粤北2座不同营养水平水库浮游植物功能类群的季节演替

于2011年1—12月对广东省韶关市白水礤水库和苍村水库这2座中型居民供水水库进行每月1次、为期1a的采样,利用营养状态指数(TSI)进行水质综合评价,将水库中的浮游植物按功能类群进行分类,并结合水库的水文、水质和浮游植物的生境特征,分析全年优势功能类群的演替特点及其主要的环境影响因子。结果表明,白水礤水库为贫营养型水库,苍村水库为低中营养型水库,全年共检出浮游植物7门45属(种),可划分为16个功能类群,其中,白水礤水库全年以适应低营养盐环境的功能类群占优势,耐富营养化的功能类群仅在丰水期有检出;而苍村水库全年都能监测到耐富营养环境的功能类群,且在丰水期明显占优势,但在枯水期和平水期因营养盐含量的降低,演变为以适应低营养盐环境的功能类群为主。营养盐含量的不同是导致2座水库浮游植物功能类群产生差异的根本原因,而因降水季节的变化所致水体环境因子的变化则是造成2座水库浮游植物功能类群演替不可忽视的因素。     

三座不同营养类型水库春季细菌生理群分布特征

运用实验室培养的方法,于2005年4月调查了热带亚热带过渡区的三座不同营养类型的水库:大镜山(富营养型),梅溪(贫中营养型),流溪河(贫中营养型),并对3座水库水体和底泥异养细菌及N、P细菌生理群的分布特点进行了初步分析。3座水库水体和底泥细菌生理群的分布差异明显,这些差异主要取决于水库水体和底泥的营养状况。大镜山水库和流溪河水库底泥中有机营养物质丰富,2座水库底泥中主要细菌生理群的分布相似。流溪河水库与梅溪水库为贫中营养型水库,两座水库水体中主要细菌生理群的密度分布相近。在流溪河水库和大镜山水库中不同采样点之间细菌生理群的分布存在一定的空间差异,梅溪水库大坝和出水口之间差异不显著,这种差异取决与水库的水动力学特征。3座水库水体硝酸还原菌与TP(R2=0.6668,P<0.05)和Chl.a(R2=0.6734,P<0.05)以及有机磷分解菌与TP(R2=0.5977,P<0.05)和Chl.a(R2=0.5968,P<0.05)之间存在着显著的相关关系。     

Estimation of algal growth parameters from vertical primary production profiles

Phytoplankton maximum growth rate and the saturation light intensity, I_s, can be estimated from vertical profiles of primary production by non-linear least-squares estimation. Solution through the normal equations leads to formulae which are relatively simple and easy to implement. The computation of confidence contours is demonstrated, and the results are contrasted to the confidence limits on the parameters individually. These can be quite misleading due to model non-linearity and correlation between parameter estimation.The procedure has been applied to primary production data from Lake Balaton, a shallow lake in Hungary. The growth rate-temperature relation is analysed by separating the parameters into two groups characteristic for “warm” and “cold” water phytoplankton, respectively. A bell-shaped curve is found for “cold” water communities, with an optimum at about 7–9°C, whereas the “warm” water phytoplankton exhibits a strong exponential dependency in the temperature range of interest (up to 25°C). I_s also appears to be related to temperature except for the “cold” water group, where I_s is essentially constant. However, a roughly linear relation with considerably less scatter is obtained when I_s is plotted directly versus day-averaged solar radiation. This apparent fast adaptation is attributed to the extremely short turnover time in Lake Balaton. Maximum growth rates of 10–20 d^?1 have been found for temperatures between 20 and 25°C. These results and a critical appraisal of available literature suggest that the common notion of maximum growth rates being in the order of 1–3 d^?1 needs revision, at least for lakes with relatively high summer temperatures.     

三峡库区生态系统服务功能重要性评价及其空间分布研究

以长江上游重点生态脆弱区三峡库区(重庆段)为研究区,结合RS和GIS软件,选取生物多样性维护功能、水源涵养功能和水土保持功能为评价指标,采用植被净初级生产力(vegetation net primary productivity,NPP)定量指标评估法,综合分析研究区2020年生态系统服务功能的重要性程度以及空间分异特...     

