退耕还林地桦木林生态系统碳素密度、贮量与空间分布

对退耕还林5年生的桦木林生物量、碳素密度、碳贮量及其空间分布进行测定。结果表明,桦木各器官的碳素密度在0.4519~0.5137gC.g-1,排列顺序为枝>干>叶>根颈>粗根>中根>细根;死地被物层的碳素含量为0.3953gC.g-1,土壤平均碳素密度为0.0150gC.g-1,随土层深度的增加,各层次土壤碳素密度呈逐渐减少的趋势;桦木林生态系统总的碳贮量为127.9298tC.hm-2,其中乔木层为21.9282tC.hm-2,占整个生态系统的17.14%,死地被物为0.3401tC.hm-2,占0.27%,林地土壤(0~60cm)为105.6615tC.hm-2,占82.59%;桦木各器官的碳贮量与其生物量成正比例的关系,树干的生物量最大,其碳贮量也最大,占乔木层碳贮量的57.33%;5年生桦木林年净生产力为8.9912t.hm-2.a-1,有机碳年固定量为4.4537tC.hm-2.a-1。较之退耕前,桦木林生态系统碳贮量增加15.4797t.hm-2。     

观光木人工林生态系统碳储量及其分布格局

在生物量调查的基础上,对南亚热带27年生观光木(Tsoongiodendron odorum)人工林生态系统的碳储量及分配格局进行了研究.结果表明:观光木人工林生态系统植被层生物量为101.26 t · hm-2,乔木层生物量占86.90％;观光木的各器官碳素含量在426.5～496.9 g·kg-1,大小排序为:树干＞枝条＞枯枝＞根兜＞粗根＞树叶＞中根＞树皮＞细根.观光木人工林生态系统总碳储量为180.49 t·hm-2,其中0～80 cm土壤层碳储量是植被层的2.67倍;乔木层年净固碳量为3.07 t·hm-2·a-1,并主要以地上部分为主.     

山西油松人工林生态系统生物量、碳积累及其分布

油松是我国北方主要的造林树种之一,准确估计油松人工林生态系统的生物量及碳储存对研究区域人工林的碳储功能具有重要意义。本研究采用固定样地方法对38年生油松人工林的生物量、碳贮量及其空间分布进行测定,并估算了其净生产力与年净碳固定量。结果表明:(1)油松单木生物量与胸径和树高之间均存在着紧密的相关关系。林分平均生物量为145.35t.hm-2,其中乔木层为123.98t.hm-2,占林分生物量的85.30%。(2)油松人工林生态系统各组分碳含量为:树干0.5032gC.g-1,树皮0.4887gC.g-1,树枝0.5414gC.g-1,树叶0.4774gC.g-1,树根0.4862gC.g-1;灌木层0.4468gC.g-1;草本层0.4417gC.g-1;枯落物层0.4112gC.g-1;土壤层(0～100cm)0.0090gC.g-1,随土层深度增加各层次土壤碳含量逐渐减少。(3)油松人工林生态系统总碳贮量为172.95t.hm-2,各层碳贮量的大小顺序为土壤(0～100cm)(102.07t.hm-2)>乔木层(62.08t.hm-2)>枯落物层(7.75t.hm-2)>灌木层(0.58t.hm-2)>草本层(0.47t.hm-2)。油松各器官的碳贮量与其生物量呈正比,树干的生物量最大,其碳贮量也最大,占乔木层碳贮量的58.80%。(4)油松人工林年净生产力为10.19t.hm-2.a-1,有机碳年固定量为5.03tC.hm-2.a-1。     

施肥对西双版纳橡胶林土壤CO_2排放的影响

对土地的人工管理影响到土壤CO2的排放。西双版纳是中国橡胶主要种植区,施肥是橡胶林获取更好效益的主要管理措施之一。为探讨施肥对橡胶林土壤CO2排放的影响,选取西双版纳大面积种植的橡胶林,采用静态箱-气相色谱法开展了不同施肥处理试验。结果表明:(1)施肥处理没有改变西双版纳橡胶林土壤CO2排放的时间变化特征;(2)不同施肥处理和对照的西双版纳橡胶林土壤CO2排放均呈现出雨季大于干季的趋势,年排放总量在7.88~7.93 t C·hm-2·a-1;(3)不同施肥处理的土壤CO2月排放量大于对照;(4)施肥处理在一定程度上可促进土壤呼吸,使土壤CO2排放增加,但差异不显著(P0.05)。本研究结果为进一步揭示西双版纳橡胶林生态系统碳循环过程及其机理提供支持,为把握橡胶林碳平衡动态和应对全球变化提供参考,也可为橡胶林的可持续利用提供科学依据。     

