Distribution and risk assessment of heavy metals in surface sediments of coastal mudflats on Leizhou Peninsula,China

Mudflats play a vital role in maintaining the dynamic balance between sea and land.To understand the characteristics,sources,and pollution risks of six heavy metals(As,Cd,Cr,Cu,Hg,and Pb)in the coastal mudflats on the Leizhou Peninsula,257 surface sediment samples were studied using mathematical statistics,correlation analysis,and factor analysis.The results show that the overall concentrations of these heavy metals are low although there are several high abnormal points in the local areas.The strong correlation between these heavy metals indicates that the sources of some of the metals are similar,yet their elemental combinations in different cities(counties)varied.According to the calculated enrichment factor(EF),anthropogenic activity-induced heavy metals were determined in order of decreasing influence:As,Cd,Pb,Cr,Cu,and Hg.The low EF values of Hg indicate that it does not present as a contaminant in the study area,while low values of Cr and Cu from the Lianjiang City suggest that these two metals were also attributed to natural sources.The presence of As,Cd,Cr,Cu,and Pb from the remaining cities(counties)should be influenced by anthropogenic activities.The overall potential ecological risk index indicates that the ecological risks posed by the six analyzed heavy metals to the Leizhou Peninsula mudflats,in order of decreasing risk,are Cd,As,Hg,Pb,Cu,and Cr.It is noteworthy that only Cd in Lianjiang City demonstrated substantial ecological risk.Other examined heavy metals in other cities of the study area showed slight ecological risk.

Using benthic macrofauna to assess environmental quality of four intertidal mudflats in Hong Kong and Shenzhen Coast

Intertidal zone is a significant wetland between land and ocean. It plays an important rolein maintaining local ecological balance. Both Mai Po and Futian intertidal mudflats are located in Shenzhen Bay and are important 'refueling' point along the East Asian/Australian flyway of migratory birds. The environmental quality of Mai Po and Futian mudflats have aroused great concern due to rapid economic developments in Hong Kong and Shenzhen in recent decades. Macroinfauna of Mai Po and Futian mudflats was investigated in December 2000 and the faunal data were used to assess their environmental quality. Two other mudflats, namely Ma Wan Typhoon Shelter (a more disturbed area) and Luk Keng intertidal mudflat (a place with relatively less human disturbance), were also sampled for macroinfauna and used as reference mudflats. Shannon - Weaver species diversity index (Isd), biotic coefficient (Cb) and macrofaunal pollution index (Imp) of the macrofauna community on four intertidal mudflats were used to determine their environmental quality. The results showed that Luk Keng intertidal mudflat was unpolluted, Mai Po and Futian mudflats were slightly polluted, and Ma Wan was moderately polluted. The pollution in Ma Wan Typhoon Shelter mainly came from various types of rubbish and fishing boats that disturbed the sediment, while pollution sources in Mai Po and Futian mudflats were discharges of industrial water, municipal sewage and from nearby rivers.

Responses of Ryegrass(Lolium perenne L.) Grown in Mudflats to Sewage Sludge Amendment

Sewage sludge amendment （SSA） is an alternative waste disposal technique and a potential way to increase fertility of mudflats for crop growth. The present study aimed to assess the suitability of SSA by assessing the nitrogen （N） and phosphorous （P） uptakes, heavy metal accumulation, growth, biomass, and yield response of ryegrass （Lolium perenne L.） at 0, 30, 75, 150, and 300 t ha-1 SSA rates at various growth stages. The results showed that the highest biomass ofryegrass at seedling and vegetative stages were at 300 and 150 t ha-1 SSA rate, respectively. The increments of ryegrass yield at reproductive stage at 30, 75, 150, and 300 t ha1 SSA rates were 98.0, 122.6, 88.1, and 61.2%, compared to unamended soil. N and P concentrations in ryegrass increased with increasing SSA rates at all stages except N and P in roots dropped significantly at 300 t ha-1 rate at vegetative stage. The metal concentration for Mn, Cu, Zn, Ni, Cd, Cr, and Pb in shoot of ryegrass at 300 t ha-1 S SA rate increased by 0.63-, 2.34-, 15.02-, 0.97-, 10.00-, 0.01- and 1.13-fold, respectively, compared to unamended soil. However, heavy metal concentrations in shoot of ryegrass were lower than the standard for forage products in China. The study suggested that sewage sludge amendment in mudflat soils might be feasible. However, the impacts of sludge application on edible crop plants and soil environment need further investigations.

