Surface water quality of factory-based and vegetable-based peri-urban areas in the Yangtze River Delta region,China

Detailed surveys of surface water in two contrasting peri-urban areas in the Yangtze River Delta region of China were conducted to determine the distribution of heavy metals, nitrogen (N) and phosphorus (P) as well as the speciation of N and P. A factory-based (FB) area was compared with a vegetable-based (VB) area during the dry season. The concentrations of heavy metals in the surface water in the FB area were higher than those in the VB area, suggesting modest contamination of surface water with Zn, Cu, Cr and Pb but not Cd, from discharge of factory effluent in the FB area but not the VB area. Although total N (TN) and total P (TP) levels in the surface water were high in both areas, the surface water in the VB area had significantly higher levels of nitrate N (NO₃–N), organic N (ON) and TN than those in the FB area. In both areas, the levels of water-soluble P (WP), organic P (OP) and TP were high in the river water that received municipal wastewater. The distribution of N and P species throughout the surface water system indicated that the NO₃–N and ON mainly came from vegetable fields, while ammonium N (NH₄–N), WP and OP were mainly from municipal wastewater. Treatment of municipal wastewater prior to discharge to reduce N and P by purification is recommended together with research and extension to develop more efficient use of N and P fertilizer by vegetable farmers.     

A COMPARISON OF FLUORIMETRIC AND COLORIMETRIC METHODS FOR THE DETERMINATION OF α-MANNOSIDASE ACTIVITY IN BOVINE PLASMA

This paper compares both manual colorimetric and fluorimetric methods for the assay of acidic alpha-mannosidase activity in bovine EDTA plasma. The effect of variable blood volumes per 10 ml blood collecting tube has been investigated, and the colorimetric assay conditions adjusted (for example, zinc concentration in pre-incubation buffer) to cope with low blood volumes resulting in high EDTA/plasma ratios. We have shown that with non-haemolysed EDTA plasma samples, the two methods give similar results, but for haemolysed samples, the colorimetric method yields significantly lower results than those obtained fluorimetrically. Using the manual fluorimetric method, samples can be assayed more rapidly and simply than by using the colorimetric method. This provides definite advantages in a laboratory receiving variable numbers of samples, or which cannot afford the high cost of automated equipment.