Water quality assessment at Jinhae Bay and Gwangyang Bay,South Korea

A new water quality index for evaluating the water quality of Jinhae Bay and Gwangyang Bay was developed. Four water quality parameters were selected as water quality indicators for the water quality index: dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), chlorophyll-a (Chl-a), and dissolved oxygen (DO). Reference levels of DIN, DIP, and Chl-a were determined as 6.22 μmol L^?1, 0.38 μmol L^?1, and 2.32 μmol L^?1, respectively, on the basis of a long-term dataset that was collected monthly in the Korea Strait over a period of seven years (2006–2012). The water quality index established for Jinhae Bay and Gwangyang Bay is (bottom DO grade × 0.33) + (surface Chl-a grade × 0.33) + (surface DIN grade × 0.17) + (surface DIP grade × 0.17). On the basis of a three-year observation, the water quality of Jinhae Bay was classified as “good” in winter and spring, “poor” in summer, and “fair” in autumn and exhibited large spatial variation, with the lowest-quality water observed in Masan Bay. The water quality of Gwangyang Bay was classified as “good” in winter, “fair” in spring, “poor” in summer, and “fair” in autumn. Unlike Jinhae Bay, the water quality of Gwangyang Bay exhibited minimal spatial variation. In both bays, water quality among the four seasons was worse during summer. It is essential that a survey for water quality evaluation be conducted during summer.     

Preliminary optical classification of lakes and coastal waters in Estonia and south Finland

A preliminary optical classification of lakes in Estonia and south Finland which can also be used for small bays of the Baltic Sea is elaborated. The classification is based on the optical properties of water (diffuse attenuation coefficient, diffuse reflectance) and parameters that are routinely monitored in water bodies (Secchi depth, concentration of chlorophyll-a, total suspended matter and yellow substance). The data complex used for our classification covers different types of water ecosystems (ranging from oligotrophic to hypertrophic) and the variability of water constituent concentrations in the ice-free period in Estonia and south Finland. Using cluster analysis, we found 5 optical classes of waters: clear (C), moderate (M), turbid (T), very turbid (V) and brown (B). There is satisfactory correspondence between class of water, shape of diffuse attenuation coefficient and diffuse reflectance spectra and trophic state of the lakes.     

Benthic trophic status and nutrient fluxes in shallow-water sediments

Proliferation of fast-growing ephemeral macroalgae in shallow-water embayments constitutes a large-scale environmental change of coastal marine ecosystems. Since inorganic nutrients essential for the initiation and maintenance of macroalgal growth may be supplied from the underlying sediment, we investigated the coupling between benthic inorganic nutrient (mainly N and P) fluxes and sediment properties in 6 bays representing a wide gradient of sediment characteristics (grain size, organic matter content, solid phase C and N). The initial characterization of bays was made in June and also included measurements of oxygen flux and microphytobenthic and macrofaunal biomass. In September, still within the growth season of the macroalgae, complementary experiments with sediment-water incubations for benthic flux measurements of oxygen and nutrients focused on trophic status (balance between auto- and heterotrophy) as a controlling factor for rates of measured benthic nutrient fluxes. Generally, sediments rendered autotrophic by microphytobenthic photosynthesis removed nutrients from the overlying water, while heterotrophic sediments supplied nutrients to the overlying bottom water. Estimations of the green-algal nutrient demand suggested that late in the growth season, net heterotrophic sediments could cover 20% of the N-demand and 70% of the P demand. As the benthic trophic status is a functional variable more closely coupled to nutrient fluxes than the comparably conservative structural parameter organic matter content, we suggest that the trophic status is a more viable parameter to classify sediments and predict benthic nutrient fluxes in shallow-water environments.     

Integrative assessment of sediment quality in terms of chemical contamination in Jinhae Bay,South Korea

The assessment of sediment quality by considering chemical contaminants is required for the effective management of coastal environments. In this study, complex data sets of heavy metals and organic pollutants were integrated to evaluate sediment quality. Thirty-two target pollutants were quantitatively determined in surface sediments from 80 stations in Jinhae Bay, South Korea. A sediment quality index (SQI) was derived by combining the functions of “scope” (the number of variables that do not meet guideline objectives) and “amplitude” (the magnitude by which these variables exceed the guideline objective). The SQI reflects the spatial gradient and differences in the contamination status with regard to heavy metals and organic pollutants in Jinhae Bay. Fifty-nine out of eighty stations surveyed (74%) were classified as being in “excellent” or “good” condition according to the SQI, and no stations were in a “poor” condition. The mean sediment quality guideline quotient (mSGQq) ranged from 0.06 to 0.31 (from nontoxic to marginally toxic). Acute sediment toxicity leading to amphipod mortality was recorded at 17 stations (21%) of the 80 surveyed, where the mortality rate was slightly over 20%. No significant relationship was observed between sediment toxicity and the concentration of each toxicant or mSQGq.     

