磷 ,洗涤剂和富营养化的控制——欧洲和北美经验(英文)

Phosphorus, Detergents and Eutrophication Control——a Summary of Experience in Europe and North America

富营养化引起一系列严重问题。早期在北部温暖岩地区的研究认为磷是导致富营养化的决定元素 ,控制磷含量是治理富营养化的最佳途径。废水中的磷大约有 2 5 %来自于洗涤剂所含的磷酸盐 ,因此一直存在要求改进洗涤剂配方的压力。然而要使环境产生显著改善光靠减少这部分磷的含量是远远不够的。目前 ,控制富营养化的手段仍主要依靠控制废水中的磷含量 ,但人们清楚 ,不同地区影响因素是各不相同的。在低洼地区 ,水中的磷主要来源于农业活动。而在另一些土壤肥沃的地区 ,氮化物相对于磷更缺乏 ,这是因为在湖盆边缘潮湿地区的脱氮作用 ,大量硝酸盐可能从土壤中淋溶出去 ,在这种环境下只能通过控制氮来加以改善。其他地区如浅湖 ,温带热带地区的湖泊 ,在富营养化问题上也都是氮比磷重要。在某些地区强调控制磷含量是正确的 ,但并不适用于所有地区。片面强调污水处理同样也不是包治百病的灵丹妙药。只改变洗涤剂的配方并不能显著地改善环境。这些观点反映了我们对富营养化问题虽己有所了解但还需要更加全面。

Eutrophication may cause serious problems. Early research, in north temperate, siliceous rock catchments, established phosphorus as the driving nutrient and phosphorus control was determined as the best solution. Phosphates in laundry detergents were contributing about 25% of the phosphorus in the waste water and there was pressure to change the formulation of detergents. This was, however, insufficient to reduce the phosphate concentrations in effluents to values that could have any significant environmental effects. Additional phosphorus precipitation from effluents (phosphorus stripping) was always necessary. Policies on eutrophication control have nonetheless been dominated by phosphorus control in waste waters but it is now clear that the problem is different in other areas. In lowlands, the sources of phosphorus to freshwaters may be dominated by agriculture. In other lowland areas, with naturally fertile soils, nitrogen compounds may be relatively scarcer than those of phosphorus owing to denitrification in wetlands surrounding the lake basins. The process in these areas has probably been driven by leaching of nitrate from cultivated soils and the solution must then be by nitrogen control. Other situations where nitrogen is likely to be of greater importance than phosphorus include shallow lakes, and lakes in warm temperate and tropical areas. All of these considerations are relevant to the control of eutrophication in Chinese lakes.The current emphasis on phosphorus control is correct in some areas, but inappropriate in many others; the emphasis on waste water treatment is likewise not a universal panacea. Pressures to change detergent formulations are unlikely to result in measurable improvements. They reflect an understandable but limited historical view of the eutrophication problem.