共查询到20条相似文献，搜索用时 187 毫秒
1.
水生生态系统蓝藻固氮作用研究进展与展望 总被引：4，自引：2，他引：2
固氮蓝藻在水生生态系统中占优势是由多种因素所引起的,如营养盐浓度及形态、氮磷比、水温和微量元素等.一般认为,湖泊中正磷酸盐浓度≥0.01 mg/L、溶解性无机氮浓度≤0.1 mg/L时,固氮蓝藻出现,并且低的氮磷比是表征水体中固氮蓝藻出现的重要指标,但引起固氮与非固氮蓝藻分异的驱动机制还需要深入研究.此外,光照、无机氮浓度与形态、异形胞丰度和溶解性有机物对蓝藻固氮速率有重要影响,进而决定蓝藻氮释放通量及对水体中氮库的贡献作用.固氮蓝藻是贫营养盐海域和海洋生态系统中氮库的重要贡献者,但在富营养化湖泊中,其贡献作用还存在争议.因此就目前国内外对固氮蓝藻相关研究做综述,以期待业界同行能够对蓝藻固氮作用及其氮释放对水生生态系统中氮循环的贡献引起重视. 相似文献
2.
秋季聚积蓝藻打捞对蓝藻生长及水质影响的原位实验 总被引：1，自引：0，他引：1
在巢湖西北半湖近岸设置3组小型围隔模拟秋季湖岸带蓝藻聚积,并用单片鳃式过滤器原位打捞蓝藻,研究秋季打捞对蓝藻生长的影响及其对营养盐、藻源性有机物的控制效应.初始围隔水体叶绿素a浓度为309.5±3.7μg/L,总氮和总磷浓度分别为3.32±0.14和0.30±0.04 mg/L.蓝藻衰亡分解释放的藻源性有机物为水体溶解性有机物的主要来源,荧光有机物以类蛋白物质为主.经过打捞,浮游植物生物量削减了41.7%,解除了蓝藻生长"密度制约",24 h细胞分裂频率及原位生长速率均增大,说明打捞在短期内增强蓝藻细胞生长活力,减缓藻源性有机物的释放.与秋季蓝藻衰亡趋势一致,实验周期内围隔中叶绿素a浓度逐渐降低,秋季打捞不会造成蓝藻水华再次暴发.打捞通过削减蓝藻生物量,使水体初级生产力、氮、磷、高锰酸盐指数得到显著控制;而且打捞还可以控制藻源性有机物的释放,使藻源性大分子有机物更易降解为小分子有机物.因此,在秋季对湖岸带聚积蓝藻进行物理打捞,不仅可以控制蓝藻生物量,还可以有效控制营养盐和有机物的释放,降低生态风险. 相似文献
3.
高密度蓝藻厌氧分解过程与污染物释放实验研究 总被引：18，自引：6，他引：12
采用批次培养实验模拟高密度蓝藻堆积发生的厌氧分解过程,分析蓝藻的分解速率及污染物释放规律.厌氧分解实验中,设置三组蓝藻初始密度分别为2.23×1012、1.19×1013、4.47×1013cells/L,得到叶绿素a的分解速率常数分别为0.074、0.133、0.081 d-1.蓝藻厌氧分解过程中水体呈酸性,电导率呈上升趋势,最高值为949μS/cm.化学需氧量持续升高,而UV254值先升高后降低,说明水体中有机物浓度增大,并逐渐由大分子分解为小分子有机物.蓝藻厌氧分解释放出大量溶解态氮、磷,溶解态有机氮逐渐被降解为无机氮,铵态氮含量占90%以上.研究表明,高密度蓝藻堆积发生厌氧分解可释放大量有机物和溶解态营养盐至水体中,并且随着蓝藻密度升高,污染物释放强度增大.因此水华期间应及时打捞蓝藻,以避免蓝藻大量堆积死亡导致水源区水质下降并影响自来水出水质量. 相似文献
4.
