上海市土壤中持久性毒害污染物和盐分含量特征研究

Some farmland soils in Shanghai had high salinity levels, suggesting secondary salinization of the soils. The soil problems in Shanghai were studied, including the salinity and nitrate nitrogen (NO₃^--N) concentrations, heavy metal pollution characteristics, and organochlorine pesticide (OCP) residual levels and polycyclic aromatic hydrocarbon (PAH) contents. Accumulation of NO₃^--N in vegetable soils was the most significant among different functional soils. Heavy metal pollution was significant in the samples collected from the sewage-irrigated land and roadside. The identification of the metal sources through multivariate statistical analysis indicated that Pb, Zn, Cu and Cr in urban soils were from the traffic pollutants; excessive application of fertilizer and irrigation were the main reasons for the metal pollution in agricultural soils; Ni in the observed soils was controlled by parent soils. OCPs could still be detected in farmland soils but degraded greatly in last 20 years after prohibition of their usage. PAHs with 2-3 rings were the main components in industrial soils. The concentrated PAHs in the investigated soils were likely from petroleum and coal combustion.     

根迹土壤根诱导的化学变化对植物吸收重金属的影响

It is increasingly recognized that metal bioavailability is a better indicator of the potential for phytoremediation than the total metal concentration in soils; therefore, an understanding of the inffuence of phytoremediation plants on metal dynamics at the soil-root interface is increasingly vital for the successful implementation of this remediation technique. In this study, we investigated the heavy metal and soil solution chemical changes at field moisture, after growth of either Indian mustard (Brassica juncea) or sunffower (Helianthus annuus L.), in long-term contaminated soils and the subsequent metal uptake by the selected plants. In addition, the fractions of free metal ions in soil solution were determined using the Donnan membrane technique. After plant growth soil solution pH increased by 0.2-1.4 units and dissolved organic carbon (DOC) increased by 1-99 mg L^-1 in all soils examined. Soluble Cd and Zn decreased after Indian mustard growth in all soils examined, and this was attributed to increases in soil solution pH (by 0.9 units) after plant growth. Concentrations of soluble Cu and Pb decreased in acidic soils but increased in alkaline soils. This discrepancy was likely due to a competitive effect between plant-induced pH and DOC changes on the magnitude of metal solubility. The fractions of free Cd and Zn ranged from 7.2% to 32% and 6.4% to 73%, respectively, and they generally decreased as pH and DOC increased after plant growth. Metal uptake by plants was dependant on the soil solution metal concentration, which was governed by changes in pH and DOC induced by plant exudates, rather than on the total metal concentrations. Although plant uptake also varied with metal and soil types, overall soluble metal concentrations in the rhizosphere were mainly inffuenced by root-induced changes in pH and DOC which subsequently affected the metal uptake by plants.     

两种矿山生态型香薷对铜的吸收、分布和积累特性研究

Two ecotypes of Elsholtzia, Elsholtzia splendens and E. argyi, are dominant plants growing on Cu and Pb-Zn smelters, respectively. Samples of the two ecotypes and the corresponding soils from fields of a copper mining area and a Pb-Zn mining area of Zhejiang Province, China, were analyzed to investigate Cu or Zn tolerance of these two ecotypes. Effects of nine Cu levels (0, 5, 10, 20, 40, 80, 160, 240 and 320 mg Cu L^-1 as CuSO₄·5H₂O) on growth and uptake, translocation and accumulation of Cu in these two ecotypes were examined in a solution culture experiment. The experimental results showed that dry weights (DW) of shoots and roots were depressed, and growth of E. splendens was less depressed than that of E. argyi when treated with ≥ 5 mg Cu L^-1. Concentrations of Cu in shoots of E. splendens and E. argyi exceeded 1 000 mg kg^-1 DW at ≥ 40 mg Cu L^-1. The maximum Cu accumulated in the shoots of Cu-treated E. splendens and E. argyi reached 101 and 142 μg plant^-1. Furthermore, analysis of plant samples from the fields showed that these two ecotypes can tolerant excess heavy metals and produced high dry matter, and E. splendens can accumulate 11.7 mg Cu plant^-1 grown on the Cu smelter. Therefore, E. splendens and E. argyi could be good plants for phytoremediation.     

