Ace Lake: three decades of research on a meromictic, Antarctic lake

Ace Lake (Vestfold Hills, Antarctica) has been investigated since the 1970s. Its close proximity to Davis Station has allowed year-long, as well as summer only, investigations. Ace Lake is a saline meromictic (permanently stratified) lake with strong physical and chemical gradients. The lake is one of the most studied lakes in continental Antarctica. Here we review the current knowledge of the history, the physical and chemical environment, community structure and functional dynamics of the mixolimnion, littoral benthic algal mats, the lower anoxic monimolimnion and the sediment within the monimolimnion. In common with other continental meromictic Antarctic lakes, Ace Lake possesses a truncated food web dominated by prokaryote and eukaryote microorganisms in the upper aerobic mixolimnion, and an anaerobic prokaryote community in the monimolimnion, where methanogenic Archaea, sulphate-reducing and sulphur-oxidizing bacteria occur. These communities are functional in winter at subzero temperatures, when mixotrophy plays an important role in survival in dominant photosynthetic eukaryotic microorganisms in the mixolimnion. The productivity of Ace Lake is comparable to other saline lakes in the Vestfold Hills, but higher than that seen in the more southerly McMurdo Dry Valley lakes. Finally we identify gaps in the current knowledge and avenues that demand further investigation, including comparisons with analogous lakes in the North Polar region

Statical electrocoagulation of model wastewater

Przedstawiono wyniki elektrochemicznego oczyszczania ścieków modelowych. Porównano parametry oraz efekty elektrolitycznego oczyszczania ścieków w warunkach chronopotencjometrycznych (CHRP), tj. przy stałym natężeniu prądu (I = const), oraz chronoamperometrycznych (CHRA), tj. przy stałym napięciu (U = const). Elektrolizę prowadzono w układzie statycznym z użyciem elektrolizera z elektrodami glinowymi. Zastosowano 6-elektrodowy (3 katody i 3 anody) elektrolizer. Po elektrokoagulacji i sedymentacji osadu w roztworze oznaczano chemiczne zapotrzebowanie na tlen ChZT, mętność, barwę, zawiesiny oraz stężenie fosforu ogólnego.This paper presents the results of electrochemical treatment of model wastewater. Parameters and results of electrolytic treatment of the model wastewater under chronopotentiometric (CHRP) conditions, ie at constant current (I = const), and under chronoamperomtric (CHRA) conditions, ie at constant voltage (U = const), were compared in the study. Electrolysis was performed in a static system, using an electrolyser with aluminium electrodes. Six-electrode (three cathodes and three anodes) electrolyzers were applied. Chemical oxygen demand (COD), color, turbidity, suspended solids and total phosporus concentration were measured after electrocoagulation and sludge sedimentation. The process of static electrocoagulation was found to be an effective method for model wastewater treatment

Holocene elemental, lead isotope and charcoal record from peat in southern Poland

This article presents a mid-resolution elemental, isotopic and charcoal record from 10700 BC to AD 500 in a peat core located in Żyglin (southern Poland). The objective is to give insight into the proxies with emphasis on lead (Pb) sources in this minerogenic peat deposit. During the Early Holocene (10700–7550 BC) the average 206Pb/207Pb quotient was around 1.196. This isotopic signature is consistent with natural dust derived from long-distance soil and rock weathering. The Mid-Holocene period (7550–3200 BC) shows a significant change in the peat accumulation conditions. The growth rate is approximately 0.04 mm yr-1 and the 206Pb/207Pb quotients are shifted toward values that are found in local galena ores. This is simultaneous with a significantly increased lead flux which further confirms local sources of material in this peat deposit. In the Late Holocene period (3200 BC–AD 500) a large quantity of charcoal particles with diameters ranging from 2 mm up to 3 cm is found; also, Pb, Zn and Cu fluxes reach their highest values. This period corresponds to the Eneolithic, Bronze and Iron Ages, and human impact is recorded as charcoal

Destabilization of model wastewater in the chemical coagulation process

W niniejszej pracy przedstawiono, opisano i zinterpretowano wyniki badań laboratoryjnych procesu koagulacji-flokulacji ścieków modelowych. Zastosowane ścieki modelowe okazały się podatne na oczyszczanie metodą koagulacji chemicznej. Zastosowano i porównano dwa komercyjne koagulanty: PAC - wyprodukowany w zakładach chemicznych DEMPOL-ECO oraz PIX - wyprodukowany przez firmę KEMIPOL. Do przedstawienia i analizy uzyskanej bazy danych doświadczalnych z powodzeniem zastosowano model matematyczny w postaci wielomianu drugiego stopnia. Minimum takiej paraboli każdorazowo stanowiła dawka koagulantu precyzyjnie obliczana i traktowana jako dawka optymalna. Zastosowanie wyższej, aniżeli optymalna, dawki koagulantu prowadziło każdorazowo do obniżenia stopnia oczyszczenia koagulowanych ścieków. Szczegółowa analiza wyników usuwania mętności, zawiesin, fosforu ogólnego i zanieczyszczeń określanych w skali ChZT pokazała, że PAC skuteczniej i wydajniej, aniżeli PIX, koagulował badane ścieki modelowe.This paper discusses the results of laboratory analyses of the coagulation and flocculation of model wastewater. The investigated wastewater was susceptible to treatment by chemical coagulation. The effectiveness of two commercial coagulants, PAC produced at the DEMPOL-ECO Chemical Plant and PIX manufactured by KEMIPOL, was compared. A mathematical model relying on a second-degree polynomial was used to describe and analyze experimental data. In each case, the parabola minimum point was a precisely determined coagulant dose, regarded as the optimal dose. The application of a coagulant dose higher than the optimal dose reduced the effectiveness of wastewater treatment by coagulation. A detailed analysis of turbidity, suspended solids, total phosphorus and pollutant removal measured by the COD test revealed that PAC was a more effective and a more efficient coagulant than PIX