福建主要港湾的水质单项评价与综合评价

根据2000年和2001年福建主要港湾的水质监测资料，对福建16个港湾的海洋环境质量进行了评价．结果显示：福建部分港湾的无机氮和活性磷酸盐超过二类海水水质标准．局部海域已达到富营养化，要重视和防范赤潮的发生和危害．有些港湾还存在不同程度的污染，其综合评价指数在0．43～1．07之间．     

桑沟湾养殖生态系统浮游植物的粒径结构及浮游生物对栉孔扇贝碳需求的贡献

The biomass and size fraction of phytoplankton in terms of chlorophyll a(Chl a) was measured during four cruises conducted in April, July, October 2013 and January 2014 in mariculture area, the Sanggou Bay, China.Results show that total Chl a levels in the surface seawater of the Sanggou Bay generally range from 0.10 to 20.46μg/L, with an average value of 2.13 μg/L. Nano-phytoplankton was the most important size-fraction and accounted for about 65.1% of total Chl a. In order to evaluate the importance of the "protozoan trophic link" for energy transfer from the microbial loop to filter-feeding feeders, Zhikong scallop Chlamys farreri was then offered a natural planktonic community as potential prey. Results show that scallops obtained carbon source from natural plankton with the rate of 11 033.05 μg/(g·d). Protists(nanoflagellates and ciliates) were the dominant source of carbon retained by scallop(48.78%). The microbial loop provided 58.45% of the carbon source for farmed scallops. These results indicate that the microbial loop represent a valuable trophic resource in mariculture system of the Sanggou Bay.     

基于时空矩阵方法对福建省海湾水质变化特征分析

基于2005—2011年8月和2012—2015年5月、8月的水质监测数据,应用水质指标的主成分分析结果,对福建省海湾划分环境单元,通过时空矩阵方法对福建省海湾水质指标变化特征进行了分析。结果显示:（1）通过主成分分析,4个水质指标聚成两类成分,磷酸盐和叶绿素a聚为一类主成分,硝酸盐和溶解氧聚为另一类主成分;（2）以主成分权重值为坐标,划分福建省海湾表层水体为6个环境单元,以此建立水质指标相对含量的时间序列组合矩阵,对福建省海湾水质指标变化分析;（3）水质指标时空矩阵表现出一定的周期性变化趋势,环境单元的指标变化模式具有同步性,指标含量变化的绝对值从叶绿素a到营养盐再到溶解氧呈轻微增长;（4）两类主成分具有一定相关性,营养水平高低影响营养-浮游植物动态关系,当磷酸盐含量高于0.03 mg/L、硝酸盐含量高于0.25 mg/L,且营养盐时间周期变化显著时,叶绿素a时间周期变化与营养盐发生同步联动效应;（5）夏季福建省海湾水体生产力较低,大量陆源有机物输入、降解耗氧,表层溶解氧含量降低明显;（6）福建省海湾主要受两种性质差异很大的水体影响,富含高营养盐径流水团影响了河口及邻近海域的环境单元,而福建省南部海湾主要受台湾暖流及上升流影响,台湾暖流是东海海域磷酸盐的重要来源。     

大亚湾和大鹏湾两个相邻海湾潮波浅水变形的异同分析

利用实测资料分析重构了大亚湾和大鹏湾潮汐水位“双峰”现象,确定了浅水分潮的异常增长是潮位“双峰”现象的主要成因,其中四分之一日分潮和六分之一日分潮起着至关重要的作用。通过SCHISM模型构建大亚湾和大鹏湾附近海域高分辨率水动力模型,模拟结果表明近岸海域,在大亚湾以东,潮汐类型为不规则全日潮,以西为不规则半日潮,在两个海湾内均为不规则半日潮;研究海域的潮流均表现为不规则半日潮流。四分之一日分潮和六分之一日分潮在大亚湾和大鹏湾的不同变形过程是造成两个相邻海湾水文差异的直接原因。通过构建不同底摩擦强度、消除水底地形以及改变海湾水深的数值实验研究表明,分潮传播方向与水深变浅方向是否一致,是导致两个海湾潮波浅水变形不同的根本原因。     