不同密度藻屑堆积下沉积物碳氮磷释放特征 总被引：2，自引：2，他引：0
蓝藻碎屑分解引起氮磷释放已受到广泛关注,但堆积的藻屑与沉积物交互作用引发污染物释放的效应知之甚少.采集于桥水库沉积物柱状样,设置5个藻屑添加组和对照组(无藻屑添加),恒温培养(27±1℃),模拟夏季温度条件下不同密度藻屑堆积下沉积物中碳氮磷释放特征.结果表明:藻屑堆积后加强了上覆水中溶解氧与硝态氮的消耗,5个藻屑添加组18小时后上覆水均处于厌氧状态.各实验组上覆水中的溶解性有机碳(DOC)浓度在第3小时增加,且SUVA254值处于0.54~1.74 L/(mg·m)之间,说明DOC可能来源于藻源性释放.各藻屑添加组培养过程中上覆水的溶解性有机氮(DON)、铵态氮和正磷酸盐浓度持续增加,最高平均释放速率分别达4.44、0.20和0.03 mg/(L·h),分别为对照组的21.73、1.76和67.58倍;其中DON为溶解性总氮主要存在形态,在实验结束时DOC/DON比值降低,说明藻屑或者沉积物有机质短期内并未完全矿化,且DOC优先DON被微生物利用.因此蓝藻碎屑堆积增强了沉积物需氧量,加快沉积物与水之间的氮磷营养盐、DOC循环,从而对沉积物中污染物地球化学循环过程造成进一步的影响. 相似文献
5.
为探究富营养化浅水湖泊所富集的有机物对湖泊碳循环和水质的影响,本研究构建微宇宙系统,模拟蓝藻和芦苇碎屑单独分解及混合分解过程.通过测定各组上覆水营养盐浓度、有机质含量及结构的变化,揭示富营养化湖泊藻草残体混合分解过程中养分和有机碳的释放特征.结果表明,在实验0～88 h内,在添加相同的碳源条件下,蓝藻和芦苇混合处理组总碳(TC)释放量显著高于理论值,表明藻草碎屑混合分解存在共代谢效应.在培养初期,沉积物通过共代谢效应对水质产生了较大的影响,加速向水体中释放氮、磷物质.相较单独的植物分解,混合处理组中总氮(TN)、总磷(TP)的最大释放量分别提高了13.49%和26.84%;通过三维荧光光谱表征的类富里酸荧光强度变化也表明:较芦苇处理组,混合处理组中芦苇的分解速率更快.在培养开始后,各处理组均快速转变为厌氧状态,TC、TN、TP浓度随时间变化总体上呈先快速上升再逐渐平缓的趋势,分别在第228、108和324小时达最大值(372.4±2.98)、(138.45±2.97)和(7.95±1.11) mg/L.细菌特异性脂肪酸含量变化表明,将蓝藻碎屑添加到芦苇碎屑中,会增加芦苇碎屑中细菌的丰度,从而提高分解速率,激发共代谢效应.在全球气候变暖的背景下,随着富营养化湖泊藻类暴发频次增加,共代谢效应可能还会进一步加强,对富营养化湖泊水质将会持续产生影响. 相似文献
6.
在实验条件下研究了高浓度蓝藻堆积后水体中的藻源性颗粒物中氨基酸的分解速率、分解量和氨基酸态氮形态的变化情况.在自然光照组中,颗粒态氨基酸(PAA)的浓度从实验前的0.46 mmol/L降至实验后的0.30 mmol/L;而在无光分解组中PAA从0.44 mmol/L降至0.06 mmol/L.两种处理下PAA的降解速率常数分别为0.03916和0.17424 d~(-1).溶解态氨基酸(DAA)在分解过程中浓度比较低,随时间的变化表现出先增大后减小的趋势,在两种不同的处理下,最大值分别为10.94和7.94μmol/L,21 d后减小到与实验开始时持平,甚至低于初始值.实验初期,PAA所占比例高达74%~80%,但迅速被分解转化为DAA和铵态氮(NH_4~+-N),随着实验的进行NH_4~+-N又逐渐转化为硝态氮,其中无光分解组中的分解更为彻底,而自然光照组中PAA分解量小于无光分解组.实验结果表明,氨基酸作为水体中浮游植物的潜在氮源,可以被分解为水华过程中藻类所需的NH_4~+-N,对水华的维持具有一定的促进作用. 相似文献
7.
