تغییرات زمانی

The aim of this research was to investigate temporal variation of biodiversity and abundance of fish caught by the intertidal fixed stake net traps (Moshta) in coastal waters of Bandar Abbas between October 2019 to June 2021.

Sampling operation was carried out biweekly and nine fishing gears (3 in the west, 3 in central region and 3 in the west of Bandar Abbas) were sampled for three consecutive days at tide time.

The species composition included 54 species belonging to 29 for autumn, 35 species belonging to 26 families for winter, 28 species belonging to 21 for spring. The highest and lowest occurrence was observed for Liza subdivides (with 87%) and Upeneus doriae (with 8%). Commercial catch to discard ratios were 1:4.33, 1:2.08 and 1:1.12 for autumn, winter and spring seasons, respectively. Mean CPUE (±SD) of commercial catch for autumn, winter and spring were (10 ±2.88), (5.41 ±0.98) and (8.69 ±1.73) kg. day-1. N- 1, respectively, which had not differed significantly (F=1.93 P=0.166). As well as, mean CPUE (±SD) of discards were 43.33 ±14.18, 6.08 ±1.47 and 18.08 ±5.21 for these seasons, respectively. Discards in spring were more significantly than other two seasons (F=4.123 P=0.142). Results of nMDS and ANOSIM tests showed a high similarity of fish assemblages in the seasons.

Given that the catch to discards ratio in the sampled intertidal fixed stake net traps (Moshta) is a large value, this fishing gear have many negative effects on the diversity of coastal species.

Every year a great deal of chemical fertilizers, pesticides and sewage sludge used in agriculture soils; this may cause the increase in concentration of Soil heavy metals. The purpose of this study was to investigate the effects of assessment of agriculture activities on accumulation of Cadmium, Cobalt and Chromium; and determines the trend of heavy metal accumulation in soil.

To achieve this purpose 97 soil samples were taken from different agriculture fields with different cultivation archaism in Hamedan province in western IRAN by systematic approach. ANOVA test has been used to compare the concentration of heavy metals in different farms, the trend of accumulation heavy metals obtained in regards to cultivation archaism and the mean of metals concentration in different cultivations. Moreover, contamination Factor Index has been used for comparison of contamination risk in cultivations with various archaisms.

Mean concentrations in 20-, 35- and 65-year-old cultures for cadmium metal were 0.14, 0.16 and 0.19, respectively, for cobalt metal, 17/94, 18/05 and 79/20, respectively and for chromium metal 58.89, 72.99 and 88.09 mg / kg, respectively. The results showed that the longevity of cultivation affected on heavy metal accumulation in soil. The trend of Cd, Co and Cr accumulation in soil was exponential.

Due to the fact that agricultural soils are one of the important routes for the transfer of heavy metals to the human food chain, it is necessary to monitor soils that are potentially exposed to toxic metals.

One of the current problems of climate change and the threat of human society and is considered a disaster for the planet the review and forecast its elements both in terms of water resource planning and for management of crisis situations is important. So to predict and estimate the rainfall for each area and watershed as one of the most important factors in use (model for operation) of water resources is considered.
One of the common methods for the analysis of time series Hydrometeorology, the presence or absence of the process in the time series using statistical tests. In this study, annual precipitation trends over the period 1377 to 1391 plain of Ardabil, using data from stations: Ardabil, Nir, Namin, Hare, Kolur non-parametric Mann-Kendall method of Ardabil with which one is the most common non-parametric methods, were studied.
The results of the annual climate and time change parameters of Ardabil Plain stations showed an annual precipitation data from 1383 have reduction mode And from this year onwards Ardabil plain stations of incremental changes to the show. And precipitation fluctuations in some great seasons at the same time, in winter precipitation in the eastern plains of Ardebil process and increase positive mood and a decrease in rainfall in the western desert state of Ardabil show.
To determine drought in the study area of the graph 3-year moving average data is used, Check the graph of the results obtained during the wet years 1998-2000-2002-2003-2004-2007 and 1999-2001-2005-2006 years because of the lower than average rainfall amounts reflect periods of drought in the region.