Decoupling of Macromolecular Compositions of Particulate Organic Matters between the Water Columns and the Sediment in Geoje-Hansan Bay,South Korea

The biochemical composition of particulate organic matter (POM) is very important to understand in relation to the trophic conditions of marine ecosystems since it forms the primary trophic base. The present study investigated the biochemical compositions (i.e., carbohydrates, proteins, and lipids) of POM monthly from January to December 2015 in Geoje-Hansan Bay to determine if the macromolecular composition of POM is coupled between the water columns and sediment. A spatial difference in the macromolecular compositions was observed in the water columns between the inner and outer bays, which may be caused by the different physiological conditions of phytoplankton growth that are due to the water circulation pattern in the bay. In contrast, no distinctive spatial difference in the macromolecular compositions was found in the sedimentary organic matter. Overall, while carbohydrates were the dominant (45.7%) macromolecules of the POM in the water columns, proteins were dominant (47.9%) in the sedimentary organic matter during our observation period. Decoupling of the macromolecular compositions between the water columns and underneath the sediment in Geoje-Hansan Bay appears to be a result of the various effects of selective filter feeding by oysters and protein-dominant benthic microalgae and fouling organisms.     

辽东大、小窑湾营养盐和铅、锌的时空变化新探

针对大、小窑湾湾内外海域的营养盐和铅、锌的分布规律与季节变化进行了调查,并以海水水质、营养结构和营养水平方面评价了两个海域的环境质量状况。结果表明：冬春季节N,P,Si三种营养盐的水平分布均有从湾项向湾口海域降低、再向湾外上升的趋势;夏季三种营养盐的湾顶含量大大增加,水平分布趋势则表现为由湾里向湾口方向减少。冬季Pb含量较低,且分布均匀;春季小窑湾沿岸已受到Pb的污染。大窑湾北部沿岸冬季Zn污染严重,春季两湾内外海域Zn分布较均匀。夏季Pb,zn的污染严重,水平分布为从北部沿岸向湾口方向下降。两个湾内环境质量劣于湾外;调查年度中,夏季两湾水质除总无机氮不超标外,其他三项指标均超标,达到轻度或重度污染状态;冬春两季只有锌污染指数大于1,其他皆低于清洁指数,水质处于较清洁状态。大、小窑湾海域的海水营养水平指数小于或接近一级的阈值,处于贫营养状态。     

Seasonal variability in free-living marine nematode community structure in a sandy beach of the Taiping Bay of Qingdao, China

Nematode assemblage composition, trophic structure and biodiversity were followed over an annual cycle in a sandy beach of the Taiping Bay of Qingdao, China. Nematode assemblage in the sandy beach maintained a high genus diversity （75 genera）. Mlero- laimus and Bathylaimus were the dominant genus of the nematode assemblage, accounting for 66% of the total nematode abundance. The nematodes＇ dominant trophic structure changed seasonally as a response to the seasonal changes in food quality. Epigrowth-feeder nematodes （2A） were the dominant trophic groups in the trophic structure with the highest abundance in spring because of phytoplankton bloom, while the feeding type （ 1 B） showed higher abundance in summer that was due to the increasing of sediment detritus after spring bloom. Furthermore, species diversity and evenness calculated on nematodes identified to the genus level displayed significant temporal changes, which was also reflected by the index of trophic diversity. According to the cluster analysis, the nematode community structure of the whole year was clearly separated into two periods （A and B）. Biota-Envlron- ment matching （BIOENV） results showed that seawater temperature, sediment Chl a and grain size were responsible for the nema- tode community structure variation in spring and summer period （Period A）. However, seawater/interstitial water temperature, interstitial water dissolved oxygen concentration,interstitial water salinity, and sediment Ph a a were more important in constructing the autumn and winter period （Period B） nematode community structure.     

Eutrophication and hypoxia in the upper Gulf of Thailand

In this study, we investigated the mechanism of eutrophication and hypoxia in the upper Gulf of Thailand from August 2014 to June 2015 based on field observation data, box model analysis, and the unscaled trophic status index (UNTRIX). Fresh water residence time derived from a simple box model was long (38.61 days) during the transition period between the southwest to northeast monsoon in September 2014. In contrast, fresh water residence time was short (2.63 days) during the late northeast monsoon in February 2015. Long residence time was related to the development of widespread strong hypoxia in near-bottom waters in over half of the gulf during the transition between the southwest and the northeast monsoon, when river discharge was also very large. UNTRIX is used to assess water trophic levels, and is based on water qualities including concentrations of chlorophyll-a (Chl-a), dissolved oxygen (DO), dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphorus (DIP). Hypertrophic and eutrophic conditions were observed at river mouths; their seasonal eutrophication was related to river discharge and circulation. Nutrients were mainly increased by river discharge. Water column stratification and long residence time were required for the development of severe hypoxia in the study area.

