汉江襄阳城区段水质变化规律及特征分析

为全面掌握汉江襄阳城区段沿程水质变化情况,合理制定相应保护措施,基于2018—2022年汉江襄阳城区段出入境断面及支流水质监测数据,对汉江襄阳城区段水环境质量、变化趋势和相关特征开展综合分析评价。结果表明,2018—2022年汉江襄阳城区段入境与出境断面水质状况总体为优,但出境断面氨氮、总磷、总氮的质量浓度较入境断面均有明显增高,主要支流唐白河、清河及南渠的汇入对出境断面水质影响较大。2018—2021年汉江襄阳城区段出入境断面主要监测指标质量浓度分布表现为丰水期＞枯水期,2022年表现为枯水期＞丰水期。汉江襄阳城区段水质氮污染贡献明显高于磷污染,仍以氮污染为主,水质中氮主要以游离氨和铵盐以外的形式存在。相关性分析结果表明,入境断面与出境断面中氨氮、总氮与各指标相关性差别较大,总磷、溶解氧与各参数间的相关性基本一致。研究结果可为制定汉江水环境改善及污染防治措施提供科学依据。     

水磨河氮含量分布及时空变化初探

根据2005年水质监测结果,对水磨河无机氮的特征分布及相互之间的相关性进行了初步分析探讨,结果显示,水磨河无机氮中硝酸盐氮含量最高,亚硝酸盐氮含量最低,亚硝酸盐氮与氨氮之间有非常显著的线性关系.通过对1991-2005年的监测资料分析,表明水磨河各断面无机氮含量呈下降趋势,但水磨河自上而下无机营养盐N总体浓度升高,说明氮污染还在延续,形势不容乐观.     

福建泉州市东、西湖水体中氮的空间分布研究

初步探讨了东湖和西湖水体中氯的空间分布特征以及3种不同形态的氮与溶解氧的相关性.结果表明,(1)泉州东湖、西湖水体中总氮的平均含量分别为3.396、3.929mg/L,氨氮的平均含量分别为1.927、2.182mg/L,硝酸盐氮的平均含量分别为1.061、1.236mg/L,亚硝酸盐氮的平均含量分别为0.084、0.059 mg/L,东湖和西湖水体的主要氮素形式均是氨氮.(2)东湖出水口和位于动物园附近的采样点总氮、氨氮和亚硝酸盐氮浓度较其它采样点高,入水口、湖区北部及湖心区采样点的氨氤和硝酸盐氮的分布趋势基本一致.西湖东南部采样点总氮、氨氯、硝酸盐氯和亚硝酸盐氮的含量都较其它采样点高.(3)东湖水体的DO浓度与氨氛、硝酸盐氮和亚硝酸盐氯的含量都不具有相关性,而西湖水体的DO浓度与这3种形态氮显著相关.     

江苏某县地下水邻苯二甲酸酯类的检测与风险评价

在江苏某癌症高发区对地下水进行布点,采用固相萃取与气相色谱-质谱联用方法测定深层地下水和浅层地下水中邻苯二甲酸酯类(PAEs)的浓度。检测结果表明,地下水中PAEs污染程度较严重,邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)均有超标现象,其中,丰水期深层地下水和枯水期浅层地下水中DBP超标率达到100%,最大超标10.7倍。PAEs总质量浓度均值为10 034.56~14 872.91 ng/L,丰水期总浓度均值大于枯水期,浅层地下水的总浓度均值大于深层地下水。采用优化的USEPA风险评价模型,对PAEs进行人体健康风险评价,评价结果表明,该地区52.5% 地下水的PAEs总致癌风险超过10^-6的水质监控值,总非致癌风险在可接受范围内。     

总氮、三氮之间浓度变化的外部条件影响

试验表明 ,由于水体中存在硝化和反硝化反应 ,随着条件的改变对总氮及三氮的浓度影响比较大。比如 ,水样在三天常温中性下保存 ,氨氮浓度降低 81 .9% ;而亚硝酸盐氮浓度则增高541 .8% ;硝酸盐氮略有升高。因此 ,为使结果准确 ,采来的水样尽量能同步、及时地进行分析。如确实需要保存 ,除亚硝酸盐氮不能在酸化后保存外 ,其余样品均应在低温、酸化 ( p H<2 )后保存。总氮、三氮之间浓度变化的外部条件影响@罗宏德$宁波市环境监测站!浙江宁波315012 @朱斌波$宁波市环境监测站!浙江宁波315012…     

