Ecosystem Modeling Applied to Nutrient Criteria Development in Rivers

Threshold concentrations for biological impairment by nutrients are difficult to quantify in lotic systems, yet States and Tribes in the United States are charged with developing water quality criteria to protect these ecosystems from excessive enrichment. The analysis described in this article explores the use of the ecosystem model AQUATOX to investigate impairment thresholds keyed to biological indexes that can be simulated. The indexes selected for this exercise include percentage cyanobacterial biomass of sestonic algae, and benthic chlorophyll a. The calibrated model was used to analyze responses of these indexes to concurrent reductions in phosphorus, nitrogen, and suspended sediment in an enriched upper Midwestern river. Results suggest that the indexes would respond strongly to changes in phosphorus and suspended sediment, and less strongly to changes in nitrogen concentration. Using simulated concurrent reductions in all three water quality constituents, a total phosphorus concentration of 0.1 mg/l was identified as a threshold concentration, and therefore a hypothetical water quality criterion, for prevention of both excessive periphyton growth and sestonic cyanobacterial blooms. This kind of analysis is suggested as a way to evaluate multiple contrasting impacts of hypothetical nutrient and sediment reductions and to define nutrient criteria or target concentrations that balance multiple management objectives concurrently. Any opinions, findings, conclusions, or recommendations expressed in this article are those of the authors alone, and do not necessarily reflect the views of the U.S. Environmental Protection Agency or of the U.S. Government.     

不同溶剂对化感物质抑藻效果的影响

以铜绿微囊藻作为生物材料,邻苯二甲酸二丁酯和没食子酸作为化感物质,研究了这两种化感物质在不同浓度下对铜绿微囊藻生长的影响,对比了不同溶剂中两种化感物质的抑藻效果.结果表明,低浓度的邻苯二甲酸二丁酯对铜绿微囊藻的生长具有一定促进作用.但高浓度时抑制其生长;没食子酸对铜绿微囊藻的生长具有一定的抑制作用,但浓度的影响规律性并不明显;对邻苯二甲酸二丁酯来说,乙醇溶剂可以增强其对铜绿微囊藻生长的抑制作用,而对没食子酸来说,甲醇溶剂可以减弱其对铜绿微囊藻生长的抑制作用.可见,在化感物质发生作用时,化感物质用量和溶剂种类起着极其重要的作用.     

Formaldehyde in China: Production, consumption, exposure levels, and health effects

Formaldehyde, an economically important chemical, is classified as a human carcinogen that causes nasopharyngeal cancer and probably leukemia. As China is the largest producer and consumer of formaldehyde in the world, the Chinese population is potentially at increased risk for cancer and other associated health effects. In this paper we review formaldehyde production, consumption, exposure, and health effects in China. We collected and analyzed over 200 Chinese and English documents from scientific journals, selected newspapers, government publications, and websites pertaining to formaldehyde and its subsequent health effects.Over the last 20 years, China's formaldehyde industry has experienced unprecedented growth, and now produces and consumes one-third of the world's formaldehyde. More than 65% of the Chinese formaldehyde output is used to produce resins mainly found in wood products — the major source of indoor pollution in China. Although the Chinese government has issued a series of standards to regulate formaldehyde exposure, concentrations in homes, office buildings, workshops, public places, and food often exceed the national standards. In addition, there have been numerous reports of formaldehyde-induced health problems, including poisoning and cancer. The lack of quality epidemiological studies and basic data on exposed populations emphasizes the need for more extensive studies on formaldehyde and its related health effects in China.     

猫跳河流域梯级水库夏季N2O的产生与释放机理

为了研究河流筑坝对河流氮生物地球化学循环的影响,在夏季水体分层期间对猫跳河梯级水库坝前分层采集水样进行了相关地球化学分析。结果显示,在上游的两座水库存在2个明显的温度分层现象,并影响到了水体N2O的产生和分布。红枫水库整个剖面的氮分布主要受硝化作用控制,而百花湖、修文及红岩水库则表现为上层水体为硝化作用,中层为硝化反硝化共同作用。所有水库表层水和下泄水高饱和度的N2O含量表明这些水体为大气N2O的源。百花湖底层反硝化作用强烈,中间产物N2O大量消耗。底层泄水的方式对于温室气体释放影响重大,因此不同水库下泄水的N2O含量在时间和空间上的变化与水库运行和调蓄模式有关。研究结果表明,梯级水库过程对N2O的排放影响很大,在水电开发的环境保护中应当引起重视。     

Evaluating the air quality impacts of the 2008 Beijing Olympic Games: On-road emission factors and black carbon profiles

The aggressive traffic interventions and emission control measures implemented to improve air quality during the 2008 Beijing Olympic Games created a valuable case study to evaluate the effectiveness of these measures on mitigating air pollution and protecting public health. In this paper, we report the results from our field campaign in summer 2008 on the on-road emission factors of carbon monoxide, black carbon (BC) and ultrafine particles (UFP) as well as the ambient BC concentrations. The fleet average emission factors for light-duty gasoline vehicles (LDGV) showed considerable reduction in the Olympic year (2008) compared to the pre-Olympic year (2007). Our measurement of Black Carbon (BC), a primary pollutant, at different elevations at the ambient site suggests consistent decrease in BC concentrations as the height increased near the ground level, which indicates that the nearby ground level sources, probably dominated by traffic, contributed to a large portion of BC concentrations in the lower atmospheric layer in Beijing during summertime. These observations indicate that people living in near ground levels experience higher exposures than those living in higher floors in Beijing. The BC diurnal patterns on days when traffic control were in place during the Olympic Games were compared to those on non-traffic-control days in both 2007 and in 2008. These patterns strongly suggest that diesel trucks are a major source of summertime BC in Beijing. The median BC concentration on Olympic days was 3.7 μg m⁻³, which was dramatically lower than the value on non-traffic-control days, indicating the effectiveness of traffic control regulations in BC reduction in Beijing.     

