Design and Application of Multi-layer Starch-Latex Blends as Phosphorous Delivery System

Journal of Polymers and the Environment - The search for highly productive agriculture has considerably increased the use of fertilizers, becoming a worrying source of environmental and health...     

Source analysis of high particulate matter days in Hong Kong

This study identifies major contributing sources of high particulate matter (PM) days in Hong Kong and conducive meteorological conditions leading to high PM. The PM₁₀ chemical composition of 3393 ambient samples collected at ten monitoring stations in Hong Kong during 1998–2005 were used as input for positive matrix factorization (PMF) modeling to identify and quantify the aerosol sources in Hong Kong. Days with PM₁₀ levels exceeding 56 μg m^?3, the average plus one standard deviation of the mass concentration of all samples, are defined as high PM days. A total of 401 samples fell in the high PM category during the study period. Biomass burning, secondary sulfate and secondary nitrate were found to be the major contributors leading to high PM, responsible for 68–73% of PM₁₀ mass on high PM days. The contributions by these sources on high PM days were 140–180% higher than their respective average concentration contributions. These sources were identified to be regional sources on the grounds of little spatial variation in their concentrations among the monitoring stations and a temporal pattern of higher in the winter and lower in the summer. Sampling days of high PM in 2004 and 2005 were individually examined for weather charts and regional surface wind maps. Weak high pressures over mainland China were the most important synoptic event leading to high PM days in the fall and winter, while typhoon episodes were responsible for most summer cases. Approximately 80% of the high PM days were in the fall and winter months (September–February). Almost all the high PM days were associated with northwesterly, northerly or northeasterly regional transport. Anthropogenic primary sources (coal combustion, vehicular exhaust, and residue oil combustion) showed the highest contributions associated with northwesterly wind, indicating the strong influence of the more urbanized areas to the northwest of Hong Kong in the Pearl River Delta region.     

Use of high-resolution MM5/CALMET/CALPUFF system: SO2 apportionment to air quality in Hong Kong

Recent research has highlighted the substantial health-related costs of air pollution in the Hong Kong Special Administrative Region (HKSAR) and the potential threat from air pollution to HKSARs economic competitiveness. In order to address the air pollution problems, this paper seeks to analyse the individual contributions of major sulphur dioxide (SO₂) sources in the Pearl River Delta Region (PRDR) (Pearl River Delta + HKSAR) on the air quality in the HKSAR. This study employed the coupling of the MM5/CALMET system with the CALPUFF, the multi-layer, non-steady-state puff dispersion model, where major power plants, marine vessels and vehicles, all in the PRDR, are taken into account. The observation data and simulation results at 11 Hong Kong Environmental Protection Department (HKEPD) general (non-road-side) stations are analyzed. Urban (in-zone) and Rural (out-zone) stations are defined in order to examine the SO₂ contribution of different emission sources in different regions of the HKSAR. The model results show that the contribution of the HKSAR marine sources is significant both in summer and in winter, especially for the locations around the in-zone stations (in general 60%, and 55% in summer and winter respectively). In addition, the contribution of the HKSAR power plants is slightly higher than that of the PRD power plants in early summer, with a contribution difference of up to 20% when the prevailing wind is from the south. However, in late summer, this situation reverses. In winter, the contribution of the PRD power plants is two to three times greater than that of the HKSAR power plants. Moreover, Yantian port affects the northern part of the HKSAR when a northeasterly wind dominates the HKSAR. In order to solve these air pollution problems, the main implication of these results suggests that the HKSAR government, in close co-operation with the Guangdong government, needs to take immediate action.     

Antioxidative responses of duckweed (<Emphasis Type="Italic">Lemna minor</Emphasis> L.) to short-term copper exposure

Goal, Scope and Background

Elevated concentrations of copper in the environment result in accumulation of the metal in plants and cause an increase in reactive oxidative species (ROS). The first response to elevated amounts of ROS is increased levels of enzymatic and non-enzymatic antioxidants that reduce oxidative stress. The aim of our study was to evaluate the early stages of antioxidative responses to the low copper concentrations usually present in moderately polluted environments. In addition, some other parameters were examined to evaluate the effect of copper on plants.