     

近30年长江口海域生态系统健康状况及变化趋势研究

为评估长江口海域生态系统健康状况,本文以鱼类浮游生物为指示生物,选择1986年、1999年、2007年和2016年4个年份的数据,选取鱼类浮游生物总种类数、底栖鱼种类数、水层鱼种类数、低耐污鱼种类数、高耐污鱼种类数百分比、杂食性鱼种类数百分比、虫食性鱼种类数百分比、肉食性鱼种类数百分比、鱼类取样个体数、天然杂交种种类数百分比等10个评价指标,采用1、3、5赋值法计算4个不同年份的河口生物完整性指数(Estuarine Biotic Integrity Index,EBI),并以此评价近30年长江口海域生态系统健康状况变化趋势。结果显示,1986年、1999年、2007年和2016年4个不同年份的EBI值分别是52、40、36、34,对应的EBI等级分别为“好”、“一般”、“一般?差”、“差”。通过分析EBI年际变化的结果,发现近30年来长江口海域生态系统健康状况呈现先下降,而后稳定在较低水平的趋势,说明长江口海域生态系统亟需及时进行保护和修复工作。     

南宁邕江网箱养殖区浮游生物种群结构特征

浮游生物是评价水体质量的一项重要生物指标,为了解广西南宁邕江网箱养殖区的水质状况,于2009年9月-2010年9月在金陵至清川桥江段网箱养殖区设置2个监测断面,每两个月采样1次,对其水质和浮游植物种群组成、密度和优势种变化进行了系统研究.结果表明:邕江网箱养殖区共检出浮游植物8门98属(种),绿藻、硅藻分别占浮游植物总种数的42.8％、24.5％;共检出浮游动物4大类44属(种),优势种为轮虫类,占浮游动物总种数的43.2％.总体看来,邕江网箱养殖区浮游生物种数夏秋季节多,冬春季节少;浮游生物密度与种数季节变化趋势一致.邕江网箱养殖区综合营养状态指数(TLI)介于59.28-66.87之间,属于中度富营养化水平.Shannon-Wiener多样性及均匀度指数分别介于1.35-1.56和0.2275-0.2586之间,表明邕江网箱养殖区在监测期内处于中营养—富营养状态,这与采用相关加权综合营养状态指数法的评价结果一致.     

Assessing the ecosystem health status of Korea Gwangyang and Jinhae bays based on a planktonic index of biotic integrity (P-IBI)

To assess the responses of planktonic organisms to pollutants in the coastal ecosystems of Gwangyang and Jinhae bays in Korea, we investigated seasonal changes in various biological factors during the period from 2010 to 2012. Based on the characteristics of nutrient uptake by planktonic organisms under the coastal pollution conditions, we focused on four major parameters: total phytoplankton, harmful algal bloom (HAB) species, heterotrophic bacteria (HB) and Escherichia coli to develop a planktonic index of biotic integrity (P-IBI). The threshold values for abundances of total phytoplankton, HAB species and HB were based on the zero Z-score following normal distribution of the data for each parameter during the three years. Based on this approach, the threshold values were: 1.2 × 10⁶ cells L^?1 for total phytoplankton; 3.3 × 10⁴ cells L^?1 for HAB species; and 1.7 × 10⁶ cells mL^?1for HB. Five grade levels for the P-IBI were established, based on the zero Z-scores. The threshold value for E. coli not to be normalized was based on the USEPA and the Korean Ministry of Oceans and Fisheries guidelines. Validity of the grades and threshold values for each parameter established using the field data were tested by algal bioassays in a mesocosm enclosure, which supported the threshold values obtained in the field. In Gwangyang Bay, the annual integrated score for the P-IBI in 2010 was better than in the other years of the study. In Jinhae Bay, the P-IBI for the inner area of Masan Bay was Grade IV–V, indicating unhealthy conditions relative to the central and western outer areas, where the P-IBI varied from Grade II to III. The P-IBI values for Gwangyang and Jinhae bays were mostly rated as “Good (Grade II) or Fair (Grade III)”, except for a few stations in the semi-enclosed areas of the inner part of Jinhae Bay. From an overall view based on the P-IBI developed in this study, the coastal ecosystem health status in Gwangyang Bay was in a better condition than Jinhae Bay. The P-IBI indicated also a change to an unhealthy status during the rainy periods of spring and summer, whereas during winter and autumn the index indicated healthy conditions.     

