Application of zeolite to trace metal removal from groundwater in permeable reactive barrier systems (PRB)

Przedstawiono wyniki badań laboratoryjnych mających na celu określenie możliwości usuwania jonów cynku, kadmu i ołowiu z wód podziemnych na naturalnym zeolicie w postaci przepuszczalnej bariery aktywnej. Wykazano, że skuteczność usuwania jonów badanych metali w testach nieprzepływowych zależała od dawki sorbentu, początkowej zawartości jonów metali, pH wody i czasu kontaktu. Wysoką skuteczność usuwania jonów metali (>90%) w tym procesie uzyskano stosując dawkę zeolitu 50 g/m3, pH=6÷7 oraz czasu kontaktu 2 h. Przeprowadzone badania w układzie przepływowym (test kolumnowy) umożliwiły odtworzenie warunków panujących podczas przepływu zanieczyszczonych wód podziemnych przez przepuszczalną barierę aktywną. Skuteczne działanie zeolitu jako bariery aktywnej (>99%) utrzymywało się w czasie odpowiadającym 5÷6-krotności wymiany objętości złoża. Niewielkie zmiany pH wody oraz brak oddziaływania zeolitu z obecnymi w niej anionami sugerują długą żywotność i stabilność tego materiału jako bariery aktywnej w oczyszczaniu wód podziemnych.The laboratory results were presented aiming at evaluation of natural zeolite (clinoptilolite) potential as PRB material in removal of lead, zinc and cadmium from groundwater. It was demonstrated that efficacy of trace metal removal in jar tests depended on sorbent dose, initial metal ion concentration, groundwater pH and contact time. High efficacy of metal ion removal (>90%) was received using zeolite at a dose of 50 g/m3 at pH=6÷7 and with contact time of 2 h. The continuous-flow column experiment allowed imitating conditions of contaminated groundwater flow through PRB. Performance of the zeolite permeable reactive barrier (>99%) remained effective for the time corresponding to 5÷6 zeolite bed volumes. Insignificant changes in groundwater pH and lack of interactions between zeolite and groundwater anions suggest longevity and stability of zeolite as the reactive barrier in groundwater remediation

Efektywność wspomagania biodegradacji w gruncie zanieczyszczonym węglowodorami ropopochodnymi

Studies were conducted using a 10-chamber Micro-Oxymax (Columbus, OH, USA) respirometer to determine the effect of bioaugmentation, biostimulation and combination of them on enhancing intrinsic biodegradation of oil hydrocarbons in soil. Contaminated soil was collected from a former military airport in Kluczewo, Poland. Bioaugmentation was realized by addition of indigenous or exogenous bacteria to soil. Biostimulation was done by aerated water supply and surfactant addition. Bioaugmentation + addition of a surfactant was applied as the combined treatment. The intrinsic and enhanced hydrocarbons biodegradation rates were estimated from the slopes of linear regressions of cumulative curves of O2 uptake. Pertinent biodegradation rates were recalculated on the basis of the stoichiometric reaction (mass balance equation) and conversion equation. The results showed that combined treatment (indigenous bacteria bioaugmentation + addition of a surfactant) was the most effective method of biodegradation enhancement as the 20-fold increase of biodegradation rate was observed.Przeprowadzono badania mające na celu określenie efektywności wspomagania biodegradacji węglowodorów ropopochodnych w gruncie w wyniku zastosowania bioaugmentacji, biostymulacji lub metody kombinowanej. Próbki gruntu użyte do badań zostały pobrane z terenu Centralnej Stacji Tankowania (CST) lotniska Kluczewo niedaleko Stargardu Szczecińskiego. Bioaugmentację przeprowadzono z użyciem autochtonicznych i allochtonicznych mikroorganizmów zdolnych do rozkładu węglowodorów ropopochodnych. Z kolei biostymulacja obejmowała wprowadzenie napowietrzonej wody lub substancji powierzchniowo czynnej (SPC) do zanieczyszczonego gruntu. Biodegradację węglowodorów ropopochodnych szacowano na podstawie konsumpcji O2 przy użyciu respirometru Micro-Oxymax V6.0 COLUMBUS INSTRUMENTS. Średnie szybkości konsumpcji O2 podczas biodegradacji węglowodorów wyznaczono z równań aproksymacji liniowej krzywych kumulacyjnych. Na podstawie równania bilansu masy i wyznaczonych szybkości konsumpcji O2 obliczono szybkość biodegradacji węglowodorów, tj. szybkość ubytku substratu w czasie. Z przeprowadzonych badań wynika, że metoda kombinowana (kombinacja bioaugmentacji z dodatkiem SPC) była najbardziej efektywną metodą wspomagania biodegradacji węglowodorów ropopochodnych w gruncie - odnotowano wtedy 20-krotny wzrost szybkości biodegradacji

Effect of dose and application site on quinclorac absorption by barnyardgrass biotypes Efeito de dose e local de aplicação na absorção de quinclorac em biótipos de capim-arroz