Organochlorine pesticides in Avicennia marina from the Mumbai mangroves, India

This paper examines the concentration levels of organochlorine pesticides (OCPs) such as hexachlorocyclohexane (HCH) (α, β and γ), Aldrin, Endosulfan (α, β), DDE, DDD, and DDT in the leaf, root and sediment part of Avicennia marina, a dominantly distributed mangrove species in Mumbai. The overall pattern of accumulation of OCPs was observed as ∑HCH > ∑DDT > ∑Endosulfan > Aldrin. The occurrence of αHCH was found to be frequent in all the samples. The leaf and root samples showed better uptake of organochlorine pesticides whereas lower concentration levels of OCPs was observed in case of sediment samples. The mean concentration of OCPs was observed highest in case of root samples. This study indicated towards the capability of A. marina in bioaccumulation of the OCPs. The present data will serve as the baseline against which future study of OCPs uptake in the mangrove plant species may be assessed.     

Predicting the effects of ionising radiation on ecosystems by a generic model based on the Lotka–Volterra equations

The present work describes a model for predicting the population dynamics of the main components (resources and consumers) of terrestrial ecosystems exposed to ionising radiation. The ecosystem is modelled by the Lotka–Volterra equations with consumer competition. Linear dose–response relationships without threshold are assumed to relate the values of the model parameters to the dose rates. The model accounts for the migration of consumers from areas characterised by different levels of radionuclide contamination. The criteria to select the model parameter values are motivated by accounting for the results of the empirical studies of past decades. Examples of predictions for long-term chronic exposure are reported and discussed.     

Nature Documentaries,Connectedness to Nature,and Pro-environmental Behavior

We investigate the effects of nature documentaries on pro-environmental cognition and behavior. Of central interest is the concept of connectedness to nature, which describes an individual's sense of being connected to nature. Based on previous research showing that a direct nature experience in zoos can increase connectedness to nature, we questioned whether watching a nature documentary could increase connectedness to nature and pro-environmental behavior. An experiment using one control group (watching a documentary about Einstein's theory of relativity) and one treatment group (watching a nature documentary) revealed that a mediated nature experience is not sufficient to elicit an increase in connectedness to nature. However, we found that exposure increased actual donation behavior for animal and environmental protection organizations. It is important to note that nature documentary exposure increased pro-environmental donation behavior only in those already having a strong sense of connectedness. We discuss real-world implications for donation-accepting, non-profit organizations.     

A Case Study of Ecosystem Services in Urban Planning in Finland: Benefits,Rights and Responsibilities

The concept of ecosystem services is entering the agenda of land-use planning and scientists optimistically expect it to inform planners and decision-makers about the benefits that ecosystems provide. While tools and methods have been developed for mapping and valuing ecosystem services, only little attention has been paid to the practical application of the approach or its institutional preconditions and implications. We empirically analysed two urban planning processes for building residential areas in the outskirts of growing population centres in Finland. Our analysis of documents and interviews with planners focused on the benefits provided by ecosystems as well as the associated rights and responsibilities. We found that the concept ‘ecosystem service’ was not used, yet various benefits were identified. The rights of different stakeholders to ecosystem services were not explicitly identified, but many ecosystem services were perceived as public goods and particularly access to recreation was highlighted as an important justification for green areas. The results show that while the ecosystem services approach introduces new insights to land-use planning, it is still not embedded in the current practices or institutions. Operationalizing ecosystem services requires institutional adaptation, case-specific tailoring of methods, and deliberation among practitioners and stakeholders.     

Multi-effects of gravity and geometric flow channel on the performance of continuous microbial fuel cells

Nowadays microbial fuel cells (MFCs) are a rapidly evolving field and studied extensively because of their simultaneous dual functions of decomposing organic waste matter and eco-power generation. Now, facing their low power density, multiple effects including various gravity conditions ranging from 0 G to 2 G and three kinds of geometric flow channel (serpentine channel, serpentine tapered channel and bio-mixer channel) in MFCs were studied because of their ability to significantly impact the performance of MFCs.Numerical simulation technology, with its significant lessening of time needed and saving experimental costs required was used in this study. Results show that a better power performance was found at a condition of 0.125 G and Reynolds number Re = 41.3 regardless of flow channel in MFCs. In addition, the bio-mixer channel of the flow channels in MFCs will have a better performance than the other two channels because of its lower pressure drop and higher power generation. These findings will provide useful information on enhancing the performance of MFCs, especially with the application of low gravity conditions in the future.