تم من خلال هذه الدراسة لقاع (أبو قرضي) في شمال شرق الأردن التعرف على نوع الرسوبيات في تلك المنطقة، وحجومها، وطريقة توزيعها: أفقيا وعموديا، بالاعتماد على الظروف البيئية، ونوع الصخور المحيطة بالمنطقة، وذلك من خلال أخذ عدد من العينات السطحية، وتحت السطحية ودراسة التكوين المعدني والكيميائي لها، وعلاقته بالتوزيع الكمي والنوعي للحجوم المختلفة لتلك الرسوبيات: أفقيا وعموديا، ومدى ارتباط ذلك بعوامل التجوية والظروف البيئية خلال الزمن الجيولوجي، وكذلك بنوعية الصخور والمواد الرسوبية المحيطة بمنطقة قاع 
(أبو قرضي). كما تم تحديد كل ذلك مع العلاقات الجيومورفولوجية للقاع وما يحيط به. وبينت الدراسة أن نسبة الغرين تقع تقريبا بين 40-90، وتزداد بالانتقال العمودي في رسوبيات القاع مع العمق، وأن الرسوبيات لوم غضاري طيني الى لوم غضاري. ووجد أن معادن الكالسايت، والكوارتز، والبلاجيوكليز، وبعض المعادن الطينية: (الكاؤلينايت، والمسكوفايت، والإليت، والمونتموريلينايت) والدولومايت، والجبص هي المعادن الأساسية المكونة لتلك الرسوبيات.
 يعتقد أن معادن الكالسايت والدولومايت تكونت بنفس الحوض الترسيبي، والقليل منها يعد منقولا، أما الكوارتز والبلاجيوكليز والمعادن الطينية فهي ذات مصدر فتاتي منقول من خارج منطقة القاع نتيجة عمليات التجوية للصخور الرسوبية والبازلتية المحيطة بالمنطقة، بينما يترسب معدن الجبص نتيجة ارتفاع نسبة التبخر في بعض الفصول في تلك المنطقة.
 ويزداد تركيز بعض العناصر بشكل واضح نتيجة امتزازها من قبل المعادن الطينية، مثل: ازدياد تركيز عنصري الحديد والبوتاسيوم نتيجة وجود معدن الإليت، كذلك يرتبط البوتاسيوم بوجود المعادن الطينية المختلفة، أما عنصرا الحديد والمغنيسيوم فيزداد تركيزهما نتيجة عمليات التجوية الكيميائية والفيزيائية لصخور البازلت الموجودة في المنطقة، كما تعود النسبة العالية لعنصر السيليكون نتيجة وجود المعادن الطينية السيليكاتية وحبات معدن الكوارتز. وهذه التراكيز جميعها لتلك العناصر وغيرها مرتبطة ارتباطا وثيقا ومباشرا بالظروف المناخية وعمليات التجوية السائده بالحوض، والمنطقة المحيطة به بشكل عام.

Mineralogy and Geochemistry of the Sediments of

Potential urban runoff impacts and contaminant distributions in shoreline and reservoir environments of Lake Havasu, southwestern United States.

Application of geochemical techniques for prospecting unconventional phosphate sources: A case study of the lake sediments in Eppawala area Sri Lanka

Osmoregulation in birds is complicated, with different organs acting concurrently to regulate this physiological process. Of particular interest is how the urinary excretions of birds can remove excess nitrogen while minimizing the need for dietary water and balancing the physiological demands of oviparity. It has long been concluded from chemical analyses, and more recently from genetic studies, that uric acid is the principal constituent of urine in Aves. However, research has also demonstrated that waste material may be modified in the ceca immediately prior to it being expelled. Here, we quantify the chemical composition of the urine component of excreta of six avian species using X-ray diffraction techniques to test the hypothesis that it is principally composed of uric acid, as commonly reported. None of the analyzed samples were found to contain uric acid. Instead, a variety of compounds including ammonium urate, struvite (magnesium ammonium phosphate), and two unknown compounds, were found. Our results show that the uric acid pathway is indeed the system by which nitrogen is removed in these birds, but that additional modification occurs in the urine prior to excretion. These results raise questions for future research on the urinary excretions of birds, including identification of the unknown compounds found in the present study.

A re-evaluation of the chemical composition of avian urinary excreta

Ambient sediment quality conditions in Minnesota lakes, USA: Effects of watershed parameters and aquatic health implications.

