## 4 Conclusions  
Sediments from the Guadalquivir River were assessed through a battery of bioassays with amphiopods, sea urchins, bacteria, and worms in laboratory conditions. Based on the results obtained for metal contamination and toxicity assessment, the present study demonstrated alterations associated with the contamination measured in sediments. Sediments from the AL and SE stations showed an important relationship between metals and toxic endpoints which are higher in AL than in the area of SE. Sediments at the AR station showed a complex mixture of sources of metals with a moderate effect compared to the other two stations with a potentially different origin of Cd, Cu, Co, and As at the location of the dam upstream of the estuary. A sediment quality guideline for metals analyzed was calculated and compared to international and national guidelines showing the action level gap between them, with a contamination range higher than those from this study. For this reason, this set of chemical guidelines derived based on toxic studies could be useful for future river \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**CCME 1**} & \multicolumn{2}{c}{**Riba [6]**} & \multicolumn{2}{c}{**CEDEX 2**} & \multicolumn{2}{c}{**Present Study**} \\ \cline{2-9}  & **ISQG** & **PEL** & **V1** & **V2** & **AL1** & **AL2** & **AL3** & **ALR** \\ \hline As & 7.24 & 41.6 & 27.4 & 213 & 35 & 70 & 280 & 9.77–9.84 \\ Cd & 0.7 & 4.2 & 0.51 & 0.96 & 1.20 & 2.40 & 9.60 & 0.13–0.26 \\ Cu & 18.7 & 108 & 209 & 979 & 70 & 168 & 675 & 35.37–35.51 \\ Ni & & - & - & 30 & 63 & 234 & 23.39–23.56 \\ Pb & 30.2 & 112 & 260 & 270 & 80 & 219 & 600 & 27.29–28.4 \\ Zn & 124 & 271 & 513 & 1310 & 205 & 410 & 1640 & 66.79–69.95 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: SQGs comparison for marine sediments. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Contaminant**} & \multicolumn{2}{c}{**Sediment Quality Guidelines (SQGs)**} \\ \cline{2-5}  & **Not Polluted** & **Moderately Polluted** & **Highly Polluted** \\ \hline Cu & \(\leq\)35.37 & 35.37–35.51 & \(\geq\)35.51 \\ Zn & \(\leq\)66.79 & 66.79–69.65 & \(\geq\)69.65 \\ Fe & \(\leq\)21,920 & 21,920–22,140 & \(\geq\)22,140 \\ Co & \(\leq\)5.82 & 5.82–7.70 & \(\geq\)7.70 \\ Ni & \(\geq\)23.39 & 23.39–23.56 & \(\geq\)23.56 \\ Cd & \(\leq\)0.13 & 0.13–0.26 & \(\geq\)0.26 \\ Pb & \(\leq\)27.29 & 27.29–28.40 & \(\geq\)28.40 \\ As & \(\leq\)9.77 & 9.77–9.84 & \(\geq\)9.84 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of calculated benchmark sediment quality guidelines (SQGs; mg kg\({}^{-1}\) dw) proposed to evaluate sediment quality in the Guadalquivir River course between the Alcalá del Rio and Seville for the metals Cu, Zn, Fe, Co, Ni, Cd, and Pb, and the metalloid as associated with toxic effects. ine/estuarine/coastal management plans. The approach used in this study by means of different lines of evidence (contamination of metals and sediment toxicity) is a first step of sediment quality assessment in the area. Similar studies including other contaminants (organics and an emergent like pharmaceuticals) will improve the integrated analysis for a correct sediment quality assessment in the area. [PERSON] has contributed to all the aspects of the article from the conceptualization to the funding acquisition, including contributions in methodology, software, validation, formal analysis, investigation, resources, data curation and writing, and editing the paper from the start to the final version. [PERSON] has contributed in most of the aspects including the conceptualization, investigation, resources, data curation, writing, original draft preparation, writing--review and editing, visualization, supervision, and project. [PERSON] has also contributed to most of the aspects including methodology; software; validation; formal analysis; writing--original draft preparation; writing--review and editing; visualization; supervision; project administration; and funding acquisition.