凡纳滨对虾露天土池底泥硫化物含量及其与其他环境因子的关系

通过定期监测分析凡纳滨对虾露天养殖土池水化学指标和底泥硫化物(S~(2-))、单质硫(S~0)、总硫(TS)含量和动态变化特征,探讨其与溶解氧(DO)、p H、总磷(TP)、总氮(TN)和总有机碳(TOC)的相关性,为凡纳滨对虾的健康养殖和养殖塘底质的科学管理提供理论依据。结果如下:周边河道底泥中硫化物含量(18.13~232.56 mg/kg)和露天土池底泥中硫化物含量(0.31~5.86 mg/kg)都低于渔业沉积环境中硫化物的安全下限;养殖塘底泥S~0和TS含量分别是0.39~3.06 mg/kg和221~4421 mg/kg。S~(2-)和TS随养殖时间呈波浪式增加趋势,S~0含量箱型区间增减变化;土池底泥TS中0.12%~1.76%为S~(2-),0.12%~1.04%为单质硫;水源底泥TS中4.30%~17.85%为硫化物,0.09%~0.37%为单质硫;主要水化学指标符合凡纳滨对虾养殖需求,底泥中TOC与TN均随养殖时间波浪式累积,TP动态变化规律不明显;相关分析表明,底泥S~(2-)、TS与底泥中TOC、TN呈极显著正相关(P0.01),与DO、p H显著负相关。结果表明:残饵、代谢产物和生物尸体等虾塘有机质的累积,易造成大量氧气被消耗,从而导致低氧状态下底泥中硫化物含量增加。建议通过合理投饵、提高溶解氧含量、定时清淤等途径有效减少虾塘底质硫化物和有机质的含量。

Sulfide content in sediment of outdoor ponds of Litopenaeus vannamei and its relationship with other environmental factors

By regularly monitoring and analyzing the water chemical indexes and the content variation trend of S^2-, S⁰ and TS in sediments of the outdoor ponds of Litopenaeus vannamei, their relationships with DO, pH, TP, TN and TOC were investigated for guiding the healthy aquaculture of Litopenaeus vannamei. The results indicate that S^2- content in sediments of the outdoor ponds and surrounding rivers were respectively 0.31~5.86mg/kg and 18.13-232.56 mg/kg, which were all lower than the safety low-limit of sulfide content in fishery sedimentary environment; S⁰ and TS contents in sediments of the outdoor ponds were 0.39~3.06 mg/kg and 221-4421 mg/kg, respectively. S^2- and TS contents showed wave-like increase trend with aquaculture time, and S⁰ content varied within a cube-type range. S^2- and S⁰ proportions of TS in sediments of outdoor ponds were respectively 0.12%-1.76% and 0.12%-1.04%, and those in sediments of water source were respectively 4.30%-17.85% and 0.09%-0.37%; The main water chemical indexes met the Litopenaeus vannamei aquaculture demand. TOC and TN contents showed wave-like increase trend versus aquaculture time but the variation trend of TP content was not obvious. Additionally, it was found that S^2- and TS had a significant positive correlation with TOC and TN but a negative correlation with DO and pH. The results demonstrate that accumulation of organic matters including residual feeds, metabolites and biological carcasses in shrimp pond could result in higher oxygen consumption and the sulfide content increase under low-oxygen condition. Hence, it was suggested that the key solutions to reducing the sulfide and organic matter contents in shrimp pond sediments were the rational feeding, the maintenance of abundant dissolved oxygen in shrimp ponds and the thorough desilting.