利用改性粘土治理蓝藻水华堆积的湖泊近岸区域以及发生水华的养殖水体成为应急治理蓝藻的重要措施,然而负载有毒藻体的改性粘土沉积水体可能引发的安全性风险尚缺乏研究.选取PAC改性粘土作为研究对象,通过模拟实验,研究改性粘土处理蓝藻水华后沉积水体对负载的藻细胞结构、水体营养盐与藻毒素的释放与削减以及对其他水体功能性细菌(硝化、反硝化细菌)的影响.结果表明,PAC改性粘土的施用对低水华水体蓝藻细胞的去除率为96.04%±0.99%,高水华水体与低水华水体施用的去除率之间差异不显著,PAC改性粘土的施用能够在较长的时间内有效地控制水体中的蓝藻浓度.透射电镜结果表明,PAC改性粘土沉降蓝藻第4 d后,蓝藻细胞膜出现了一定程度的不完整,细胞内规则的类囊体片层结构出现了实质性损伤.随着粘土负载蓝藻细胞的损伤,水体中的总可溶性氮浓度迅速上升,但总可溶性磷浓度仍可在较长一段时间内维持在较低水平.PAC改性粘土施用后,水体的总细菌数与空白对照组趋于一致,但硝化、反硝化细菌数却呈显著下降趋势.PAC改性粘土施用下的藻毒素释放风险主要集中在高水华水体.高水华水体中,PAC改性粘土施用导致藻毒素MC-LR和MC-RR加速释放,其最高峰值分别达到空白对照组的1.69±0.09和2.04±0.09倍,但水体MC-LR浓度达到安全限(1μg/L)的时间明显比空白对照组早8 d.此外,PAC改性粘土的施用并没有导致水体中Al~(3+)和Cl~-浓度超标. 相似文献
8.
氨氮是地表水常见污染物,尤其在农业区域,氮类化肥的不合理施用会导致周边水体氮浓度迅速升高并保持较高水平.然而,当前对高氮水平下沉水植物腐败和附着氮循环微生物的影响尚不清楚.以轮叶黑藻(Hydrilla verticillata)为研究用沉水植物,在实验室内模拟水体内8和16 mg/L氮浓度下轮叶黑藻腐解过程中营养盐释放及残体表面微生物氮循环功能基因丰度的变化.研究发现水体两种氮浓度下轮叶黑藻腐解过程中残体腐解及营养盐释放速率无显著差异;与对照相比,植物腐败初期水体内碳、磷浓度迅速增加,而溶解氧浓度及氧化还原电位迅速降低,随着时间的推移上述水质指标逐步恢复至初期状态(第146天);水体荧光溶解性有机质主要包括紫外类富里酸、可见类富里酸、色氨酸类蛋白质和酪氨酸类蛋白质等类型.在5个氮循环相关基因中,氮负荷增加对轮叶黑藻残体生物膜内amo A、napA和narG的丰度有显著影响.冗余分析表明氮循环基因丰度受水体总氮浓度的影响较小,与植物总有机碳含量和水体化学需氧量及溶解氧浓度存在相关性.研究结果表明虽然当前氮水平对植物腐败过程影响不大、对氮循环基因丰度有一定影响,但是对该水生植被(尤其是植物腐败初期)和农业退水排放的管理仍需加强,以降低其对水体的影响. 相似文献
9.
水库建设改变了河流水文情势及物质迁移转化过程，从而影响水环境质量。为探究梯级筑坝影响下河流氮、磷的空间分布特征及其形成机制，以澜沧江为研究对象，于2016年和2021年分别开展了沿程水环境监测，对比分析水体中氮、磷及其形态浓度在水库建成前后的变化及沿程分布特征，探究氮、磷变化及其沿程分布的主控因子和影响机制。结果表明：由于河流建库蓄水淹没的土地释放大量土壤有机氮，新建水库段(2021年)水体总氮(TN)浓度相比于建库前(2016年)显著上升；由于建库后水流流速减缓而促进颗粒态磷沉降，水体总磷(TP)浓度显著下降。此外，河流建库蓄水后原自然河道的水环境特征改变且利于沉积物磷的释放，筑坝后水体磷酸盐(PO43--P)占生物可利用磷(Bio-P)的比例显著上升。受沿程土地利用的影响，从上游到下游水体TN浓度总体上逐渐升高，而水体TP浓度由于水库的截留效应逐渐降低。筑坝增加的水力停留时间为水库氮、磷转化提供了有利条件，主要表现为溶解性无机氮以硝态氮为主转变为以氨氮为主；同时，Bio-P中PO43--P的占比... 相似文献
10.
