# The Accumulation Characteristics of Different Heavy Metals in Sea Rice
However, many salinization areas are affected not only by salinization but also by heavy metal pollution. This severely endangers the plant growth and development and the stability of the local ecosystem and aggravates the food security problem. In recent years, one of the primary reasons for heavy metal pollution is the irrational application of organic fertilizers to soil [8]. Continuous application of organic fertilizers such as livestock manure and municipal sludge in farmland increased the accumulation of heavy metals such as Cu and Zn in soil [9]. Moreover, human activities in coastal areas become more common, when a marine development strategy is implemented, thereby making the potential environmental problems of coastal beaches more prominent. [PERSON] et al. [10] found that, compared with the geochemical background value in the 1980s, tidal flat reclamation in Jiangsu Province has led to mild-to-moderate metal pollution risks due to human activities; the pollution was mainly attributable to Cd, As, and Ni. [PERSON] et al. [11] found that Cr, Cu, Pb, and Zn concentrations in the mangrove wetland of Shenzhen Bay were mostly higher than their respective background values, particularly Cd. Cd was the major heavy metal pollutant in surface sediments. This heavy metal pollution was mainly due to human activities such as ship pollution and aquaculture activities. To improve different saline-alkali soil types, comprehensive treatment must be adopted according to local conditions. In particular, saline land polluted by various heavy metals should be continuously enhanced and developed through ecological methods such as \"water and salt control\" and \"production while repairing.\" Therefore, suitable plants that can grow on saline-alkali soil and repair heavy metal pollution must be selected. Salt tolerance and heavy metal detoxification mechanisms of sea rice have some common characteristics [12; 13; 14; 15], which are mainly reflected through the following aspects: (1) The root osmotic potential of sea rice is low under salt stress, which promotes rice to synthesize numerous organic solutes, such as proline, betaine, and soluble sugar. These organic solvents bind more water by binding with protein and can also form complex stable chelates with heavy metals to reduce heavy metal effectiveness in plants, which is a heavy metal detoxification mechanism in plants. (2) Endogenous hormones also play a vital regulatory role during salt stress. For example, the increased abscisic acid content can regulate sodium ion absorption and transportation; and the closure of stomata can reduce water loss in plants. In plants, these plant hormones also directly or indirectly promote the operation of the antioxidant system and reduce the oxidative toxicity of heavy metals to plants. (3) Activities of superoxide dismutase (SOD), peroxidase (POD), and other antioxidant enzymes in sea rice were positively correlated with the degree of salt stress, thereby reducing the damage caused by numerous reactive oxygen species. The antioxidant system composed of these antioxidant enzymes is also a type of heavy metal detoxification mechanism in plants. Therefore, the ability of sea rice to adsorb heavy metals may be stronger than that of ordinary rice. The application of this characteristic can provide a new theoretical basis and ideas for \"production while repairing\" in saline-alkali areas with heavy metal pollution. The sea rice industry will concentrate not only on its economic benefits but also on its good ecological benefits. In addition, the uptake and transport of heavy metals by rice are often through the channels of iron, manganese, phosphorus, and other essential elements into the plant roots and then gradually to the grain [16; 17; 18; 19]. Because of the long-term evolution of sea rice that lea to its adaption to a saline-alkali environment, the expression of physiological transport channels and regulatory genes may be different from that in common rice.