Performance optimisation of a passive sampler for monitoring hydrophobic organic pollutants in water

The performance of an integrative passive sampler that consists of a C18 Empore disk sorbent receiving phase fitted with low density polyethylene membrane was optimised for the measurement of time-weighted average concentrations of hydrophobic micropollutants in water. A substantial improvement of sampling characteristics including the rate of sampling and the sampling precision was achieved by decreasing the internal sampler resistance to mass transfer of hydrophobic organic chemicals. This was achieved by adding a small volume of n-octanol, a solvent with high permeability (solubility [times] diffusivity) for target analytes, to the interstial space between the receiving sorbent phase and the polyethylene diffusion-limiting membrane.     

Government plans and farmers intentions: a study on forest land use planning in Vietnam

In 1998, the Vietnamese National Assembly approved a Five Million Hectare Reforestation Program, (5MHRP) 1998-2010. It would increase forest cover by some 45%, use barren hills, produce wood, and generate socioeconomic development. It would, however, also put demands on Vietnamese planning. Experiences from a former development project and two case studies from a commune and village are used as a basis for analyzing the planning system. The study describes the objectives and strategies of government and farmers in one commune and one village and analyzes how planning data influence scenarios on future development. Official planning data do not reflect reality but are derived through negotiations. In the commune and village studied, it would be difficult for the 5MHRP to materialize, as most of the forest land, officially not yet used, is actually used for food production. The approach and method used by the study offers alternatives to current planning practices.     

A one year study of the seasonal variations of sDDT and PCB levels in fish from heated and unheated areas near a nuclear power plant

An investigation of the influence of excess heat discharge from a nuclear power plant on the residual levels of the sDOT and PCB in roach and perch has been made during a period of one year. A seasonal variation of the residual concentrations was observed, with the highest levels during spring and early summer and lower more stable levels in the autumn. Significantly higher levels of the sDDT and PCB was observed in perch from the cooling water recipient as compared to values in perch from the intake area. No significant differences could however be verified for roach. The result stress the importance that, in a monitoring program, a sampling period with stable ecological conditions is selected.     

A Regional Cadmium Inventory: interpretation and management

Local authorities in Sweden are responsible for the management of sewage treatment and municipal solid waste. Due to this, they handle large flows and stocks of materials and substances that may be harmful for the environment. However, knowledge about these flows is sometimes deficient. In addition, the capacity to influence the composition of these flows is mainly beyond the jurisdiction of the local authorities. Flow-oriented studies, such as substance flow analysis (SFA), have proven to be a useful tool in order to understand and quantify these flows. Furthermore, SFA is sometimes claimed to be beneficial to the process of decision making, since it generates comprehensive overviews of the substance in focus. However, quantification of stocks and flows of a certain substance does not necessarily provide sufficient information for environmental management on the local level. Hence, for SFA to further contribute to the environmental management process, there is also a need for development in the interpretation of the results. The main objective of this paper is to contribute to the discussion about (1) how to interpret the results from SFA and (2) how the results from an SFA can be used in environmental management by local authorities. A tentative framework for interpretation is discussed in the paper, focusing on five aspects: total material quantities, exposure to humans and the environment, resource economy, function and capacity to influence the substance flows. Furthermore, the paper discusses the suggested framework applied to results of a regional cadmium inventory.     

Cadmium in sewage sludge in a Swedish region: sources and reduction opportunities

To create a more sustainable future, one of the Swedish government’s aims is to close the eco-cycles between urban consumption areas and arable land. Increasing the use of sewage sludge from municipal wastewater treatment plants (MWTPs) is one method of achieving this goal. However, the use of sewage sludge is often prohibited due to its high concentrations of cadmium. As a consequence, large amounts of sewage sludge are deposited each year in landfills. This disposal has become more expensive for local authorities due to a new deposit tax introduced in the year 2000. Based on a survey of cadmium sources to MWTPs in a Swedish region this paper focuses on opportunities local authorities in Sweden have to influence the occurrence of cadmium in the sewage sludge. The results from the study show that cadmium in sewage sludge originates from diffuse sources, which are hard for local authorities to influence by direct means. This is most obvious for sources of cadmium in wastewater from households, which causes about one-third of the inflow of cadmium to MWTPs. Thus, the local authorities’ possibilities are, in general, still restricted to downstream actions (such as disconnecting identified industrial sources and reconstructing the sewage system to further separate collection of wastewater and storm water). Local authorities could also implement changes in the process at the MWTP or an extended treatment of the sewage sludge generated. Nonetheless, these possible measures do not provide a sustainable solution to the cadmium issue since the origins of the sources remain. Hence, long-term strategies — outside of the scope of local authorities — need to focus on a general decrease of cadmium in society. However, increased knowledge about the distribution among different sources of cadmium to MWTPs may encourage local authorities to establish priorities for measures that will improve the quality of the sewage sludge.     

西印度洋地区海草生态系统

海草是海洋被子植物,广泛分布在温带和热带的海岸带水域,是地球上水生生态系统中最具生产力的生物之一.     