粤西三座重要供水水库沉积物营养盐负荷与重金属污染特征

为揭示粤西3座供水水库（高州水库、鹤地水库、大水桥水库）沉积物营养盐负荷及重金属污染特征,于2008年6月在各水库大坝前湖泊区采集柱状沉积物,运用SMT法、碱性过硫酸钾消解法、烧失法和ICP-MS法分别测定其柱状沉积物中氮磷营养盐、有机质和7种重金属（Cu、Pb、Zn、Cd、Ni、Cr与Hg）的含量,并采用潜在生态风险指数法对表层重金属污染的潜在生态风险进行评价,同时通过相关性分析重金属的可能来源。结果表明：3座水库沉积物总氮质量分数为1.13~3.37 mg·g-1,有机质为11.83~20.37 mg·g-1,其表层总氮、有机质的质量分数大小顺序为高州水库〉大水桥水库〉鹤地水库,总磷的质量浓度在0.22~0.77 mg·g-1之间,其表层总磷质量分数大小顺序为高州水库〉鹤地水库〉大水桥水库,在垂直剖面上,总氮、总磷与有机质的质量分数在16 cm至表层沉积物垂直断面显著高于其他断面,表明近些年来水库内源营养盐负荷逐渐加重。重金属质量分数平均值均高于广东省土壤环境背景值,总体呈现随深度增加而降低的趋势,但3座水库间重金属质量分数差异较大,其中鹤地和高州水库的Zn和Pb污染相对严重（质量分数分别为Zn：353.15、693.35 mg·kg-1;Pb：74.51、127.91 mg·kg-1）,大水桥水库的Cr和Ni污染相对严重（质量分数分别为Cr：238.69 mg·kg-1;Ni：251.06 mg·kg-1）。潜在生态风险评价表明,3座水库Cd和Hg具有高的生态危害,应引起重视,其他重金属则处于轻微的生态危害等级。同时沉积物高有机质的质量浓度经矿化分解可能加剧水体重金属生态危害。根据相关性分析和其他相关资料可知,粤西农业区大量化肥农药面源污染汇入造成水库初级生产力提高并最终沉降可能是沉积物营养盐、有机质与重金属的主要来源。     

Pretreatment for dissolved organic nitrogen testing by gas stripping

ABSTRACT

Total dissolved nitrogen (TDN), including dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON), is of significant importance in aquatic systems due to its roles in numerous environmental processes, such as nutrients for agriculture activities, sources for lake and estuary eutrophication, and one of the major factors contributing to disinfection byproduct formation. The distribution and impact of DIN on these processes are relatively well-understood; however, information on DON is extremely limited, as there is no direct method for its quantification. DON is conventionally determined by subtracting DIN from TDN. However, significant errors may be introduced if DIN is the predominant species in samples with high concentrations of TDN. In order to deal with this challenge, pretreatment method for nitrogen gas stripping was investigated using 56 water samples collected from various ecosystems. The results indicated that after nitrogen gas stripping pretreatment, removal % of ammonia nitrogen (NH₃–N) was more than 87.5%, and the ratios of removal of NH₃–N/removal of TDN (β) were over 86.5% for most of 56 samples with high [NH₃–N], indicating a high efficiency for removal of NH₃–N, and that NH₃–N was the predominant nitrogen species removed for the samples with high [NH₃–N]. Therefore, nitrogen gas stripping is an appropriate pretreatment method for DON testing when NH₃–N is the dominant inorganic nitrogen species.     