达州市城区环境空气质量变化趋势及CMAQ模型预报分析

利用Spearman秩相关系数法、污染日历图、浓度分析法和CMAQ预测模型研究了达州市城区2015—2019年空气质量状况。结果表明:2015—2019年,达州市城区O_3浓度变化趋势为显著上升(P0.05),季度变化明显,8月易发生因O_3超标导致的轻度污染状况;CO年均值变化趋势为显著降低(P0.05);NO_2年均值呈上升趋势,但尚未达到显著水平(P0.05);SO_2、PM_(10)和PM_(2.5)年均值呈下降趋势,但变化趋势不明显(P0.05)。2019年,1月和12月污染最重,PM_(2.5)超标是主因,PM_(10)和PM_(2.5)年均值达标形势严峻,全年一半以上天数的PM_(2.5)浓度超过年均值二级标准限值,PM_(10)也近半;NO_2年均值达标形势严峻,全年212 d超过年均值二级标准限值。CMAQ模型对不同污染指标的预测准确率不同,预测PM_(2.5)浓度、首要污染物和空气质量等级时的准确率不及人工预测,预测AQI时的准确率高于人工预测,更多污染指标的预测比较还有待进一步研究。     

渤海湾无机氮、活性磷酸盐的变化对海洋初级生产力(叶绿素)的影响

通过三年海洋监测结果显示了渤海湾无机营养盐的变化对初级生产力的影响。其中无机氮严重超标达66%,无机氮与叶绿素的关系在枯水期、丰水期呈正相关;活性磷酸盐与叶绿素关系显著性不明显(仅枯水期显著),活性磷酸盐含量较低,限制了初级生产力。     

近年来淮河干流氮污染状况与变化趋势

对淮河干流1990年至2002年氮污染和溶解氧监测数据的分析表明,沿淮河干流上游至下游氮污染加重,溶解氧含量降低。在一年中的6～9月,淮河干流无机氮和溶解氧浓度为最低。溶解氧的浓度直接影响到氨氮向亚硝酸盐氮和硝酸盐氮转化这一氧化自净过程。     

赣江主要河流丰水期-枯水期氮磷营养盐分布特征

对2006—2019年赣江水体及水库丰水期-枯水期的总氮(TN)、氨氮(NH₃-N)、硝态氮(NO^-₃-N)和总磷(TP)浓度变化和分布特征进行分析。将赣江按河谷地形和河道特征划分为上游、中游、下游3段；根据水流来源将赣江划分为章水、桃江、湘水、贡水、泸江、赣江干流。结果显示：桃江TN质量浓度在2011年枯水期取得最大值8.26 mg/L;章水TP质量浓度在2007年枯水期取得最大值0.18 mg/L,整个赣江丰水期-枯水期的TP质量浓度在0.02～0.18 mg/L范围内浮动，变化幅度较小；章水NH₃-N浓度在2008年枯水期取得最大值1.86 mg/L,而在2017—2019年NH₃-N的浓度基本处于0.5 mg/L以内，达到《地表水环境质量标准》(GB 3838—2002)Ⅲ类水质标准。万安水库和峡江水库对总氮的滞留率，丰水期分别为24.26%、17.44%,枯水期分别为21.36%、16.60%;对总磷的滞留率，丰水期分别为24.78%、19.05%,枯水期分别为33....     