Seasonal and Spatial Variations of Macro Benthos in the Intertidal Mudflat of Southern Yellow River Delta,China in 2007/2008

In order to examine the seasonal and spatial distributions of benthic animals in the intertidal mudflat of the southern Yellow River Delta,field investigations were carried out in 2007 and 2008 and multiple methods were applied.Results showed that,the biomass of macro benthos ranged at 0.75-1151.00 g wet m^(-2) and averaged at 156.31 g wet m^(-2),in which Mactra veneriformis accounted for 75.6%-93.4% of the total macro benthic biomass.More than 90% of macro benthos inhabited in the middle and low tide lines,and higher biomass occurred in early summer and lower in winter.Statistical analysis showed that:1)M.veneriformis growth was primarily favored at higher temperature and lower salinity;2)after long time interaction,benthic bivalve grazers led to patching distributions of Chlorophyll a(Chl a);3)macro benthic biomass positively related with Chl a when the concentration of Chl a was low,but they were negatively related when Chl a concentration was high;and 4)furthermore,the biomass of benthic bivalves peaked in the sediment with median grain size about 0.55 mm,but decreased gradually in coarse or fine sediments.The secondary productivity ranged at 0.37-283.68 g m^(-2)yr^(-1) and averaged at 47.88 g m^(-2) yr^(-1),in which 69.7% was contributed by M.veneriformis It was estimated that primary production was transformed to secondary production at a rate of 6.87%approximately,which implies that there is a local sustainability of high bivalve production.

High-yield Cultivation Technique of Salt-tolerant Spartina and Rice in Coastal Mudflat

Directing at the characteristics of coastal mudfiat saline and alkaline land, the yield of salt-tolerant Spartina and rice could reach 5 925-8 280 kg/hm^2 by the techniques of land and water resource utilization, farming improvement, construction of matched water system, seed selection and treatment, water direct seeding, seedling raising on seedbed, field transplanting, weeding, nutrient and water management, and disease and pest control, providing a scientific basis for the cultivation of Spartina and Rice in coast mudflat.

Coastal mudflats as reservoirs of extracellular antibiotic resistance genes: Studies in Eastern China

Despite coastal mudflats serving as essential ecological zones interconnecting terrestrial/freshwater and marine systems,little is known about the profiles of antibiotic resistance genes(ARGs)in this area.In this study,characteristics of typical ARGs,involving both intracellular(iARGs)and extracellular ARGs(eARGs)at different physical states,were explored in over 1000 km of coastal mudflats in Eastern China.Results indicated the presence of iARGs and eARGs at states of both freely present or attached by particles.The abundance of eARGs was significantly higher than that of iARGs(87.3%vs 12.7%),and their dominance was more significant than those in other habitats(52.7%-76.3%).ARG abundance,especially for eARGs,showed an increasing trend(p<0.05)from southern(Nantong)to northern(Lianyungang)coastalmudflats.Higher salinity facilitated the transformation from iARGs to eARGs,and smaller soil particle size was conducive to the persistence of eARGs in northern coastal mudflats.This study addresses the neglected function of coastal mudflats as eARGs reservoirs.

有限元法作为滩涂光伏阵列桩基设计计算方法的适用性研究

【目的】滩涂光伏电站的建设处于起步阶段,光伏阵列桩基在土建工程中占比很大,对投资有显著影响,目前承载力设计计算主要借鉴建筑行业规范,其适用性值得探讨。为改进滩涂光伏桩基设计计算方法,探索有限元方法对此的适用性,【方法】以既有滩涂光伏桩基设计方案为例,依据行业规范方法进行竖向、抗拔、水平承载工况复核计算,同时使用有限元超载法和强度折减法进行计算和分析。【结果】分析及对比结果显示:两类方法所依据的力学机理基本相同,计算得出的承载力规律一致,安全系数值接近,沉降值接近;竖向承载和抗拔工况,有限元法得出的安全系数略大于规范方法;水平承载工况,有限元法得出的安全系数略小于规范方法;对于滩涂光伏阵列桩基而言,竖向承载力安全系数最低,是承载力设计的控制工况;抗拔承载安全系数最高,远高于规范要求值,不是控制性工况;水平承载安全系数居中,有较充足的安全裕度,该工况容易满足要求。【结论】结果表明:有限元法计算能够生动展示桩基及支架的空间、过程和细部力学响应,有利于指导和改进设计,对滩涂光伏阵列桩基设计有良好的适用性;有限元法用于桩基承载力计算应优先使用超载法;滩涂光伏阵列桩基的承载特点和工作环境与建筑桩基不同,目前规范规定的竖向承载力安全系数偏保守,应适当放宽,对设计理论创新做出尝试,并合理地控制工程投资。

