Study of harmful algal blooms in a eutrophic pond, Bangladesh

The purpose of this research was to analyze the underlying mechanisms and contributing factors related to the seasonal dynamic of harmful algal blooms in a shallow eutrophic pond, Bangladesh during September 2005–July 2006. Two conspicuous events were noted simultaneously throughout the study period: high concentration of phosphate–phosphorus (>3.03; SD 1.29 mg l^???1) and permanent cyanobacterial blooms {>3,981.88 × 10³ cells l^???1 (SD 508.73)}. Cyanobacterial blooms were characterized by three abundance phases, each of which was associated with different ecological processes. High nitrate–nitrogen (>2.35; SD 0.83 mg l^???1), for example, was associated with high cyanobacterial abundance, while low nitrate–nitrogen (0.36; SD 0.2 mg l^???1) was recorded during moderate abundance phase. Extremely low NO₃–N/PO₄–P ratio (>3.55, SD 2.31) was recorded, and all blooming taxa were negatively correlated with this ratio. Cyanobacterial blooms were positively correlated with temperature (r?=?0.345) and pH (0.833; p?=?0.05) and negatively correlated with transparency (r?=???0.956; p?=?0.01). Although Anabaena showed similar relationship with water quality parameters as cyanobacteria, the co-dominant Microcystis exhibited negative relationship with temperature (r?=???0.386) and nitrate–nitrogen (r?=???0.172). This was attributed to excessive growth of Anabaena that suppressed Microcystis’s growth. Planktothrix was the third most dominant taxa, while Euglena was regarded as opportunistic.     

Development of rapid bioassessment approaches using benthic macroinvertebrates for Thai streams

Thailand currently lacks formal bioassessment approaches and protocols to assist management decisions for water quality. The aim of this research is to develop a practical method of rapid bioassessment for a professional level by using benthic macroinvertebrate assemblages for streams in Thailand. Eleven reference and nine test sites were sampled in the headwater streams of the Loei River and adjacent areas to explore the development of a practical protocol. Specific physico-chemical parameters were selected to provide ecological information supplemental to the biological indicators. The biological research was designed around the USEPA Rapid Bioassessment Protocols (RBPs) using the multi-habitat approach. Four fixed-count subsamplings (100, 200, 300 and 500 organisms) were randomly conducted using a standardized gridded pan to evaluate an appropriate level for bioassessment in Thai streams. A 300 organism subsample is adequate for bioassessment purposes in Thai stream (evaluated by calculating dissimilarity values and ordination techniques). A systematic selection of candidate reference sites, metric selection, and index calibration was part of this research. Multimetric and multivariate analyses were examined as a foundation for bioassessment in Thailand. The multimetric approach appears to be more practical for a rapid bioassessment technique. Nine core metrics were identified for biological index score including number of total taxa, Diptera taxa, Ephemeroptera, Plecoptera, Trichoptera, and Coleoptera taxa, (%) Plecoptera, (%) Tolerant organisms, Beck's Biotic Index, (%) Intolerant organisms, Shredders taxa and Clingers taxa were calibrated for the final index. As a result of multimetric and multivariate analyses, family level identification data effectively discriminated reference condition and broad-scale environmental gradients. Hampered by incomplete taxonomic knowledge of benthic macroinvertebrates in Thailand, family-level identification may be sufficient taxonomic resolution for rapid bioassessment in Thailand.     

Variations in the physicochemical characteristics of the Buffalo River in the Eastern Cape Province of South Africa

The physicochemical characteristics of the Buffalo River in the Eastern Cape Province of South Africa were evaluated using standard methods. The assessment was carried out with total of 72 water samples collected from six sites over a 12-month period, from August 2010 to July 2011. Water temperature ranged from 11 to 28 °C, while pH varied from 6.6 to 10.7 and turbidity from 1.7 to 133 NTU. Electrical conductivity, total dissolved solids (TDS) and salinity showed drastic variations (42.3–46,693 μS/cm, 20.3–23,350 mg/l and 0.02–33.8 PSU, respectively) and the significantly (P?<?0.05) higher mean values of these parameters recorded at Parkside reflect the influence of seawater at the Buffalo River estuary. The concentrations of other parameters ranged as follows: chloride (3.7–168 mg/l), DO (6.9–11.1), BOD (0.6–9.4), COD (3.7–45.9), nitrite–nitrogen (0.02–0.21), nitrate–nitrogen (1–4.47) and orthophosphate (0.01–1.72). There was a significant positive correlation between water temperature and DO (r?=?0.200; P?<?0.01). Significant (P?<?0.01) positive correlations also existed between TDS and salinity (r?=?0.921), COD and each of salinity (r?=?0.398), TDS (r?=?0.375) and chloride (r?=?0.330), nitrate and phosphate (r?=?0.323) and BOD and turbidity (r?=?0.290). Significant (p?<?0.01) inverse relationships existed between DO and each of phosphate (r?=??0.295) and nitrate (r?=??0.168). We conclude that the Buffalo River water quality deteriorated in the plains, compared with the upper reaches. Urgent measures are needed to safeguard the river in view of the potential health concerns as many households rely solely on the untreated river water.     