Root zone microbial populations, urease activities, and purification efficiency for a constructed wetland

In order to investigate the effects of microorganisms and their urease activities in macrophytic root zones on pollutant removal, four small-scale plots (SSPs) of vertical/reverse-vertical flow wetlands were set up to determine: a) the relationship between the abundance of microorganisms in the root zones and water purification efficiency; and b) the relationship between urease activities in the root zones and pollutant removal in a constructed wetland system. Total numbers of the microbial population (bacteria, fungi, and actinomyces) along with urease activities in the macrophytic root zones were determined. In addition, the relationships between microbial populations and urease activities as well as the wastewater purification efficiencies of total phosphorus (TP), total Kjeldahl nitrogen (TKN), biochemical oxygen demand in 5 days (BOD₅), and chemical oxygen demand (COD) were also analyzed. The results showed that there was a highly significant positive correlation (r = 0.9772, P < 0.01) between the number of bacteria in the root zones and BOD₅ removal efficiency and a significant negative correlation (r = -0.9092, P < 0.05) between the number of fungi and the removal efficiency of TKN. Meanwhile, there was a significant positive correlation (r = 0.8830, P < 0.05) between urease activities in the root zones and the removal efficiency of TKN. Thus, during wastewater treatment in a constructed wetland system, microorganism and urease activities in the root zones were very important factors.     

伊朗Zanjan城市尾矿土壤中入侵植物的抗氧化能力和金属积累情况

Tailings of a Pb and Zn mine as a metal-contaminated area (Zone 1) with two pioneer plant species, Peganum harmala and Zygophyllum fabago, were investigated and compared with a non-contaminated area (Zone 2) in the vicinity. Total concentrations of Pb, Zn, and Cu in the soil of Zone 1 were 1 416, 2 217, and 426 mg kg-1 , respectively, and all exceeded their ranges in the normal soils. The soil pH was in the neutral range and most of the physical and chemical characteristics of the soils from both zones were almost similar. The species Z. fabago accumulated higher Cu and Zn in its aerial part and roots than the normal plants. On the other hand, their concentrations did not reach the criteria that the species could be considered as a metal hyperaccumulator. The species P. harmala did not absorb metals in its roots; accordingly, the accumulation factor values of these metals were lower than 1. The contents of chlorophyll, biomass, malondialdehyde, and dityrosine in these two species did not vary significantly between the two zones studied. In Zone 1, leaf vacuoles of Z. fabago stored 35.6% and 43.2% of the total leaf Cu and Zn, respectively. However, in this species, the levels of phytochelatins (PCs) and glutathione (GSH) and antioxidant enzyme activities were significantly higher in Zone 1 than in Zone 2. In conclusion, metal exclusion in P. harmala and metal accumulation in Z. fabago were the basic strategies in the two studied pioneer species growing on the metal-contaminated zone. In response to metal stress, elevation in antioxidant enzyme activities, increases in the PCs and GSH levels in the aerial parts, and metal storage within vacuoles counteracted each other in the invasion mechanism of Z. fabago.     

长江口崇明岛土地利用方式对滨海土壤中重金属和砷的分布和形态特征的影响

The reclamation of tidal flats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the study of heavy metals due to the relative high pollutant concentrations in wetlands. To understand the impact of land use change on heavy metal and arsenic(As) geochemistry by the reclamation of wetlands for agriculture, surface soils and soil profiles were collected from the agricultural land reclaimed in the 1990 s and the intertidal flat wetland at Dongtan on Chongming Island in the Yangtze River Estuary, China. The soil samples were analyzed for total concentrations and chemical speciation of chromium(Cr), zinc(Zn), copper(Cu), lead(Pb), nickel(Ni), cadmium(Cd) and As using inductively coupled plasma mass spectrometry(ICP-MS). Results showed that soil properties(salinity, total organic carbon and grain-size distribution) and the concentrations of heavy metals and As in the soils differed under the different land use types. The conversion of wetland to forest had caused obvious losses of all the measured heavy metals. In paddy field and dryland with frequent cultivation, the concentrations of Cr, Zn, Cu, Ni and As were higher when compared to forest land which was disturbed rarely by human activities. Speciation analysis showed that Cr, Zn, Cu, Ni and As were predominated by the immobile residual fraction, while Pb and Cd showed relatively higher mobility. In general, metal(except Ni) and As mobility decreased in the following order: wetland dryland ≥ paddy field forest land, which suggested that the reclaimed soils had lower metal and As mobility than the intertidal flat wetland. The results of this study contribute to a better understanding of the effects of land use on heavy metals and As in the reclaimed soils of the study area and other similar coastal areas.     