城市郊区小尺度森林生态系统服务功能评估

该研究以沙塘林场为例,筛选出沙塘林场森林生态系统服务功能评估指标体系,包括7项功能13个指标,并制定具体评价方法。利用广西柳州市沙塘林场2009年森林资源二类调查数据、连续观测数据和社会公共数据,采用?森林生态系统服务功能评估规范?( LY/T1721-2008),评估柳州市郊区小尺度森林生态系统服务功能的总物质量及其价值量。结果表明：沙塘林场每年每公顷涵养水源量为5051.04 m3,固土29.30 t,林分年保肥量1.09 t,固碳5.27 t,释氧11.49 t。沙塘林场森林生态系统服务功能的总价值为78077001元.a-1,每公顷提供的生态服务价值为79630元. hm-2. a-1,沙塘林场各功能项价值量从大到小顺序为涵养水源(52.02％)>固碳释氧(22.36％)>生物多样性保护(12.61％)>净化大气环境(5.06％)>保育土壤(3.84％)>森林游憩(3.09％)>积累营养物质(1.03％)。不同林分类型单位面积生态系统服务功能价值由大到小的顺序为桉类(104673.43元.hm-2.a-1)>其他阔叶林(95538.66元.hm-2.a-1)>经济林(69537.58元.hm-2.a-1)>松类(69433.52元.hm-2.a-1)>杉木类(58820.11元.hm-2.a-1)。沙塘林场单位面积涵养水源量(5051.04 m3.hm-2.a-1)大于广西区单位面积涵养水源量(3368.32m3.hm-2.a-1);沙塘林场的固碳量(5.27 t.hm-2. a-1)大于广西森林的平均固碳量(3.52 t.hm-2.a-1),森林游憩的单位面积价值量也大于广西全区的平均价值量。这说明城市郊区小尺度森林在涵养水源、固碳释氧、森林游憩等方面的生态功能价值在当地生态系统服务功能中起到关键作用。该研究结果可为城市郊区小尺度森林生态功能的评估提供理论参考,为柳州市生态文明建设提供科学依据。     

西藏高原云南松生物量模型及碳储量

云南松林是西藏高原亮针叶林生态系统的重要组成部分,准确估算其生态系统碳储量不但有助于弄清西藏森林生态系统固碳现状,而且可为准确估算青藏高原乃至全国森林生态系统的固碳潜力和固碳速率提供基础数据.本研究以云南松为研究对象,采用实地调查与建模相结合的方法,建立了各器官(叶、枝、干、根)与株高、胸径的生物量回归方程,并以此为基础计算了云南松幼龄林、中龄林、近熟林和成熟林生态系统的生物量和碳储量.结果表明:(1)用胸径和树高估测单株林木器官生物量的较优模型为指数模型,所建立的生物量回归方程相关性较好(R2＞0.90),估计精度较高.(2)在云南松幼龄林、中龄林、近熟林和成熟林生态系统中植被总生物量分别为(63.80±9.21)、(134.76+12.69)、(142.91±13.02)、(316.72+42.57)t·hm-2,其中乔木层生物量分别为(49.48±10.32)、(120.57±9.37)、(124.70±12.92)、(304.76±32.47)t·hm-2,灌草层生物量为(13.09±3.02)、(12.81±2.54)、(11.88±3.12)、(3.47±0.98)t·hm-2,凋落物生物量为(1.23±0.24)、(1.38±0.31)、(0.72±0.11)、(1.13±0.39)t·hm-2.(3)各龄级云南松林生态系统植被碳储量分别为(30.67±7.13)、(67.63±19.06)、(71.00±4.15)、(159.32±39.95)t·hm-2,碳储量随林龄增加的变化规律明显,碳汇潜力巨大.     

热带季节雨林与人工橡胶林土壤碳氮比较

选取我国西南部西双版纳地区的热带季节雨林和人工橡胶林为对象,比较了2006—2007年两种土地利用方式下凋落物输入、土壤总碳氮含量及活性碳、氮的季节性变化.结果表明:与热带季节雨林相比,橡胶林的地上年凋落物量较低,而地面凋落物残留量较高,反映了橡胶林凋落物分解速率(凋落物消失率常数值,K )较低;橡胶林凋落物和土壤的C/N比值较高,暗示了其林内有机物的可降解性较热带季节雨林弱;橡胶林表层土壤总有机碳、生物活性有机碳和微生物生物量碳含量只有热带季节雨林土壤的60%～70%,硝态氮含量较少,pH 值则比热带季节雨林土壤低1.1.说明热带季节雨林转变为橡胶林后,林内地上凋落物向土壤输入的碳、氮量减少,土壤碳、氮含量和有效性降低,并且土壤呈现酸化倾向.应制定合理的橡胶林土壤管理措施,阻止土壤质量的下降趋势,以维持橡胶林的生产可持续性.     