城市河流各水期水质变化分析

选取宁波市区20个监测断面作为研究对象,选择溶解氧、高锰酸盐指数、五日生化需氧量、氨氮、铜、锌、挥发酚、石油类作为评价指标,利用主成分分析法分别对其枯水期、平水期、丰水期进行综合水质评价。根据计算结果提取了3个主成分因子(有机物因子、氨氮和重金属因子、挥发酚因子),累计方差贡献率达到84.02%,基本保留了选取指标的有效信息。结果发现,各监测断面污染状况均显示为枯水期>平水期>丰水期,枯水期、平水期、丰水期断面达标率分别为20%、50%、80%,主要超标水域为鄞州河网、中大河、鄞江下游,评价结果与实际情况相符合。     

三峡水库干流氮和磷含量的季节变化

三峡水库成库后对6个水平断面、4个垂直断面采样分析,对水体水质参数、不同化学形态N以及不同物理形态P的水平分布和垂直分布进行了研究。研究结果表明,成库后TP、NH3-N、NO2--N、NO3--N、IN含量范围分别在0.06～0.34、0.01～0.72、0.002～0.100、0.76～2.09、0.855～2.52 mg/L。TP分布为丰水期>平水期>枯水期,受悬浮物沉降的影响,TP在水库区域含量低于上游区。枯水期、平水期水体中TP以可溶解态为主,丰水期以颗粒态为主。NO2--N、NO3--N、IN含量均为平水期>枯水期>丰水期。水体中IN以NO3--N为主,占IN70%～90%。NO2--N比例最低,占IN3.5%以下。表明水体虽受成库影响流速减缓,但水体依然有较强的自净能力。垂直分布上,TP、IN在3个层次变化不显著,未出现分层现象。各采样站点TP、NO3--N、IN通量和流量有显著相关。     

Spatial and seasonal distribution of nitrogen in marsh soils of a typical floodplain wetland in Northeast China

Horizontal and profile distributions of nitrogen in marsh soils in different seasons were studied in a typical site within the Erbaifangzi wetland in Northeast China. Results showed that there was higher spatial heterogeneity for nitrate nitrogen (NO₃^--_{3}^{-}-N) and ammonium nitrogen (NH₄⁺_{4}^{+}–N), as well as available nitrogen (AN), in surface soils in July compared to that in September. Relative to July, the mean nitrogen contents in surface soils were slightly higher in September; however, in November, soils contained significantly lower NO₃^--_{3}^{-}-N and NH₄⁺_{4}^{+}–N, higher AN, organic nitrogen (Org-N), and total nitrogen (TN). Except for mineral nitrogen, no significant differences were observed between Org-N and TN contents in September and November. Nitrogen contents generally declined exponentially with depth along soil profiles in three sampling dates (July, September, and November), except for a significant accumulation peak of NO₃^--_{3}^{-}-N at the 20–30 cm depth in September. However, NH₄⁺_{4}^{+}–N contents showed a vertical alternation of “increasing and decreasing” in both July and September, while nearly kept constant with depth in November. The depth ranking of nitrogen showed the shallowest distribution for AN, followed by Org-N and TN, while deeper distributions for NO₃^--_{3}^{-}-N and NH₄⁺_{4}^{+}–N. TN, Org-N, and AN were significantly correlated with soil organic matter and total phosphorus. Soil pH values were significantly correlated with TN and AN contents in surface soils. Clay contents showed significant correlations with nitrogen contents except for NO₃^--_{3}^{-}-N in surface soils and NH₄⁺_{4}^{+}–N in profile soils. However, soil moisture was not significantly correlated with nitrogen contents among all soil samples.     

富营养化湖泊叶绿素a时空变化特征及其影响因素分析

基于内蒙古乌梁素湖区20个监测点5、7、9、11月的监测数据,分析水体中叶绿素a浓度时空变化情况。同时,分析水体中总氮、总磷、氨氮、硝酸盐氮、COD、p H、总有机碳与叶绿素a的相关性。结果显示,叶绿素a浓度呈现由西北向东南逐渐减少的趋势,而浓度峰值出现在7月下旬,低值出现在11月下旬。相关因素与叶绿素a的相关性呈复杂性,线性拟合结果显示,与COD没有明显相关性;与总有机碳呈弱负相关性,与p H呈负相关性;而与总磷、总氮、氨氮、硝酸盐氮呈正相关性。期望该研究为干旱区湖泊水体富营养化控制和水资源管理提供科学依据。     

Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe

To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s average) for sulphate (SO₄), inorganic nitrogen (NO₃-N; NH₄-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada, the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more than 9 years of data were available (14 regions, 17 sites). Annual average SO₄ deposition during the 1990s ranged between 7.3 and 28.4 kg ha⁻¹ per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha⁻¹ per year, of which 41–67% was nitrate (NO₃-N). Over the period of record, SO₄ concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO₄ in runoff decreased at 14/17 catchments. In contrast, NO₃-N concentrations in deposition decreased in only 1/14 regions, while NH₄-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH₄-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively, which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at 18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31–100%; median 94%) was retained in the catchments, although there was a tendency for greater NO₃-N leaching at sites receiving higher (<7 kg ha^-1 per year) bulk inorganic N deposition. Mass balance calculations show that export of Ca and Mg in runoff exceeds input at all 21 catchments, but K export only exceeds input at 16/21 sites. Estimates of base cation weathering were available for 18 sites. When included in the mass balance calculation, Ca, Mg and K exports exceeded inputs at 14, 10 and 2 sites respectively. Annual Ca and Mg losses represent appreciable proportions of the current exchangeable soil Ca and Mg pools, although losses at some of the sites likely occur from weathering reactions beneath the rooting zone and there is considerable uncertainty associated with mineral weathering estimates. Critical loads for sulphur (S) and N, using a critical base cation to aluminium ratio of 10 in soil solution, are currently exceeded at 7 of the 18 sites with base cation weathering estimates. Despite reductions in SO₄ and H⁺ deposition, mass balance estimates indicate that acid deposition continues to acidify soils in many regions with losses of Ca and Mg of primary concern. The U.S. Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged. The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.     

The Pollution Load by Nitrogen and Phosphorus IN the Jadro River

The objective of the investigations of the Jadro River, located in Croatia, was to estimate the nitrogen and phosphorus loads in the Jadro River spring and its streamflow by calculating the load in kg/day or tons/year and to compare this with the load for the maximum allowed concentrations (MAC) for drinking water (Official Bulletin, No 46/94) expressed in kg/day or tons/year.Daily pollution loads at the Jadro River spring for total N ranged from 0 to 304 kg, for NH₃-N from 0 to 38 kg, for NO₃-N from 0–1321 kg and for PO₄-P from 0–92 kg in the period from September 1993 to September 2003. When compared with MAC loads the results prove that the Jadro River spring is not polluted by nitrogen compounds and phosphorus.The average annual load for total N ranged from 10 to 33 t, for NH₃-N from 0.25 to 5.15 t, for NO₃-N from 40 to 190 t, and for PO₄-P from 0.3 to 11.5 t. The nitrogen compounds and phosphorus loads vary from one year to another without any constant decreasing or increasing trends. The annual average loads compared with the average annual MAC loads (especially for NH₃-N and PO₄-P) show that there were no threats of constant pollution of the spring.The loads for total N and PO₄-P along the Jadro River flow from the spring to the fishpond entrance were monitored over a five year period from September 1999 to September 2004. The results show no regularities. The highest annual total nitrogen load of 45 t was recorded at the entrance to the fishpond during the 2002/2003 period. The highest annual PO₄-P load of 10 t was measured at the Vidović Bridge during the 2003/2004 period; however, the concentrations of N and P did not exceed the MAC concentrations which are prescribed for drinking water.According to the investigation results of the daily and average annual loads compared with MAC loads for drinking water, it can be concluded that the Jadro River spring and its streamflow are not polluted by nitrogen and phosphorus.     