两种人工湿地处理富营养化景观水体的性能对比研究

The efficiencies of two types of constructed wetlands for the treatment of low-concentration polluted eutrophic land-scape river water were studied in the western section of the Qingyuan River at the Minhang campus of Shanghai Jiaotong University. The first wetland was a single-stage system using gravel as a filtration medium, and the second was a three-stage system filled with combinations of gravel, zeolite, and fly ash. Results from parallel operations of the wetlands showed that the three-stage constructed wetland could remove organics, nitrogen, and phosphorus successfully. At the same time, it could also decrease ammoniacal odour in the effluent. Compared to the single-stage constructed wetland, it had better nutrient removal efficiencies with a higher removal of 19.37%-65.27% for total phosphorus (TP) and 21.56%-62.94% for total nitrogen (TN), respectively, during the operation period of 14 weeks. In terms of removal of chemical oxygen demand (COD), turbidity, and blue-green algae, these two wetland systems had equivalent performances. It was also found that in the western section of the test river, in which the two constructed wetlands were located, the water quality was much better than that in the eastern and middle sections without constructed wetland because COD, TN, and TP were all in a relatively lower level and the eutrophication could be prevented completely in the western section.     

Treatment Efiiciencies of Constructed Wetlands for Eutrophic Landscape River Water

The efficiencies of two types of constructed wetlands for the treatment of low-concentration polluted eutrophic landscape river water were studied in the western section of the Qingyuan River at the Minhang campus of Shanghai Jiaotong University. The first wetland was a single-stage system using gravel as a filtration medium, and the second was a three- stage system filled with combinations of gravel, zeolite, and fly ash. Results from parallel operations of the wetlands showed that the three-stage constructed wetland could remove organics, nitrogen, and phosphorus successfully. At the same time, it could also decrease ammoniacal odour in the effluent. Compared to the single-stage constructed wetland, it had better nutrient removal efficiencies with a higher removal of 19.37%-65.27% for total phosphorus （TP） and 21.56%- 62.94% for total nitrogen （TN）, respectively, during the operation period of 14 weeks. In terms of removal of chemical oxygen demand （COD）, turbidity, and blue-green algae, these two wetland systems had equivalent performances. It was also found that in the western section of the test river, in which the two constructed wetlands were located, the water quality was much better than that in the eastern and middle sections without constructed wetland because COD, TN, and TP were all in a relatively lower level and the eutrophication could be prevented completely in the western section.     

中国太原市农业土壤的重金属污染状况

To evaluate the current state of the environmental quality of agricultural soils in Taiyuan City, a hotspot for China’s industrial development, the concentrations of 8 heavy metals in soils were investigated by means of extensive sampling in farmlands, forestlands, and grasslands in the city. Statistical analyses and spatial distribution maps were used to identify the most significant heavy metal pollutants. The mean concentrations of As, Cd, Cu, Hg, Pb, Zn, Ni, and Cr were slightly higher than their background values in Taiyuan’s topsoil, but were lower than the maximum permissible concentrations in the Chinese Environmental Quality Standard for agricultural soils. Farmland soils in Taiyuan had the highest average Cd, Cu, Hg, Pb, Zn, and Cr concentrations, but the As and Ni concentrations did not differ significantly among the farmland, forestland, and grasslands. Soil contamination by Cd, Cu, Hg, Pb, Zn, and Cr was mainly derived from farming practices, especially the use of sewage water for irrigation. In contrast, As and Ni might derive mainly from the soil parent material. The identification of heavy metal sources in agricultural soils may provide a basis for taking appropriate action to protect soil quality.     

共培养对土壤重金属污染植物修复的调控作用

A co-culture of two plant materials, Astragalus sinicus L., a leguminous plant with concomitant nodules, and Elsholtzia splendens Naki-a Cu accumulator, along with treatments of a chelating agent (EDTA), root excretions (citric acid), and a control with E. splendens only were used to compare the mobility of heavy metals in chelating agents with a co-culture and to determine the potential for co-culture phytoremediation in heavy metal contaminated soils. The root uptake for Cu, Zn, and Pb in all treatments was significantly greater (P < 0.05) than that of the control treatment. However with translocation in the shoots, only Cu, Zn, and Pb in plants grown with the EDTA treatment and Zn in plants co-cropped with the A. sinicus treatment increased significantly (P < 0.05). In addition, when a co-culture in soils with heavy and moderate contamination was compared, for roots in moderately contaminated soils only Zn concentration was significantly less (P < 0.05) than that of heavily contaminated soils, however, Cu, Zn, and Pb concentrations of shoots were all significantly lower (P < 0.05). Overall, this "co-culture engineering" could be as effective as or even more effective than chelating agents, thereby preventing plant metal toxicity and metal leaching in soils as was usually observed in chelate-enhanced phytoremediation.     