Abstract In 2010-2013, 528 samples of surface sediments were collected from the profundal zone of lakes to determine concentrations of phosphorus, Al, Ca, Fe, K, Mn, Na and S, as well as trace elements (As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sn, Sr, Ti, V and Zn) using the ICP-OES method. Additionally, Hg concentration (by the TMA method) and organic carbon concentration (using the coulometric titration method) were also determined. Phosphorus concentration was found to range from 0.005 to 1.925% (0.109% on average). High phosphorus concentrations in sediments were reported in lakes located within and around urban areas, in lakes on which recreation centres and leisure facilities are situated, and in lakes adjoining special protection areas of birds. The phosphorus concentration in sediments shows a clear correlation with the contents of Al, Fe, Mn, S and TOC, which indicates the presence of phosphorus in both organic and inorganic forms. It also correlates with the contents of most of the trace elements examined for this study, including Zn, Hg and Pb. A certain regional variability was found; water sediments of lakes in the Masurian and Pomeranian lakelands, located in the area covered by the Pomeranian phase ice sheet, are characterised by a slightly higher phosphorus concentration compared with those from the Greater Poland Lakeland situated in the area of the Poznań phase glaciation.

/pdf/phosphorus-in-lake-sediments-of-poland-results-of-monitoring-2c56561d9g.pdf

Phosphorus in lake sediments of Poland – Results of monitoring research

Abstract In the years 2010-2013, 528 samples of surface sediments were collected from lake depths in the area of Poland. The content of 7 PCB congeners, HCH isomers and p,p’-DDT, p,p’-DDE and p,p’-DDD was determined using the GC-ECD method. The studies showed the common occurrence of organochlorine compounds in lake sediments in Poland. The presence of HCHs, at a concentration above the determination limit, was detected in 83.71% of samples, that of DDTs in 98.86% of samples, and of PCBs in 98.86% of samples. The maximum HCH concentration was 60.7 ng g-1, that of DDTs 602.9 ng g-1, and of PCBs 50.7 ng g-1, while the averages were 6.3 ng g-1, 19.2 ng g-1 and 2.8 ng g-1, respectively. High levels of DDTs are found in sediments of those lakes upon which major towns are located, whereas the highest HCH concentrations are observed in sediments of the lakes upon which holiday centres and agrotourism facilities have developed. The ratio of concentrations of total DDT metabolites to p,p’-DDT was above 2 in almost all samples, and the value was most frequently from several to tens (average 28.3). Sediments of some lakes contain higher concentrations of γ-HCH and DDT metabolites than their PEC values, the content of γ-HCH was higher in 1.89% of the analysed samples, the content of p,p’-DDE in 3.78% of the samples, and the content of p,p’-DDD in 7.38% of the samples. Concentrations of p,p’-DDT and PCB in excess of the PEC value were not found in any of the samples tested.

/pdf/assessment-of-ddt-hch-and-pcb-pollution-of-lake-sediments-in-4l1htppkms.pdf

Assessment of DDT, HCH and PCB pollution of lake sediments in Poland

DDT AND ITS METABOLITES IN SURFACE SEDIMENTS OF LAKES AND RIVERS OF POLAND Abstract. The contents of p,p'-DDT, p,p'-DDh, p,p'-DDD were determined in 300 samples of river sediments and 150 samples of lake sediments, collected from the whole area of Poland, by using the GC-ECD method. In river sediments the maximum contents were as follows: p,p'-DDT - 2780 µg/kg, p,p'-DDD - 913 µg/kg. and p,p'-DDE -298 µg/kg. The presence of p,p'-DDT was detected in 38.9% of the samples, p,p'-DDE - in 90.0%, and p,p'-DDD - in 78.4%. The ratio of p,p'-DDD/p,p'-DDT in river sediments ranged from 0.08 to 46.3, and the ratio of p,p'-DDE/p,p'-DDT was in the range of 0.04—24.7. In the lake sediments the contents of p,p'-DDT ranged up to 4.7 µg/kg, p,p'-DDE - up to 63.5 µg/kg, and p.p'-DDD - up to 70.1 µg/kg. The presence of p.p'-DDT was detected in 36% of the samples, p,p'-DDD - in 96.67%, and the metabolite p,p'-DDE - in alt samples. The ratio of p,p'-DDD/p,p'-DDT in lake sediments ranged from 0.4 to 112.2, and the ratio of p,p'-DDE/p,p'-DDT was in the range of 0.2-163.8. In the lake sediments, a high correlation of the contents of DDTs with the concentrations of Cd, Hg, Pb and Zn, and a significant correlation with the phosphorus and sulphur content were found. In the river sediments, a weak correlation with the TOC content is the only one noticed.

https://geojournals.pgi.gov.pl/bp/article/download/29023/20695

Izabela Bojakowska

Papers

Phosphorus in lake sediments of Poland – Results of monitoring research

Assessment of DDT, HCH and PCB pollution of lake sediments in Poland

Ddt i jego metabolity w powierzchniowych osadach jezior i rzek polski