富营养化是现今各国面临的主要水环境问题,其中蓝藻水华暴发是全球富营养化水体最常见的现象之一.蓝藻水华将产生大量的蓝藻碎屑,其对水质及生物的影响还尚不清楚.本研究通过向中宇宙系统添加微囊藻碎屑,分析其对水体不同形态营养盐及水生生物生物量的影响.结果表明:微囊藻碎屑加入后,水体不同形态的营养盐浓度均在短期内迅速增加,其中水体总氮和总磷平均浓度最高分别达到3.86和0.36 mg/L;浮游植物生物量(用叶绿素a表示)在前9天随营养盐浓度的升高而增加,随后逐渐下降至实验初始水平.此外,附着藻类生物量在微囊藻碎屑加入后呈逐渐下降趋势,这可能与浮游植物快速增殖引起的水体透明度下降有关.微囊藻碎屑加入后,水丝蚓生物量随微囊藻碎屑的分解持续增长,在第20天达到生物量最大值.本研究通过模拟太湖梅梁湾生态系统,探讨微囊藻碎屑对水质及水生生物生物量的影响,结果有助于进一步了解蓝藻水华对水生态系统影响的途径及机理,为富营养化湖泊管理提供理论依据. 相似文献
11.
滇池沉水植物生长过程对间隙水氮、磷时空变化的影响 总被引：4，自引：0，他引：4
2015年6-10月通过原位采集滇池沉水植物分布区和无植物对照区柱状沉积物间隙水,分析其溶解性总氮(DTN)和溶解性总磷(DTP)、溶解性无机氮(DIN)和溶解性无机磷(DIP)及溶解性有机氮(DON)和溶解性有机磷(DOP)浓度的时空变化,探讨沉水植物分布对间隙水氮、磷浓度、形态贡献及氮磷比的影响.结果表明:滇池沉水植物生长过程显著影响间隙水氮、磷浓度.与无植物对照区相比,沉水植物生长过程对间隙水氮浓度的削减主要发生在6、8月,而对间隙水磷浓度的削减主要发生在7月,反映了沉水植物对氮、磷两种元素的生物地球化学循环作用机制不同;间隙水氮形态贡献受季节性影响较大,6-7月以DON贡献为主,沉水植物分布区和无植物对照区分别达到61%和84%;而8-10月以DIN贡献为主,沉水植物分布区和无植物对照区分别为76%和75%;沉水植物分布区磷形态贡献随季节波动变化,沉水植物分布区以DOP贡献为主(63%),无植物对照区以DIP贡献为主(62%);沉水植物生长对沉积物间隙水各形态氮磷比影响显著.沉水植物生长显著增加间隙水DTN/DTP比,尤其是DIN/DIP比,相反降低DON/DOP比.沉水植物对间隙水氮、磷吸收及转化过程改变了沉积物氮、磷释放机制,从而影响上覆水氮、磷组成及氮磷比,很可能会影响到浮游植物生长及藻类水华过程,这对于湖泊水质管理具有重要意义. 相似文献
12.
