Water Level Effects on Growth of Melaleuca Seedlings from Lake Okeechobee (Florida, USA) Littoral Zone

Melaleuca quinquenervia, is expanding rapidly throughout seasonally wet areas of southern Florida (USA), including the littoral zone of Lake Okeechobee. Natural resource managers are concerned that a lower lake level regulation schedule under consideration for Lake Okeechobee, while potentially beneficial to overall ecosystem health, might increase the rate of Melaleuca expansion. To investigate this possibility, Melaleuca saplings (harvested from the littoral zone) and 7-week-old seedlings (grown from harvested seeds) were subjected to various hydroperiod treatments in replicated mesocosms. Hydroperiod treatments were selected based on a simulation of historical water level variations. Saplings grew taller under longer hydroperiods with fluctuating water levels, including periods of submersion. Time since germination affected the response of seedlings to inundation. Submersed 7-week-old seedlings grew slower and had less biomass than submersed 12-week-old seedlings, yet mortality was low at both ages. Melaleuca's plasticity allows it to adapt to hypoxic, aquatic conditions by means of aquatic heterophylly and adventitious roots. Algae and drought also increased mortality. Based on faster growth of Melaleuca under longer hydroperiods and its adaptability to seasonal flooding, a lower lake regulation schedule may not stimulate its expansion. Therefore, water levels should not be manipulated only to control Melaleuca. Control of Melaleuca should continue using current practices such as manual removal or chemical treatment.     

城乡垃圾无害化资源化处理的探讨

本文针对我国城乡垃圾污染问题，以辽宁省盘山县为城乡代表，对城乡垃圾无害化、资源化处理进行了探讨。根据县城、场、乡、镇、农村排放垃圾的不同，因地制宜地提出了相应的处理模式，并对城乡垃圾无害化、资源化处理进行了效益分析。     

Estimate of sea loading by pollutants originating from the littoral counties in the Republic of Croatia

The paper reviews the data of 10 yr of following up sewage (waste water) inflows of anthropological origin into the sea from all the coastal settlements in Croatia. In particular, we report the sea loading by biochemical oxygen demand (BOD₅), expressed by the inhabitant equivalent (I.E.), for seven littoral counties. We estimated the loading of a coastal sea area for each county separately. The objective was to avoid any over- or underestimation of amounts and significance of sewage inflows into the seawater. For this purpose, a precisely determined sea volume up to the 10 m isobath has been chosen. Because of the inadequate treatment of wastewater, the total loading of that maritime territory expressed in terms of i.e. was found to be 26% higher than expected from the actual number of inhabitants. However, daily input represents only 12‰ of the considered volume of the sea. Recipient spent only 0.7% of the disposable oxygen quantity in the sea.     

鲁豫黄河沿线县域经济发展和居住环境差异研究

县级行政区人口占全国人口比重大约70％,改善县城人居环境对于加快中国城镇化进程,提高城市化水平具有重要作用。通过选择具有代表性的人居环境指标,采用主成分和聚类分析方法对鲁豫黄河沿线的12个县域进行了综合评价,分析了各县人居环境现状差异。通过量化比较和综合分析,发现研究区域发展不均衡性明显。主成分分析表明,前三个主成分分别代表人口、经济和财政情况,是影响居住环境的关键因素。通过聚类分析把县城发展程度分为三类。结合实地考察的成果,分析区域差异存在的原因,提出一些改善现状的建议。