Methods

Duckweed (Lemna minor L.) was exposed to different concentrations of copper sulphate for up to 24 hours. Glutathione concentration and enzymatic activities of catalase, guaiacol peroxidase and glutathione reductase were measured spectrophotometrically. Additionally, delayed and prompt chlorophyll fluorescence was measured by luminometry and fluorometry, respectively. The accumulation of copper in plants exposed for 24 hours to various concentrations of copper sulphate was measured by flame atomic absorption spectrophotometry.

Results

The treatment of plants with copper sulphate resulted in an immediate decrease of the glutathione pool, which was replenished after 24 hours at CuSO₄ concentrations lower than 2 μM. Higher CuSO₄ concentrations caused a decrease of reduced glutathione. The responses of the antioxidant enzymes glutathione reductase, guaiacol peroxidase and catalase to CuSO₄ differed during the first six hours of exposure, but their enzyme activities all increased after 24 hours of exposure. All these enzymes displayed biphasic activity curves with maximum values between 0.5 μM and 1 μM CuSO₄. The response of guaiacol peroxidase was the most pronounced and statistically significantly specific and that of catalase the least. Delayed chlorophyll fluorescence decreased after exposure to 1 μM CuSO₄, but no significant effect on maximum quantum yield of photosystem II (Fv/Fm) was observed. L. minor accumulated relatively high concentrations of copper. The accumulation rate was higher at lower concentrations of copper in the test medium (up to 2 μM CuSO₄) than at concentrations above 2 μM CuSO₄.

Discussion

One of the most pronounced antioxidative responses to copper exposure was modified levels of oxidized and reduced forms of glutathione. The decrease of the glutathione pool is most probably coupled with induced production of phytochelatins. Antioxidative enzymes showed the biphasic enzyme activity characteristic of stress response. Guaiacol peroxidase exhibited the greatest significant increase of activity, even at higher CuSO₄ concentrations at which the activity of catalase and glutathione reductase dropped. The intensity of delayed chlorophyll fluorescence decreased, indicating reduced photosynthesis of plants under stress. All the measured parameters showed that plants respond to even low copper concentrations very soon after exposure. The accumulation rate of copper in duckweed tissues indicates that L. minor is an accumulator species.

Conclusions

The synchronized and prompt inducibility of antioxidants indicates their involvement in a general plant defence strategy for coping with metal-induced oxidative stress. Glutathione concentration and guaiacol peroxidase activity were found to be the most sensitive of the early indicators of exposure to copper concentrations present in polluted water bodies.

Recommendation and Perspectives

The experimental design of the present study allowed us to compare the sensitivity of various methods and parameters for detecting plant responses to heavy metal-induced oxidative stress. The level of glutathione and the enzyme activities of guaiacol peroxidase and glutathione reductase could be used as a rapidly determined early warning system in toxicity studies.

     

PCDD/F and dioxin-like PCB in Hong Kong air in relation to their regional transport in the Pearl River Delta region

PCDD/F and dioxin-like PCB were measured in 142 air samples of Hong Kong. The annual average PCDD/F and dioxin-like PCB concentrations obtained for Hong Kong air at Tap Mun (PCDD/F: 1724+/-1984; dioxin-like PCB: 1572+/-1170 fg m(-3)), Yuen Long (PCDD/F: 2927+/-2695; dioxin-like PCB: 4331+/-1962 fg m(-3)) and Tsuen Wan (PCDD/F: 1875+/-1502; dioxin-like PCB: 2972+/-1510 fg m(-3)) from January 2004 to March 2005 were comparable to other urban centers around the world and were within the Japanese and USA ambient air quality guidelines. A clear seasonal pattern was observed for PCDD/F, generally with a 50-60 times higher air concentration in winter when background northerly wind was weaker and land-sea breeze prevailed, resulting in regional transport; and a lower concentration in summer, due to the inflow of clean oceanic southeasterly wind from the South China Sea. A higher WHO-TEQ value of dioxin-like PCB (mainly attributed to the relatively higher WHO-TEQ value of PCB 126) in Yuen Long during winter, compared with other months, could also be related to the regional transport by the winter monsoon wind and the low mixing height in winter. Spatially, air concentrations of PCDD/F and dioxin-like PCB demonstrated a west-to-east gradient (with Yuen Long>Tsuen Wan>Tap Mun). It is suggested that PCDD/F and dioxin-like PCB were transported into the western airshed of Hong Kong from the Pearl River Delta by land-sea breeze circulation and confined to the northwestern part, due to the blocking effect of the northwestern airshed in Hong Kong.     

