SPATIAL VARIATION OF Zn GEOCHEMICAL FRACTIONS IN THE SURFACE SEDIMENTS OF THE STRAITS OF MALACCA: NATURAL OR ANTHROPOGENIC?

Total concentrations of Zn in the sediments of the offshore and intertidal areas of the west coast of Peninsular Malaysia were recently reported in the literaturs. However, total concentrations of metals in the sediment samples do not reflect the portion or carrier phase which is attributable to anthropogenic activities and those of natural origins. In this work, geochemical fraction of Zn in the sediments of the same areas was studied and the potential use of CV as an indicator of Zn pollution was determined. The geochemical study by using sequential extraction technique revealed that nonresistant fraction of the offshore and intertidal sediments (summation of ‘easily or freely leachable and exhangeable (EFLE)’, ‘acid-reducible’ and ‘oxidisable-organic’) covered about 30% and 48% of total zinc concentrations, respectively, in the sediments while most of the total zinc concentrations (offshore: 70%; intertidal: 52%) found in the sediments could be mostly due to natural origins (nonresistant fraction). Thus, the Zn levels in the Straits of Malacca should not pose a risk to the living organisms. Based on Spearman’s correlation coefficients, the source of Zn contamination in the Straits of Malacca was mainly contributed by the intertidal coastal area rather than offshore area. The present study also indicated the coefficient of variation can be used as a potential indicator of total summation of geochemical Zn concentrations in the coastal sediment but of different geochemical of Zn needs further validation.

Landslide Susceptibility Mapping along Bhalubang–Shiwapur Area of Mid-Western Nepal Using Frequency Ratio and Conditional Probability Models

Roads constructed in fragile Siwaliks are prone to large number of instabilities. Bhalubang–Shiwapur section of Mahendra Highway lying in Western Nepal is one of them. To understand the landslide causative factor and to predict future occurrence of the landslides, landslide susceptibility mapping(LSM) of this region was carried out using frequency ratio(FR) and weights-of-evidence(W of E) models. These models are easy to apply and give good results. For this, landslide inventory map of the area was prepared based on the aerial photo interpretation, from previously published/unpublished reposts, and detailed field survey using GPS. About 332 landslides were identified and mapped, among which 226(70%) were randomly selected for model training and the remaining 106(30%) were used for validation purpose. A spatial database was constructed from topographic, geological, and land cover maps. The reclassified maps based on the weight values of frequency ratio and weights-of-evidence were applied to get final susceptibility maps. The resultant landslide susceptibility maps were verified andcompared with the training data, as well as with the validation data. From the analysis, it is seen that both the models were equally capable of predicting landslide susceptibility of the region(W of E model(success rate = 83.39%, prediction rate = 79.59%); FR model(success rate = 83.31%, prediction rate = 78.58%)). In addition, it was observed that the distance from highway and lithology, followed by distance from drainage, slope curvature, and slope gradient played major role in the formation of landsides. The landslide susceptibility maps thus produced can serve as basic tools for planners and engineers to carry out further development works in this landslide prone area.

Allelopathy of Medicinal Plants: Current Status and Future Prospects in Weed Management

An attempt has been made in this article to accumulate and elucidate the literatures about the allelopathic potentiality of medicinal plants, and its role on the development of bio-herbicides for eco-friendly weed management strategies to conserve bio-diversity and ecological balance. This review paper has been prepared by comprehensive studies of various published research articles, books and proceedings available in the world literature. The farmers of different countries use several weed management techniques in order to minimize the deleterious effect of weeds. Among them most commonly used practice is application of herbicides due to its high efficacy and cost effectiveness, less time-consuming nature, flexibility and easy accessibility, and more rapid out return. Although use of synthetic herbicides in the crop fields has increased the crop production as well as the productivity by reducing the weed infestation, over time it causes a number of environmental hazards. Hence, to avoid these detrimental effects of synthetic herbicide, a lot of efforts have been dedicated by the researchers to search the novel natural plant products mainly allelochemicals and try to apply them as a tool for the development of bio-degradable natural herbicides. This paper intended to reflect the current state of allelopathic medicinal plants and their potentiality to develop eco-friendly and natural product-based herbicides for sustainable agriculture, and to invite further debate on this issue.