Bioassessment in A Harsh Environment: A Comparison of Macroinvertebrate Assemblages at Reference and Assessment Sites in An Australian Inland River System

The Lachlan River system of inland New South Wales, which extends into semi-arid areas, is prone to natural extremes of climate and water quality and has been almost entirely modified since European settlement in Australia. We used this system as a proving ground for the mainly qualitative bioassessment metrics for river macroinvertebrates that are used widely in Australia – the EPT (Ephemeroptera, Plecoptera and Trichoptera) index, the SIGNAL (Stream Invertebrate Grade Number Average Level) biotic index and the AUSRIVAS O/E (Australian River Assessment System Observed over Expected) index – plus a recently developed qualitative index, the observed proportion of potential taxa (OPP). We tested these metrics on their ability to discriminate between sites judged to be less disturbed by human activities (reference sites) and sites selected by a semi-random process and therefore expected to have a higher average level of human disturbance (assessment sites). All metrics except the AUSRIVAS O/E index differed significantly between the two types of sites at higher altitudes, with SIGNAL showing the greatest discrimination. Assessment at these altitudes was more effective if based on composite data from multiple mesohabitats rather than data from single mesohabitats. No metric differentiated the two types of sites in the more arid, lowland, floodplain region of the river system. We suggest that Australia relies too heavily on bioassessment concepts developed to assess water pollution in well-watered regions of the Northern Hemisphere. Effective assessment of human impacts on macroinvertebrates in the rivers of inland Australia requires a better understanding of the roles of flow regimes, including flood and drought sequences, and of microhabitat structure and invasive alien species. Quantitative approaches may also be required.     

Relationships of relative humidity with PM<Subscript>2.5</Subscript> and PM<Subscript>10</Subscript> in the Yangtze River Delta,China

Severe particulate matter (PM, including PM_2.5 and PM₁₀) pollution frequently impacts many cities in the Yangtze River Delta (YRD) in China, which has aroused growing concern. In this study, we examined the associations between relative humidity (RH) and PM pollution using the equal step-size statistical method. Our results revealed that RH had an inverted U-shaped relationship with PM_2.5 concentrations (peaking at RH = 45–70%), and an inverted V-shaped relationship (peaking at RH = 40 ± 5%) with PM₁₀, SO₂, and NO₂. The trends of polluted-day number significantly changed at RH = 70%. The very-dry (RH < 45%), dry (RH = 45–60%) and low-humidity (RH = 60–70%) conditions positively affected PM_2.5 and exerted an accumulation effect, while the mid-humidity (RH = 70–80%), high-humidity (RH = 80–90%), and extreme-humidity (RH = 90–100%) conditions played a significant role in reducing particle concentrations. For PM₁₀, the accumulation and reduction effects of RH were split at RH = 45%. Moreover, an upward slope in the PM_2.5/PM₁₀ ratio indicated that the accumulation effects from increasing RH were more intense on PM_2.5 than on PM₁₀, while the opposite was noticed for the reduction effects. Secondary transformations from SO₂ and NO₂ to sulfate and nitrate were mainly responsible for PM_2.5 pollution, and thus, controlling these precursors is effective in mitigating the PM pollution in the YRD, especially during winter. The conclusions in this study will be helpful for regional air-quality management.     