阿什河流域底栖硅藻群落特征及水环境健康评价

为探索黑龙江省阿什河流域底栖硅藻群落特征及环境相关性,并对阿什河流域进行水环境健康评价,本研究于2018年7月(丰水期)和2018年10月(枯水期)对阿什河流域8个典型采样点进行调查。基于相似性分析检验(analysisofsimilarities,ANOSIM)和相似百分比分析(similarity percentages,SIMPER)分析探索枯水期与丰水期之间底栖硅藻的群落差异,通过冗余分析(redundancyanalysis,RDA)对驱动底栖硅藻的关键环境因子进行筛选;使用硅藻生物指数(biological diatom index, IBD)、硅藻属指数(generic index of diatom, GI)和水体营养指数(trophic state index, TSI)对研究区域水体营养状态进行初步评价。结果表明,研究期间共鉴定底栖硅藻89种,其中丰水期80种、枯水期57种。独立样本T检验(T-test)表明阿什河流域物种丰富度丰水期显著高于枯水期(P0.05),Shannon-wiener指数变化不显著(P0.05)。ANOSIM结合SIMPER分析结果显示阿什河流域硅藻群落格局存在一定的时空异质性。RDA分析表明水的电导率是驱动阿什河流域底栖硅藻空间分布的环境因子,枯水期与丰水期之间高锰酸盐指数(COD_(Mn))含量的变化是影响硅藻群落演替的因素之一。IBD、GI和TSI指数结果显示阿什河流域受人为活动干扰区域营养状态较差, IBD指数较GI指数能更有效的反映阿什河流域水体营养状况。     

Meiobenthos under mariculture conditions of the brown seaweed <Emphasis Type="Italic">Saccharina japonica</Emphasis> in Rifovaya Bay,Peter the Great Gulf,Sea of Japan

The qualitative and quantitative compositions of free-living marine nematodes were studied in Rifovaya Bay (Peter the Great Gulf, Sea of Japan). It was found that the density distribution of nematode populations in bottom sediments of Rifovaya Bay is nonuniform. In total, 72 nematode species were found, including Oncholaimium paraolium, Viscosia epapilosa, and Monoposthia latiannulata on all types of substrates. The dominant trophic group comprised “predators” (2B) and “scrapers” (2A). It was shown that the species composition of nematodes in Rifovaya Bay is very similar to the species composition of nematodes in the other areas of Peter the Great Gulf.     

Chemistry of sediments in relation to trophic condition of eight Rotorua Lakes

Abstract

Chemical parameters (pH, Eh, carbon, Kjeldahl nitrogen, total phosphorus, 0.5M H₂SO₄‐extractable phosphorus, organic phosphorus, and water‐soluble phosphorus) were measured in the surface layers of sediments collected from various depths in Lakes Rotowhero, Okaro, Ngapouri, Rotokakahi, Okareka, Tikitapu, Okataina, and. Rotoma during October 1972. The sediments of the productive geothermal lake, Rotowhero, were markedly different from those of the cold‐water lakes: they had relatively low pH values, high carbon (mean 8.5%) and organic phosphorus (mean 4160 μg.g^?1) concentrations, and very high total phosphorus concentrations (mean 4770 μg.g^?1), probably as a result of enrichment by hot springs.

The mean concentrations in the sediments of the cold‐water lakes were carbon 3.2–7.9%, Kjeldahl nitrogen 3380–8310 μg.g^?1 and phosphorus 690–1780 μg.g^?1. These concentrations are within the ranges for New Zealand terrestrial topsoils, but the lake sediments appear enriched in phosphorus relative to local topsoils. Total carbon, nitrogen, and phosphorus concentrations of sediments tended to be highest in the eutrophic lakes (Okaro, Ngapouri) although the deep oligotrophic lakes (Okataina, Rotoma) had relatively high total phosphorus concentrations (means 1400, 1510 μg.g^?1). Overall, the carbon, nitrogen, and phosphorus concentrations of the sediments showed little relationship to the trophic state of the lake.

Organic phosphorus concentrations of the surface layers of sediments were similar in all the cold‐water lakes (mean 319 μg.g^?1). The proportion of the total phosphorus apparently ‘fixed’ in mineral material was minimal (0–1%) in sediments from the eutrophic and mesotrophic lakes, but in the oligotrophic lakes was similar to that in New Zealand topsoils (9–14%). Reducing conditions may cause solution of a high proportion of the ‘fixed’ phosphorus in the eutrophic lakes.

