Zhang Ming-kui, Fang Li-ping
Institute of Soil and Water Resources and Environmental Science, College of Natural Resource and Environmental Sciences, Zhejiang University, Hangzhou, China.
J Environ Sci (China). 2006;18(4):816-21.
The rapid growth and intensification of freshwater fishery can cause imbalances between phosphorus (P) input in feed and its output in produce. This aquaculture can result in enriching exogenous P in fishponds and, consequently, accelerates the process of eutrophication. To assess relations among input, accumulation, release of P and as a consequence degrading water quality in terms of chlorophyll-a (Chl-a) in freshwater fishponds, fourteen fishponds with feed supply, nine fishponds without feed supply, and five non-fish ponds in Shaoxing Plain, southeast China were selected for comparing P accumulation in their waters and surface sediments. Surface sediment samples were collected from each pond to evaluate their total P, water soluble P, Olsen P, algal available P, and P fractions. Water samples were also collected from the ponds to measure concentrations of dissolved P and Chl-a. Total P in the sediments ranged from 0.88 to 1.73 g/kg in the fishponds with feed supply, that in the non-fish ponds ranged from 0.47 to 0.86 g/kg. Organic P, accounted for 23% to 60% of total P in the sediments, was an important P fraction and increased linearly with increasing organic matter. Long-term application of feeds resulted in increased P availability in the bottom sediments and degradation of water quality in the freshwater fishponds. Compared with non-fish ponds, sediments from the feed-supplied fishponds contained considerably higher Olsen P, algal available P, and water soluble P. Higher proportions of the labile P (NH4Cl-P) and potentially labile P (NaOH-IP) were also found in the sediments from the fishponds. High solubility of P in the sediments resulted in elevation of P and chlorophyll-a concentration in the pond water. The dissolved P concentration in the pond water increased in the order of non-fish ponds (12 microg/L) < fishponds without feed supply (24 microg/L) < fishponds with feed supply (66 microg/L). Linear correlations between concentrations of total P, Olsen-P, algal available P, water-soluble P and P concentration in saturation extracts in the sediments and dissolved P in the pond water indicated that there was a buffering action of the sediment constituents on the dissolved P.
淡水渔业的快速发展和集约化可能导致饲料中磷（P）的输入与其在产品中的输出之间失衡。这种水产养殖会导致鱼塘中外源磷的富集，进而加速富营养化进程。为了评估淡水鱼塘中磷的输入、积累、释放以及由此导致的以叶绿素-a（Chl-a）衡量的水质退化之间的关系，在中国东南部绍兴平原选取了14个有饲料供应的鱼塘、9个无饲料供应的鱼塘和5个非鱼塘，比较它们水体和表层沉积物中的磷积累情况。从每个池塘采集表层沉积物样本，以评估其总磷、水溶性磷、 Olsen磷、藻类可利用磷和磷组分。还从池塘采集水样，测量溶解磷和叶绿素-a的浓度。有饲料供应的鱼塘沉积物中总磷含量在0.88至1.73 g/kg之间，非鱼塘中总磷含量在0.47至0.86 g/kg之间。有机磷占沉积物总磷的23%至60%，是一个重要的磷组分，且随有机质增加呈线性增加。长期投喂饲料导致淡水鱼塘底部沉积物中磷的有效性增加和水质退化。与非鱼塘相比，有饲料供应的鱼塘沉积物中 Olsen磷、藻类可利用磷和水溶性磷含量显著更高。在鱼塘沉积物中还发现了较高比例的活性磷（NH4Cl-P）和潜在活性磷（NaOH-IP）。沉积物中磷的高溶解度导致池塘水体中磷和叶绿素-a浓度升高。池塘水体中溶解磷浓度的增加顺序为：非鱼塘（12μg/L）<无饲料供应的鱼塘（24μg/L）<有饲料供应的鱼塘（66μg/L）。沉积物中总磷、Olsen-P、藻类可利用磷、水溶性磷浓度与饱和提取液中磷浓度以及池塘水体中溶解磷之间的线性相关性表明，沉积物成分对溶解磷有缓冲作用。