The changes in different ozone metrics and their implications following precursor reductions over northern Taiwan from 1994 to 2007

The changes of different O₃ metrics such as O_{3_avg} (daily mean), O_X (NO₂ + O₃), O_{3_8h} (daily maximum 8-h moving average), O_{3_max} (daily maximum 1-h average), and exceedances of O_{3_8h} and O_{3_max} at 16 air quality monitoring stations over northern Taiwan from 1994 to 2007 are evaluated. The O_{3_avg} at the background site displays an increasing trend at 0.54 ±0.21 ppb (1.28 ±0.49%) per year. The O_X at urban sites shows a significant increase, indicating that even with the effect of reduced NO titration increasing photochemical production is evident. The exceedances of O_{3_8h} (>80 ppb) are about 14.9% higher than O_{3_max} (>120 ppb) with more exceedances at coastal or background sites, where the anthropogenic O₃ precursor emissions are lower. In addition to increasing background O₃ and reductions in NO titration, increasing O₃ production efficiency also plays a key role in the increase of moderate to high O₃ concentrations. The findings help explain the different trends in exceedances and levels of O_{3_8h} and O_{3_max} and are likewise important in the formation of O₃ control strategies.     

Nutrient spatial pattern of the upstream,mainstream and tributaries of the Three Gorges Reservoir in China

A comprehensive monitoring program was conducted to investigate the nutrient spatial pattern in the mainstream of the Yangtze River from the Baihetan Dam down to the Three Gorges Dam located at the upper region of the Yangtze River in China. Samples were taken from 33 different sites from July 30 to August 19, 2011. The nutrient patterns of the three representative tributaries of the Three Gorges Reservoir (TGR)—the Modao, the Daning, and the Xiangxi Rivers—were also investigated. The results show that the mainstream of the TGR has a higher concentration of nitrogen and a lower concentration of phosphorus than that of the upper mainstream before the TGR. Moreover, it was found that nitrate-nitrogen (NO₃-N) is the main nitrogen component, while particulate phosphorus predominates the total phosphorus (TP). It was found that the three representative tributaries of the TGR have lower total nitrogen (TN) concentrations compared to the corresponding sections of the mainstream TGR. Based on the nutrient spatial pattern, the nutrient flux was calculated. The total fluxes of TN, NO₃-N, TP, and orthophosphate (PO₄-P) from the upstream reach into the TGR are 2,155.06, 1,674.97, 212.98, and 83.42 t day^?1, respectively. The amount of nutrients imported from the TGR into its tributaries is more than the amount exported. It was determined that the Xiangxi River has the largest net rate of imported nitrogen at 7.66 t day^?1, whereas the Daning River has the largest net rate of imported phosphorus at 1.75 t day^?1. In addition, compared with the nutrients imported from the TGR into its tributaries, the nutrient flux from the upstream reach into the TGR contributes approximately less than 3 %.     

NDVI indicated characteristics of vegetation cover change in China��s metropolises over the last three decades

How urban vegetation was influenced by three decades of intensive urbanization in China is of great interest but rarely studied. In this paper, we used satellite derived Normalized Difference Vegetation Index (NDVI) and socioeconomic data to evaluate effects of urbanization on vegetation cover in China??s 117 metropolises over the last three decades. Our results suggest that current urbanization has caused deterioration of urban vegetation across most cities in China, particularly in East China. At the national scale, average urban area NDVI (NDVI_u) significantly decreased during the last three decades (P?<?0.01), and two distinct periods with different trends can be identified, 1982?C1990 and 1990?C2006. NDVI_u did not show statistically significant trend before 1990 but decrease remarkably after 1990 (P?<?0.01). Different regions also showed difference in the timing of NDVI_u turning point. The year when NDVI_u started to decline significantly for Central China and East China was 1987 and 1990, respectively, while NDVI_u in West China remained relatively constant until 1998. NDVI_u changes in the Yangtze River Delta and the Pearl River Delta, two regions which has been undergoing the most rapid urbanization in China, also show different characteristics. The Pearl River Delta experienced a rapid decline in NDVI_u from the early 1980s to the mid-1990s; while in the Yangtze River Delta, NDVI_u did not decline significantly until the early 1990s. Such different patterns of NDVI_u changes are closely linked with policy-oriented difference in urbanization dynamics of these regions, which highlights the importance of implementing a sustainable urban development policy.     