以太湖重度蓝藻水华发生的西北湖区为研究对象,从河口至湖心区设置5个采样点,于2012年10月至2013年10月逐月采集表层水体样品,测定了水温、溶解氧和浮游细菌丰度,并分析了浮游植物群落结构的组成、溶解性无机氮(DIN)和有机氮(DON)浓度以及氮磷比.研究结果表明,太湖西北湖区浮游植物主要由蓝藻、硅藻、绿藻和隐藻组成.可能由于风、浪等混合作用使太湖西北湖区不同采样点之间蓝藻细胞密度没有显著差异.蓝藻生物量在浮游植物中所占比例最高为34%±15%,春季部分点位隐藻生物量高于50%,表明隐藻与蓝藻的相互竞争趋势显著.CCA排序图结果表明,DIN、DON浓度以及总氮∶总磷比(TN∶TP比)是影响西北湖区浮游植物优势属分布的重要环境因子.5个采样点铵态氮(NH_4~+-N)与DIN浓度具有显著差异,与DON浓度没有显著差异.夏季蓝藻水华暴发期间,可能由于蓝藻的吸收利用引起NH_4~+-N和硝态氮(NO_3~--N)浓度迅速降低.此外,由于NH_4~+-N浓度还可能受到沉积物NH_4~+-N释放的影响,因此,蓝藻细胞密度与NO_3~--N的相关系数和显著水平均高于NH_4~+-N.夏季TN∶TP比和DIN∶TP比降至最低,表明该湖区浮游植物,尤其是蓝藻的生长可能受到氮限制.蓝藻细胞密度与DON浓度呈显著负相关,表明在氮限制条件下,DON可能是蓝藻氮素利用的重要补充. 相似文献
13.
滇池入湖河流磷负荷时空变化及形态组成贡献 总被引：5，自引：2，他引：3
研究了2013年滇池主要入湖河流总磷(TP)及各形态磷浓度的时空变化与入湖负荷特征,并探讨了不同形态磷的入湖负荷贡献.结果表明:(1)滇池河流入湖TP浓度在0.11~1.93 mg/L之间,以溶解性无机磷(DIP)和颗粒态磷(PP)为主,溶解性有机磷(DOP)浓度较低;(2)滇池河流入湖磷负荷总量为280.51 t/a,绝大多数河流主要以DIP形态入湖,平均贡献率为43.48%;PP形态入湖负荷次之,平均贡献率为31.64%;DOP入湖负荷较低,平均贡献率为24.88%;(3)DIP入湖负荷贡献率较高值出现在3、4和11月的枯水期,平均入湖负荷贡献率达到55.30%;PP入湖负荷贡献率较高值出现在1和7月,平均入湖负荷贡献率为56.14%;DOP入湖负荷贡献率月变化差异较小,最高值出现在12月,贡献率为21.85%;(4)研究滇池入湖河流污染负荷不仅要考虑溶解态无机磷的贡献,而且需要重视PP和DOP负荷,控制滇池入湖河流污染负荷需要考虑不同河流不同形态磷负荷组成及月变化差异特征,有针对性地采取相应措施. 相似文献
14.
Temporal and spatial distributions of nutrients under the influence of human activities in Sishili Bay,northern Yellow Sea of China 总被引：1，自引：0，他引：1
《Marine pollution bulletin》2012,65(12):2708-2719
The temporal and spatial distributions of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), soluble reactive phosphorus (SRP) and dissolved reactive silica (DRSi) together with chlorophyll-a, temperature and salinity were analyzed monthly from December 2008 to March 2010 at four zones in Sishili Bay located in the northern Yellow Sea. The nutrient distribution was impacted by seasonal factors (biotic factors, temperature and wet deposition), physical factors (water exchange) and anthropogenic loadings. The seasonal variations of nutrients were mainly determined by the seasonal factors and the spatial distribution of nutrients was mainly related to water exchange. Anthropogenic loadings for DIN, SRP and DRSi were mainly from point sources, but for DON, non-point sources were also important. Nutrient limitation has changed from DIN in 1997 to SRP and DRSi in 2010, and this has resulted in changes in the dominant red tide species from diatom to dinoflagellates. 相似文献
15.
为研究崇明岛河网浮游植物和无机、有机氮的时空分布特征及其相互关系,于2014年1、4、7和10月在崇明岛河网内选取界河、堡镇港、八滧港3条河道9个采样点采集浮游植物和表层水样,并选取崇西水闸作为对照点进行研究.结果表明:河网内浮游植物以绿藻和硅藻为主,其中水闸和堡镇港夏季裸藻生物量所占比例超过50%.八滧港总溶解性氮(TDN)的主要组分是溶解性无机氮,而水闸、界河和堡镇港溶解性有机氮(DON)在TDN中的比例在夏、秋季低于冬、春季,农田土壤释放可能是DON的重要来源.水温、溶解氧和化学需氧量是影响铵态氮浓度变化的重要环境因素.此外,通过冗余分析发现,铵态氮影响绿藻和裸藻分布,尿素影响甲藻分布. 相似文献
16.