土地利用方式对西双版纳热带森林土壤微生物生物量碳的影响

2006年1月至2007年9月,通过去除凋落物和切根控制试验,研究了热带森林不同土地利用方式(次生林/橡胶林)对西双版纳热带森林土壤微生物生物量碳的影响.结果表明:次生林转变为橡胶林后,土壤养分及植物碳输入均明显减少,土壤微生物生物量碳显著降低;两种林型雨季土壤微生物生物量碳均高于干季,其中次生林土壤微生物生物量碳与土壤温度呈显著正相关,而橡胶林则与土壤湿度呈正相关关系;次生林土壤微生物生物量碳受植物根系养分输入的调控,地上凋落物数量的影响较小,土壤微生物生物量碳与细根生物量及其C、N输入量呈显著正相关;橡胶林细根生物量及其C、N输入量,以及地上凋落物均未显著影响土壤微生物生物量碳.橡胶种植导致土壤养分含量和土壤pH值降低,加上严重的人为干扰,土壤微生物生物量碳减少,且其调控因素发生显著变化,最终可能影响土壤的其他生态过程.     

岷江上游亚高山林区老龄林地上生物量动态变化

中国川西亚高山森林中的天然林大部分为成过熟的老龄林,对其生物量动态研究有助于了解其碳储量的动态变化规律.利用全国森林资源连续清查的27个固定样地数据,基于地上各器官生物量与树干胸径(D)和树高(h)的异速生长方程,估算了岷江上游亚高林山老龄林地上生物量密度的动态变化特征及其时空变化规律.结果表明,(1)从1988～2002年期间,老龄林地上生物量密度净增量为(27.311±15.580)Mg·hm-2,平均每年增长率为(1.930±1.091 )Mg·hm-2·a-1,平均每年枯损率为(2 271±1.424)Mg·hm-2·a-1;(2)地上生物量变化受各径级保留木生长量、枯损量及进界生长量影响,其中20～40cm径级保留木生长量与生物量净增量最大,>80cm径级生物量增量最小,40～60cm和60～80cm径级生物量在调查期间净增量出现负增长.(3)岷江上游老龄林地上生物量动态变化具有时空异质性,同一样地在不同调查间隔期或同一调查期间不同样地间生物量变化不同,不仅有增量数值大小差异,还表现为生物量增量的正负差异.     

红壤侵蚀地马尾松林恢复后土壤有机碳库动态

运用RothC(version 26.3)模型,并结合“时空代换法”对长汀河田红壤侵蚀退化地马尾松人工恢复后林地表层(0-20cm)土壤有机碳库的动态变化进行了反演和预测,研究结果表明:RothC 26.3模型的模拟结果能够较好地反映红壤侵蚀地植被恢复过程中土壤有机碳的变化趋势;RothC 26.3模型适用于中亚热带季风气候条件下马尾松林地土壤碳库的动态模拟;侵蚀退化地在马尾松林建植后,林地表层土壤碳吸存速率以非线性的形式上升,并在15-25a时间内达到最大,马尾松恢复后前30a林地土壤平均碳吸存速率约为0.385 tC·hm-2· a-1,自马尾松建植后演替至当地顶级群落(次生林)全过程中平均碳吸存速率约0.156 tC·hm-2·a-1;根据模拟结果得到的拟合方程,计算得到研究区红壤侵蚀退化地的碳饱和容量约为36.85 tC/hm2,固碳潜力约为33.26 tC/hm2.     

Distribution of N,P, K,Ca, Mg,S, Zn,Fe, Mn and Cu in groundnut

Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.     

Simultaneous measurement of the trace elements Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum and their reference ranges by ICP-MS

The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.     

Reference values for the concentrations of As,Cd, Co,Cr, Cu,Fe, I,Hg, Mn,Mo, Ni,Pb, Se,and Zn in selected human tissues and body fluids

This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues and body fluids. A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America, Australia, and New Zealand. This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world. It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different countries reflected some interesting associations for elements, such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as Cu, Fe, and Zn were not available. In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions, which sadly lack data of any kind at present.     

Crystal structure, detonation performance, and thermal stability of a new polynitro cage compound: 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptacyclo [5.5.1.13, 11. 15, 9] pentadecane

A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability.     

