# Risk Assessment of a Coastal Ecosystem from SW Spain
## 3 Results and Discussion  
The results obtained for each of the LOEs used in this study are summarized in Table 2. The concentrations of most of the studied metal(loid)s in the TRO sediment sample were higher than in RSP sediment samples. Concentrations of Al, Cr, and Fe showed little variation among the pH values for both sediment samples (RSP and TRO). The Cu concentration in sediment decreased with pH for both sampling sites, whereas an increase in Zn concentration was observed in the TRO sediment at pH 6.0. However, greater variability in the concentration of metals was observed in the samples of overlying water and elutriates when compared with the sediment samples. Overall, the metal concentrations were higher in the elutriate treatment than in the overlying seawater. The concentrations of the studied elements were higher in sediment from TRO elutriates, while RSP sediments exhibited higher concentrations for most of the metals than for the overlying seawater samples.  
\begin{table}
\begin{tabular}{l l l l l l l l l l l} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Variable**}} & \multicolumn{6}{c}{**pH Treatments**} \\ \cline{2-11}  & \multicolumn{1}{c}{**RSP**} & \multicolumn{6}{c}{**TRO**} \\  & \multicolumn{1}{c}{**Control**} & \multicolumn{1}{c}{**pH 7.5**} & \multicolumn{1}{c}{**pH 7.0**} & \multicolumn{1}{c}{**pH 6.5**} & \multicolumn{1}{c}{**pH 6.0**} & \multicolumn{1}{c}{**Control**} & \multicolumn{1}{c}{**pH 7.5**} & \multicolumn{1}{c}{**pH 7.0**} & \multicolumn{1}{c}{**pH 6.5**} & \multicolumn{1}{c}{**pH 6.0**} \\ \hline Contamination & & & & & & & & & & & \\ Cr sed & 1.60 & 1.80 & 2.00 & 2.30 & 2.00 & 5.00 & 5.00 & 5.20 & 5.20 & 5.30 \\ Cr sw & bdl & bdl & bdl & bdl & bdl & bdl & bdl &  
Regarding the toxicity tests, the mortality of amphipods and mussels were 14% and 20%, respectively, for the control (not CO\({}_{2}\) injection, RSP sediment). Significant mortality (\(p<0.05\)) of amphipods was found at pH 7.0, and for mussels at pH 6.0 when exposed to RSP sediment. However, exposure to TRO sediment control displayed a mortality of 37% for amphipods and 35% for mussels. The absence of acidification treatment with TRO sediments implies that contamination strongly influenced the obtained results [18].  
However, for the embryo-larval development test, a percentage of inhibition of less than 20% was observed for both species (sea urchin and mussel) and both sediment and elutriates samples (RSP and TRO) for the control treatment (not CO\({}_{2}\) injection). The mussel-larval development inhibition differed significantly between the control and pH 6.5 and 6.0 for RSP elutriates; though it was statistically significant (\(p<0.05\)) for pH 7.5 and below for TRO samples. On the other hand, the sea urchin larval-development inhibition presented significant differences (\(p<0.05\)) at pH 7.0 for both sediment samples.  
In general, a different bioaccumulation trend for each metal(loid) was shown by _M. galloprovincialis_ with acidification. Organisms exposed to RSP samples accumulated greater concentrations of elements than those exposed to TRO samples for all the studied elements, except for Zn and Cr. Results are further detailed in [32].  
Results using the ecological integrity showed a decrease in the total abundance, richness, and diversity of benthic fauna for pH 6.0 when compared to the control for both sediment samples tested (Table 2), in agreement with [33].