The water‐soluble phosphorus concentrations in the sediments of the five shallow cold‐water lakes (Okaro, Ngapouri, Rotokakahi, Okareka, Tikitapu) correlated positively with trophic state and with concentrations of dissolved phosphorus in the lake waters.

Carbon, nitrogen, and phosphorus concentrations in the sediments tended to vary with overlying water depth. This should be considered when comparisons are made between lakes.     

Variability of suspended organic matter in the surface layer of the Black Sea (deep-sea areas)

The peculiarities of the distribution of the components of the suspended organic matter (SOM) and their interannual and seasonal variability have been analysed in the surface water layer and photic water layer of the Black Sea (the deep-sea areas) for the period of 1978–1995. The statistical assessment of the seasonal and monthly dynamics of the SOM components and their ratios was performed. The seasonal dynamics of the concentration of particulate organic carbon have been calculated based on the data on the Chlorophyll “a” (Chl “a”) concentration in the surface water layer based on the regression relationship between these two parameters measured in situ simultaneously. Taking these relationships into account, the interannual dynamics of the Chl “a” concentration have been analysed for the period of 1978–2010. It was found that the concentrations of the SOM components increased significantly in the 1980’s and early 1990’s with the maximum reached in the summer of 1992. It was also found that the seasonal interannual dynamics of the components of the SOM were mainly preconditioned by the interannual dynamics of the phytoplankton biomass, which, in turn, depended on the climatic conditions.     

Could the conventionally known Abu Roash “G” reservoir (upper Cenomanian) be a promising active hydrocarbon source in the extreme northwestern part of Egypt? Palynofacies,palaeoenvironmental, and organic geochemical answers

In different areas of the Western Desert of Egypt, the Abu Roash “G” Member exhibits either a reservoir or source affinity. Thus, thirteen cutting samples covering the Abu Roash “G” Member were selected from the Nest-1A well at Matruh Basin to investigate its hydrocarbon source potential. Palynological age dating of the section that is calibrated with foraminifera and ostracodes enabled a proper identification of the “G” Member. Detailed analysis of the vertical distribution of particulate organic matter of this member shows two palynofacies types. PF-1 reflects an outer middle shelf depositional environment of prevailed reducing (suboxic-anoxic) conditions for the organic-rich shales of the lower “G” Member (samples 1–8). While, PF-2 reflects a minor regression that resulted in deposition of another organic-rich shales of the upper “G” Member (samples 9–13) in an inner middle shelf setting under the same prevailing reducing (suboxic-anoxic) conditions.Organic geochemical analysis reveals good to very good potential of the “G” Member as a hydrocarbon source rock (1.8–2.41, avg. 2.15 total organic content wt %). It also shows good to very good petroleum potential (PP: 4.8–11 , avg. 8 mg HC/g rock). Pyrolsis and palynofacies analyses show kerogen type II for the lower “G” Member (samples 1–8), which is characterized by high Hydrogen index (HI: 396 and 329 mg HC/g TOC at depths 1500 and 1560 m) and very high dominance of oil-prone material (amorphous organic matter “AOM”, marine palynomorphs, and sporomorphs) and very rare occurrence of gas-prone material (brown phytoclasts). The upper “G” Member (samples 9–13) shows kerogen type II-III, which is characterized by a lower HI value of 213 mg HC/g TOC at depth 1340 m and it contains fewer amounts of gas-prone material and relatively lower AOM and marine palynomorphs in comparison to the upper “G” Member. Maturation parameters T_max (430–433 °C), production index (PI: 0.1 mg HC/g rock), and thermal alteration index (TAI: 2+) indicate the lower “G” Member has already entered the early oil-window kitchen, and it is expected to produce oil. The upper “G” Member is expected to produce only oil with no gas shows, because it is marginally mature (T_max 426 °C, PI 0.2, TAI 2). The source potential index (SPI: 5.3 t HC/m²) of the “G” Member shows it as currently generating moderate quantities of oil in the area of Nest-1A well.Consequently, the organic-rich shales of the “G” Member are suggested here as a promising, active oil source rock in that extreme northwestern part of the Western Desert of Egypt. However, for commercial oil recovery from the Abu Roash “G” Member, it is highly recommended to explore the depocentre of Matruh Basin at about 150 km east the Nest-1A well.