Insight into atmospheric corrosion evolution of mild steel in a simulated coastal atmosphere

The corrosion behavior of mild steel in a simulated coastal atmosphere environment has been investigated by the indoor accelerated wet/dry cyclic corrosion acceleration test(CCT),scanning electron microscopy(SEM),Raman spectroscopy and electrochemical measurements.During the CCT test of 60 cycles,the evolution of logarithmic(corrosion rate)vs.logarithmic(CCT cycles)presents a turning point at the 5th cycle,presenting a tendency to increase first and then decrease to gradually stabilize as the CCT cycle prolonged.Before the 5th cycle,γ-FeOOH and β-FeOOH and Fe3O4 were detected,respectively.And then,α-FeOOH as a new chemical composition was detected in the subsequent corrosion cycles.It is found that,after long term corrosion,the rust separated into a relatively dense inner layer rich with α-FeOOH and a loose outer layer rich with γ-FeOOH,both of which have poor electrical conductivity.The rapid increase of corrosion rate in the early stage since reducible corrosion products are involved in the reduction process of the cathode which promotes the dissolution of the anodic metal substrate.Afterward,as the rust layer thickens,the resistance of the rust increases,and the aggressive ions diffusion is blocked,gradually suppressing the electrochemical corrosion process.At last,when the composition and distribution of the rust layer remain stable,the corrosion presents a fluctuating speed around a certain value during the cracking and self-repairing process of the rust layer.     

利用夜间灯光分析胡焕庸线两侧社会经济发展不均衡状况

利用遥感技术评估我国东西部社会经济发展情况及差异,对我国制定发展战略和具体实施具有重大意义。研究利用夜间灯光遥感数据表征社会经济发展状况,在县一级分析了胡焕庸线两侧的发展速率、重心转移情况;结合遥感植被指数引入“灯光/植被”比值指数,分析经济发展和绿色空间的动态权衡;将海岸带不同距离缓冲区灯光与西部灯光比重进行对比;利用基尼系数测度东西部发展的不均衡状况。结果表明：全国、东西部社会经济快速发展,灯光重心基本稳定,分别在开封市、淮北市、阿拉善南部地区小范围漂移; 我国海岸带聚集了高强度的社会经济活动,30 km缓冲区内灯光总量基本已经与西部灯光总量相当;东西部基尼系数逐年降低;比值指数的空间自相关分析探测到沿海灯光趋于饱和,相邻的内陆县域为潜在的高强度开发空间。研究结果说明了我国东西部内部经济发展差异仍然显著,但是均衡性趋好,东部发展应进入更加注重绿化维持的阶段,内陆地区也将逐渐进入快速发展阶段。研究结论对我国乡村振兴重点地区的精准识别、生态治理修复规划等都具有借鉴意义。     

Coastal geomorphic response to seasonal water-level rise in the Laurentian Great Lakes: An example from Illinois Beach State Park,USA

Hydrodynamic processes, such as fluctuating water levels, waves, and currents, shape coastlines across timescales ranging from minutes to millennia. In large lacustrine systems, such as the Laurentian Great Lakes, the role of water level in driving long-term (centuries to millennia) coastal evolution is well understood. However, additional research is needed to explore short-term (weeks to months) beach geomorphic response to fluctuating water level. Developing a process-focused understanding of how water level fluctuations shape coastal response across these shorter time scales is imperative for coastal management. Here, we present measurements of geomorphic response along a lacustrine beach ridge plain to seasonal water level fluctuations during a decadal high-stand in Lake Michigan water level. Frequent topographic change measurements revealed high spatial and temporal variability in geomorphic response to rising lake level. Sites immediately downdrift of shore protection began to erode immediately as lake level increased. The co-occurrence of peak seasonal lake levels and a modest increase in wave energy resulted in erosion and overwash at sites that resisted erosion during the initial seasonal rise in lake level. None of the sites in this study returned to their initial morphology following seasonal lake level rise. Given that peak water levels were nearly identical in 2017 and 2018, yet the majority of erosion at our sites occurred in 2017, we postulate that erosion associated with seasonal lake level rise is primarily a function of the change in annual maximum water level from year to year, rather than solely the elevation of the water level.     

Water quality of Vistonis Lagoon, Northern Greece: seasonal variation and impact of bottom sediments

The aim of this study is to present the seasonal variation of nutrients in the water column and the bottom sediments of Vistonis Lagoon, a hypereutrophic Mediterranean coastal lagoon located in Northern Greece, and to estimate the impact of bottom sediments on the water quality of this lagoon. Nutrient concentrations in the water column and in bottom sediments were determined throughout seven seasonal sampling cruises from May 2003 to October 2004. Physicochemical parameters, such as transparency, temperature, salinity, pH and dissolved oxygen, were measured in situ in the water column using suitable equipment. Nutrient concentrations in bottom water were found generally higher than those in surface water. Nitrogen, mainly as nitrates, and phosphorus are released into the water column from the bottom sediments, especially during the summer period. Anoxia in the bottom water, as well as resuspension of the sediments are the main factors affecting nutrient internal loading in this lagoon. An approximate calculation showed that total phosphorus release was about 80 mg m⁻² d⁻¹ for the period March–August 2004. Vistonis Lagoon restoration will be possible only through the minimization or elimination of both external and internal nutrient loadings.     