Water quality in Minho/Miño River (Portugal/Spain)

Minho River, also called Miño (in Spain), extends to about 300 km from Spain to Portugal. The source of the river lies in Spain and in the last 75 km, the river defines the border between Portugal and Spain. Under the scope of a cooperation project between North Portugal and Galicia region of Spain, titled: “Valorization of the natural resources of the Minho/Miño drainage basin”, seven water-sampling campaigns were carried out during the last 2 years in Minho River basin. Seven sampling sites were selected along the international stretch, and five were chosen in the main Portuguese and Spanish tributaries of Minho River. Water quality based on the physicochemical and microbial parameters was assessed. According to the Portuguese legislation for surface waters, the international section of Minho River presents a reasonably good water quality (BOD₅ <5 mg/L, TNK <2 mg/L, and total phosphorous <1 mg P/L). Valença and Louro were found to be the most polluted sampling sites and Louro the most polluted tributary (maximum values observed: TSS?=?26 mg/L, BOD₅?=?6.6 mg O₂/L, COD?=?20.8 mg O₂/L, total nitrogen?=?9.9 mg N/L; minimum value observed: OD?=?1.3 mg O₂/L). A one-dimensional stream water quality model QUAL2Kw was calibrated using data measured in field surveys along the international stretch of Minho River. QUAL2Kw was also used to predict the impact of flow conditions, discharges, and tributaries on the water quality of international stretch of Minho River, essential to establish proposals for management and planning of Minho River Basin.     

Measurement of soil radioactivity levels and radiation hazard assessment in southern Rechna interfluvial region, Pakistan

Rechna interfluvial region is one of the main regions of Punjab, Pakistan. It is the area which is lying between River Ravi and River Chenab, alluvial-filled. Radioactivity levels in soil samples, collected from southern Rechna interfluvial region, Pakistan, have been estimated by using gamma-ray spectrometric technique. ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K, and the artificial radionuclide ¹³⁷Cs have been measured in the soil of the study area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs were found to be 50.6 ± 1.7, 62.3 ± 3.2, 662.2 ± 32.1, and 3.1 ± 0.3 Bq kg^???1, respectively. The mean radium equivalent activity (Ra_eq), outdoor radiation hazard index (H _out), indoor radiation hazard index (H _in), and terrestrial absorbed dose rate for the area under study were determined as 190.8 ± 8.7 Bq kg^???1, 0.52, 0.65, and 69.8 nGy h^???1, respectively. The annual effective dose to the general public was found to be 0.43 mSv. This value lies well below the limit of 1 mSv for general public as recommended by the International Commission on Radiological Protection. The measured values are comparable with other global radioactivity measurements and are found to be safe for the public and the environment.     

Mayfly (Insecta: Ephemeroptera) community structure as an indicator of the ecological status of a stream in the Niger Delta area of Nigeria

Ephemeroptera is an important group of insects used in the bioassessment and monitoring of freshwater bodies worldwide because of their relative abundance in a wide variety of substrates and their increasing chances of detecting pollution impacts. In this study, their faunistic composition and spatiotemporal variations in density and diversity in River Orogodo (Southern Nigeria) was investigated at five ecologically distinct stations over a 12-month period. The mayfly nymph community responses to environmental variables were evaluated by means of biological measures and multivariate analysis (redundancy analysis [RDA]). Thirteen morphologically distinct taxa belonging to six families were identified. The dominant taxa were Afrobaetodes pusillus (23.1%), Baetis sp. (13.7%), and Caenis cibaria (11.4%). The density of Ephemeroptera differed significantly (p?<?0.05) both in space and time. Diversity was influenced by substrate heterogeneity which in turn was influenced by catchment processes such as flooding and anthropogenic activities especially abattoir effluent. Based on the RDA ordination and relative abundance data, Baetis sp. dominated at impacted stations while a more equitable distribution of species were observed in less disturbed sites. Water velocity, canopy cover, nature of bottom sediments, and the amount of dissolved oxygen also accounted for the variations in Ephemeroptera densities at the different stations. Shannon diversity, taxa richness, and evenness were lowest in station 3 (the abattoir discharge site).     

Total suspended matter observation in the Pearl River estuary from in situ and MERIS data

Based on the cruise data collected in the Pearl River estuary (PRE) in May 2008, an empirical two-band model by using the ratio of R _rs at 629 and 671 nm was established to retrieve total suspended matter (TSM) concentration with the determination coefficient (R²) of 0.854, mean relative error (MRE) of 7.483%, and root-mean-square error (RMSE) of 1.295 mg L^???1. To match with medium resolution imaging spectrometer (MERIS) bands, in situ remote sensing reflectance was re-sampled to the bandwidth of 10 nm. The relationship between TSM and re-sampled R _rs at 620 nm (MERIS band 6) and 665 nm (MERIS band 7) are obtained (R² = 0.748, RMSE = 1.697 mg L^???1, MRE = 8.785%, n = 13). Additionally, to map the spatial distribution of TSM in the PRE, MERIS level_1B data were calibrated using a multiple linear regression model based on in situ R _rs. Another dataset collected in the PRE in January 2004 was used to validate the two-band model and also applied to map TSM distribution from MERIS image. The comparison between measured TSM values and modeled ones showed satisfactory results (R² = 0.753, MRE = 22.199%, and RMSE = 2.603 mg L^???1).     