铬对人工湿地净化生活污水的影响及铬积累规律

采用沙培法,研究了不同浓度Cr6＋（0、10、20、40 mg.L-1）对风车草湿地和薏米湿地净化生活污水的影响及铬积累规律。结果表明：（1）COD的去除率在苗期随铬浓度增大而逐渐升高,其余时期在20、40 mg.L-1处理下受到显著抑制（除了花期风车草湿地外）;随铬处理浓度的增大,风车草湿地对TN的去除率变化不明显,薏米湿地对TN的去除率则受到抑制作用（除了花期10 mg.L-1外）;这两种湿地对生活污水中铬的净化效果较好,仅在40 mg.L-1处理的风车草湿地出水中检测出铬。（2）10 mg.L-1铬促进风车草和薏米的生物量增大,较高浓度铬（20、40 mg.L-1）则抑制。（3）基质细沙及植物根系对污水中铬具有较好的吸附及积累作用,铬含量在细沙及植物中均随铬浓度增大而显著升高,其中两种植物对铬的积累量都表现为地下部显著大于地上部,表明风车草和薏米的根部中铬较难转移到其地上部。     

美人蕉（Canna indica Linn.）和芦苇（Phragmites australis L.）人工湿地对含铬生活污水的净化效果及植物的生理生态变化

选取美人蕉（CannaindicaLinn.）、芦苇（PhragmitesaustralisL.）为植物材料,以不同浓度K2Cr2O（7分别含0、1、20、50mg.L-1Cr6＋）的生活污水作为Cr6＋污染源,研究了不同浓度Cr6＋及处理时间下两种湿地对污水净化效果、植物体Cr6＋积累量及根系活力（TTC）、叶片超氧化歧化酶（SOD）活性、过氧化物酶（POD）活性、净光合速率（Pn）和丙二醛（MDA）等生理指标的影响。结果表明：（1）在试验的初期30d内,随处理时间的延长,两种人工湿地COD、氨氮去除率均呈逐渐上升的趋势,30d后,随着Cr6＋处理时间的延长及Cr6＋浓度的逐渐升高,两种湿地系统对COD、氨氮去除率均逐渐下降。在20、50mg.L-1Cr6＋处理条件下,两种湿地对COD、氨氮的净化效果显著低于对照及1mg.L-1Cr6＋处理,对照与1mg.L-1Cr6＋处理条件下差异不显著。（2）在不同Cr6＋浓度处理下,两种人工湿地对TP净化效果的能力较为稳定,同时随处理时间的延长,美人蕉、芦苇体内Cr6＋积累量逐渐加大。（3）1mg.L-1Cr6＋处理可提高美人蕉和芦苇的TTC、叶片的SOD、POD、Pn,而20、50mg.L-1Cr6＋处理对以上指标均有不同程度的抑制作用,且抑制效果与处理浓度、时间呈正相关。（4）MDA含量随处理时间的延长和浓度升高呈逐渐增加趋势。可见,低浓度Cr6＋能有效促进美人蕉、芦苇生长,使之能够维持正常的净化功能,因此,利用它们作为人工湿地植物来修复Cr6＋污染具有一定的实用价值。     

垂直流-水平潜流一体化人工湿地对菜地废水的净化效果

广州市番禺区东升农场菜地废水未经处理直接排入水生植物塘,最终流入附近河流,由于菜地废水水质较差,对其造成了严重的污染,严重威胁了附近居民的饮水安全。为了提高菜地出水水质,减轻对河流的污染,通过构建垂直流-水平潜流一体化人工湿地,对菜地废水进行净化处理。湿地经过9个月的运行,结果显示,湿地对COD、NH4＋-N和TP的平均去除率分别达56.40%、79.09%和79.79%以上,COD、NH4＋-N和TP出水平均浓度分别为9.45、0.47mg.L-1和0.06mg.L-1,均达到《地表水环境质量标准》（GB3838—2002）Ⅱ类水质标准。湿地对TN的平均去除率较低,仅为35.08%,通过补充甘蔗叶作为碳源,湿地对TN的平均去除率显著提高,但随着碳源投加量的增加,去除率逐渐降低。本实验碳源投加量以1.62kg.m-3为宜,TN的平均去除率最高,达80.85%,出水TN平均浓度从3.06mg.L-1降低至0.90mg.L-1。     