A simulation model of carbon and oxygen dynamics in a reservoir

The CORES model represents the long-term carbon and oxygen dynamics of the Conowingo Reservoir. The model, formulated using subsetted historical data, is readily validated using the remaining historical data for all state variables of importance. Sensitivity analyses make it clear that the flux of particulate organic carbon from upstream sources and its subsequent “trapping” and metabolism in the deeper regions of the reservoir are the major factors controlling the oxygen declines historically observed in the summer months. Increased natural vertical mixing (i.e., transport of oxygen from shallow to deep waters) can increase deep-water oxygen concentrations to some extent, but not to the degree necessary to meet water quality standards. Air-to-water diffusion adds substantial quantities of oxygen to surface waters in these mixing events. Simple solutions, such as requiring continuous flow, do not appear to adequately increase the dissolved oxygen levels in the deeper portion of the reservoir.     

城市生态气象监测评估初步研究与实践——以北京为例

气象条件作为影响生态系统最活跃、最直接的驱动因子,影响着生态系统的质量和人类生存的环境,关系着生态保护和建设的成果,而城市生态系统具有与其他系统不一样的气候特征,目前还未形成一套有关城市的生态气象监测评估方法。基于生态气象学理论,分别从城市气候环境、与气候相关的陆表环境、大气环境、人居环境以及城市高影响天气气候事件等5个方面选择不同的要素和指标开展了城市生态气象监测评估初步研究,并以北京为例,利用2018年国家和区域自动气象站资料、大气成分观测资料、2002—2018年MODIS卫星资料、Landsat及环境一号卫星资料,开展了2018年北京城市生态气象监测评估。监测评估显示,(1)2018年北京城市“热岛”和“干岛”气候特征明显,并在北京二环与五环之间存在一个“冂”形风速低值区。(2)2018年北京陆表生态环境、大气环境、人居环境进一步好转:其中植被覆盖度达61.6%,创2002年以来新高,气象条件贡献率达50%,生态涵养区植被生态质量处于正常偏好的面积比例达93.2%;中心城区陆表温度为2011年以来最低值;重要水源地密云水库、官厅水库水体面积均为2000年以来最大值;气溶胶光学厚度、霾日数、大气静稳指数分别较过去4年平均值下降14%、31%和8%,大气扩散条件偏好,对霾日减少贡献率达21%,外地污染传输对PM2.5贡献达到53%;城市生态冷源较2013年明显增加,城市“热岛”得到缓解。(3)历史罕见的夏季高温闷热、冬季阶段低温、极端强降水以及持续无降水等高影响天气气候事件给城市安全运行和生态环境带来不利影响。综合评估表明2018年北京气象条件总体利于陆表生态环境改善,有利的气候条件提高了生态环境的质量,但城市生态质量仍面临着极端天气气候事件、城市热岛、低风速以及外来大气污染输送等风险。     

Trace analysis of off-flavor/odor compounds in water using liquid-liquid microextraction coupled with gas chromatography—positive chemical ionization-tandem mass spectrometry

A rapid, inexpensive and laboratory friendly method was developed for analysis of off-flavor/odor compounds in fresh and salt water using gas chromatography with chemical ionization-tandem mass spectrometry. Off-flavor/odor compounds included geosmin, 2- methylisoborneol (MIB), 2-isobutyl-3-methyoxypyrazine (IBMP), and 2-isopropyl-3-methoxypyrazine (IPMP). Using this method, a single sample can be extracted within minutes using only 1 mL of organic solvent. The ion transitions for IPMP, IBMP, MIB, and geosmin were 153>121, 167>125, 152>95, and 165>109, respectively. The linearity of this method for analyzing MIB ranged from 4 to 200 ng·L^–1, and from 0.8 to 200 ng·L^–1 for the other analytes. Method recoveries ranged from 97% to 111% and percent relative standard deviations ranged from 3% to 9%, indicating that the method is accurate, precise, and reliable.     

