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441.
Identifying the cause of toxicity in an algal whole effluent toxicity study - an unanticipated toxicant 总被引:1,自引:0,他引:1
Toxicity was observed in whole effluent toxicity (WET) studies with the freshwater alga, Pseudokirchneriella subcapitata, in three consecutive monthly studies, (NOEC = 50-75%). Toxicity was not observed to Ceriodaphnia dubia or the fathead minnow, Pimephales promelas in concurrent studies. Selected toxicity identification evaluation (TIE) tests were conducted in a tiered approach to eliminate possible toxicants and progressively identify the causative agent. Filtration following alkaline adjustment (pH 10 or 11) was effective in eliminating significant growth effects and also reduced phosphate concentration. The TIE studies confirmed that the observed effluent toxicity was caused by excess ortho-phosphate in the effluent not by overstimulation or related to unfavorable N:P ratios; but due to direct toxicity. The 96-h 25% inhibition concentration (IC25) of ortho-phosphate to P. subcapitata was 3.4 mg L−1 while the maximum acceptable toxicant concentration was 4.8 mg L−1. This study illustrates the value of multi-species testing and also provides an example of an effective TIE using algae identifying an unanticipated toxicant. 相似文献
442.
The U.S. Environmental Protection Agency has proposed permitting ballast water discharges—a benefit of which would be to reduce
the economic damages associated with the introduction and spread of aquatic invasive species. Research on ship-borne aquatic
invasive species has been conducted in earnest for decades, but determining the economic damages they cause remains troublesome.
Furthermore, with the exception of harmful algal blooms, the economic consequences of microscopic invaders have not been studied,
despite their potentially great negative effects. In this paper, we show how to estimate the economic benefits of preventing
the introduction and spread of harmful bacteria, microalgae, and viruses delivered in U.S. waters. Our calculations of net
social welfare show the damages from a localized incident, cholera-causing bacteria found in shellfish in the Gulf of Mexico,
to be approximately $706,000 (2006$). On a larger scale, harmful algal species have the potential to be transported in ships’
ballast tanks, and their effects in the United States have been to reduce commercial fisheries landings and impair water quality.
We examine the economic repercussions of one bloom-forming species. Finally, we consider the possible translocation within
the Great Lakes of a virus that has the potential to harm commercial and recreational fisheries. These calculations illustrate
an approach to quantifying the benefits of preventing invasive aquatic microorganisms from controls on ballast water discharges.
The views expressed in this paper are those of the authors and do not necessarily reflect the views or policies of the U.S.
Environmental Protection Agency. 相似文献
443.
近年来,尽管太湖主要水质指标有所改善,但蓝藻水华暴发的频次和面积并未明显减少。为了探讨太湖蓝藻水华暴发的环境驱动因子,统计了2012—2020年历年4—10月预警期间的太湖蓝藻水华发生规模与频次,结合同步浮标自动监测数据和实验室分析数据,构建了蓝藻水华预测模型。以太湖蓝藻水华综合指数(Ic)表征蓝藻水华强度,并通过Ic与环境因子的相关性分析,筛选出1月水温、1月电导率、1月生化需氧量和3月总氮浓度4项环境指标,最终构建了以该4项环境指标为自变量、Ic为因变量的太湖年度蓝藻水华强度多元线性回归预测模型。该预测模型的决定系数达到了0.908,平均相对误差为10.35%,预测精度总体表现较好。 相似文献
444.
445.
Research on biofuel production pathways from algae continues because among other potential advantages they avoid key consequential effects of terrestrial oil crops, such as competition for cropland. However, the economics, energetic balance, and climate change emissions from algal biofuels pathways do not always show great potential, due in part to high fertilizer demand. Nutrient recycling from algal biomass residue is likely to be essential for reducing the environmental impacts and cost associated with algae-derived fuels. After a review of available technologies, anaerobic digestion (AD) and hydrothermal liquefaction (HTL) were selected and compared on their nutrient recycling and energy recovery potential for lipid-extracted algal biomass using the microalgae strain Scenedesmus dimorphus. For 1 kg (dry weight) of algae cultivated in an open raceway pond, 40.7 g N and 3.8 g P can be recycled through AD, while 26.0 g N and 6.8 g P can be recycled through HTL. In terms of energy production, 2.49 MJ heat and 2.61 MJ electricity are generated from AD biogas combustion to meet production system demands, while 3.30 MJ heat and 0.95 MJ electricity from HTL products are generated and used within the production system.Assuming recycled nutrient products from AD or HTL technologies displace demand for synthetic fertilizers, and energy products displace natural gas and electricity, the life cycle greenhouse gas reduction achieved by adding AD to the simulated algal oil production system is between 622 and 808 g carbon dioxide equivalent (CO2e)/kg biomass depending on substitution assumptions, while the life cycle GHG reduction achieved by HTL is between 513 and 535 g CO2e/kg biomass depending on substitution assumptions. Based on the effectiveness of nutrient recycling and energy recovery, as well as technology maturity, AD appears to perform better than HTL as a nutrient and energy recycling technology in algae oil production systems. 相似文献
446.
Yuxiong Huang Manyu Gao Wenjing Wang Ziyi Liu Wei Qian Ciara Chun Chen Xiaoshan Zhu Zhonghua Cai 《Frontiers of Environmental Science & Engineering》2022,16(9):122