粤港澳大湾区PM2.5本地与非本地污染来源解析

粤港澳大湾区(简称"大湾区")建设是我国新时代重大国家战略之一.虽然大湾区空气质量在我国处于领先地位,但与世界先进湾区相比还有较大差距.制定大湾区PM_2.5精细化防控策略,需要在识别大湾区各城市PM_2.5污染来源的基础上,量化PM_2.5本地和非本地贡献及时空变化规律.基于此,本研究首次在大湾区15个站点同步开展持续一年的PM_2.5采样和组分分析,并将正定矩阵因子分析模型与后向轨迹结合,建立一种定量识别PM_2.5本地与非本地贡献的新方法.通过对大湾区不同季节所属空气域进行划分,厘清大湾区各城市PM_2.5本地与非本地贡献的动态化特征.结果发现,在2015年,大湾区15个站点共解析出9种PM_2.5污染源,分别为机动车、重油、老化海盐、扬尘源、二次硫酸盐、二次硝酸盐、金属冶炼、生物质燃烧和新鲜海盐.其中,二次硫酸盐和机动车是大湾区最主要的两个PM_2.5污染源.不同站点非本地贡献占比为51%～72%,表明外来传输是大湾区P...     

开发心血管和神经发育指标作为鱼类胚胎毒性实验中的亚致死终点

黑头软口鲦的胚胎毒性实验(fish embryo toxicity, FET)是一个更加人性化的替代方法，因为年轻生物被认为在毒物暴露中受到的危害更小。FET实验草案没有包括毒性终点以预测亚致死有害结局，这限制了它的应用。研究者针对FET实验提出了亚致死毒性终点的开发以增进该方法的应用范围。本研究针对黑头软口鲦开发了用于以往未测定过的亚致死指标的方法(例如自主收缩频率和心率)；考察了一些亚致死效应终点的响应情况，包括成长相关的(湿重、体长、生长相关基因表达)，神经发育方面的(自主收缩频率和神经发育基因表达)，心血管功能和发育(心包区面积、眼睛大小和心血管相关基因表达)，这是指标均作为FET实验的额外指标，模式毒物为3,4-二氯苯胺。其中，体长、眼睛尺寸和心包区面积相比于其他终点响应更为敏感。建立长时间有害影响与这些终点变化的关系对全面评价这些指标的毒性预测能力十分必要。 精选自Julie C. Krzykwa, Alexis Olivas, Marlo K. Sellin Jeffries. Development of cardiovascular and neurodevelopmental metrics as sublethal endpoints for the fish embryo toxicity test. Environmental Toxicology and Chemistry,2018,37:2530-2541.
详情请见 https://doi.org/10.1002/etc.4212
     

U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes

U-series data relating to groundwater, fracture coatings and the adjoining rock matrix in a groundwater flow system at the Palmottu natural analogue site was examined. The aim was to obtain an experimental reference for migration modelling in a transport section defined within the flow system. The U-series reference obtained turned out to be a very useful tool for fine tuning the flow route and for migration mechanism considerations. The U-series data are well in line with other interpretations of the migration system.     

A decision framework for estimating the cost of marine plastic pollution interventions

Marine plastic pollution has emerged as one of the most pressing environmental challenges of our time. Although there has been a surge in global investment for implementing interventions to mitigate plastic pollution, there has been little attention given to the cost of these interventions. We developed a decision support framework to identify the economic, social, and ecological costs and benefits of plastic pollution interventions for different sectors and stakeholders. We calculated net cost as a function of six cost and benefit categories with the following equation: cost of implementing an intervention (direct, indirect, and nonmonetary costs) minus recovered costs and benefits (monetary and nonmonetary) produced by the interventions. We applied our framework to two quantitative case studies (a solid waste management plan and a trash interceptor) and four comparative case studies, evaluating the costs of beach cleanups and waste-to-energy plants in various contexts, to identify factors that influence the costs of plastic pollution interventions. The socioeconomic context of implementation, the spatial scale of implementation, and the time scale of evaluation all influence costs and the distribution of costs across stakeholders. Our framework provides an approach to estimate and compare the costs of a range of interventions across sociopolitical and economic contexts.