Novel oil spill indices for sentinel-2 imagery: A case study of natural seepage in Qaruh Island, Kuwait.

Oil spills are a paramount and immediate challenge affecting marine ecosystems globally. Effective and timely monitoring tools, such as oil detection indices, offer a swift means to track oil spill spread across vast oceanic expanses. Moreover, these indices enhance data clarity, making it more conducive for machine learning and deep learning algorithms. This study leverages the natural seepage occurring around Qaruh Island, Kuwait as a unique context for the spectral analysis of oil spills using Sentinel-2 multispectral imagery due to repeated occurrences in the same region. This research evaluated 859 single band and 455 multichannel combinations to identify the most effective combinations in oil-water separability, employing the Jeffries-Matusita (JM) distance measure as a key metric. Bands 1, 2, 3, 8A, 11, and 12 consistently featured among the top-performing indices combinations B1-B11B1+B11;B1+B2B3+B11;B1+B2B3+B12;B1+B2B3+B8A affirming the significant effect of oil spills on visible, Near-Infrared (NIR), and Shortwave Infrared (SWIR) bands. Notably, the indices developed in this study outperformed those from prior research in terms of suitability to unsupervised classification algorithms. A significant conclusion of this study is that incorporating a higher number of bands in the analysis did not correlate with an increase in JM values, suggesting that the selection of specific, informative bands is more critical than the volume of input data. These findings underscore the indispensable role of Sentinel-2 imagery in environmental investigations and highlight the potential for focused, efficient analysis using strategic band combinations for effective oil spill detection.•This study identified optimized Sentinel-2 band combinations for oil-water separability, benefiting from naturally occurring spills around Qaruh Island.•The proposed indices outperformed the previous indices for oil spill visualization and clustering.•The new indices highlighted the critical role of specific band selection over the volume of input data for effective oil spill detection.

Environmental assessment of drainage water impacts on water quality and eutrophication level of Lake Idku, Egypt.

Lake Idku, northern Egypt, receives large quantities of drainage water from four main discharging drains. Ecological and biological status of Lake Idku has been monitored during (autumn 2012 to summer 2013) to examine the lake water quality and eutrophication level in response to the quality as well as the source of the discharging water. Discrete water samples were collected from the lake body and the drains. Chemical analyses revealed an excessive nutrient load goes into the lake. A range of 1.4-10.6 mg nitrites/L was determined for drain waters, however a sudden increase was observed in lake and drain water samples of up to 84 and 74.5 mg/L, respectively. Reactive silicate ranged between 2.9 and 4.8 mg/L; while inorganic phosphate fluctuated between 0.2 and 0.43 mg/L. Transparency varied from 45 cm to 134 cm with better light conditions at drain sites. Biological results indicated a hyper-eutrophic status for the lake with a range of chlorophyll-a varied from a minimum of 39.9 µg/L (at Idku Drains) and a maximum of 104.2 µg/L (at El-Khairy drain). Phytoplankton community structure revealed higher abundance at lake sites compared with the drains. Maximum phytoplankton density was detected during summer with the dominance of Bacilariophyceae (e.g. Cyclotella meneghiniana, Cyclotella comate, Melosira varians) followed by Chlorophycean taxon (e.g. Scenedesmus dimorphus, S. bijuga and Crucigenia tetrapedia). Five indices were applied to evaluate the water quality of the lake. Diversity Index (DI) indicated slight to light pollution along all sites; while Sapropic Index (SI) indicated slight pollution with acceptable oxygen conditions and an availability of sensitive species. Palmer Index (PI) gave a strong evidence of high organic pollution at some sites in the lake, while Generic Diatom Index (GDI) revealed that levels of pollution varied from average to strong. Trophic Index (TI), suggest that there are an obvious signs of eutrophication in the lake.

Variations in phytoplankton carbon biomass, community assemblages and species succession along Lake Burullus, Northern Egypt.

Phytoplankton assemblages and species succession along Lake Burullus (Southern Mediterranean) is expressed as carbon biomass (mg cm3) using a standard spreadsheet based on the species cell volume cell(-1) carbon relationship. High Chl a levels were measured (maximum 85-126 mg m(-3)) reflecting a dense phytoplankton population (up to 8.3 x 10(3) cell ml(-1) and 5.5 x 10(3) mg cm(-3)) throughout the lake body with maximum concentrations at the western sector of the lake (S1). Adiverse phytoplankton community was determined. Cell count data revealed the dominance of a mixed phytoplankton taxa, however biomass data indicates over-dominance of Bacillariophyceae (up to 98%). Good correlation (r = 0.73, p < 0.05) was found between Chl a and carbon biomass with various cell carbon/Chl a ratio according to variations in community structure. Bacillariophyceae were the most dominant, particularly at the middle (S2) and the western parts (S1) during periods of high nutrient (silicate) and good weather conditions (during spring/summer months). Chlorophyceae were abundant with Scenedesmus sp. mostly dominant, particularly at P-rich sites. Dinoflagellates peaked only during calm and high light summer months (May-July) being at a maximum level at S1. Euglenophyceae were less contributed to total phytoplankton abundance and peaked only; as a transition stage; at S1 during Jannuary and March (winter months). Cyanophyceae were numerous along with maximum peak at S2 affected by the southern drains. Excessive nutrient enrichment into the lake alters the existent structure of phytoplankton community. The water quality index indicated a poor water quality status of the lake.This may led to increase the possibility of toxic algal blooms to invade the lake ecosystem and, in turn, affect the lake fish yield.