Preliminary toxicity evaluation of water from rice fields using cost‐effective microbiotests

A study was performed in a Protected Area (Natural Reserve of Sado Estuary) in 1996, to evaluate the acute toxicity for aquatic life of surface water from rice fields treated with pesticides, particularly with molinate and quinclorac. As a preliminary assessment, the following rapid toxicity tests were used: “Rotoxkit F”;, “Thamnotoxkit F”; and the recently introduced “Daphtoxkit F magna”; and “Algaltoxkit F”;. Water samples were collected from: a water source for irrigating the rice fields, two rice plots, a drainage channel and from Sado river in which the water is discharged. The results showed that samples from the rice plot treated with molinate were more toxic than those obtained from rice plot treated with quinclorac. Water samples from the river were the most toxic, causing 100% of immobility in all organisms and a substantial inhibition in the algal growth. Water collected from the drainage channel in late July, was also found to be quite toxic. The results obtained until now indicate that some characteristics of these microbiotests, like their rapidity, simplicity and relatively low cost, make them a practical tool to evaluate acute effects of pesticides in freshwater ecosystems. They may also contribute to suggest some changes in pesticides use to promote agricultural practices with lower impact to aquatic life.     

Dynamic simulation of water depletion in the root zone

The joint effect of the distribution of the soil water potential and of the root mass in the crop root zone upon the water uptake by the crop is represented by a simple equation. This expression is used to join a layered crop canopy model for finding the evapotranspiration, as controlled by stomatal action and the weather, with a hydraulic flow model for the root zone and the underlying soil. The complete model is used for the calculation of the water extraction pattern and the changes, with time, of other plant and soil processes. A simulation of a 20-day drying period is performed, using S/360 CSMP, for a constant diurnal weather pattern, and for a fully developed sorghum crop. The results show that, after a few days of essentially constant water use by the crop, a monotonic decline sets in, that is principally attributable to the decrease in transpiration. For the entire drying period a substantial amount of water - about 30% of the total used - is contributed by upward flow into the root zone from the soil below. The results demonstrate the difficulty of quantitative definition of concepts such as “field capacity”, “wilting percentage”, and “available” or “extractable” water.     

Experimental investigations on the stability of riprap layers on overtoppable earthdams

In Germany small dams (<10 m) on flood retention reservoirs are often provided with an overtoppable dam section for flood relief. In case of overtopping a protection of the dam body is absolutely mandatory as the mainly cohesive dam material is not capable to withstand the affecting erosive forces of the flow. There is a big number of possibilities how to protect the dam whilst overtopping. Some of the most common construction types of slope protection layers for a sufficient dam protection such as riprap and placed stones, have been tested in large scale physical models at the Hydraulic Laboratory at Universität Stuttgart. Thereby different experiments for the failure scenarios “erosion of single stones”, “sliding of the protection layer” as well as “disruption of the protection layer” have been conducted and analysed aiming to find some design criteria for the construction of such dams.     

零价铁原位控制底泥磷释放及联合磁性分离除磷技术

水体富营养化是常见的世界性水体生态系统障碍问题之一,给人类生产、生活造成了广泛而严重的影响,同时也是造成世界各地结构性缺水的重要原因之一。底泥磷释放是水体富营养化的重要原因,但目前常用的控磷技术往往成本较高,内源磷再释放风险仍然较大。该研究按铁-泥质量比1.00%、3.33%、5.00%、10.00%,分别向富磷底泥投加的铁粉来模拟零价铁控磷过程,通过分析3、7、14、21、28、35d内底泥磷形态的变化趋势,研究零价铁控磷过程及磁性分离除磷技术的应用前景。结果表明:底泥中水溶性磷、弱结合态磷是水体磷元素的主要来源,零价铁对底泥中高生物活性的弱吸附态磷(NH4Cl-P)去除率最高可达75%,对水溶性磷的去除率可达90%以上,向富磷底泥投加零价铁能够原位富集、降低内源磷生物有效性,阻断底泥向水体释磷的过程;零价铁原位控制底泥磷释放主要依赖于零价铁氧化形成的铁离子和铁氧化物与磷酸根的沉淀和共沉淀过程,加入零价铁后水溶性磷和弱结合态磷主要向铁结合态(Fe-P)转化,联合外加磁场后大部分可随铁粉拔出,最终达到安全高效地去除水体和底泥表层中高生物有效性磷的目的。该方法可以有效解决挖掘清淤、疏浚等控磷方法高成本、易反复的问题,为高效原位治理水体富营养化,保障湖泊、水库生态环境安全提供有价值的技术方法。     

