Changes in Soil Properties of Abandoned Shrimp Ponds in Southern Thailand

Chemical soil properties between active shrimp ponds andabandoned ones on the Bangkok soil series were compared,at Ranote District, Songkhla Province in southern Thailand.Soil samples were collected at depth intervals of 0–10, 10–20, 20–30, 30–40 and 40–50 cm from pond bottoms at the same ponds used in a former study conducted in 1994, fora total of 6 ponds with 3 sampling sites for each pond. Theseponds were active during the previous study in 1994, abandonedin 1996 and investigated by this study in 1999. All the samples were analyzed for exchangeable Ca, Mg, K and Na electrical conductivity (EC), organic matter, S, P and pH, and statistically compared with the analytical results of theprevious study. An increase in amounts of Ca, Mg, K, Na and EC in the abandoned ponds as compared with the active ones by1.3–3.4, 1.4–2.1, 7.0–30.0, 1.2–6.3 and 1.3–10.9 timesrespectively was observed. That more of these elements weregained than lost each time the seawater was introduced intothe ponds, is explained by the Element Input/Output Consideration as proposed herein. Furthermore, a decreasein organic matter, S and P was also observed in the abandonedpond soils, and attributed to the absence of shrimp food and shrimp excreta following the cessation of shrimp raising activities. An unexpected decline in the soil pH of the abandoned ponds was found as well. Aerobic decomposition of organic matter during the absence of shrimp raising activitiescaused by soil microorganisms triggering SO₂ and H₂SO₄ formation probably played a more significantrole than the increase in the amounts of the basic elements (Ca, Mg, K, and Na) eventually reducing soil pH in the abandoned ponds. The significant depletion of the amounts of organic matter in the abandoned pond soils also supports this observation.     

Phosphorus removal by the multipond system sediments receiving agricultural drainage in a headstream watershed

Wetland systems in headstream watersheds are important to control the nonpoint source pollutant phosphorus. Experiments were conducted using intact sediment-water columns obtained from the multipond system in Liuchahe watershed of Chaohu Lake to determine its capacity to retain P. It was found that pond sediments had strong P retention ability. For the Hill pond, Village pond and Rice pond, their retention coefficient(A) were 288.3, 279.2 and 260.8 L/m^2, respectively. The equilibrium P concentration(EPCw) were 0.016, 0.028 and 0.018 mg/L, respectively. The Hill pond indicated the highest P retention ability. P retained in the pond sediments indicated high stable degree. P removal from the overlying water column into the pond sediments followed a first-order kinetic model. Under the experimental hydrological conditions, the retention time had a positive correlation with the P loading. The multipond system could provide enough retention time to retain P in drainage runoffs. At the P levels evaluated, the sediments of the multipond system are effective sinks to retain P from nonpoint source runoffs.     

斑节对虾Penaeus monodon养成期间池水CODMn和BOD5的变化及其相互关系

研究了有益微生物制剂调控下,斑节对虾生长周期内,池水中CODMn和BOD5的变化规律.结果表明,CODMn和BOD5的动态变化大致分为3个阶段：前期在低浓度下缓慢增长,中期由较低浓度向较高浓度快速增长,后期在较高浓度波动,回归分析结果显示二者呈显著的线性正相关关系（P〈 0.01）.在养殖后期,未投放微生物的对照池中CODMn和BOD5浓度比投放微生物的试验池中有所增高,分别增高约9 %和21 %.     

The Environmental Impact of Shrimp Aquaculture: Causes, Effects, and Mitigating Alternatives