The quantitative evaluation of the effects of bedrock groundwater discharge on spatial variability of stream dissolved organic carbon (DOC), dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP) concentrations has still been insufficient. We examined the relationships between stream DOC, DIN and DIP concentrations and bedrock groundwater contribution to stream water in forest headwater catchments in warm-humid climate zones. We sampled stream water and bedrock springs at multiple points in September and December 2013 in a 5 km2 forest headwater catchment in Japan and sampled groundwater in soil layer in small hillslopes. We assumed that stream water consisted of four end members, groundwater in soil layer and three types of bedrock groundwater, and calculated the contributions of each end member to stream water from mineral-derived solute concentrations. DOC, DIN and DIP concentrations in stream water were compared with the calculated bedrock groundwater contribution. The bedrock groundwater contribution had significant negative linear correlation with stream DOC concentration, no significant correlation with stream DIN concentration, and significant positive linear correlation with stream DIP concentration. These results highlighted the importance of bedrock groundwater discharge in establishing stream DOC and DIP concentrations. In addition, stream DOC and DIP concentrations were higher and lower, respectively, than those expected from end member mixing of groundwater in soil layer and bedrock springs. Spatial heterogeneity of DOC and DIP concentrations in groundwater and/or in-stream DOC production and DIP uptake were the probable reasons for these discrepancies. Our results indicate that the relationships between spatial variability of stream DOC, DIN and DIP concentrations and bedrock groundwater contribution are useful for comparing the processes that affect stream DOC, DIN and DIP concentrations among catchments beyond the spatial heterogeneity of hydrological and biogeochemical processes within a catchment. 相似文献
17.
A review of sediment and nutrient concentration data from Australia for use in catchment water quality models 总被引：1，自引：0，他引：1
Land use (and land management) change is seen as the primary factor responsible for changes in sediment and nutrient delivery to water bodies. Understanding how sediment and nutrient (or constituent) concentrations vary with land use is critical to understanding the current and future impact of land use change on aquatic ecosystems. Access to appropriate land-use based water quality data is also important for calculating reliable load estimates using water quality models. This study collated published and unpublished runoff, constituent concentration and load data for Australian catchments. Water quality data for total suspended sediments (TSS), total nitrogen (TN) and total phosphorus (TP) were collated from runoff events with a focus on catchment areas that have a single or majority of the contributing area under one land use. Where possible, information on the dissolved forms of nutrients were also collated. For each data point, information was included on the site location, land use type and condition, contributing catchment area, runoff, laboratory analyses, the number of samples collected over the hydrograph and the mean constituent concentration calculation method. A total of ～750 entries were recorded from 514 different geographical sites covering 13 different land uses. We found that the nutrient concentrations collected using "grab" sampling (without a well defined hydrograph) were lower than for sites with gauged auto-samplers although this data set was small and no statistical analysis could be undertaken. There was no statistically significant difference (p<0.05) between data collected at plot and catchment scales for the same land use. This is most likely due to differences in land condition over-shadowing the effects of spatial scale. There was, however, a significant difference in the concentration value for constituent samples collected from sites where >90% of the catchment was represented by a single land use, compared to sites with <90% of the upstream area represented by a single land use. This highlights the need for more single land use water quality data, preferably over a range of spatial scales. Overall, the land uses with the highest median TSS concentrations were mining (～50,000mg/l), horticulture (～3000mg/l), dryland cropping (～2000mg/l), cotton (～600mg/l) and grazing on native pastures (～300mg/l). The highest median TN concentrations are from horticulture (～32,000μg/l), cotton (～6500μg/l), bananas (～2700μg/l), grazing on modified pastures (～2200μg/l) and sugar (～1700μg/l). For TP it is forestry (～5800μg/l), horticulture (～1500μg/l), bananas (～1400μg/l), dryland cropping (～900mg/l) and grazing on modified pastures (～400μg/l). For the dissolved nutrient fractions, the sugarcane land use had the highest concentrations of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP). Urban land use had the highest concentrations of dissolved inorganic phosphorus (DIP). This study provides modellers and catchment managers with an increased understanding of the processes involved in estimating constituent concentrations, the data available for use in modelling projects, and the conditions under which they should be applied. Areas requiring more data are also discussed. 相似文献
18.