粤北三座典型中型水库富营养化与浮游植物群落特征

于2010年丰水期（8月）和枯水期（12月）采集粤北地区3座中型水库（沐溪、苍村和赤石迳水库）的水和浮游植物,分析植物群落与水质,以考察季节性温度差异与鱼类养殖对水库水质和浮游植物群落结构的影响。结果表明,3座水库分别属富营养、中营养和中营养水平,营养盐质量浓度丰水期高于枯水期。共鉴定浮游植物7门56种（属）,群落组成以蓝藻、绿藻和硅藻为主。沐溪水库丰枯两季均以蓝藻为优势类群,其浮游植物丰度和生物量明显高于其余两座水库（p〈0.01）;苍村和赤石迳水库丰水期优势门类均为蓝藻,枯水期均为硅藻。3座水库浮游植物丰度均表现为丰水期高于枯水期,生物量则枯水期高于丰水期,但均无显著性差异（p〉0.05）。RDA（冗余分析）结果表明,透明度、总氮和悬浮物是影响浮游植物群落结构的主要因素;其中,沐溪水库的营养盐和悬浮物与浮游植物群落正相关,苍村和赤石迳水库浮游植物群落则与水深和透明度正相关;温度对浮游植物群落的影响主要体现在种类组成的季节差异上。营养盐和优势种类的季节差异造成了浮游植物丰度和生物量在丰水期和枯水期的不一致。聚类分析将不同季节的3座水库分为2个类区,非养鱼水库苍村和赤石迳水库为第一类区,养鱼的沐溪水库为第二类区。沐溪水库库区内发展鱼类养殖业为浮游植物提供了高质量浓度营养盐（尤其是总磷）,即使在温度较低的冬季仍支持蓝藻种类的优势性。     

Ontogenetic switch between alternative antipredatory strategies in the leopard gecko (Eublepharis macularius): defensive threat versus escape

Ontogenetic changes in antipredator behavior optimize survival of growing animals. Leopard geckos (Eublepharis macularius) respond to a simulated predator either by postural and vocal threats, sometimes followed by biting, or alternatively by a rapid escape. The former “confrontational” and the latter “avoidance” behavior rarely occurs in a sequence; in fact, they represent mutually exclusive defensive strategies. We examined 552 individuals of a leopard gecko (E. macularius) of various ages, from hatching up to adulthood (31 months). Each experimental animal was exposed to a sequence of five “water-spraying” and ten “stick” (stick poking on base of the tail) stimuli, and the emitted behavior was recorded. We analyzed the effects of age, body size, body condition, adult–juvenile coloration, and sex on observed behavioral traits. The results showed that in the case of water-spraying stimulus, the usage of deterrent vocalization or escape tactic was affected by age and condition. In addition to that, using deterrent vocalization was influenced by the coloration of the animal. Stick stimulus evokes antipredator strategies that correspond with age and coloration (deterrent vocalization) and also with standardized body size (escape). Thus, leopard geckos exhibit clear ontogenetic change of defensive strategies, from threat–vocalization–bite strategy prevailing in juveniles to an escape strategy typical for adults. This behavioral change is accompanied by the ontogenetic switch of coloration from presumably warning contrasting light–dark banded pattern of juveniles to a cryptic spotted coloration of the adults.     