自动增氧型垂直流人工湿地处理农村生活污水试验研究

针对人工湿地中溶解氧浓度不足的问题,采用自动增氧型垂直流人工湿地处理系统进行了农村生活污水脱氮除磷对比试验研究。结果表明,自动增氧型湿地内的DO浓度比非增氧型人工湿地高0.3 mg.L-1左右,TN、NH4＋-N去除率分别达到了67.41%、69.04%,比非增氧型湿地高14.57%、19.79%,但TP去除率与非增氧型湿地差异不显著。说明自动增氧措施对于增加人工湿地中的DO浓度,提高脱氮效率是有效的,但对于除磷效率无显著影响。     

The influence of flow conditions on the removal of heavy metals in the primary sedimentation process

A pilot scale primary sedimentation pilot plant, treating raw sewage, was used to assess the efficiency of removal of Cd, Cr, Cu, Ni, Pb, and Zn. Heavy metal removals were determined during conditions designed to simulate normal dry weather flow, three times dry weather flow and diurnal variations in flow. During these experiments, the flow of sewage to the works where the pilot plant was sited also varied. It was found that short term variations in heavy metal concentrations in the raw sewage were related to the flow, although percentage removals appeared to be relatively unaffected by heavy metal concentrations. Removals during normal dry weather flow conditions were generally in the range of 25 to 50%, with Cu and Pb removals highest and Ni removal lowest. Lower removal efficiencies were observed when the flow to the pilot plant was increased three-fold, and the poorest removals were observed under variable flow conditions.     

Accumulation of Metals in the Sediment and Reed Biomass of a Combined Constructed Wetland Treating Domestic Wastewater

This study assessed the accumulation of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the sediment and biomass of P. australis (Cav.) Trin. ex Steud. in a combined constructed wetland (CW) designed for the treatment of domestic wastewater of 750 population equivalents. The CW consists of two vertical subsurface flow (VSSF) reed beds followed by two horizontal subsurface flow (HSSF) reed beds. The sediment in the VSSF reed bed was contaminated with Cu (201 ?±? 27 mg kg^?1 DM) and Zn (662 ?±? 94 mg kg^?1 DM) after 4 years of operation. Concentrations of Cd, Cu, Pb and Zn in the sediment generally decreased along the treatment path of the CW. On the contrary, higher Al, Cr, Fe, Mn and Ni concentrations were observed in the sediment of the inlet area of the HSSF reed bed. Redox conditions were presumably responsible for this observed trend. Metal concentrations in the reed biomass did not show excessive values. Accumulation in the aboveground reed biomass accounted for only 0.5 and 1.4% of, respectively, the Cu and Zn mass load in the influent. The sediment was the main pool for metal accumulation in the CW.     

高氨氮浓度下湿地植物筛选及脱氮效果研究

为研究潜流人工湿地处理农村生活污水的脱氮效果,实验采用氨氮浓度为20、30、40、50 mg.L-1的人工配置生活污水,通过实验室盆栽法研究7种典型水生植物风车草（Cyperus alternifolius）、花叶芦竹（Arundo donax var.）、再力花（Thalia dealbata）、东方香蒲（Typha orientalis Presl.）、千屈菜（Spiked Loosestrlfe）、黄花鸢尾（Iris pseudacorus）、梭鱼草（Pontederia cordata）的生长状况、发育规律以及对污水中氮的同化吸收作用,结合植物本身的形态指标,对处理农村生活污水的高效脱氮型潜流湿地的植被的脱氮效果进行综合评定。结果表明：植物在20 mg.L-1的处理中长势最好,各植物的形态指标随氨氮浓度的增加而递减;黄花鸢尾（Irispseudacorus）在NH3-N浓度50 mg.L-1以上的条件下不能生长,花叶芦竹（Arundo donax var.）在NH3-N浓度30 mg.L-1以上的条件下不能生长,梭鱼草（Pontederia cordata）在NH3-N浓度20 mg.L-1以上的条件下不能生长;植物脱氮效果随氨氮浓度的增加而递减。综合评定7种植物的脱氮效果,比较好的是再力花（Thalia dealbata）、东方香蒲（Typha orientalis Presl.）、风车草（Cyperus alternifolius）这3种植物。     