滩涂光伏GFRP管桩原位承载试验及反馈分析研究

目前滩涂光伏基础结构主要采用预应力混凝土(PHC)管桩方案,在经济性与施工便利性上存在一定劣势。为提高滩涂光伏施工效率,针对滩涂场地地基承载力较弱、土方开挖困难等特点,在满足承载性能的基础上,优化桩基础施工便利性,提出采用具有重量优势的纤维复合材料桩——玻璃纤维(GFRP)管桩,探索GFRP管桩的承载性能。通过开展现场承载试验,获取GFRP管桩的承载力表现并与PHC管桩进行对比,同时结合数值模拟进行反馈分析。反馈分析及对比成果显示:PHC管桩能够稳定加载至2.0倍设计荷载,而GFRP管桩加载至1.2倍设计荷载之后出现较大挠度。结果表明GFRP管桩的承载性能满足设计荷载要求,但是在变形控制方面劣于现有PHC管桩方案,相比之下PHC管桩具有更充足的安全裕度。通过对GFRP材料桩基础的研究和探索,提出GFRP管桩制作工艺的改进措施,对GFRP管桩今后需要进一步研究的重点进行了展望。

江苏沿海滩涂地区暗管排水土工布外包滤料的试验研究

暗管排水治理盐渍化问题是利用江苏省丰富沿海滩涂资源的有效途径,但由于土壤渗透性低、结构较差,暗管存在较大的淤堵风险,亟须筛选适合当地土质的土工布合成外包滤料。研究选取4种土工布外包滤料进行水力渗透试验,分析比较在2种土壤中的透水、反滤与防淤堵性能。结果显示,试验进行至70 d时,8组处理均达到稳定,渗透性能良好,土壤流失量均不超过1 g,淤堵率在6%~20%之间。4种土工布在砂粒含量较高的土壤A中能更快达到稳定,所形成的天然反滤层结构更佳,土工布SF44各性能表现均为更优。研究成果可为江苏省沿海滩涂地区暗管排水土工布外包滤料的选择提供理论支撑和技术参考。

基于EDEM的采捕机械轮胎与滩涂土壤耦合性研究

本研究使用EDEM模拟软件和Solidworks搭建滩涂土壤模型和采捕车辆轮胎模型进行仿真分析,研究了轮壤耦合特性。结果显示EPDM60材质轮胎扭矩达到峰值速度最快,并对土壤颗粒势能有影响。调整轮胎材质可以提高工作效率和性能。天然橡胶材质的轮胎土壤压实性较强,势能高。该研究可为采捕设备设计提供参考依据。

不同有机物料对滩涂盐碱地有机碳损失·重金属含量及水稻产量的影响

通过田间小区试验,研究不同有机物料(对照CK、鸡粪T_(1)、羊粪T_(2)、菌菇渣T_(3)、生物腐植酸T_(4))在等有机碳投入量下滩涂盐碱地中有机碳损失、土壤各类有机质分布及其对土壤重金属含量及水稻产量的影响。结果表明,不同有机物料施入土壤后,T_(1)、T_(2)、T_(3)、T_(4)有机碳损失率分别为64.52%、58.69%、47.04%和29.56%;未损失部分转化为土壤有机质,虽然T_(3)处理有机碳损失率较低,但土壤中的活性有机质占比低于其他处理。T_(3)、T_(4)能降低滩涂盐碱地土壤中的有效态汞、砷、镉、铅、铬含量,其中以T_(4)效果最好,T_(1)、T_(2)处理能降低汞、镉、铬有效态含量,但在一定程度上分别增加有效态砷、有效态铅含量。T_(1)~T_(4)对水稻有效穗、穗粒数有显著提高作用,较对照分别增产10.17%、14.03%、6.65%和24.52%,其中T_(4)能显著增加水稻穗粒数。由此可见,在滩涂盐碱地综合改良利用中,生物腐植酸在有机碳损失率、增加土壤活性有机质、降低土壤重金属含量及提高水稻产量方面具有较显著优势,是滩涂盐碱地改良的优良有机物料投入品。

沉降监测在滩涂路基中的应用实例分析

文中对已经通车的228国道福清东阁农场至三山沁前段公路的K185+730—K185+752段落进行2个阶段周期合计9个月路面监测,对K186+350—K186+365处PTC桩与填石路基交界处进行4个月的路面监测,滩涂路基结构受公路两旁水产鱼塘的蓄水养殖和放水修整影响,路基呈现周期性沉降和上浮,导致路面结构破坏,形成不规则裂缝,文中提出了相应的技术处理措施,以保障路面质量。