Attracted by the demand for shrimp in the developed countries, shrimp aquaculture has expanded rapidly, mainly in the subtropical and tropical lowlands of America and Asia. This work provides a global review and viewpoint on the environmental impacts of shrimp aquaculture, considering the causes and effects of the siting and operation of shrimp ponds and abandonment of farm facilities. Additionally, mitigating alternatives are discussed. To date, approximately 1–1.5 million ha of coastal lowlands have been converted into shrimp ponds, comprising mainly salt flats, mangrove areas, marshes, and agricultural lands. The impact of shrimp farming of most concern is the destruction of mangroves and salt marshes for pond construction. Compatibility with other users, the presence of buffer zones, maintaining an acceptable balance between mangroves and shrimp pond area, improved pond design, reduction of water exchange, and an improved residence time of water, size and capacity to assimilate effluents of the water body, are examples of ways to mitigate the adverse effects. The use of mangroves and halophytes as biofilters of shrimp pond effluents offers an attractive tool for reducing the impact in those regions where mangrove wetlands and appropriate conditions for halophyte plantations exist. Healthy seed supply, good feed with the use of prophylactic agents (including probiotics), good water quality, and lower stocking densities are examples of actions suggested to control disease in shrimp farming. Finally, in the context of integrated management, research priorities are suggested.     

小型养殖塘水体中CH4、CO2和N2O浓度的时空变化特征及影响因素

养殖塘作为重要的温室气体排放源,水体中温室气体浓度的变化不仅是准确量化温室气体排放量的基础,还是明确其影响因素的重要依据.基于顶空平衡-气相色谱仪法对长三角一处典型的小型养殖塘水体中CH₄、CO₂和N₂ O浓度的时空变化特征以及影响因素进行了分析.结果表明,除春季外,在水温影响下,CH₄和N₂ O浓度在午间或午后出现高值;受水温和水生植物光合作用影响,CO₂浓度的高值出现在晨间光合作用较弱的时候.养殖塘水体中CH₄和CO₂浓度呈现秋季最高、冬季最低的季节变化特征,c（CH₄）在秋季和冬季的均值分别为176.34 nmol·L^-1和32.75 nmol·L^-1,主要受气温、水温和溶解氧（DO）影响;c（CO₂）秋季和冬季的均值分别为134.37 μmol·L^-1和23.10 μmol·L^-1,主要受水生植物光合作用和pH影响;c（N₂ O）在夏季最高,冬季最低,均值分别为97.05 nmol·L^-1和19.41 nmol·L^-1,主要受气温和水温影响.在空间上,垂直方向上,夏季养殖塘c（CH₄）随水深的加深而降低,表层与底层、中间层的浓度差值为71.28 nmol·L^-1和42.80 nmol·L^-1,秋季随水深的加深而升高,底层与表层的浓度差值为163.94 nmol·L^-1.c（CO₂）在夏季和秋季都表现为随着水深的加深而升高,其底层与表层的浓度差值分别为18.69 μmol·L^-1和29.90 μmol·L^-1.N₂ O浓度在垂直方向上无明显变化规律.水平方向上,夏季饲料及春季鸡粪投放的区域会出现CH₄、CO₂和N₂ O浓度的高值,春季和夏季CH₄浓度约为其他区域的1.34~1.98倍和1.95~2.42倍,春季N₂ O浓度和夏季CO₂浓度约为其他区域的1.13~1.26倍和1.39~1.74倍.     

不同溃坝条件下尾矿库溃坝试验与灾害影响研究*

为探究不同溃坝条件下尾砂流的演进规律与灾害影响,提高应对尾矿库溃坝灾害的防灾减灾能力。以四川某尾矿库为研究背景,采用模型试验与数值模拟相结合的方法,研究不同溃坝条件下溃坝砂流的演进和沉积规律,并预估溃坝灾害影响。研究结果表明:溃坝方式对溃坝砂流的演进过程、尾砂的沉积分布情况与致灾程度有显著影响;与漫顶溃坝相比,瞬时溃坝砂流的淹没范围更广、破坏性更强;砂流在流动过程中存在水-砂分层流动与沉淀的动态变化过程,其淹没面积大于尾砂的沉积面积;试验与数值模拟结果的一致性较高,采用两者相结合的方法研究溃坝砂流流动规律及灾害影响具有一定的可靠性。     

Hydrologic Impact Assessment of Land Cover Change and Stormwater Management Using the Hydrologic Footprint Residence

