Can the sensitivity of soil-dwelling organisms to landfarmed soils contribute to asess the sustainablity of landfarming of oil refinery waste?

Abstract

Beneficial soil organisms inhabiting healthy soils participate in providing soil ecosystem sevices. Oil refineries generate large quantities of solid waste containing several classes of hydrocarbons as well as metals, which are ploughed into the soil during landfarming to utilise the biodegradation capabilities of the ecosystem of the soil. The contaminants may be toxic to these organisms. For the sustainable use of the services of the ecosystem of the soil, it is crucial to know whether remediation had been sufficient for the intended land use. Indicators are needed to assess the degree of recovery. This study aimed to analyse landfarmed soil at an oil refinery chemically and to assess the toxicity and recovery by using a variety of standardised bioassays with the vermicomposting species Eisenia andrei (Oligochaeta) and the springtail Folsomia candida (Collembola). The results showed that soil from the landfarming site, despite remediation, still contained several hazardous chemicals such as diesel range organics, but that the soil mixture was not acutely toxic to the exposed test organisms. It did cause a loss in earthworm (E. andrei) biomass, inhibited cocoon production and also decreased juvenile production of the springtail F. candida. The results suggested the site still needs remediation before landfarming should continue. Bioassays provide a more ecologically relevant assessment of the remediation status of the soil and its toxicity than chemical analysis alone. This finding supports the use of bioassays as an ecotoxicological tool for assessment of landfarmed soils.

The suitability of potworms (<i>Enchytraeidae</i>) and plants to test the toxicity of oil refinery sludge

“…Die aktiwiteite van die olienywerheid genereer soliede afval wat verskeie chemiese stowwe bevat soos swaarmetale, vlugtige organiese verbindings (VOV's), polisikliese aromatiese koolwaterstowwe (PAK's), houtpreserveermiddels (pentachloorfenool en kreosoot), oplosmiddels en totale petroleum koolwaterstowwe (TPK's) (Vidali 2001;Reinecke, Reinecke & Van Wyk 2015). Hierby is karsinogene, endokriene en metaboliese versteurders ingesluit (Carpenter, Arcaro & Spink 2002).…”

“…Naas voordele het die grondbewerking van olieslik ook beperkinge. Die chemiese stowwe kan onder meer voordelige grondorganismes soos myte, erdwurms, potwurms, springsterte en verskeie ander wat in gesonde gronde voorkom, benadeel (Cermak et al 2010;Reinecke et al 2015). Loehr en Webster (1996) het aangetoon dat remediёring wel in grond kan plaasvind sodat die chemiese konsentrasies van sommige stowwe met verloop van tyd afneem, maar metodes is steeds nodig om die herstelstatus van sodanige grond te meet, asook om die toksisiteit van die afval self te meet.…”

“…Toetse soortgelyk aan dié wat deur Reinecke et al (2015) vir erdwurms beskryf is, is uitgevoer in rondeboomplastiekhouers (9 cm radius en hoogte van 18 cm, met oppervlak van 1781 cm 2 ) deur die flesse in twee gelyke dele met 'n plastiektussenskot te verdeel. Elke afdeling is met 30 g van die spesfieke substraat gevul in die volgende kombinasies: (1) Verwysingperseelgrond aan beide kante (negatiewe kontrole), (2) verwysingsperseelgrond versus noordperseelgrond, (3) verwysingsperseelgrond versus suidperseelgrond, (4) verwysingsperseelgrond versus verwysingsperseelgrond + 3% API-slik (positiewe kontrole) en (5) verwysingsperseelgrond versus OECD-grond.…”

“…'LOEC of lowest observed effect concentration') en GWEK (geen waarneembare effekkonsentrasie) (Eng. 'NOEC of no observed effect concentration') is met behulp van die rekenaarprogram ToxRat Professional (ToxRat ® 2003) bereken, gebaseer op die protokol van die OECD-riglyn 208(OECD 2006).Die eienskappe van die substrate wat in die studie gebruik is, was dieselfde as watReinecke et al (2015) gebruik het en word nie weer volledig herhaal nie, maar wel weergegee waar dit in die bespreking ter sake is.Die EK 50 vir voortplanting is bereken as 26 550 mg/kg (2.66%). Potwurms wat vir drie weke blootgestel is aan grond van die verwysingsperseel, wat met 2.5% slik gekontamineer is, het betekenisvol (p < 0.05) minder juveniele geproduseer as potwurms in dieselfde ongekontamineerde grond.Potwurms wat aan 'n slik-konsentrasiereeks in OECD-grond blootgestel is (Figuur 2) het 'n LK 50 hoёr as 5% gehad.…”

“…Vergelyking van die effekkonsentrasies (waar 50% van die voortplanting geaffekteer is) van drie spesies naamlik: E. doerjesi (hierdie studie), E. andrei en F. candida(Reinecke et al 2015) na blootstelling aan 'n konsentrasiereeks van API-slik in verskillende grondtipes. http://www.satnt.ac.za Open Access met vorige bevindings (Adam & Duncan 1999; Ogbo 2009; Wyszkowski & Ziólkowska 2009) dat boontjies potensiaal het as fitoremedieerders van koolwaterstofbesoedeling.…”