The “pelagic larvaton” and its role in the biology of the World Ocean,with special reference to pelagic larvae of marine bottom invertebrates

Ecological subdivision of marine organisms is often based on two characteristics: presence in a defined environment, and types of locomotion (degree of free active movement) in such an environment. The use of these characteristics results in a simple scheme: (1) Inhabitants of the boundary surface “ocean-atmosphere” (a zone including not only the surface film but also the thin subsurface water layer below it and the air layer just above it, i.e., pleuston and neuston). (2) Inhabitants of the deeper water layers of the ocean i.e., excluding the zone mentioned under (1): (a) passively drifting forms with very limited locomotory capacity, moving practically in the vertical plane only (plankton); (b) actively moving forms which migrate both vertically and horizontally (nekton). (3) Inhabitants of the “bottom”-benthos (level-bottom of oceans and coastal waters, tidal zones up to the upper supralittoral, different types of drifting and floating substrata, e.g. ship bottoms, harbour structures, buoys, driftwood, sargassum, whales, etc.). This simple scheme is essentially based on characteristics of adults. If developmental stages are considered, pelagic larvae of bottom invertebrates, eggs and larvae of fishes and other forms, usually present only temporarily in the plankton, neuston, and pleuston, can be distinguished as “mero-plankton”, “mero-neuston” and “mero-pleuston”, from the permanent “holo”-components of these groups. Division into “mero”-subgroups opposes all these larvae to those of planktonic, neustonic and pleustonic forms developing within the “parental” groups and their environments. However, the last category of larvae in the light of world-wide distribution of the seasonal reproductive pattern of marine invertebrates and some other organisms — especially in temperate and high latitudes — can also be rated to some degree as “mero”-(not “holo”-) components. The present paper proposes to unite all larvae of marine invertebrates (and of other organisms) undergoing pelagic development into one biological group, the “pelagic larvaton”. The main characteristic for all forms of this group is the presence of one and the same life-cycle stage in one and the same environment. All forms of the “pelagic larvaton” are, to various degrees, biologically different from their respective adult forms. Even the pelagic larvae of the holoplanktonic species exhibit some differences. Within the “pelagic larvaton”, 3 subgroups can be distinguished on the basis of their ecological peculiarities;

1. Larvae undergoing their whole development in an environment different from that inhabited by their parents and belonging to a group different from that of their parental forms; e.g. the pelagic larvae of bottom invertebrates which develop in the plankton, neuston or pleuston.
2. Larvae undergoing development in the same general pelagic environment, but in “non-parental” ecological groups; e.g. larvae of nektonic species developing in the plankton, neuston or pleuston; larvae of planktonic species in the neuston or pleuston; larvae of neustonic and pleustonic species in the plankton.
3. Larvae undergoing development in the “parental” groups; e.g. larvae of planktonic species in the plankton, of neustonic species in the neuston, or of pleustonic species in the pleuston.

In contrast to the 5 ecological groups: benthos, plankton, nekton, neuston and pleuston, the “pelagic larvaton” represents rather a biological than an ecological group. The “pelagic larvaton” comprises the 5 ecological groups and maintains the permanent turnover of organic substances between water and bottom. This group short-circuits the interrelations between the 5 ecological groups in all possible combinations. The existence of the “pelagic larvaton” presents another illustration of the unity of the biological nature of the oceans. The present paper also discusses the specific distributional patterns of the pelagic larvae of bottom invertebrates and their biological role in the seas.     

Critical ranges of pollution indices: a tool for predicting soil metal pollution under long-term wastewater reuse

A greenhouse experiment was conducted in pots, for two years (2015–2016), in Amaliada, Greece, using a randomized block design, including six treatments with mixtures composed of Zn, Mn, Cd, Co, Cu, Cr, Ni, and Pb, each metal taking part in the mixture at concentrations of 0, 10, 20, 30 40, and 50 mg/kg soil in four replicates each. Beta vulgaris (beet) was used as a test plant. The aim of the experiment was to calibrate the following pollution indices: “pollution load index,” “elemental pollution index,” “heavy metal load,” and “total concentration factor,” in order to determine the level of soil pollution under variable levels (low to very high) of metal mixtures. The irrigation of the plants was conducted with treated municipal wastewater based on field capacity and percent wilting point. The above pollution indices were classified into four soil pollution classes, i.e., “optimum,” “low,” “high” and “very high” on the basis of percent dry matter plant losses.     