Preservation potential of individual couplet and deposition rates on mudflats in the Changjiang Estuary

Non-barrier mudflats in the Changjiang Estuary is examined to obtain preservation potentials and deposition rates over different time scales. The preservation potential of couplet is ca. 46.6% within daily scale and decreases as the time-interval extending, with 9.2% on a semi-lunar scale and 3.7% on a seasonal scale. In the long term, only 1.6% of daily deposition can potentially be preserved in the tidal flat sequence and other 98.4% have been eroded and leave sedimentary discordances, discernable or un-discernable, in the mudflat deposits. A negative log-linear relationship is examined between sedimentation rates and the time spans. The length of sedimentary hiatuses on the mudflat deposition were estimated with considerable uncertainty, but it can provide from an actualistic base some further insights into the nature and origin of ancient mudflat deposits with emphasis on the sedimentary discordances.

南大港滩涂湿地土壤有机碳分布特征研究

滨海滩涂湿地是提高“蓝碳”碳汇、补偿碳排放的重要空间资源。为研究滨海滩涂土壤有机碳分布特征,在河北南大港滩涂湿地内设置采样地,对不同湿地类型、不同植被覆盖下土壤有机碳含量进行测定。结果表明,南大港滩涂湿地土壤有机碳含量平均值为8.03±3.39 g/kg,略低于全国平均水平。土壤有机碳空间分布有一定差异,内陆滩涂湿地土壤有机碳含量高于沿海滩涂湿地。土壤有机碳含量随土层深度增加呈下降趋势,不同深度下土壤有机碳含量差异显著。不同植物群落下土壤有机碳含量不同,表现为芦苇群落>莎草群落>碱蓬群落>金鱼藻群落>光滩地。南大港滩涂湿地土壤有机碳密度分布与土壤碳含量分布相似,土壤结构、地表植被类型对土壤有机碳含量、碳密度分布产生影响。

Variable diffusion boundary layer and diffusion flux at sediment-water interface in response to dynamic forcing over an intertidal mudflat

The diffusion boundary layer (DBL) significantly limits the exchange between sediment and overlying water and therefore becomes a bottleneck of diffusive vertical flux at the sediment-water interface (SWI). Variable DBL thickness and diffusion flux in response to dynamic forcing may influence replenishment of nutrients and secondary pollution in coastal waters. In situ measurements of velocity in the bottom boundary layer (BBL) and oxygen concentration in the DBL were made over an intertidal mudflat, using an acoustic Doppler current and mini profiler. A linear distributed zone in the oxygen profile, the profile slope discontinuity and variance of concentration can be used to derive accurate DBL thickness. Diffusion fluxes calculated from the water column and sediment are identical, and their bias is less than 6%. A numerical model PROFILE is used to simulate the in situ dissolved oxygen profile, and layered dissolved oxygen consumption rates in the sediment are calculated. The DBL thickness (0.10-0.35 mm) and diffusion flux (15.4-53.6 mmol m 2 d 1) vary with a factor of 3.5 during a tidal period. Over an intertidal mudflat, DBL thickness is controlled by flow speed U in the BBL, according to δDBL=1686.1DU 1+0.1 (D is the molecular diffusion coefficient). That is, the DBL thickness δDBL increases with decreasing flow speed U. Changes of diffusion flux at the SWI are caused by variations in the water above the sediment and the turbulent mixing intensity. The diffusion flux is positively related to the turbulent dissipation rate, friction velocity and turbulent energy. Under the influence of dynamics in the BBL, DBL thickness and flux vary significantly.

珠江三角洲沙田系统经营的传统生态模式与潮汐灌排技术

珠江三角洲的沙田系统不仅有其重要的农业文化遗产价值,沙田的开发中还有许多适应河口环境进行自然资源合理利用开发的历史经验。本文对清代以来珠江三角洲河口区沙田经营的传统生态农业模式与技术进行研究。在沙田经营中,有着基于河口潮汐滩涂生态演替、河口潮汐水文环境特点与河口生物多样性方面一定程度的科学认识与利用。这些地方性知识与技术,对今天珠江三角洲河口滨海湿地的生态修复仍然有很好的指导意义。

