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红树林是以红树植物为主体的湿地木本植物群落[1-2],主要生长于海陆潮间带,在净化海水水质、抵御风浪和维护生物多样性等方面发挥着重要作用[1-4]。随着沿海城市工业快速发展,大量污水随河流排入海洋,导致红树林海岸带的原生生态系统结构遭受了严重破坏[5],给海洋生态环境带来了重大威胁,因此重建和恢复已被破坏的红树林生态系统刻不容缓[5-7]。红树林海岸带生态修复往往伴随着水生环境的改变及海洋生态系统的重建。目前已有众多学者对红树林生态系统修复全过程进行研究,其中谢宗琳[8]研究红树植物恢复特征及影响因素时发现红树植被高度与土壤黏粒含量呈正相关关系,同时红树林对土壤中重金属有较高的耐受力;徐新良[9]发现在一定的浓度范围内的污水可以促进红树林茎高的生长;RODRÍGUEZ-RODRÍGUEZ et al[10]研究发现红树林海岸带生态修复效果主要取决于恢复类型和所用技术,其中以群落为基础的红树林生态恢复是最有效方式;LIANG et al[11]发现通过红树林海岸带湿地恢复和海岸生态廊道建设等一系列措施,可以一定程度净化海水水质并保持水生动植物种群密度及物种数量的稳定。红树林海岸带生态恢复的关键是红树林植被的恢复[12],在植被恢复的过程中伴随着生物多样性的恢复[13],生物多样性可以表明环境因子与物种群落之间关系,亦可以呈现群落或者物种丰富度以及分布的格局[14-18]。
本研究以虎门大桥(广州段)北侧红树林海岸带为研究区,在生态修复工程前后分别进行海水、沉积物及浮游生物样品的采集与测试,通过对区内海水水质、沉积物化学特征、浮游动植物种类与细胞密度的对比分析,探寻出了研究区生态修复前后水生环境变化规律,取得的成果在红树林海岸带生态修复和生物多样性方面具有重要的意义。
生态修复工程前后水生环境变化研究
——以虎门大桥(广州段)北侧红树林海岸带为例The changes of the aquatic environment before and after ecological restoration projects
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摘要: 为了研究虎门大桥(广州段)北侧红树林海岸带生态修复工程前后水生环境变化,文章对研究区内海水水质、沉积物化学特征、浮游动植物种类与细胞密度进行对比分析,结合Shannon-Wiener生物多样性指数,探寻出研究区生态修复工程前后水生环境变化规律。结果表明:生态修复工程前,浮游植物群落以绿藻类为主,浮游动物群落以轮虫类为主;生态修复工程后,浮游植物群落以硅藻类为主,浮游动物群落以枝角类为主;生态修复工程后较前,区内海水与沉积物中锌、铬、铜和铅等重金属浓度明显减少,浮游植物细胞密度与种群数量均增加,浮游动物细胞密度增加但种群数量下降。综合研究发现海岸带生态修复工程对水生环境有积极的改善作用。Abstract: To investigate the changes in the aquatic environment before and after the ecological restoration project in the mangrove coastal zone on the northern side of Humen Bridge (Guangzhou section), the seawater quality, sediment chemical characteristics, phytoplankton species and density, and combined with the Shannon-Wiener diversity index was used to explore and investigate the change performance of the aquatic environment before and after the ecological restoration in the study area. The results showed that before the ecological restoration project, the dominant planktonic plant community was composed of green algaes, while the zooplankton community was dominated by rotifers. After the ecological restoration project, the phytoplankton community was dominated by diatoms, and the zooplankton community was dominated by cladocerans. Compared to the pre-restoration conditions, the concentrations of heavy metals such as zinc, chromium, copper, and lead in seawater and sediments were significantly decreased after the ecological restoration project. The cell density and population of phytoplankton was increased while the cell density of zooplankton increased with a lower population. Thus, coastal ecological restoration projects have a positive effect on the improvement of the aquatic environment.