Urbanization impacts the stormwater regime through increased runoff volumes and velocities. Detention ponds and low impact development (LID) strategies may be implemented to control stormwater runoff. Typically, mitigation strategies are designed to maintain postdevelopment peak flows at predevelopment levels for a set of design storms. Peak flow does not capture the extent of changes to the hydrologic flow regime, and the hydrologic footprint residence (HFR) was developed to calculate the area and duration of inundated land during a storm. This study couples a cellular automata land cover change model with a hydrologic and hydraulic framework to generate spatial projections of future development on the fringe of a rapidly urbanizing metropolitan area. The hydrologic flow regime is characterized for existing and projected land cover patterns under detention pond and LID‐based control, using the HFR and peak flow values. Results demonstrate that for less intense and frequent rainfall events, LID solutions are better with respect to HFR; for larger storms, detention pond strategies perform better with respect to HFR and peak flow.     

广东典型海水养殖区沉积物及鱼体中磺胺类药物的残留及其对人体的健康风险评价

采用高效液相色谱-紫外检测器(HPLC-UV)分析了广东沿海大亚湾和阳江两个典型海水养殖区中沉积物以及7种养殖鱼类肌肉和肝脏组织中磺胺嘧啶(SDZ)、磺胺二甲嘧啶(SM2)和磺胺甲基异噁唑(SMX)的残留量,并依据药品最高残留量(MRL)值和每日允许摄入量(ADI)值对海水养殖鱼类中磺胺类抗生素污染进行人体健康风险评价.结果表明,在所有沉积物样品中都能检出磺胺类抗生素.含量(干重)范围为:2.1~35.2 ng·g-1,检出率大小顺序为SDZ(85.7%)>SM2(71.4%)>SMX(28.6%).大亚湾养殖区磺胺药物在沉积物和鱼类样品中的检出频率大于阳江养殖区.3种磺胺类药物在鱼肝脏组织中的含量显著高于在肌肉组织中的含量(P<0.05).SDZ、SM2和SMX在鱼体肌肉组织中的含量(湿重)范围分别为11.6~37.9、16.3~27.8和4.9~20.0 ng·g-1.3种磺胺类药物的平均日摄入量范围为3.37~36.72 ng·kg-1,仅占食用肉类ADI的最高限值(50μg·kg-1)的0.007%~0.073%(<1%ADI),健康风险为可以忽略,膳食安全性高.     

新型农村集约化养殖业发展中环境问题及管理对策

随着人们生活水平的提高,肉、蛋、奶等畜禽食品的消费量日趋上升,极大的刺激了畜禽养殖业的发展。这一发展使畜禽养殖特点发生了如下的变化,即由过去的分散经营,饲养头数少,主要分布在农区转变成现在的集中经营,饲养头数多,分布在城市郊区或新城区。本文分析了新型农村集约化养殖业发展中的环境问题,并针对这些问题提出了新型农村集约化养殖业的管理对策。     

闽江口养殖塘水-大气界面温室气体通量日进程特征

湿地围垦养殖是人类对于滨海湿地的主要干扰方式之一.以闽江口鳝鱼滩湿地围垦养虾塘和鱼虾混养塘为研究对象,利用悬浮箱-气相色谱法对养殖塘秋季水-大气界面CO2、CH4和N2O通量日进程进行了观测并同步测定了地面气象及表层水的物理、生物和化学指标.养虾塘和鱼虾混养塘水-大气界面CO2、CH4和N2O通量均具有明显的日变化特征,2种养殖塘整体上均表现为吸收CO2的汇,CO2通量平均值分别为-48.79 mg·（m2·h）-1和-105.25 mg·（m2·h）-1,排放CH4的源,CH4通量平均值分别为1.00 mg.（m2.h）-1和5.74 mg·（m2·h）-1,鱼虾混养塘水-大气界面CH4排放量和CO2吸收量均高于养虾塘.养殖塘水-大气界面温室气体通量受到诸多环境因子的影响,多元逐步回归分析结果表明,对于养虾塘,叶绿素a是影响其水-大气界面CO2通量日变化的主要环境因子,PO34-和SO24-是影响水-大气界面CH4通量日变化的主要环境要素;鱼虾混养塘水-大气界面CO2通量主要受到水温、叶绿素a的影响,而溶解氧、PO34-和pH是影响其CH4通量的主要环境因子。