This work aimed to evaluate the uptake and translocation of quinclorac in function of application sites (shoot or roots) by Echinochloa crusgalli biotypes resistant and susceptible to this herbicide. The treatments consisted of quinclorac doses (0; 0.5; 1; 2; 4; 16 and 64 ppm), applied on the shoot or roots of seedlings of barnyardgrass biotypes. The experimental units consisted of plastic cups containing 250 cm³ of sand. The treatments were applied 10 days after emergence, when barnyardgrass plants reached a 2- to 3- leaf growth stage. The barnyardgrass biotypes were irrigated with nutritive solution weekly and maintained for 40 days after emergence, when length, fresh and dry matter of shoot and roots were evaluated. Variance analysis was carried out using the F test at 5% probability, and in case of significance, a non-linear regression analysis was also carried out using a three-parameter logistic model. In the susceptible biotype, quinclorac was more absorbed by the roots than by the shoot. Comparing dry mass production of the different plant parts of the susceptible biotype per application site, it was verified that quinclorac action is higher when applied to the plant roots. However, for the resistant biotype, it was not possible to determine the dose causing 50% reduction in dry mass accumulation (GR50) and in the resistance index (RI) between both biotypes, due to its high resistance to quinclorac (128 times the recommended dosage). The results showed that quinclorac resistance by the evaluated biotype is not due to differences in the absorption site, strongly suggesting that the resistance acquired by the biotype may result from alteration in the target site.<br>Objetivou-se com este trabalho avaliar a absorção e a translocação do quinclorac em função dos locais de aplicação (parte aérea ou raiz) em biótipos de capim-arroz (Echinochloa crusgalli) resistente e suscetível a esse herbicida. Os tratamentos foram compostos por doses de quinclorac (0; 0,5; 1; 2; 4; 16; e 64 ppm), aplicadas na parte aérea ou nas raízes das plântulas dos biótipos de capim-arroz resistente e suscetível ao herbicida. As unidades experimentais foram compostas por copos plásticos contendo 250 cm³ de areia. Dez dias após a emergência aplicaram-se os tratamentos, com as plantas de capim-arroz em estádio de duas a três folhas completamente expandidas. Os biótipos de capim-arroz foram irrigados com solução nutritiva semanalmente e mantidos até 40 dias após a emergência, quando foram avaliados o comprimento e as massas fresca e seca da parte aérea e das raízes. A análise de variância foi realizada pelo teste F a 5% de probabilidade e, em caso de significância, realizou-se análise de regressão não linear pelo modelo logístico de três parâmetros. No biótipo suscetível, o quinclorac foi mais absorvido pelas raízes em relação à parte aérea. Comparando a produção de massa seca das diferentes partes da planta do biótipo suscetível, por local de aplicação do herbicida, verificou-se que a ação do quinclorac é maior quando aplicado às raízes das plantas. Todavia, para o biótipo resistente, em razão da alta tolerância deste ao quinclorac (superior a 128 vezes a dose recomendada), não foi possível determinar a dose que causa 50% de redução no acúmulo de massa seca (GR50) nem o índice de resistência (RI) entre ambos os biótipos. Os resultados desta pesquisa evidenciam que a resistência do biótipo avaliado ao quinclorac não se deve a diferenças em relação ao local de absorção e indicam que a resistência do biótipo avaliado ao quinclorac pode resultar de uma alteração no local de ação do herbicida na planta

A hole in the nematosphere: tardigrades and rotifers dominate the cryoconite hole environment, whereas nematodes are missing

The worldwide distribution of microinvertebrates on glaciers, the coldest biome, is poorly known. Owing to their tolerance to hostile conditions, small size and dispersal abilities, nematodes, tardigrades and rotifers are considered cosmopolitan and together inhabit various ecosystems. In this study, we investigated their global distribution in cryoconite holes - a type of freshwater reservoir forming directly in the glacial ice that creates biodiversity hotspots on glaciers. We analysed cryoconite samples (using classical microscopic observations and environmental DNA metabarcoding) from 42 glaciers located around the world (the Arctic, Subarctic, Scandinavia, the Alps, the Caucasus, Siberia, Central Asia, Africa, South America and Antarctica), as well as using literature data. Samples from Antarctic, Karakoram and the Alps were analysed using next-generation sequencing (NGS) and classical observations under microscopes, while all other samples were analysed by microscope alone. Three general outcomes were found: (1) tardigrades and rotifers represented the most common invertebrates in cryoconite holes; (2) tardigrades and rotifers often coexisted together, with one or the other dominating, but the dominant taxon varied by region or by glacier; (3) nematodes - the most abundant, hyperdiverse and widespread metazoans on Earth, including in environments surrounding and seeding glacial surfaces - were consistently absent from cryoconite holes. Despite the general similarity of environmental conditions in cryoconite holes, the distribution of tardigrades and rotifers differed among glaciers, but not in any predictable way, suggesting that their distribution mostly depended on the random dispersal, extreme changes of supraglacial zone or competition. Although nematodes have been found in supraglacial habitats, cryoconite hole environments seem not to provide the necessary conditions for their growth and reproduction. Lack of physiological adaptations to permanently low temperatures (similar to 0 degrees C) and competition for different food resources in the cryoconite hole environment may explain the absence of nematodes in cryoconite holes