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Key words:
- humen bridge /
- mangrove coast /
- ecological restoration /
- aquatic environment
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表 1 水质评价结果表
Table 1. Water quality assessment results
指标 采样点A(修复前) 采样点B(修复前) 采样点A(修复后) 采样点B(修复后) 检测值 结果 检测值 结果 检测值 结果 检测值 结果 pH 7.660 Ⅲ类 7.460 Ⅲ类 7.350 Ⅲ类 7.370 Ⅲ类 无机氮/mg·L−1 1.870 劣Ⅳ类 1.980 劣Ⅳ类 1.890 劣Ⅳ类 1.890 劣Ⅳ类 镉/μg·L−1 0.001 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 汞/mg·L−1 0.001 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 化学需氧量/mg·L−1 1.760 Ⅰ类 2.080 Ⅱ类 1.880 Ⅰ类 1.980 Ⅰ类 磷酸盐/μmol·(dm3)−1 1.120 劣Ⅳ类 1.020 劣Ⅳ类 0.130 劣Ⅳ类 0.130 劣Ⅳ类 硫化物/mg·L−1 0.001 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 铅/μg·L−1 2.760 Ⅱ类 3.160 Ⅱ类 0.001 Ⅰ类 0.001 Ⅰ类 溶解氧/mg·L−1 5.200 Ⅱ类 5.100 Ⅱ类 7.560 Ⅰ类 7.580 Ⅰ类 砷/μg·L−1 2.440 Ⅰ类 2.460 Ⅰ类 0.001 Ⅰ类 0.001 Ⅰ类 油类/mg·L−1 0.038 Ⅰ类 0.025 Ⅰ类 0.002 Ⅰ类 0.001 Ⅰ类 总铬/μg·L−1 2.260 Ⅰ类 2.170 Ⅰ类 0.020 Ⅰ类 0.010 Ⅰ类 铜/μg·L−1 14.600 Ⅲ类 15.100 Ⅲ类 6.100 Ⅱ类 2.100 Ⅰ类 锌/μg·L−1 46.800 Ⅱ类 53.200 Ⅲ类 5.100 Ⅰ类 0.100 Ⅰ类 表 2 沉积物评价结果
Table 2. Sediment assessment results
指标 采样点A(修复前) 采样点B(修复前) 采样点A(修复后) 采样点B(修复后) 检测值 结果 检测值 结果 检测值 结果 检测值 结果 镉/mg·kg−1 0.46 Ⅰ类 0.49 Ⅰ类 0.21 Ⅰ类 0.14 Ⅰ类 汞/mg·kg−1 0.22 Ⅱ类 0.26 Ⅱ类 0.15 Ⅰ类 0.12 Ⅰ类 硫化物/mg·kg−1 80.60 Ⅰ类 95.65 Ⅰ类 10.62 Ⅰ类 5.01 Ⅰ类 铅/mg·kg−1 65.95 Ⅱ类 63.96 Ⅱ类 9.52 Ⅰ类 8.79 Ⅰ类 砷/mg·kg−1 27.54 Ⅱ类 30.74 Ⅱ类 18.33 Ⅰ类 16.77 Ⅰ类 铜/mg·kg−1 23.63 Ⅰ类 30.65 Ⅰ类 17.61 Ⅰ类 16.88 Ⅰ类 锌/mg·kg−1 225.15 Ⅱ类 219.43 Ⅱ类 70.81 Ⅰ类 65.33 Ⅰ类 油类/mg·kg−1 205.10 Ⅰ类 203.01 Ⅰ类 88.72 Ⅰ类 82.82 Ⅰ类 有机碳/% 1.57 Ⅰ类 1.51 Ⅰ类 0.81 Ⅰ类 0.53 Ⅰ类 总铬/mg·kg−1 106.14 Ⅱ类 107.37 Ⅱ类 44.73 Ⅰ类 33.41 Ⅰ类 表 3 浮游植物种群类别统计结果
Table 3. Statistical results of phytoplankton species
浮游植物
门类生态修复工程前种类 生态修复工程后种类 属/种 占全部种类
比例/%属/种 占全部种类
比例/%硅藻 35 37.63 61 58.65 绿藻 38 40.86 22 21.15 甲藻 5 5.38 3 2.88 裸藻 8 8.60 12 11.54 蓝藻 6 6.45 4 3.85 隐藻 1 1.08 0 0.00 黄藻 0 0.00 2 1.93 汇总 93 100.00 104 100.00 表 4 浮游动物种群类别统计结果
Table 4. Statistical results of zooplankton population category
浮游动物
门类生态修复工程前种类 生态修复工程后种类 属/种 占全部种类
比例/%属/种 占全部种类
比例/%原生动物 10 23.82 9 37.5 轮虫 20 47.62 5 20.84 枝角类 6 14.28 2 8.33 桡足类 6 14.28 8 33.33 汇总 42 100.00 24 100.00 表 5 Shannon-Wiener生物多样性指数计算结果
Table 5. Shannon-Wiener biodiversity index calculation results
采样
点位浮游植物H’ 浮游动物H’ 修复前 修复后 修复前 修复后 1 2.55 3.59 2.82 2.30 2 2.67 4.73 3.01 0.57 3 2.78 4.63 2.90 1.47 4 2.71 4.08 2.58 1.23 -
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