North East File Collection - NEFC

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Gorham-Test is an alternative approach used to assess PAHs as there is no [[CEFAS - Action Levels]] 2 for PAHs.  This is best described in [[https://www.cefas.co.uk/publications/aquatic/aemr63.pdf|CEFAS Science Series - Aquatic Environment Monitoring Report no. 63 - Monitoring of the quality of the marine environment - 2008–2010]]



At present there is no UK legislation regarding the acceptability of levels of PAHs found in marine sediments.  Cefas currently has action level limits for contaminants such as trace elements and PCBs in dredged material for possible disposal to sea, but none currently for PAHs. Reviews of the approaches taken in other countries to the development of sediment quality guidelines (SQGs) has indicated that the most promising of the currently available co-occurrence methods is the Effects Range Low/Effects Range Median (ERL/ERM) methodology, which is founded on a large database of sediment toxicity and benthic community information (Long et al., 1998; Rowlatt et al., 2002).



The ERL/ERM methodology derives SQGs representing, respectively, the 10th and 50th percentiles of the effects dataset, and these are usually derived for individual parent PAH compounds. In a regulatory context, where SQGs are to be used as informal (non-regulatory) benchmarks to aid in the interpretation of sediment chemistry (Long et al., 1998), this becomes complicated when a large number of individual PAH compounds are determined, as is usually the case and was also in this study.



This has led to separate ERL/ERM derived SQGs being set for ‘Low molecular weight PAHs’ and ‘High molecular weight PAHs’ (Gorham-Test, 1998). In this context, LMW PAH includes the 2- and 3-ring PAH compounds naphthalene, monomethyl naphthalenes, acenaphthene, acenaphthylene, fluorene, phenanthrene and anthracene, primarily oil-derived compounds; HMW PAH includes the 4- and 5-ring PAH compounds fluoranthene, pyrene, benz[[a]]anthracene chrysene, benzo[[a]]pyrene and dibenz[[a,h]]anthracene, primarily combustion-derived compounds. Although a wider suite of PAH is determined routinely for both licensing and monitoring purposes, these subsets can be considered as toxicity markers for the PAH as a whole. The ERL and ERM concentrations for low molecular weight PAHs (LMW PAH) and high molecular weight PAHs (HMW PAH) applied to this assessment are given below.


|PAH compounds|ERL|ERM|
|LMW PAH|552|3,160|
|HMW PAH|1,700|9,600|

EPA EPA/906/R-98/00

ERL (Effects Range-Low) and ERM (Effects Range-Median) are sediment quality guideline values used to assess the potential ecological risks of chemical contaminants, including polycyclic aromatic hydrocarbons (PAHs), heavy metals, and other pollutants in sediments.

  * ERL (Effects Range-Low): This is the lower threshold value, below which adverse biological effects are rarely observed. If contaminant concentrations in sediments are below the ERL, there is a low probability of toxic effects on aquatic organisms.

  * ERM (Effects Range-Median): This is the median effects level, above which adverse biological effects are frequently observed. If contaminant concentrations exceed the ERM, there is a higher likelihood of negative impacts on marine life.

These values were developed based on empirical data from toxicity studies and are commonly used in environmental risk assessments to determine sediment quality in marine and estuarine environments.


SQG stands for Sediment Quality Guidelines. These guidelines are used in environmental science and risk assessment to evaluate the levels of chemical contaminants in sediments and their potential effects on aquatic organisms.

SQGs provide benchmark values to help determine whether contaminant concentrations in sediment pose ecological risks. Common types of SQGs include:

  * ERL (Effects Range-Low) & ERM (Effects Range-Median) – Define contaminant concentration ranges where ecological effects are rarely (ERL) or frequently (ERM) observed.
  * TEL (Threshold Effects Level) & PEL (Probable Effects Level) – Similar to ERL/ERM but based on a different statistical approach; TEL represents a low-risk threshold, while PEL indicates concentrations likely to cause harm.
  * ISQG (Interim Sediment Quality Guidelines) – Used in Canada to provide threshold values for sediment contamination assessments.

SQGs help regulatory bodies, scientists, and policymakers assess sediment contamination, set cleanup targets, and guide environmental protection measures.