雄性波罗的海灰海豹(Halichoerus grypus)骨组织的矿物密度

本文利用非侵入计算层析X射线摄影法(pQCT)研究了雄性波罗的海灰海豹(4～23岁龄)骨组织的矿物密度(mg/cm3).资料按照收集的年份分组.A组1850～1955年,有机氯(OCs)大量引入之前的时期;B组1965～1985年,OC污染十分严重的时期;C组1986～1997年,OCs浓度逐渐减小的时期.测量结果的复现性良好,变异系数(CV)为0.1%～2.1%.1986～1997年收集的标本中桡骨小梁的矿物密度比1965～1985年收集的标本的明显要高(p＜0.05).1986～1997年收集的标本中,下颌骨的皮层骨矿物密度明显地低于1850～1955年收集的标本(p＜0.05).这些结果表明小梁和皮层骨在一段时间内的不同响应.在OC污染非常严重的时期(1965～1985年),小梁骨矿物密度最低,而在1985～1997年收集的标本中,皮层骨密度最低,该时段是一个OC污染程度相当低的时期.有关这些效应背后的机制目前尚不知道.但是,可以假定这里涉及到OCs.由于目前缺乏有关研究个体中OCs残留水平的资料,因此不可能评估OCs在这方面的影响.     

Rival recognition affects male contest behavior in sand lizards (Lacerta agilis)

Individual male sand lizards meet repeatedly during mate search and engage in costly interactions. If males can recognize rivals, the number of costly fights with a predictable outcome may be reduced. In staged contests between males, second interactions are on average significantly shorter than first ones, suggesting individual recognition. When aggressive behavior differs substantially between the sexes, the more aggressive sex may be predicted to have more variation in skin traits located on the parts of the body displayed during contests; this would facilitate individual recognition. Male (aggressive) sand lizards are more variable in two of three lateral skin traits displayed during males' contests, while females (non-aggressive) are more variable in one dorsal skin trait; in four other dorsal traits there was no difference in variability between the sexes.     

SHEBA期间北极大气边界层的模型模拟

利用COAMPSTM区域模型,我们为北冰洋地表热收支(SHEBA)实验重现了北极大气边界层.模型结果与探测、近地面测量和ECMWF模型所做的预报做了比较.除了因云顶冷却导致边界层被云笼罩且充分混合的较短时期外,冬季近地面温度通常过高.在夏季融冰季节温度也稍有偏高.其效应是造成过高的边界层湿度和形成过密的层积云,从而产生过厚的充分混合的边界层,在其顶部还存在冷偏差.温度的误差和由此带来的湿度的误差通过形成这些云使得热通量(尤其是太阳辐射)产生较大误差.我们认为主要的问题存在于地表能量平衡和对冰、雪热传导的处理,以及对低层云的处理.     

Buffer sensitivity of photosynthetic carbon utilisation in eight tropical seagrasses

Some of the mechanisms involved in inorganic carbon (Ci) acquisition by tropical seagrasses from the western Indian Ocean were described by Björk et al. (Mar Biol 129:363–366, 1997). However, since then, it has been found that an additional, buffer-sensitive, system of Ci utilisation may operate in some temperate seagrasses (Hellblom et al. in Aquat Bot 69:55–62, 2001, Hellblom and Axelsson in Photos Res 77:173–191, 2003); this buffer sensitivity indicates a mechanism in which electrogenic H⁺ extrusion may form acidic diffusion boundary layers, in which either HCO ₃ ^? –H⁺ is co-transported into the cells, or where HCO ₃ ^? is converted to CO₂ (as catalysed by carbonic anhydrase) prior to uptake of the latter Ci form. Because a buffer was used in the 1997 study, we found it important to reinvestigate those same eight species, taking into account the direct effect of buffers on this potential mode of Ci acquisition in these plants. In doing so, it was found that all seagrass species investigated except Cymodocea serrulata were sensitive to 50 mM TRIS buffer of the same pH as the natural seawater in which they grew (pH 8.0). Especially sensitive were Halophila ovalis, Halodule wrightii and Cymodocea rotundata, which grow high up in the intertidal zone (only ca. 50–65% of the net photosynthetic activity remained after the buffer additions), followed by the submerged Enhalus acoroides and Syringodium isoetifolium (ca. 75% activity remaining), while Thalassia hemprichii and Thalassodendron ciliatum, which grow in-between the two zones, were less sensitive to buffer additions (ca. 80–85% activity remaining). In addition to buffer sensitivity, all species were also sensitive to acetazolamide (AZ, an inhibitor of extracellular carbonic anhydrase activity) such that ca. 45–80% (but 90% for H. ovalis) of the net photosynthetic activity remained after adding this inhibitor. Raising the pH to 8.8 (in the presence of AZ) drastically reduced net photosynthetic rates (0–14% remaining in all species); it is assumed that this reduction in rates was due to the decreased CO₂ concentration at the higher pH. These results indicate that part of the 1997 results for the same species were due to a buffer effect on net photosynthesis. Based on the present results, it is concluded that (1) photosynthetic Ci acquisition in six of the eight investigated species is based on carbonic anhydrase catalysed HCO ₃ ^? to CO₂ conversions within an acidified diffusion boundary layer, (2) C. serrulata appears to support its photosynthesis by extracellular carbonic anhydrase catalysed CO₂ formation from HCO ₃ ^? without the need for acidic zones, (3) H. ovalis features a system in which H⁺ extrusion may be followed by HCO ₃ ^? –H⁺ co-transport into the cells, and (4) direct, non-H⁺-mediated, uptake of HCO ₃ ^? is improbable for any of the species.