Decrease of the total capacity of aquatic ecosystems and the application of hydrogen peroxide in the regulation of accelerated eutrophication and blooming of cyanobacteria

Abstract

<p>Dugoročno re&scaron;enje problema povećanog ukupnog kapaciteta vodenih ekosistema, posledičnog ubraznja eutrofizacije i cvetanja potencijalno toksičnih cijanobakterija podrazumeva smanjenje priliva nutrijenata, kao i eliminaciju vi&scaron;ka nutrijenata iz samog vodenog ekosistema, naročito azota i fosfora. Kao re&scaron;enje ovog&nbsp; problema&nbsp; se&nbsp; predlaže&nbsp; istovremena&nbsp; upotreba&nbsp; seta&nbsp; poznatih&nbsp; alternativnih&nbsp; metoda,&nbsp; označenih zajedničkim&nbsp; nazivom&nbsp; ekomanipulacija,&nbsp; koji&nbsp; uključuje:&nbsp; mehaničko&nbsp; uklanjanje&nbsp; makrofita&nbsp; i&nbsp; biomase cijanobakterija, upotreba plutajućih ostrva, masovno izlovljavanje ribe.<br />Izvr&scaron;ena&nbsp; je&nbsp; procena&nbsp; mehaničkog&nbsp; uklanjanja&nbsp; trske&nbsp; (Phragmites&nbsp; australis)&nbsp; u&nbsp; kontekstu&nbsp; za&scaron;tite&nbsp; i preči&scaron;ćavanja vodenih ekosistema i kao energetskog resursa na teritoriji Vojvodine. Procenjeno je da je oko 0,98% povr&scaron;ine Vojvodine pokriveno trskom sa prosečnim prinosom od oko 2 kg/m 2 , odnosno oko 20 t/ha. Ko&scaron;enjem i uklanjanjem nadzemne biomase bi moglo da se ukloni do 333,20 kg/ha azota i 25,20<br />kg/ha&nbsp; fosfora.&nbsp; Pored&nbsp; povoljnih&nbsp; karakteristika&nbsp; trske&nbsp; kao&nbsp; energetske&nbsp; sirovine,&nbsp; tro&scaron;kovi&nbsp; obrade&nbsp; biomase trenutno prevazilaze potencijalnu zaradu, zbog čega ova makrofita ima veći značaj na lokalnom nivou. Ispitivana&nbsp; je&nbsp; efikasnost&nbsp; usvajanja&nbsp; nutrijenata direktno&nbsp; iz&nbsp; vodenog&nbsp; stuba putem&nbsp; uklanjanja&nbsp; nadzemne biomase trske iz PPES jedinica, kao i testiranje održivosti čitavog PPES sistema. Iako uklanjanje oko<br />800&nbsp; g&nbsp; nadzemne&nbsp; biomase&nbsp; trske&nbsp; može&nbsp; smanjiti&nbsp; ukupni&nbsp; kapacit&nbsp; do&nbsp; izvesne&nbsp; mere,&nbsp; dodatne&nbsp; vrednosti upotrebe&nbsp; PPES&nbsp; sistema&nbsp; poput usvajanja&nbsp; toksičnih&nbsp; materija,&nbsp; korisne&nbsp; upotrebe&nbsp; plastičnog&nbsp; otpadnog materijala, proizvodnje biljne biomase ovu metodu čini značajnim delom sistema ekomanipulacija. Kori&scaron;ćenjem&nbsp; puferskog&nbsp; sistema&nbsp; ekoremedijacije&nbsp; baziranog&nbsp; na&nbsp; izno&scaron;enju&nbsp; biomaske&nbsp; trske&nbsp; se&nbsp; takođe<br />obezbeđuje smanjenje ukupnog kapaciteta. Na taj način se može postići kontrola ubrzane eutrofizacije na četiri funkcionalna nivoa u dinamici ekosistema, koji podrazumevaju: sprečavanje priliva materija u vodeni&nbsp; ekosistem&nbsp; iz&nbsp; spolja&scaron;nje&nbsp; sredine&nbsp; izgradnjom&nbsp; mokrih polja,&nbsp; povećanje&nbsp; procesa&nbsp; razgradnje uvođenjem aeracije, preči&scaron;ćavanje mulja ili efluenta i manipulacija trskom u priobalju. Procenjena&nbsp; je&nbsp; efikasnost&nbsp; mehaničkog&nbsp; uklanjanja&nbsp; toksične&nbsp; biomase&nbsp; cijanobakterije&nbsp; vrste Planktothrix rubescens iz&nbsp; akumulacije&nbsp; Vrutci. Rezultati&nbsp; ukazuju&nbsp; na&nbsp; efikasnost&nbsp; ove&nbsp; metode&nbsp; u&nbsp; smanjenju&nbsp; ukupnog kapaciteta,&nbsp; međutim&nbsp; samo&nbsp; tokom&nbsp; perioda&nbsp; cvetanja.&nbsp; Ispitivana&nbsp; je&nbsp; sposobnost&nbsp; 14&nbsp; sojeva&nbsp; bakterija, izolovanih iz sakupljenje povr&scaron;inske skrame P. rubescens, da degradiraju cijanotoksin mikrocistin-LR. Degradacija toksina posle devet dana nije detektovana, &scaron;to je moglo da bude posledica dužeg perioda<br />adaptacije (lag faze) koji je bio potreban da bi se aktivirali odgovarajući geni i enzimski putevi odgovorni za biodegradaciju.