新乡市寺庄顶污灌区土壤及小麦重金属污染特征的研究

通过田间采样及室内样品分析,对新乡市寺庄顶污灌区土壤和小麦子实中重金属污染特征进行了初步探讨。结果表明,土壤中cr含量达标,Cd、Ni、Zn和Cu的含量超标,其平均含量分别为65．31、1196．64、2799．25和145．78mg·kg-1,是国家土壤环境二级标准的108．85、19．94、9．33和1．46倍;污染最严重的Cd主要以铁-锰氧化物结合态存在,所占比例平均为56．84％,Ni主要以铁-锰氧化物结合态和残渣态存在,所占比例平均为37．44％和39．55％,Zn主要以残渣态存在,所占比例平均为78．24％,Cu主要以有机结合态存在,所占比例平均为57．70％。小麦子实中cd污染最严重,其平均含量为2．55mg·kg-1,是国家食品卫生标准的25．5倍,这主要是由于土壤中Cd总量严重超标且迁移能力最强的可交换态所占比例较高引起的,Ni、Cr和Zn含量分别是国家食品卫生标准的12．98、6．12和1．32倍,表明长期污水灌溉对寺庄顶灌区小麦的食品安全造成严重威胁,应引起足够的重视。     

The Efficacy of a Tropical Constructed Wetland for Treating Wastewater During the Dry Season: The Kenyan Experience

Constructed wetlands have recently received considerable attention as low cost and efficient means of cleaning up many different types of wastewaters at secondary and tertiary levels. This is an environmentally sound method of wastewater treatment that does not use hazardous chemicals, and is based on the high productivity and nutrient removal capability of the wetland that strongly relies on its intricate ecosystem structure and function. Research work was conducted on a tropical constructed wetland to establish its capability to treat wastewater during the dry season. A comparison of its efficacy with that of conventional wastewater treatment plants was made on the basis of the measured water quality parameters. Temperature, pH, dissolved oxygen, and conductivity were measured in situ. Total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), phosphorus, ammonia, and nitrites were analyzed in the laboratory. Fecal coliforms were enumerated and Escherichia coli counts were determined. The TSS values reduced from a mean of 102 mg/l at the influent point to 16 mg/l at the effluent point, depicting a reduction of 84.3%. Influent TDS averaged 847 mg/l, while the effluent averaged 783 mg/l. Dry season BOD₅ levels were reduced from an average of 286 at the inlet point to 11 mg/l at the outlet representing a reduction efficiency of 96.2%. COD levels were reduced from a mean of 2,002.5 to 47.5 mg/l depicting a removal efficiency of 97.6%. Phosphorus was reduced from a mean of 14 to 11 mg/l representing a percentage removal of 21.4%. Levels of ammonia reduced from a mean of 61 at the influent point to 36 mg/l at the effluent point representing a percent reduction of 41.0%. There was a 99.99% reduction for both the fecal coliforms and E. coli counts. Conductivity of wastewater increased from 1.08 to 1.98 mS, while the pH increased from 6.23 at the inlet point to 7.99 at the outlet of the system. Temperature and dissolved oxygen measurements showed a diurnal variation. The dry season wastewater heavy metal concentrations were in the following ranges: Pb (0.7?C6.9 ppm), Cr (0.2?C0.5 ppm), Zn (0.1?C2.3 ppm), Ni (0.1?C1.3 ppm) with Cd and Cu not being detected in the wastewater streams. Overall, tropical constructed wetlands are effective in treating wastewater streams and they perform a lot better than the popularly used waste stabilization ponds. This paper recommends that they can be widely used within the tropics.     

福建闽江河口湿地土壤重金属污染特征及评价研究

为掌握福建闽江河口湿地重金属污染特征,对闽江河口湿地不同监测点重金属污染状况进行全面调查采样,利用综合污染指数法和地累积指数法对重金属污染状况进行评价。结果表明,福建闽江河口湿地重金属污染比较严重,除Ni和Cr外,Cu、Pb、Zn、Cd、Mn均超过土壤环境质量标准（I级）。除Ni和Cr单项污染指数无污染外,其他监测点均有不同程度的重金属污染,污染程度表现为Pb〉Cu〉Zn〉Cd;综合污染指数除潭头港和鳝鱼滩为轻度污染,其他6个监测点均达到中度污染以上,表明闽江河口湿地存在严重的重金属复合污染。地累积指数除Pb、Zn、Cd污染达到中或轻度污染水平,其他重金属均无污染。