浙江滩涂贝类种业科技创新发展及展望

我国拥有1 512 300 hm^(2)沿海滩涂,而滩涂贝类是潮间带滩涂的优势种类,具有生长快、适应性强、环境友好等诸多优点,因此发展滩涂贝类养殖空间广阔、条件优越、潜力巨大。浙江滩涂贝类养殖历史悠久,在养殖技术与模式、人工采苗与育苗、大规格苗种培育、新品种培育等方面具有明显特色和优势,同时在种业科技创新与发展方面面临巨大挑战。本文综述了浙江滩涂贝类养殖产业、苗种生产技术、种质创新与良种创制的历史与现状,围绕经济性状精准测评、育种技术创新、优质抗逆新品种培育、高效扩繁关键技术和装备研发、种业体系建设等方面,提出了未来特别是“十四五”期间滩涂养殖贝类良种创制与种业发展的重点任务。

滩涂围垦区农田土壤中无机磷解磷菌的分离鉴定及解磷特性

植物根际促生菌对植物有效利用土壤养分具有重要贡献,但关于滩涂农田土壤中促生菌解磷功能方面的研究较少。为此,从南通市和宁波市滩涂围垦区农田耕层土壤中分离出5株具有促生作用的细菌,并就其溶磷功能开展研究。经16S rRNA基因序列鉴定,所分离菌株分别为:Microbacterium flavescens(Mib.flavescens)、Pseudomonas chlororaphis(Ps.chlororaphis)、Pseudomonas jessenii(Ps.jessenii)、Massilia varians(M.varians)和Brevundimonas nasdae(Brv.nasdae)。在不同碳源、氮源、碳氮摩尔比(C/N)、pH和温度下测定细菌解磷能力,结果表明:与对照组相比,Mib.flavescens、Brv.nasdae在中性条件下解磷能力优越,解磷量保持在80.27~85.51 mg/L之间;较其他菌株而言,Ps.jessenii在4~37℃环境中的解磷能力显著,解磷量保持在13.59~81.94 mg/L之间。这3株菌株具有良好的微生物肥料开发应用潜力,为日后其菌肥开发奠定了基础。

不同植被类型对淤泥质潮滩有机碳来源和储量的影响——以茅埏岛为例

滨海湿地具有较强的碳汇能力,不同植被类型会对沉积物中有机碳的来源和储量产生重要影响。在茅埏岛无植被、老红树林、幼红树林和互花米草等4种淤泥质潮滩各采集1根沉积物柱状样品(柱样长度均为1 m,按10 cm间隔分样),测定沉积物粒度、总有机碳(TOC)、总氮(TN)等参数,分析和讨论沉积物有机碳来源、储量及其影响因素。结果显示:1)无植被潮滩、老红树林潮滩、幼红树林潮滩和互花米草潮滩沉积物中TOC平均含量依次为0.71%±0.03%,0.76%±0.16%,0.69%±0.12%,0.83%±0.09%。在0~20 cm层,有植被潮滩TOC含量显著高于无植被潮滩;在20~100 cm层,互花米草潮滩沉积物TOC含量高于其它潮滩类型。2)茅埏岛潮滩中互花米草潮滩沉积物有机碳储量最高,达5.79 kg m^(2),其次是老红树林潮滩(5.61 kg m^(2)),幼红树林潮滩(4.95 kg m^(2))和无植被潮滩(4.84 kg m^(2))有机碳储量较低。互花米草潮滩和红树林的覆盖均在一定程度上增强了潮滩的储碳能力。3)互花米草潮滩沉积物中的有机碳主要以陆源为主,占比57.75%;本地植物贡献在老红树林潮滩沉积物中占比最大,占比32.65%;幼红树林潮滩和无植被潮滩沉积物中有机碳均以海源贡献为主,分别占比61.47%和50.45%。

履带式滩涂贝类采收机设计与试验

针对环渤海地区滩涂贝类养殖产业贝类采收环节缺少机械化采收设备,人工采收贝类劳动强度大、作业效率低、作业环境泥泞等问题,设计了一款履带式滩涂贝类采收机。整机采用液压双联泵进行液压动力的分配,并通过液压系统仿真软件AMESim对整机液压动力系统进行仿真模拟;根据滩涂养殖贝类的生物特性、地质特点和作业需求,设计挖掘传送装置,采用固定式挖掘铲和振动筛进行贝泥沙混合物的挖掘与筛选,通过液压缸的伸缩调整采收机作业深度;基于各个机构和液压元件的分布,设计履带式底盘。通过实地试验,完成样机的性能测试。结果显示:试验地区采收机的最佳工艺参数为作业速度0.15 m/s,振动筛转速380 r/min,振动筛筛面倾角12°,可实现满足农艺要求的滩涂贝类无水化和浅水化机械化采收作业。研究表明,履带式滩涂贝类采收机具有较好的稳定性,且在提高工作效率、降低劳动强度等方面效果显著,具有较好的推广应用前景。