<br />Ispitivana je efikasnost metode masovnog izlovljavanja babu&scaron;ke (Carassius gibelio) iz sektora IV jezera Palić. Na osnovu količine iznete biomase tokom probnog izlova 2016. godine i poznatog hemijskog sastava, procenjeno je da je masovnim izlovom moguće ukloniti značajnu količinu nutrijenata na nivou čitavog jezera. Uprkos efikasnosti i pratećim povoljnim promenama u ekosistemu, zbog složenosti lanca ishrane&nbsp; i&nbsp; uop&scaron;te&nbsp; jezerskog&nbsp; ekosistema&nbsp; se&nbsp; preporučuje&nbsp; primena&nbsp; pridruženih&nbsp; metoda&nbsp; biomanipulacije<br />ribljom fondom, kao i drugih metoda ekomanipulacije. Ispitivani su cijanocidni efekti vodonik-peroksida, kao dodatne metode u procesu revitalizacije jezera. Uzorci&nbsp; vode&nbsp; iz&nbsp; srpskih&nbsp; jezera Bečmenska&nbsp; bara (sektor&nbsp; Bečmen&nbsp; 3) i jezera&nbsp; Luda&scaron;&nbsp; i&nbsp; finskog&nbsp; jezera<br />K&ouml;yli&ouml;nj&auml;rvi su bili tretirani različiti koncentrcijama vodonik-peroksida. Analize sadržaja hlorofila a i intracelularnih&nbsp; mikrocistina,&nbsp; indeksa&nbsp; vijabilnosti&nbsp; pokretnih&nbsp; grupa&nbsp; necijanobakterijskog&nbsp; fitoplanktona, zooplanktona i osetljivosti makroinvertebrata, ukazale su na mogućnost efikasne selektivne supresije cijanobakterija ravnomernim apliciranjem 2-5 mg/L vodonik-peroksida. Uočena je različita osetljivost kod ispitivanih grupa organizama na dejstvo agensa, zbog čega je u primeni ove metode neophodan<br />dodatni oprez. Da bi se obezbedio uspe&scaron;an proces revitalizacije jezera, važno je da se metode ekomanipulacije prilagode stanju i karakteristikama jezera, a da se vodonik-peroksid koristi samo u slučaju potrebe. Na takav načinmože&nbsp; nesmetano&nbsp; da&nbsp; se&nbsp; odvija&nbsp; dugotrajan&nbsp; proces&nbsp; revitalizacije.&nbsp; Zbog&nbsp; složenosti&nbsp; problema&nbsp; povećanja ukupnog&nbsp; kapaciteta,&nbsp; ubrzane&nbsp; eutrofizacije&nbsp; i&nbsp; procesa&nbsp; revitalizacije,&nbsp; neophodno&nbsp; je&nbsp; obezbediti multidisciplinarni&nbsp; pristup,&nbsp; pripremu&nbsp; akcionog&nbsp; plana&nbsp; i&nbsp; sprovođenje&nbsp; metoda&nbsp; pod&nbsp; strogo&nbsp; kontrolisanim uslovima.</p>

<p>A long-term solution for the problem of increased total capacity in water ecosystems, and consequently accelerated eutrophication and potentially toxic cyanobacterial blooms, implies the restriction of nutrient inputs to the water bodies, as well as elimination of additional nutrients directly from water ecosystems,especially nitrogen and phosphorus. As a solution for this problem, it is proposed to simultaneously use a &nbsp; set&nbsp; of&nbsp; alternative&nbsp; methods,&nbsp; entitled&nbsp; as&nbsp; ecomanipulation,&nbsp; that&nbsp; include:&nbsp; mechanical &nbsp; removal&nbsp; of macrophytes and cyanobacterial biomass, floating islands, extensive fishing. Mechanical removal of Common reed (Phragmites australis) was estimated for the purpose of protection and&nbsp; purification&nbsp; of&nbsp; water&nbsp; ecosystems,&nbsp; as&nbsp; well&nbsp; as&nbsp; an energy&nbsp; source&nbsp; in&nbsp; the&nbsp; Vojvodina&nbsp; region.&nbsp; It&nbsp; was estimated that about 0,98% of the Vojvodina region is covered with common reed, with an average yield of 2 kg/m2, eg about 20 t/ha. By harvesting and removing of above-ground biomass, it would be possible to&nbsp; remove&nbsp; up&nbsp; to&nbsp; 333.20&nbsp; kg/ha&nbsp; of&nbsp; nitrogen&nbsp; and&nbsp; 25.20&nbsp; kg/ha&nbsp; of&nbsp;&nbsp; phosphorus.&nbsp; Besides&nbsp; favorable characteristics as an energy source, the cost of biomass processing currently exceeds potential revenues, hence this macrophyte is more significant at the local level.