Reclamation Culture Alters Sediment Phosphorus Speciation and Ecological Risk in Coastal Zone of Southeastern China

Abstract

Sediment phosphorus (P) speciation plays a critical role in coastal wetland ecosystems, while the response of P speciation to reclamation culture remains unclear. In this study, sediment P species (total P [TP], organic P [Org‐P], inorganic P [IP], iron‐ and aluminum‐bound P [Fe/Al‐P], calcium‐bound P [Ca‐P], loosely adsorbed P [Lsor‐P], P sorption index [PSI], and P adsorption saturation [DPS] are investigated in the natural marsh wetland, 3‐year and 15‐year reclamation culture ponds. Sediment P pollution level and eutrophication risk are evaluated based on the single‐factor standard index (Si) and eutrophication risk index (ERI). Furthermore, a simulation experiment is conducted to reveal the effects of baits input and overlying water aeration on sediment P species and ecological risk. Measured sediment TP, Org‐P, IP, Fe/Al‐P, Ca‐P, and Lsor‐P concentrations are significantly higher in 15‐year culture ponds than in 3‐year culture ponds and natural marsh wetland. Sediment PSI is lower in reclamation culture ponds than in natural marsh wetland, while DPS is just opposite. The Si and ERI are higher in 15‐year culture ponds than in natural marsh wetland, suggesting that reclamation culture significantly increases sediment P pollution level and eutrophication risk. A short‐term simulation experiment further indicates that baits input and overlying water aeration can alter sediment P dynamics and increase sediment P loading. Overall, these results confirm that reclamation culture can make more available P accumulation and thus increase eutrophication risk of adjacent coastal water.

Ecological risk assessment of persistent organic pollutants (POPs) in surface sediments from aquaculture system

“…A study by (Gao et al, 2019) shown that shrimp aquaculture significantly increased sediment TOC as a result of the decomposition of a large number of residual feeds and excrement. A similar result reported by (Gao et al, 2018) in their previous work in the 3-yearreclamation culture ponds in Coastal Zone of Southeastern China. In addition, Yang et al (2017) found that CH 4 emission fluxes in shrimp ponds were clearly high during the mid and later part of the aquaculture season and were directly proportional with TOC level (16.2 ± 0.6%).…”

Enhancement of phosphorus storage capacity of sediments by coastal wetland restoration, Yellow River Delta, China

“…The ERI of the YRD varied between 0.68% and 13.89%. These values are similar to those of the wetlands in the Minjiang River Estuary in China (9.6-10.6%) (Gao et al, 2018), but are much lower than those of inland wetlands, such as the Beijing urban reservoirs in China (17.2-247.2%) (Lu et al, 2011) and the Taihu reservoirs in China (10-55%) (Jin et al, 2006). These ERI values indicate that the risk of P release from sediments in the YRD is generally low, which is consistent with the fact that the YRD has not experienced large-scale eutrophication (Bai et al, 2012).…”

“…generally believed that low DPS values indicate that P sorption sites in the sediment are not saturated, and the sediment will have a relatively high P sorption capacity (Nair, 2014). The DPS of the sediments in the YRD ranges between 0.27-2.07%, which is lower than that in the Okeechobee wetland of Florida, USA (5-18%) (Dunne et al, 2006), and the Minjiang River Estuary in China (7.3%) (Gao et al, 2018). It is also considerably lower than those of inland reservoirs, such as the Beijing urban reservoirs in China (7.97-50.5%) (Lu et al, 2011) and the Taihu reservoirs in China (3.8-15.3%) (Jin et al, 2006).…”

“…where PSI (L kg −1 ) denotes P sorption index, X (mg kg −1 ) is the amount of P sorbed and C (mg L −1 ) is the equilibrium P concentration of filtrate after equilibration was reached between a 1 g sediment sample and 20 mL of a 75 mg P L −1 solution in an end-over shaker for 24 h (Gao et al, 2018). Huang et al (2004) proposed a P eutrophication risk index (ERI), which is calculated on the basis of sediment PSI and DPS.…”

Land Use Change in Coastal Cities during the Rapid Urbanization Period from 1990 to 2016: A Case Study in Ningbo City, China

“…Sea reclamation is common for most coastal cities [84], and agricultural land reclaimed from the sea, such as that reclaimed from lakes, usually manifests as large plain areas, which are beneficial for scale farming [85]. However, reclamation can result in an increase in salinity due to impeded runoff [86] and in a deterioration of the marine ecological environment (such as with water pollution and a decline in sea life) [87,88]. Coastal cities with sea reclamation usually face potential disaster risks related to coastal flooding under future climate change conditions [74].…”