Pesticide concentrations in water and sediment and associated invertebrate toxicity in Del Puerto and Orestimba Creeks, California, 2007�C2008

The California??s San Joaquin River and its tributaries including Orestimba (ORC) and Del Puerto (DPC) Creeks are listed on the 2006 US EPA Clean Water Act §303(d) list for pesticide impairment. From December 2007 through June 2008, water and sediment samples were collected from both creeks in Stanislaus County to determine concentrations of organophosphorus (OP) and pyrethroid insecticides and to identify toxicity to Ceriodaphnia dubia and Hyalella azteca. OPs were detected in almost half (10 of 21) of the water samples, at concentrations from 0.005 to 0.912 ??g L^???1. Diazinon was the most frequently detected OP, followed by chlorpyrifos and dimethoate. Two water samples were toxic to C. dubia; based on median lethal concentrations (LC₅₀), chlorpyrifos was likely the cause of this toxicity. Pyrethroids were detected more frequently in sediment samples (18 detections) than in water samples (three detections). Pyrethroid concentrations in water samples ranged from 0.005 to 0.021 ??g L^???1. These concentrations were well below reported C. dubia LC₅₀s, and toxicity was not observed in laboratory bioassays. Cyfluthrin, bifenthrin, esfenvalerate, and ??-cyhalothrin were detected in sediment samples at concentrations ranging from 1.0 to 74.4 ng g^???1, dry weight. At DPC, all but one sediment sample caused 100% toxicity to H. azteca. Based on estimated toxicity units (TUs), bifenthrin was likely responsible for this toxicity and ??-cyhalothrin also contributed. At ORC, survival of H. azteca was significantly reduced in four of the 11 sediment samples. However, pyrethroids were detected in only two of these samples. Based on TUs, bifenthrin and ??-cyhalothrin likely contributed to the toxicity.     

Assessment of organochlorine pesticides and plasticisers in the Selangor River basin and possible pollution sources

A study on the quality of water abstracted for potable use was conducted in the Selangor River basin from November 2008 to July 2009. Seven sampling sites representing the intake points of water treatment plants in the basin were selected to determine the occurrence and level of 15 organochlorine pesticides (OCPs), six phthalate esters (PAEs) and bisphenol A (BPA). Results indicated OCPs were still detected regularly in 66.1 % of the samples with the Σ₁₅OCPs ranging from 0.6–25.2 ng/L. The first data on PAEs contamination in the basin revealed Σ₆PAEs concentrations were between 39.0 and 1,096.6 ng/L with a median concentration of 186.0 ng/L while BPA concentration ranged from <1.2 to 120.0 ng/L. Although di-n-butyl phthalate was detected in all the samples, concentrations of di-ethyl(hexyl)phthalate were higher. Sampling sites located downstream recorded the highest concentrations, together with samples collected during the dry season. Comparison of the detected contaminants with the Department of Environment Water Quality Index (DOE-WQI) showed some agreement between the concentration and the current classification of stream water. While the results suggest that the sites were only slightly polluted and suitable to be used as drinking water source, its presence is cause for concern especially to the fragile firefly “Pteroptyx tener” ecosystem located further downstream.     

An improved algorithm for retrieving chlorophyll-a from the Yellow River Estuary using MODIS imagery

