Impact of logging activities in a tropical mangrove on ecosystem diversity and sediment heavy metal concentrations

Productivity of mangrove ecosystems is compromised by anthropogenic activities including over-exploitation of wood. This study set out to understand how different wood harvesting regimes have affected the biodiversity of a tropical ecosystem and to identify relationships between the heavy metal concentrations in the mangrove sediments and tree felling. Soil samples were collected and plant diversity studies carried out on seven sites in the mangrove. Physico-chemical, chemical and mineralogical analyses were done on soil samples and plant population structure, species richness, evenness and diversity index at these sites were calculated. Results showed that soils across sites were characteristically clayey and acidic, with high organic matter content. Minerals identified included quartz, gibbsite, goethite, hematite and kaolinite. Heavy metal concentrations were higher in Sites 6 and 7 with a longer history of anthropogenic activity. There were strong negative correlations between the duration of logging and NO₃-N (r = ?0.838, p = 0.019), total N (r = ?0.837, p = 0.019), NH₄ ⁺-N (r = ?0.844, p = 0.017), Mg = (?0.789, p = 0.035), K (r = ?0.819, p = 0.024), and Na (r = ?0.988, p = 0.002). Sites which had experienced logging for longer periods (sites 3, 6, and 7) had lower nutrient content and lower values for species richness and diversity index. Logging in mangrove ecosystems could alter soil characteristics, decreasing plant diversity and abundance. Logging dynamics around mangrove ecosystems should be considered in the wider strategy for management and conservation of similar mangrove ecosystems.     

Synthesis of grafted natural pozzolan with 3-aminopropyltriethoxysilane: preparation,characterization, and application for removal of Brilliant Green 1 and Reactive Black 5 from aqueous solutions

Environmental Science and Pollution Research - Natural pozzolan is an amorphous silicate-based material of volcanic origin. In this work, the natural pozzolan was modified by using...     

Determination of radionuclide levels in rainwater using ion exchange resin and γ-spectrometry

The evaluation of radioactivity accidentally released into the atmosphere involves determining the radioactivity levels of rainwater samples. Rainwater scavenges atmospheric airborne radioactivity in such a way that surface contamination can be deduced from rainfall rate and rainwater radioactivity content. For this purpose, rainwater is usually collected in large surface collectors and then measured by γ-spectrometry after such treatments as evaporation or iron hydroxide precipitation. We found that collectors can be adapted to accept large surface (diameter 47 mm) cartridges containing a strongly acidic resin (Dowex AG 88) which is able to quantitatively extract radioactivity from rainwater, even during heavy rainfall. The resin can then be measured by γ-spectrometry. The detection limit is 0.1 Bq per sample of resin (80 g) for ¹³⁷Cs. Natural ⁷Be and ²¹⁰Pb can also be measured and the activity ratio of both radionuclides is comparable with those obtained through iron hydroxide precipitation and air filter measurements. Occasionally ²²Na has also been measured above the detection limit. A comparison between the evaporation method and the resin method demonstrated that 2/3 of ⁷Be can be lost during the evaporation process. The resin method is simple and highly efficient at extracting radioactivity. Because of these great advantages, we anticipate it could replace former rainwater determination methods. Moreover, it does not necessitate the transportation of large rainwater volumes to the laboratory.     

Evaluating Participatory Modeling: Developing a Framework for Cross-Case Analysis

Participatory modeling is increasingly recognized as an effective way to assist collective decision-making processes in the domain of natural resource management. This article introduces a framework for evaluating projects that have adopted a participatory modeling approach. This evaluation framework—known as the “Protocol of Canberra”—was developed through a collaboration between French and Australian researchers engaged in participatory modeling and evaluation research. The framework seeks to assess the extent to which different participatory modeling initiatives not only modify perceptions among and interactions between participants, but also contribute to collective decision-making. The article discusses the development of the framework and it’s application to three case-studies, two from Australia and one from the Pacific Island of the Republic of Kiribati. The article concludes with some comments for future use of the framework in a range of participatory modeling contexts.     

A note on the sufficiency of low resolution ecosystem models

Analysis of a system of non-linear differential equations illustrates the effects of interactions between biotic and abiotic components of a complex aquatic ecosystem model. A stochastic analysis shows that the variance of the abiotic variables is related in a simple manner to the autocorrelation function of the biotic variables. The results suggest that for oligotrophic and eutrophic conditions, relatively simple ecosystem models may be sufficient for studies of an aquatic environment. Under mesotrophic conditions, the high state variable resolution of a complex model may be necessary.     

Intrauterine brain teratoma: a case report of imaging (US,MRI) with neuropathologic correlations

Fetal brain tumors are rare and teratoma is considered as the most common. Fetal MR Imaging is currently used to evaluate cases of ventricular dilatation. We report a case of cerebral immature teratoma detected by ultrasonography because of ventricular dilatation at 24 gestational weeks. MRI was the more accurate imaging method in depicting the tumor and its consequences on brain development as well as in taking a decision with regard to the management of pregnancy. Copyright © 2003 John Wiley & Sons, Ltd.     

产奶量增多的基因选择与奶牛福利:是否需要新的育种目标?

在许多欧洲国家,平均每头奶牛的产奶量比40年前翻了一番.但随之而来的是奶牛生殖能力的降低,健康问题的增多以及寿命的减少.为了提高产奶量和利润,基因选择得到广泛应用.但人们认为这是以牺牲奶牛的福利为代价换来的.乳制品业的经济前景是与公众对育种方式的接受程度和生产方式直接相关的.对乳业来说,在遭到公众更广泛的对繁殖和管理的谴责之前,很好地解决奶牛的福利问题是很重要的.为了阻止奶牛生命质量的下降或使之提高,需要制定新的育种目标,以改善健康和对代谢压力的耐力.     

Precipitation of swine and cattle manure phosphorous using limestone dust

The effectiveness of SPS and PULPRO, fine limestone dusts, in precipitating swine and dairy manure phosphorous (P) was determined in the laboratory. Both manures were sieved before being treated with limestone, to reproduce the treatment of mechanically separated manure and to observe the precipitation effect of limestone without that of the large manure solid particles. P precipitation was optimized by varying precipitation conditions (propeller blade speeds, mixing time and limestone levels) and limestone particle size. P precipitation was optimized using a propeller blade mixing speed of 0.3 m s(-1) for at least 5 minutes, using 3% limestone (dry limestone mass over wet manure mass). In terms of particle size, PULPRO 20 (limestone with a particle size of 0.02 mm) produced the most P precipitation and the smallest volume and mass of sludge, as compared to PULPRO 10, PULPRO 3 and SPS (limestone with a particle size of 0.01, 0.003 and 0.3 to 0.003 mm, respectively). For both 9.5% TS (total solids) dairy and 8.8% TS swine manure, mechanical separation followed by limestone precipitation concentrated 90% of manure TS and TP in a sludge volume representing 45% of the initial raw manure mass.