&nbsp; The efficiency of nutrient absorption directly from the&nbsp; water column by removal of the reed biomass incorporated in the PPES unites was examined, as well as testing the&nbsp; sustainability of the whole PPES system. Although&nbsp; removal&nbsp; of&nbsp; about&nbsp; 800&nbsp; g&nbsp; of&nbsp; the&nbsp; above-ground&nbsp; reed&nbsp; biomass&nbsp; can&nbsp; decrease&nbsp; the&nbsp; total capacity up to a certain extent, additional values of PPES usage like the uptake of toxic compounds,useful use of plastic waste material, production of plant biomass makes this method important part&nbsp; of ecomanipulation system. The use of a buffer system of ecoremediation based on the removal of reed biomass also provides a reduction in total capacity. In this way,&nbsp; control of accelerated eutrophication can be achieved at four functional levels in ecosystem dynamics, which include: preventing the&nbsp; inflow of matter into the aquatic ecosystem from the external environment by building artificial wetlands, increasing the decomposition process by introducing aeration, sludge or effluent treatment, and reed manipulation in the coastal area. The efficiency of mechanical removal of toxic biomass&nbsp; of cyanobacteria Planktothrix rubescens from the Vrutci reservoir was estimated. The results indicate the effectiveness of this method in reducing the total capacity, but only during the blooming period. The ability of 14 bacterial strains, isolated from collected&nbsp; P. &nbsp; rubescens&nbsp; surface&nbsp; scum,&nbsp; to&nbsp; degrade&nbsp; cyanotoxin&nbsp; microcystin-LR&nbsp; was&nbsp; investigated. Degradation of toxin after nine days was not detected, which could be a consequence of a longer period of&nbsp; adaptation&nbsp; (lag&nbsp; phase)&nbsp; that&nbsp; was&nbsp; needed&nbsp; for&nbsp; activation&nbsp; of&nbsp; certain&nbsp; genes&nbsp; and&nbsp; enzyme&nbsp; pathways responsible for biodegradation. The efficiency of extensive fishing of Prussian carp (Carassius gibelio) from the sector IV of Lake Palić was investigated. Based on the amount of removed biomass during the trial catch in 2016, and the known chemical composition of fish, it was estimated that extensive fishing can remove a significant amount of nutrients at the level of the entire lake. Despite the efficiency and following favorable changes in the ecosystem,&nbsp; due&nbsp; to&nbsp; the&nbsp; complexity&nbsp; of&nbsp; the&nbsp; food&nbsp; chain&nbsp; and&nbsp; the&nbsp; lake&nbsp; ecosystem&nbsp; in&nbsp; general,&nbsp; the&nbsp; use&nbsp; of associated methods of biomanipulation with fish stock, as well as other methods of ecomanipulation, is recommended.<br />The potential of cyanocidal effects of hydrogen peroxide, as an auxiliary method in the&nbsp; process of lake revitalization, was investigated. Water samples from Serbian lakes Bečmenska bara (sector Bečmen 3) and Lake Luda&scaron;, as well as Finnish Lake K&ouml;yli&ouml;nj&auml;rvi, were treated with different concentrations of hydrogen peroxide. Analysis of contents of chlorophyll a and intracellular microcystins, viability index of&nbsp; non-cyanobacterial&nbsp; moving&nbsp; phytoplankton,&nbsp; zooplankton,&nbsp; and&nbsp; sensitivity&nbsp; of&nbsp; macroinvertebrate indicated the possible efficiency of the selective suppression of cyanobacteria by uniform application of 2-5 mg/L of hydrogen peroxide in the water column. Examined groups of organisms expressed different sensitivity towards the applied concentrations of the agent, which is the reason for additional caution in the &nbsp; application of this method.In order to provide successful lake revitalization, it is important to adjust methods of ecomanipulation to the condition and characteristics of the lake, and also to use hydrogen peroxide only when it is necessary.In this way, the long recovery process can proceed smoothly. Due to the complexity of the problem of increased total capacity, accelerated eutrophication, and the process of revitalization, it is necessary to provide a multidisciplinary approach, preparation of an action plan and implementation of methods under strictly controlled conditions.</p>