In this study, an improved Moderate-Resolution Imaging Spectroradiometer (MODIS) ocean chlorophyll-a (chla) 3 model (IOC3M) algorithm was developed as a substitute for the MODIS global chla concentration estimation algorithm, OC3M, to estimate chla concentrations in waters with high suspended sediment concentrations, such as the Yellow River Estuary, China. The IOC3M algorithm uses $ {{{\left[ {R_{\text{rs}}^{{ - 1}}\left( {{\lambda_{{1}}}} \right) - {k_1}R_{\text{rs}}^{{ - 1}}\left( {{\lambda_{{2}}}} \right)} \right]}} \left/ {{\left[ {R_{\text{rs}}^{{ - 1}}\left( {{\lambda_{{3}}}} \right) - {k_{{2}}}R_{\text{rs}}^{{ - 1}}\left( {{\lambda_{{4}}}} \right)} \right]}} \right.} $ to substitute for switching the two-band ratio of max [R _rs (443 nm), R _rs (488 nm)]/R _rs (551 nm) of the OC3M algorithm. In the IOC3M algorithm, the absorption coefficient of chla can be isolated as long as reasonable bands are selected. The performance of IOC3M and OC3M was calibrated and validated using a bio-optical data set composed of spectral upwelling radiance measurements and chla concentrations collected during three independent cruises in the Yellow River Estuary in September of 2009. It was found that the optimal bands of the IOC3M algorithm were λ₁?=?443 nm, λ₂?=?748 nm, λ₃?=?551 nm, and λ₄?=?870 nm. By comparison, the IOC3M algorithm produces superior performance to the OC3M algorithm. Using the IOC3M algorithm in estimating chla concentrations from the Yellow River Estuary decreases 1.03 mg/m³ uncertainty from the OC3M algorithm. Additionally, the chla concentration estimated from MODIS data reveals that more than 90 % of the water in the Yellow River Estuary has a chla concentration lower than 5.0 mg/m³. The averaged chla concentration is close to the in situ measurements. Although the case study presented herein is unique, the modeling procedures employed by the IOC3M algorithm can be useful in remote sensing to estimate the chla concentrations of similar aquatic environments.     

Distribution and sources of organochlorine pesticides in sediments of the Xiangjiang River, south-central China

The Xiangjiang River (XR), the second largest tributary of the Yangtze River, is mainly located in Hunan province in south-central China. Nineteen surface sediment samples (the top 3-cm layer) collected from XR were analyzed to determine the concentrations, distribution, sources, and ecological risk of organochlorine pesticides (OCPs). The concentrations of OCPs were 3.0–29.8 ng/g (dry weight) with a mean of 12.6?±?7.7 ng/g. The widely detected compounds included HCHs, DDTs, HCB, and dieldrin. Overall, the dominant OCPs in the sediments were mainly composed of residual and degradation products, e.g., β-HCH with a mean of 42.2 % in HCHs and p,p′-DDE with a mean of 43.5 % in DDTs, implying that OCPs in the sediments had suffered from long-term aging without fresh inputs in XR. However, there was a high proportion of p,p′-DDT to DDTs in three sites, suggesting that there was use of technical DDT from their surrounding areas at present. The ratios of α-HCH/γ-HCH and p,p′-DDD?+?p,p′-DDE/DDTs increase from the upper reaches to the lower reaches of XR, suggesting sediments enriched with α-HCH and metabolites DDD and DDE during sediment transport process and could be attributed to the transformation of γ-HCH to α-HCH and DDT to DDE or DDD. The assessment of the ecological risk indicates that the OCPs in the sediments of XR have a moderate adverse biological effect on organisms.     

Assessing spatio-temporal trend of vector breeding and dengue fever incidence in association with meteorological conditions

Th aim of this study is to investigate spatio-temporal trends of dengue vector breeding and epidemic (disease incidence) influenced by climatic factors. The spatio-temporal (low-, medium-, and high-intensity periods) evaluation of entomological and epidemiological investigations along with climatic factors like rainfall (RF), temperature (T_max), relative humidity (RH), and larval indexing was conducted to develop correlations in the area of Lahore, Pakistan. The vector abundance and disease transmission trend was geo-tagged for spatial insight. The sufficient rainfall events and optimum temperature and relative humidity supported dengue vector breeding with high larval indices for water-related containers (27–37%). Among temporal analysis, the high-intensity period exponentially projected disease incidence followed by post-rainfall impacts. The high larval incidence that was observed in early high-intensity periods effected the dengue incidence. The disease incidence had a strong association with RF (r = 0.940, α = 0.01). The vector larva occurrence (r = 0.017, α = 0.05) influenced the disease incidence. Similarly, RH (r = 0.674, α = 0.05) and average T_max (r = 0.307, α = 0.05) also induced impact on the disease incidence. In this study, the vulnerability to dengue fever highly correlates with meteorological factors during high-intensity period. It provides area-specific understanding of vector behavior, key containers, and seasonal patterns of dengue vector breeding and disease transmission which is essential for preparing an effective prevention plan against the vector.     