Lenzi M Finoia MG Persia E Comandi S Gargiulo V Solari D Gennaro P Porrello S 《Marine pollution bulletin》2005,50(5):512-519
In the shallow water of Orbetello lagoon, macroalgae harvesting boats produce sediment disturbance. To evaluate the effect of this, during 2001-2002, a trial study was carried out in the lagoon in order to: verify seasonal and diurnal trends in nutrients and estimate the quantity of resuspended organic sediment. An unbalanced and balanced ANOVA (one and two way) analysis was applied. The disturbance did not produce strong and lasting eutrophication effects. In the seasonal survey, dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) showed significant decreases in disturbed areas at the end of the trial, while the control area showed a constant, significant increase. Dissolved organic nitrogen (DON) and phosphorus (DOP) significantly increased everywhere. In disturbed areas, sediment redox (Eh((NHE))) increased and porosity values decreased, contrary to the control area. Total organic carbon (TOC) remained unchanged in disturbed areas, but increased in the control area, where the C:P ration increased. The fall-out of sedimentary material resuspended by boat action for as far as 50 m from the boat route, was 189 g(dw)m(-2) made up mainly of organic matter. This disturbance could be the cause of change in vegetation in the lagoon. 相似文献
19.
Ecological significance of alkaline phosphatase activity and phosphatase-hydrolyzed phosphorus in the northern part of Gamak Bay, Korea 总被引：1，自引：0，他引：1
We investigated the ecological significance of alkaline phsophatase (APase) and alkaline phosphatase-hydrolyzable phosphorus (APHP) in the northern part of Gamak Bay, Korea. APase activity was detectable throughout the year, and dissolved inorganic phosphorus (DIP) concentration and APase activity are highly correlated and can be regarded as an indicator of DIP-limiting conditions. Also, a strong linear positive correlation between APase activity and Chl a concentration indicated that the major part of APase activity may have been induced by phytoplanktons. The APHP proportion in dissolved organic phosphorus (DOP) was above ca. 30% from winter to spring and below ca. 15% from summer to autumn due to freshwater discharge and uptake by phytoplankton. APHP may play an important role in species competition in coastal area such as northern part of Gamak Bay where DIP is limiting. Thus, APase induction by phytoplanktons may be ecologically significant, allowing dominance by these organisms under DIP-limiting conditions. 相似文献
20.
江西柘林水库是长江中游的大型峡谷型旅游性水库,库容79.2×10~8m~3,长115 km.2015年4月在56 km的中心库区走航和定点测量了水库表层水体浮游藻类、叶绿素a(Chl.a)浓度与溶解无机氮(DIN)浓度、溶解无机磷(DIP)浓度、溶解硅(DSi)浓度、水温、浊度和溶解氧浓度等环境因子的分布特征.结果表明:1)水库属于中营养水体,表层主要浮游藻类(细胞丰度1000 cells/L)有34种,平均生物量为0.41 mg/L.主要优势藻类(优势度≥0.02)为硅藻和蓝藻,藻类组成与DIN浓度、DIP浓度、DSi浓度和水温等环境因子关系密切,4种因子对藻类结构的解释水平达60%以上.2)水库水体Chl.a浓度具有显著的次表层叶绿素最大值(SCM)现象,SCM层深度为3~8 m,厚度为2~7 m,SCM层占整个水体的25.2%~74.1%.SCM层的藻类对营养盐吸收消耗致使DIN、DIP和DSi浓度下降,同时藻类的产氧使溶解氧浓度增加.3)水库对DSi具有显著的生物过滤器效应,中、上层约有11%~12%的DSi被生物吸收利用,从上游至下游,累积约有21%的DSi被藻类吸收沉降于库底.4)人类氮、磷排放对水库生态和水质有严重影响,毗邻县城区域水体的Chl.a和DIP浓度分别是自然河段的2.9倍和3倍左右. 相似文献