Experimental Investigation of Heavy Metal Accumulation in Tissues of Stone Loach Noemacheilus Barbatulus (L.) and Rainbow Trout Oncorhynchus Mykiss (Walbaum) Exposed to a Model Mixture (Cu, Zn, Ni, Cr, Pb, Cd)

Abstract

During experiment, fish were exposed to a heavy metal model mixture (Cu, Zn, Ni, Cr, Pb, Cd) for 14 days. Heavy metal concentrations corresponded to Maximum Permitted Concentrations (MPC) in surface waters. The amount of heavy metals in fish tissues was determined using atomic absorption spectrophotometry (AAS). Though both investigated fish species accumulated heavy metals with similar general intensity, the stone loach did it in the sequence gills > liver > muscle, and the rainbow trout ‐ conversely: muscle > liver > gills. Ni concentration in the stone loach muscle made 0.607 mg/kg and Pb concentration was 0.21 mg/kg, whereas Cd concentration in the rainbow trout muscle reached 0.45 mg/kg and exceeded the MPC indicated in the Lithuanian hygiene standard. These results coincide with the data of the heavy metal research into fish species from natural water bodies. Pb and Cd concentrations in fish tissues are the highest and frequently exceed the MPC. These findings urge for the constant control of the amount of heavy metals in fish. Santrauka Bandomosios žuvys 14 paru buvo veikiamos modeliniu sunkiuju metalu mišiniu (Cu, Zn, Ni, Cr, Pb, Cd). Metalu koncentracijos atitiko ju didžiausias leidžiamas koncentracijas (DLK) paviršiniuose vandenyse. Sunkiuju metalu kiekis audiniuose buvo nustatomas atomines absorbcijos spektrofotometriniu (AAS) būdu. Nors abieju tirtu rūšiu žuvu audiniuose sunkieji metalai kaupesi vienodu intensyvumu, šlyžio audiniuose jie kaupesi tokiu eiliškumu: žiaunos > kepenys > raumenys, o vaivorykštinio upetakio ‐ atvirkščiai: raumenys > kepenys > žiaunos. Šlyžio raumenyse Ni koncentracija buvo 0,607 mg/kg, o Pb ‐ 0,21 mg/kg ,vaivorykštinio upetakio raumenyse Cd koncentracija sieke 0,45 mg/kg ir viršijo Lietuvos higienos normoje nurodytaja DLK. Šie rezultatai sutampa su sunkiuju metalu nuolatines stebesenos kontroliuojamu rūšiu žuvyse iš natūraliu vandens telkiniu tyrimu duomenimis. Žuvu audiniuose Pb ir Cd koncentracijos yra didžiausios ir dažnai viršija DLK. Tokie rezultatai ipareigoja nuolat kontroliuoti sunkiuju metalu kieki žuvyse. Резюме Подопытные рыбы в течение 14 суток подвергались воздействию смеси тяжёлых металлов (Cu, Zn, Ni, Cr, Pb, Cd) в предельно допустимых концентрациях (ПДК), предусмотренных для внутренних водоёмов. Количество тяжелых металлов в тканях рыб устанавливали при помощи атомной абсорбции спектрофотометрическим методом. Несмотря на то, что оба вида рыб накапливали металлы с одинаковой общей интенсивностью, голец их накапливал в следующей последовательности: жабры > печень> мышцы, а радужная форель – наоборот: мышцы > печень> жабры. В мышцах гольца концентрация Ni составила 0,607 мг/кг, Pb – 0,21 мг/кг, а в тканях форели концентрация Cd составила 0,45 мг/кг и превышала ПДК. Экспериментальные данные совпадают с данными, полученными в мониторинговых водоемах. Установлено также, что концентрация Pb и Cd в тканях зачастую прeвышаeт ПДК. Полученные результаты обязывают постоянно контролировать уровень тяжелых металлов в тканях рыб.

Accumulation of Heavy Metals in Different Body Tissues of Gibel Carp 𝐶𝑎𝑟𝑎𝑠𝑠𝑖𝑢𝑠 𝑔𝑖𝑏𝑒𝑙𝑖𝑜 Separately Exposed to a Model Mixture (Cu, Zn, Ni, Cr, Pb, Cd) and Nickel

“…Similar results were obtained in a previous study (Idzelis et al 2010) for rainbow trout and stone loach. Heavy metals were accumulated in different body tissues of both fish species with approximately the same total intensity.…”

“…they were below the recommended levels for human consumption. However, in previous studies under the same experimental conditions, it has been established that Ni, Pb and Cd concentrations exceeded above-mentioned limits in the body tissues of roach, perch, stone loach and rainbow trout (Idzelis et al 2008(Idzelis et al , 2010. In natural environments, HMs can migrate into fish organism not only from surrounding medium but also through food-objects (trophic chain) thus, further increasing their amount in the tissues.…”

“…Heavy metal accumulation order in Gibel carp organ tissues was following: muscle > gills > liver. Meanwhile, under the same experimental conditions in the tissues of roach and perch, they were accumulated as follows: liver > muscle > gills, in stone loach: gills> liver > muscle, and quite contrary in rainbow trout: muscle > liver > gills (Idzelis et al 2008(Idzelis et al , 2010. Without discussing possible mechanisms it is evident that HM accumulates from the water into the tissues of ecologically different fish species (roach and Gibel carp refer to freshwater limnophilous benthophagous species, stone loach -freshwater rheophylous benthophagous, perch -freshwater limnophilous euryphagous and rainbow trout -anadromous rheophylous-limnophilous euryphagous) quantitatively diversely and specifically.…”

“…Nickel was chosen because according to the results of monitoring studies of HM accumulation in fish and bottom sediments in Lithuania (Projekto… 2004), this metal often exceeds the levels recommended for human consumption in fish from natural water bodies. Actually, this study is a continuation of recently-started series of the works on experimental investigation of HM accumulation in freshwater fish of Lithuania (Idzelis et al 2008(Idzelis et al , 2010).…”

Fractionation of heavy metals in sewage sludge and their removal using low-molecular-weight organic acids

“…phosphorus and nitrogen) and organic matter, thereby increasing the number of beneficial soil organisms, reducing the need for fertilisers and pesticides, and improving the physical and biological properties of the soil (Kvasauskas, Baltrėnas 2009;Su, Wong 2003). However, a wide variety of undesirable elements, such as heavy metals (HMs), can be found in sewage sludge and have adverse effects on the environment (Alloway 1995;Jaskelevičius, Lynikienė 2009;Idzelis et al 2010). Many countries have imposed legal restrictions concerning HM content when sludge is used for on-land applications (e.g.…”