基于大型无脊椎动物完整性的赤水河健康评价体系构建

作为长江上游珍稀鱼类国家自然保护区的核心区,赤水河流域水系的健康状况虽颇受关注,但相关评价工作却较少。笔者结合现场调查(2016年)和历史数据(2007年),初步构建基于大型无脊椎动物群落的健康评价体系,对赤水河干流和部分支流的不同季节(春季和秋季)和不同河段(上中下游)的健康状况进行评估。指标筛选结果显示:赤水河上游河段在春季和秋季分别包括6、2个核心参数,中游河段分别包括5、4个,下游包括3、2个核心参数。通过四分法将健康状态划分为4个等级:健康、亚健康、一般和不健康。从整体上看,赤水河处于亚健康状态,且春季和秋季河流不同采样点健康状况有所差异,春季健康状况好于秋季。回归分析显示,BOD_5、COD_(Mn)以及NH~+_4-N是影响赤水河健康的主要环境因子。研究所构建的B-IBI评价指标较好地评估了赤水河的健康状况,可作为赤水河流域水体环境监测的有效手段之一。     

Air quality biomonitoring through pollen viability of Fabaceae

In this study, pollen viability and germination of three plant species, Cercis siliquastrum L., Robinia pseudoacacia L., and Spartium junceum L., belonging to the Fabaceae family, was evaluated in sites with different intensity of road traffic, constantly monitored with continuous analysers for air pollutants (carbon monoxide (CO), sulphur dioxide (SO₂), and nitrogen dioxide (NO₂)) by the Municipality of Catania. Two sites, in which road traffic was absent, were selected, too. The percentages of viable pollen by 2,3,5-trypheniltetrazolium chloride (TTC) test ranged from 59.0 to 90.2 % in C. siliquastrum, from 61.5 to 83.5 % in S. junceum and from 67.5 to 84.3 % in R. pseudoacacia. The percentages of germination varied from 41.0 to 72.7 % in C. siliquastrum, from 42.0 to 64.7 % in S. junceum and from 38.3 to 66.3 % in R. pseudoacacia. The highest percentages of viable pollens were found in no-road traffic stations by either TTC or germination tests, while the lowest values were detected in a site characterised by heavy road traffic. In the monitored period (2007–2009), pollen viability, germinability and tube length of C. siliquastrum resulted in a significant negative correlation to CO, SO₂ and NO₂, whereas data from TTC and germination tests on S. junceum and R. pseudoacacia pollens were not well correlated to air pollutants. The results showed that pollen viability, germination and tube growth in C. siliquastrum were affected by air pollution. S. junceum and R. pseudoacacia were not very influenced by air pollutants, suggesting a different pollen sensitivity of these species.     

Occurrence of perfluorinated compounds in the aquatic environment as found in science park effluent,river water,rainwater, sediments,and biotissues

The current article maps perfluoroalkyl acids (PFAAs) contamination in the largest Science Park of Taiwan. The occurrence of ten target PFAAs in the effluent of an industrial wastewater treatment plant (IWWTP), its receiving rivers, rainwater, sediment, and the muscles and livers of fish was investigated. All target PFAAs were found in effluent of IWWTP, in which perfluorooctane sulfonate (PFOS) (6,930 ng/L), perfluorohexyl sulfonate (PFHxS) (2,662 ng/L) and perfluorooctanoic acid (PFOA) (3,298 ng/L) were the major constituents. Concentrations of PFBS and PFOS in the IWWTP downstream areas have exceeded safe concentration levels of avian and aquatic life, indicating a potential risk to wildlife in those areas. In sediment samples, predominant contaminants were PFOS (1.5–78 ng/g), PFOA (0.5–5.6 ng/g), and perfluorododecanoic acid (PFDoA) (nd–5.4 ng/g). In biological tissue samples, concentrations as high as 28,933 ng/g of PFOS were detected in tilapia and catfish liver samples. A positive correlation for log (C _sediment/C _water) and log (C _tissue/C _water) was found. The concentration and proportion (percentage of all PFAAs) of PFOS found in biotissue samples from the Keya River (which receives industrial wastewater) were found to be much greater (200 times) than those of samples from the Keelung River (which receives mainly domestic wastewater). These findings suggest that the receiving aquatic environments and, in turn, the human food chain can be significantly influenced by industrial discharges.