Tilapia： From the Nile to the World

This study addressed the potential oftilapia aquaculture as a major contributor to food production and poverty alleviation all over the world. To encompass this subject, tilapia history, origin, aquaculture potential, constraints, current and future production levels were reviewed. Tilapias are native to the River Nile and Africa in general then they were introduced and disseminated worldwide. Positive aquacultural characteristics of tilapia made tilapias the most cultured species worldwide now and in the near future. Tilapia world production is expected to reach 3 million tons this year 2010. Thus, tilapias could make a significant contribution to the livelihoods support especially in the tropical and subtropical countries.

＂Actual Experience＂＂ Correcting Misconceptions Through Analyzing Harriet Wilson＇s Our Nig

African-American writers during the 19th century wrote in the shadow of the prominent romance, sentimental, and domestic fiction. Harriet Wilson＇s Our Nig （1859） reflects an ＂alternative social character＂, for the female protagonist suffers racism in the free North, because she is a mulatto child. Through depicting the life of free blacks, who supposedly lives a better life than Southern slaves, Wilson exposes how she has actually lived and sensed life in antebellum America. According to Raymond Williams （2011）, there are two kinds of literary writings. The first represents the general tendency of the age, and he calls it ＂dominant social character＂; representing the majority content of both the public writing and speaking. But, another different literary writing lives in its shadow; one that usually leads the conflicts of the time. It is the ＂alternative social character＂; the literature of the victims of repression and marginalization, produced by the lower class, women, and blacks. They reflected how they were dehumanized, and exposed their suffering and abasement. They also aimed to prove individualism. The novel reveals how racism in the North could be worse than the slavery of the South. This paper shows Wilson deviation from the ＂her brethren＂ in writing her novel. It unveils significant truths concerning black women＇s status in antebellum America. It discusses how the author attempts to correct certain misconceptions through her female character

The Impact of Communication Technologies on Social Structure——Take the Example of Smart City

Human society has entered the era of digit and internet,and the communication technology is one of the important factors which result in changes of social structure.Smart City is an active attempt to future urban development,to use the communication technology as an constitutive element of smart city from the economic base to the superstructure,production relation to exchange relation.Digitization and networking are committed to reflect the state of human's comprehensive development,which is an important stage of emancipation of humanity itself.Communication technology can bring people's initiative into full play and learning in development and establish the harmonious relationships during the interaction.This article is based on the example of smart city,which analyzed the impact of communication technologies on social structure from different aspects.

Application of GIS for the identification and demarcation of selective heavy metal concentrations in the urban groundwater

Groundwater is the most appropriate and widely used source of drinking water, which is increasingly threatened by pollution from industrial and agricultural activities. To check the severity of the problem, 156 groundwater samples were collected from various depths （60-110 ft） of 52 different localities in Faisalabad city, the third largest metropolis in Pakistan, and analyzed for the metals （Zn, Cu, Cd, Ni, Pb, Mn and Fe） concentration in 2009. Quantification was done by using Flame Atomic Absorption Spectrophotometer technique and the results were compared with WHO standards for drinking water quality. Results showed that the levels of Cu, Mn and Fe were below the WHO standards while the concentrations of Zn, Cd, Ni and Pb were above the recommended levels of safe drinking water. Correlation analysis among the occurrence of these heavy metals revealed a highly significant and positive correlation of Mn with Zn and Fe. A significant and positive correlation of Cd was also found with Cu and groundwater depth showing that there is strong association between Cu-Cd pair and that the Cd concentration varies with depth of groundwater in the study area. Regional patterns of heavy metals occurrence were mapped using Geographical Information System （GIS） for the identification and demarcation of risk areas. The concentration maps may be used by policymakers of the city to mitigate groundwater pollution.