Arsenic (As), a class one carcinogen, reflects a disastrous environmental threat due to its presence in each and every compartment of the environment. The high toxicity of As is notably present in its inorganic forms. Irrigation with As contaminated groundwater in rice fields increases As concentration in topsoil and its bioavailability for rice crops. However, most of the As in paddy field topsoils is present as As(III) form, which is predominant in rice grain. According to the OECD-FAO, rice is the second most extensively cultivated cereal throughout the world. This cereal is a staple food for a large number of populations in most of the developing countries in sub-Saharan Africa, Latin America, South and South-east Asia. Rice consumption is one of the major causes of chronic As diseases including cancer for Asian populations. Thus, this review provides an overview concerning the conditions involved in soil that leads to As entrance into rice crops, phytotoxicity and metabolism of As in rice plants. Moreover, the investigations of the As uptake in raw rice grain are compiled, and the As biotransfer into the human diet is focused. The As uptake by rice crop represents an important pathway of As exposure in countries with high rice and rice-based food consumption because of its high (more than the hygienic level) As levels found in edible plant part for livestock and humans.

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The paper deals with the diatoms of shrimp Ponds in Khulna. It includes description and illustration of 30 species of diatom belonging to 13 genera namely Amphora, Synedra, Coccones, Cymbella, Fragilaria, Gomphonema, Gyrosigma, Melosira, Navicula, Nitzschia, Pinularia, Surrella and Caloneis based on one year investigation. Taxonomy of unidentified species was not included but they are considered in periodicity and seasonal distribution. Irregular pulses of diatom were recorded in both the ponds and none of the genera were present round the year.

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