing carbohydrate and lactate utilization in animals. As a result it is used clinically in the treatment of acute lactic acidosis and has therapeutic potential in the treatment of stroke. Adverse effects of chronic DCA treatment include polyneuropathy and testicular degeneration. Since DCA is a principal product of the aqueous chlorination of fulvic acids concern has arisen regarding the agent's impact on environmental health. We treated male Long-Evans rats with 0, 31.25, 62.5, or 125 mg DCA/kg/day by oral gavage for 10 weeks. Compared to controls, preputial gland and epididymis weights were reduced at 31.25 mg/kg, body and liver weights at 62.5 mg/kg, and accessory organ weights at 125 mg/kg. Epididymal sperm counts were reduced and sperm morphology was impacted at the 62.5 and 125 mg/kg doses levels. Histologic examination of the testis and epididymis revealed inhibited spermiation in testes at the 125 mg/kg dose level. Computer-assisted sperm motion analysis revealed reductions in percentage motile sperm, curvilinear and straight-line velocity, linearity, and amplitude of lateral head displacement at both the 62.5 and the 125 mg/kg dose levels. In the assessment of fertility after an overnight mating, the number of viable implants on Day 14 of gestation was decreased only in the highest dose group. These studies demonstrate adverse effects of NaDCA treatment on the rat male reproductive system, primarily on the accessory organs and sperm within them at lower doses (31.25 and 62.5 mg/kg), and on the testis at the highest dose (125 mg/kg).