两座高原水库蓝藻群落结构与微囊藻毒素的分布对比研究

为了了解贵州高原水库蓝藻群落组成特征和微囊藻毒素分布,于2009年10月对贵州高原2座水库——万峰湖和百花湖采样调查。结果表明：万峰湖以蓝藻为主要优势藻,蓝藻中的拟柱孢藻（Cylindrospermopsis sp.）占绝对优势,浮游植物丰度在13.05×104～55.80×104 cells.L-1之间,蓝藻的丰度值占到了总量的82.55%,6个采样点中有3个（大坝、野鸭滩和革布）检出了微囊藻毒素MC-RR,且有1个点（革布）质量浓度超标,另外3个点（坝艾、坝达章和九里堡）未检出;百花湖以蓝藻、绿藻和硅藻共同构成优势藻,蓝藻中的假鱼腥藻（Pseudanabaena limnetica）是主要优势藻,浮游植物丰度在6.16×104～65.00×104 cells.L-1之间,蓝藻的丰度值在总体中所占比例为33.25%,3个采样点（大坝、岩脚寨和码头）均未检出微囊藻毒素。形成2个高原水库蓝藻群落结构和微囊藻毒素分布差异的原因可能是：2个水库中氮、磷营养盐水平不同引起浮游植物群落组成不同,进而导致了微囊藻毒素的分布出现差异。     

基于BP神经网络算法的密云水库水质参数反演研究

密云水库是北京市重要的地表饮用水源地,在保障首都水源安全方面起着重要作用,而密云水库水质参数的区域监测已成为当前亟待解决的问题。为了实现密云水库水质参数大范围、实时获取,该文基于遥感和GIS技术,采用BP神经网络算法,结合地面监测数据和Landsat 8遥感影像,分别建立了反演总磷、总氮、氨氮和COD(化学需氧量)4个水质参数的BP神经网络模型,并反演了密云水库2013-2018年非结冰期主要水质参数,分析了密云水库主要水质参数的年际变化特征、季节变化特征和空间分异特征。结果表明,(1)水质参数的Landsat 8敏感波段分别为:总氮为1、4波段,氨氮为1-7波段,总磷为1、3-7波段,COD为2-5波段。(2)密云水库主要水质参数在2013-2018年总体呈下降趋势,氨氮和COD为Ⅰ类水质,总磷为Ⅱ类水质,总氮为Ⅲ类水质。(3)4个水质参数指标春季最高、秋季次之、夏季最低,总氮、总磷、氨氮和COD的春季值分别是夏季值的1.08、1.36、1.6、1.45倍。(4)密云水库不同水质参数的空间差异性较大,总体来看,水库北部和东部的4个水质参数含量相对较高,这种分布与北部和东部村庄密集以及密云水库两大入库河流有关。综上所述,基于BP神经网络算法的密云水库水质反演研究是可行的,且得到了较为可信的研究结果,该研究可为密云水库水质管理与政策制定提供重要的科学依据。     

Direct determination of dichlorvos in water by partial least square-discriminant analysis

This report describes a rapid, onsite method to analyze the dichlorvos pesticide in water. Dichlorvos is a broad-spectrum pesticide that has been used worldwide. As an organophosphorus pesticide, dichlorvos disrupts the nervous system by inhibiting the activity of acetyl cholinesterase. Traditional analysis of dichlorvos by chromatography is time-consuming and environmentally unfriendly. Therefore, rapid, on-site methods to analyze dichlorvos are needed. Here, we used for the first time Fourier transform near infrared spectroscopy combined with partial least square-discriminant analysis to determine the dichlorvos directly in water samples. Results were compared with traditional high-performance liquid chromatography data as reference. We found that over 9,000–8,333?cm^?1, the new method had a good performance with a classification accuracy of 100?% and a correlation coefficient of 0.92 between measured and reference data. The new method can also be used as a “concentration sieve” by setting up different levels of boundary, a parameter of partial least square-discriminant analysis, thus allowing rapid on-site screening.