Biodiversity and Marine Environment Unit, IPIMAR, National Institute of Biological Resources, 1449-016 Lisbon, Portugal.
Environ Sci Pollut Res Int. 2010 Nov;17(9):1519-28. doi: 10.1007/s11356-010-0338-7. Epub 2010 May 22.
BACKGROUND, AIM AND SCOPE: The influence of pH (range 6.5-8.5) on the uptake of Zn, Cd, Pb, Cu, Ni, Cr, Hg, and As by juveniles of the clam Ruditapes philippinarum was examined in order to understand whether variation in sediment pH has significant repercussions on metal bioaccumulation.
Clams were exposed to sediments collected in three locations in the Gulf of Cadiz (Huelva, Guadalquivir and Bay of Cadiz) and to contaminated particles derived from an accidental mining spill in Spain.
With a notable exception of metal Cd, the concentration of metals within clams significantly increased (p < 0.1) when sediment pH was lowered by one or two units. Moreover, the magnitude of this effect was dependent on the type of sediment contamination.
Lower pH increases metal solubility and reduces or invert the metal sorption of metals to sediments. Increases in free metal ions in water favors metal uptake by clams, hence pH is an important factor controlling the mobility of these metals within sediments and their subsequent bioaccumulation within biota. Although sediment-water exchange of Cd can increase with acidification, this excess may be counterbalanced by the presence of ligands in seawater preventing the uptake by organism. Besides chlorines, Cd has also an affinity with carbonates and other ligands present in sea water. These Cd-carbonate complexes may reduce the bioavailable to organisms.
These results highlight the potential implications of sediment acidification, either due to the storage excess of organic matter or to the forced capture of CO(2), on the increasing metal availability to benthic organisms.
This kind of studies should be increased to address the influence of acidification in the behavior, bioavailability, toxicity, and risk assessment of contaminants associated with sediments either above sub-seabed geological formations in marine environments or in high enriched by organic matter in estuarine areas. Recently, the capture of CO(2) in marine environments has been approved and started; it is necessary to address the potential impacts associated with leakages or other events occurring during the procedure of injection and storage of CO2.
背景、目的和范围：为了了解沉积物 pH 值的变化是否对金属生物累积有重大影响，本研究检测了 pH 值范围在 6.5-8.5 之间时，锌、镉、铅、铜、镍、铬、汞和砷对菲律宾蛤仔幼体的吸收情况。
将蛤仔暴露于在加的斯湾（Huelva、Guadalquivir 和 Cadiz 湾）三个地点采集的沉积物以及西班牙一起意外采矿溢漏事件产生的污染颗粒中。
除金属 Cd 外，当沉积物 pH 值降低一个或两个单位时，蛤仔体内金属浓度显著增加（p < 0.1）。此外，这种效应的大小取决于沉积物污染的类型。
较低的 pH 值会增加金属的溶解度，并减少或逆转金属与沉积物的吸附。水中游离金属离子的增加有利于蛤仔对金属的吸收，因此 pH 值是控制这些金属在沉积物中迁移及其在生物群中生物累积的重要因素。虽然酸化会增加 Cd 的沉积物-水交换，但海水中配体的存在可能会抵消这种增加，从而阻止生物对 Cd 的吸收。除了氯之外，Cd 还与海水中的碳酸盐和其他配体具有亲和力。这些 Cd-碳酸盐络合物可能会降低生物可利用性。
这些结果强调了沉积物酸化（无论是由于有机物质的储存过剩还是由于 CO2 的强制捕获）对底栖生物中金属增加的潜在影响。
应该增加这类研究，以解决酸化对与沉积物相关的污染物的行为、生物有效性、毒性和风险评估的影响，这些污染物要么存在于海洋环境中的海底地质构造之下，要么存在于富含有机物的河口地区。最近，海洋环境中 CO2 的捕获已经获得批准并开始实施；有必要解决在 CO2 注入和储存过程中发生泄漏或其他事件相关的潜在影响。