Monovalent Cation Permeation through the Connexin40 Gap Junction Channel : Cs,Rb, K,Na, Li,TEA, TMA,TBA, and Effects of Anions Br,Cl, F,Acetate, Aspartate,Glutamate, and NO3

The unitary conductances and permeability sequences of the rat connexin40 (rCx40) gap junction channels to seven monovalent cations and anions were studied in rCx40-transfected neuroblastoma 2A (N2A) cell pairs using the dual whole cell recording technique. Chloride salt cation substitutions (115 mM principal salt) resulted in the following junctional maximal single channel current-voltage relationship slope conductances (γ_j in pS): CsCl (153), RbCl (148), KCl (142), NaCl (115), LiCl (86), TMACl (71), TEACl (63). Reversible block of the rCx40 channel was observed with TBA. Potassium anion salt γ_j are: Kglutamate (160), Kacetate (160), Kaspartate (158), KNO₃ (157), KF (148), KCl (142), and KBr (132). Ion selectivity was verified by measuring reversal potentials for current in rCx40 gap junction channels with asymmetric salt solutions in the two electrodes and using the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The permeabilities relative to Li⁺ are: Cs⁺ (1.38), Rb⁺ (1.32), K⁺ (1.31), Na⁺ (1.16), TMA⁺ (0.53), TEA⁺ (0.45), TBA⁺ (0.03), Cl⁻ (0.19), glutamate⁻ (0.04), and NO₃− (0.14), assuming that the monovalent anions permeate the channel by forming ion pairs with permeant monovalent cations within the pore thereby causing proportionate decreases in the channel conductance. This hypothesis can account for why the predicted increasing conductances with increasing ion mobilities in an essentially aqueous channel were not observed for anions in the rCx40 channel. The rCx40 effective channel radius is estimated to be 6.6 Å from a theoretical fit of the relationship of relative permeability and cation radius.     

Relations of the Al,B, Ba,Br, Ca,Cl, Cu,Fe, K,Li, Mg,Mn, Na,P, S,Si, Sr,and Zn mass fractions to morphometric parameters in pediatric and nonhyperplastic young adult prostate glands

The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid.     

The Effect of Age and Gender on Al, B, Ba, Ca, Cu, Fe, K, Li, Mg, Mn, Na, P, S, Sr, V, and Zn Contents in Rib Bone of Healthy Humans

The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs.     

Competitive inhibition and selectivity enhancement by Ca in the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, Hf) by carrot (Daucus carota cv. U.S. harumakigosun)

We investigated the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, and Hf) and the effect of Ca on their uptake in carrots (Daucus carota cv. U.S. harumakigosun) by the radioactive multitracer technique. The experimental results suggested that Na, Mg, K, and Rb competed for the functional groups outside the cells in roots with Ca but not for the transporter-binding sites on the plasma membrrane of the root cortex cells. In contrast, Y, Ce, Pm, and Gd competed with Ca for the transporters on the plasma membrane. The selectivity, which was defined as the value obtained by dividing the concentration ratio of an elemental pair, K/Na, Rb/Na, Be/Sr, and Mg/Sr, in the presence of 0.2 and 2 ppm Ca by that of the corresponding elemental pair in the absence of Ca in the solution was estimated. The selectivity of K and Rb in roots was increased in the presence of Ca. The selectivity of Be in roots was not affected, whereas the selectivity of Mg was increased by Ca. These observations suggest that the presence of Ca in the uptake solution enhances the selectivity in the uptake of metabolically important elements against unwanted elements.     

Reliability of Analyses of Hg,Fe, Ca,K, P,pH, Alkalinity,Conductivity, Hardness and Colour from Lakes

The aim of this report has been to present results concerning analytical quality controls of Hg analysis of fish and sediment, analyses of Fe, Ca, total-P, K, pH, alkalinity, conductivity, colour and hardness (Ca + Mg) of lake water samples. Despite the fact that these are standard parameters in many regular water control programs, there are major differences in the reliability with which these parameters can be determined. The focus here is on an overall inter-laboratory comparison between the parameters. Six laboratories have been involved in the analysis. Selected results: pH gives the lowest (average) relative standard deviation (error), about 2 %; conductivity gives an error of about 5–7 %; alkalinity yields an average error of as much as 13–25 %, which is the largest among the parameters studied here; colour also gives a high error, 9–15 %; hardness gives a relative standard deviation of about 6–7 %. Of the other parameters (i. e., Hg, Fe, Ca and P), Hg gives the best reliability and Fe and P the lowest. To have knowledge of the reliability of the analytical data is of paramount importance in most control programs and research projects.