Nature conservation and integrated coastal zone management in Europe: present and future

The present and future of integrated coastal zone management (ICZM) in Europe is discussed with an emphasis on nature conservation. The position of nature conservation in physical planning and in legislation is discussed within the historical perspective of the Netherlands. With regard to the present position of nature conservation in planning and legislation, differences in Europe between the northwest, the south and the east are discussed. The roles of various organisations (such as NGOs, GOs, Universities and the European Union) in ICZM is briefly mentioned. The paper advocates a strong position for nature conservation in integrated coastal zone management if it is to be developed on a sustainable basis.     

Environmental Implications of Treatment of Coastal Sewage Discharges

The environmental implications of implementing the requirement for treatment of coastal sewage prior to discharge, which were put forward in an EC draft Directive on municipal waste-water treatment, are examined. In order to establish the current situation, the results of a national survey of coastal and estuarine sewage discharges are presented. A review of the impact of sewage discharges on the marine environment is presented in conjunction with an assessment of the impact of sewage-treatment processes on the land and in the air. These aspects are integrated into overall conclusions about net environmental impact. Finally, a decision-tree approach to the assignment of priority to additional action required at individual locations is developed.     

Land inputs of trace metals, major elements, particulate organic carbon and suspended solids to an industrial coastal bay of the NE Atlantic

Rivers, streams and municipal and industrial effluents flowing into the Ferrol Ria (NW Spain) were analyzed for dissolved and particulate trace elements (Cd, Cu, Pb, Zn), particulate major elements (Al, Fe, Si), particulate organic carbon and nitrogen (POC and PON), and total suspended solids. Trace metal clean techniques were applied. Mean annual fluxes of these components were calculated. Dissolved trace metal concentrations in the major freshwater inputs were found to be within typical values for uncontaminated rivers: Cd: 0.020-0.035 nM; Cu: 11.7-19.2 nM; Pb: 0.40-0.71 nM and Zn: 18-54 nM. Two sources of suspended particulate matter (SPM) were observed: (i) a detrital SPM, which becomes more important at high river discharges, with metal concentrations tending to lithogenic values; (ii) an organic- and metal-rich SPM, which becomes dominant at low discharges. Municipal and industrial effluents in the northern shore, despite of constitute a minor freshwater contribution to the bay, were responsible for more than 50% of total inputs of Cu, Cd, Pb, Zn, POC and PON. The fluxes of trace metals obtained for the Ferrol Ria are in the range of other inhabited world semi-enclosed embayments.     

Impact in Scotland of UK and EC Sewage Legislation

The EC Directive (91/271/EEC) concerning urban waste water treatment has far-reaching financial and technological implications for local authorities in Scotland which are responsible for sewerage. Increased capital consent limits and additional financial assistance from central government are essential if the requirements of the legislation are to be met.
Although the Directive is welcomed in general terms, the sections of the legislation dealing with the identification of sensitive waters and the provision of primary treatment for coastal discharges to less sensitive waters are of limited environmental significance in Scotland.
The elimination of sewage sludge disposal at sea will create severe difficulties for Scottish authorities as a high percentage of sewage sludge is currently disposed of at sea. Each of the main alternative disposal options presents environmental, financial and technical problems and, in the case of incineration, the certainty of widespread unpopularity with the public.     

Sustainable reduction in the flux of microbial compliance parameters from urban and arable land use to coastal bathing waters by a wetland ecosystem produced by a marine flood defence structure

'Natural' treatment systems such as wetlands and reed beds have been proposed as sustainable means of reducing fluxes of faecal indicator organisms (FIOs) to recreational and shellfish harvesting waters. This is because FIO fluxes to coastal waters from both point (effluent) and diffuse (catchment) sources can cause non-compliance with microbiological standards for bathing and shellfish harvesting waters. The Water Framework Directive requires competent authorities in the member states to manage both point and diffuse sources of FIOs in an integrated manner to achieve compliance with 'good' water quality as defined in a series of daughter Directives. This study was undertaken to investigate the relative sources of FIOs to the popular bathing waters around Clacton, UK. In this predominantly arable (mainly cereal cropping) farming area, the principal land use predictor, explaining 76% of the variance in geometric mean presumptive Escherichia coli concentration at sub-catchment outlets during the bathing season, was the proportion of built-up (i.e. urbanised) land in each sub-catchment. This new finding contrasts with earlier studies in livestock farming regions where the proportion of improved grassland has proven to be the strongest predictor of microbial concentration. Also novel in this investigation, a flood defence wall has been built creating a wetland area which discharges every tidal cycle. The wetland produces over 97% reduction in the flux and concentrations of FIOs to the marine recreational waters. Also, FIO concentrations in water draining through the wetland to the sea were similar to concentrations measured in six UK sewage treatment plant effluents subject to secondary (biological) treatment followed by UV disinfection.     

滨海核电厂淡水水源

依据核电厂安全导则有关内容,对滨海核电厂淡水水源对核安全的影响进行了分析,结合山东核电前期工作的实际工作和体会,对滨海核电厂淡水水源的设计标准、论证方法等提出了一些初步认识。