北京夏季大气主要含氮无机化合物的变化规律与相互作用

利用SJAC-MOBIC/FIA在2006年8月16日—9月9日在线测量了北京城市大气细颗粒物中主要水溶性含氮离子组分(NO₃^-和 NH₄⁺),与重要含氮气态污染物(HNO₃、HNO₂和 NH₃),以追踪细颗粒物中含氮二次无机组分和含氮气态污染物的变化规律及其相互作用。观测期间,NO₃^- 和 NH₄⁺的平均浓度分别为13.08和11.93 μg/m³,它们与SO₄^2-浓度之和在细颗粒物(PM_2.5)中的平均比例为55%,明显高于其他季节;污染过程中,积聚模态颗粒物体积浓度及其与爱根核模态颗粒物体积浓度比值逐渐增加,说明二次转化是北京夏季细颗粒物的重要来源。白天HONO迅速光解产生OH自由基,而OH自由基是生成HNO₃的重要物种,因此HONO和HNO₃具有相反的日变化规律。在温度较高的白天,大气环境不利于NH₄NO₃的生成与存在;夜间低温高湿的条件下硝酸铵理论平衡系数Ke与气态氨和硝酸的乘积Km相当或低于后者,较有利于NH₄NO₃的生成。北京夏季大气具有足量气态NH₃以中和硫酸盐;但在NO₃^-与阳离子的电荷平衡中,金属阳离子也非常重要。     

上海青浦地区大气降水的化学特征

利用上海青浦地区2003—2014年观测的大气降水监测资料,分析该区域12 a以来大气降水的酸化程度、化学组成特征,探讨降水中化学成分的不同来源及相对贡献。结果表明:降水pH年均值为4.43~6.33,酸雨频率为2.6%~86.8%,降水酸化程度大致经历了明显恶化和波动变化2个阶段。降水电导率年均值为1.77~4.01 m S/m,呈下降趋势。降水中各离子雨量加权平均当量浓度顺序为SO_4~(2-)NH_4~+Ca~(2+)NO_3~-Cl~-Na~+Mg~(2+)F-K~+,SO_4~(2-)、NH+4、Ca~(2+)和NO_3~-是降水中的主要离子,占离子总量的83.0%;降水类型由硫酸型向硫酸和硝酸混合型转变。降水离子中的二次组分SO_4~(2-)、NO_3~-和NH_4~+绝大部分来源于人为源,Ca~(2+)、Mg~(2+)和K+主要来自于土壤源和人为源的贡献,Cl~-主要来自海洋源,同时人为源的影响也不可忽视。     

洞庭湖水体叶绿素a时空分布及与环境因子的相关性

2013年6月至2014年5月逐月对洞庭湖水体叶绿素a质量浓度和主要环境因子进行测定,分析洞庭湖水体叶绿素a质量浓度的时空分布特征,探讨洞庭湖水体叶绿素a质量浓度与环境因子的相关性。结果表明,洞庭湖水体叶绿素a质量浓度为0.11~8.62 mg/m~3,年均值为(1.89±1.23)mg/m~3,属贫营养;叶绿素a质量浓度随季节变化明显,总体呈现夏、秋季明显大于冬、春季的规律;在空间上,总体表现为西洞庭湖和东洞庭湖明显大于南洞庭湖。全湖叶绿素a质量浓度与水温、电导率、COD和TP呈极显著正相关,与DO、NH3-N、TN和TN/TP呈极显著负相关,与NO-3-N呈显著负相关,与p H和透明度无显著相关性。全湖TN/TP的年均值为28.5,磷可能是洞庭湖水体浮游植物生长的限制性营养盐。     

闽江入海断面溶解无机氮长时间序列分析及入海通量估算

为深入研究闽江口富营养化机制,于1985—2021年在闽江入海断面开展了水质监测。采用结合局部加权回归散点平滑法(LOWESS)的季节性肯达尔检验(SK检验)对断面溶解无机氮(DIN)及其各组分浓度变化趋势进行分析,同时结合水文资料对入海通量进行估算。结果表明:DIN浓度范围为0.728~3.140 mg/L,在37年间整体呈上升趋势,但不显著。各组分中NO₂-N和NH₃-N浓度分别呈显著和极显著下降趋势,而NO₃-N浓度呈极显著上升趋势。DIN组分中NO₂-N和NH₃-N比重不断减小,而NO₃-N比重不断增大,目前已成为DIN的主要组成部分。DIN入海通量范围为3.59×10⁴~14.85×10⁴ t,在37年间缓慢增加,其各组分入海通量长期变化趋势同浓度变化类似。从长期来看,DIN及其各组分浓度的变化趋势主要受流域环境变化及下游福州市含氮废水排放影响,而在短期则受台风、降水等一些突发环境事件的影响较大。