Environmental Research Institute of the Supervising Scientist, Department of Sustainability, Environment, Water, Population and Communities, GPO Box 461, Darwin, Northern Territory 0801, Australia.
Water Res. 2011 Dec 1;45(19):6393-402. doi: 10.1016/j.watres.2011.09.032. Epub 2011 Sep 29.
Flocculant blocks are commonly used as a component of (passive) water treatment systems to reduce suspended sediment loads in the water column. This study investigated the potential for aquatic biological impacts of a flocculant block formulation that contained an anionic polyacrylamide (PAM) active ingredient and a polyethylene glycol (PEG) based carrier. The toxicity of the whole flocculant block was assessed and the individual components of the block were also tested separately. Five Northern Australian tropical freshwater species (i.e. Chlorella sp. Lemna aequinoctialis, Hydra viridissima, Moinodaphnia macleayi and Mogurnda mogurnda) were exposed to a range of concentrations of the whole flocculant block, and of the individual PAM and PEG components. The concentration of Total Organic Carbon (TOC) in solution was used to provide a measure of the total amount of PAM and PEG present. An extremely wide range of toxic responses were found, with the flocculant blocks being essentially non-toxic to the duckweed, fish and algae (IC(50)>1880mgl(-1)CTOC, IC(10)>460mgl(-1)CTOC), slightly toxic to the hydra (IC(50)=610-2180mgl(-1)CTOC, IC(10)=80-60mgl(-1)CTOC) and significantly more toxic to the cladoceran (IC(50)=10mgl(-1)CTOC, IC(10)=4mgl(-1)CTOC). More detailed investigation of the two components indicated that the PAM was the primary "toxicant" in the flocculant blocks. Derived Protective Concentrations (PCs) for the flocculant blocks, expressed as equivalent TOC concentrations, were found to be lower than typically measured natural environmental concentrations of TOC. It will thus be possible to use TOC as measure of the concentration of PAM only in those situations where lower levels of ecosystem protection (i.e. higher PCs) are applicable.
絮凝块通常被用作（被动）水处理系统的一个组成部分，以减少水柱中悬浮泥沙的负荷。本研究调查了一种含有阴离子聚丙烯酰胺（PAM）活性成分和基于聚乙二醇（PEG）的载体的絮凝块配方对水生生物的潜在影响。评估了整个絮凝块的毒性，并分别测试了块的各个成分。五种澳大利亚北部热带淡水物种（即绿球藻、浮萍、水螅、大型溞和莫古恩达鳜）暴露于一系列浓度的整个絮凝块，以及单独的 PAM 和 PEG 成分。溶液中总有机碳（TOC）的浓度用于提供存在的 PAM 和 PEG 总量的度量。发现了极其广泛的毒性反应范围，絮凝块对浮萍、鱼类和藻类基本上无毒（IC（50）>1880mgl（-1）CTOC，IC（10）>460mgl（-1）CTOC），对水螅有轻微毒性（IC（50）=610-2180mgl（-1）CTOC，IC（10）=80-60mgl（-1）CTOC），对桡足类动物毒性显著更大（IC（50）=10mgl（-1）CTOC，IC（10）=4mgl（-1）CTOC）。对这两个成分的更详细调查表明，PAM 是絮凝块中的主要“毒物”。以等效 TOC 浓度表示的絮凝块衍生保护浓度（PCs）被发现低于通常测量的 TOC 天然环境浓度。因此，只有在适用较低水平的生态系统保护（即较高的 PCs）的情况下，才可以将 TOC 用作 PAM 浓度的度量。
