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1.
Axenic cultures of the microalgae species, Dunaliella tertiolecta and Phaeodactylum tricornutum were grown at arsenic (As) concentrations typically found in uncontaminated marine environments ( 2 µg L− 1) under different phosphorus concentrations. D. tertiolecta accumulated higher arsenic concentrations (mean: 13.7 ± 0.7 µg g− 1 dry mass) than P. tricornutum (mean: 1.9 ± 0.2 µg g−1 dry mass). Media phosphorus concentrations (0.6–3 mg/L) had little influence on microalgae growth rates or arsenic accumulation. Arsenic was present as lipid bound (29–38%; 4.2–9.5%), water-soluble (20–29%; 26–34%) and residue bound (41–45%; 57–69%) arsenic species in D. tertiolecta and P. tricornutum respectively. Hydrolysed lipids contained mostly glycerol arsenoribose (OH- ribose), dimethylarsinate (DMA) and inorganic arsenic (As(V)) moieties. Water-soluble species of microalgae were very different. D. tertiolecta contained inorganic arsenic (54–86%) with variable amounts of DMA (7.4–20%), arsenoriboses (5–25%) and traces of methylarsonate (MA) ( 1%). P. tricornutum contained mostly DMA (32–56%) and phosphate arsenoribose (PO4-ribose, 23–49%) and small amounts of OH-ribose (3.8–6.5%) and As(V) (9–16%). Both microalgae contained an unknown cationic arsenic species. The residue fractions of both microalgae contained predominately inorganic arsenic (99–100%). These results show that at natural seawater arsenic concentrations, both algae take up substantial amounts of inorganic arsenic that is complexed with structural elements or sequestered in vacuoles as stable complexes. A significant portion is also incorporated into lipids. Arsenic is metabolised to simple methylated species and arsenoriboses. 相似文献
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《Marine Geology》2005,216(3):127-143
This study was carried out in order to understand the early diagenetic redistribution of phosphorus and relevant mass balance in the sediments of the East Sea. In two cruises during May 1993 and October 1995, 11 box cores were collected in the southwestern part of the East Sea. Dissolved phosphorus and iron were analyzed in the porewater from the cores. Sediment samples were analyzed for solid-phase P species and solid-phase Fe oxyhydroxide by sequential extraction.Phosphorus speciation results show that organic P is the major chemical form of phosphorus in young sediments within the upper 50 cm of sediment. However, the authigenic fraction of total P increases with depth, indicating the precipitation of carbonate fluorapatite (CFA) in the sediments. The authigenic CFA (Ca5(PO4)2.6(CO3)0.4F) was formed and buried at rates of 11–110 μmol cm−2 kyr−1. The main source of dissolved phosphorus for the precipitation of CFA is organic P. Dissolved phosphorus, released from the decomposition of organic P, diffuses upward to return to bottom water, or is sorbed to iron oxides in the oxidized sediments. As sedimentation proceeds, the iron oxide-bound P is released in the reduced layer and enters the dissolved phase, which contributes P to the formation of CFA in addition to that contributed by the organic P.The burial flux of reactive P (iron oxide-bound P+authigenic P+organic P) is 0.09–0.53 g P m−2 yr−1 that accounts for 18–58% of the reactive P arriving at the sediment/water interface. The burial flux of reactive P is high in the upper and lower continental margin sediment. The burial flux of reactive P in the Ulleung Basin sediment is less than those in the continental margin sites by a factor of 6, indicating that the reactive P burial flux is mainly dependent on sedimentation rate. 相似文献
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Total arsenic, arsenate and arsenite concentration profiles for the water column of Saanich Inlet, an intermittently anoxic fjord located on Vancouver Island, B.C., Canada, were measured using independent analytical techniques for total arsenic and arsenic speciation to evaluate the accuracy of the speciation technique in both oxic and anoxic marine environments. Total arsenic profiles indicate a mid-depth minimum of about 1.0 ppb above the oxic—anoxic interface and an enrichment in the anoxic zone to about 2.0 ppb. This minimum may be due to either advection of arsenic-poor water into Saanich Inlet at mid-depth or arsenic incorporation onto solid phases within a bacteria- and manganese-rich particulate layer located immediately above the oxic—anoxic interface and subsequent removal via sinking particulate material. Ratios of total arsenic to phosphorus in the deep, anoxic waters of the basin are similar to those reported for marine algae, suggesting that the enrichment of total arsenic within the anoxic bottom layer may be due to its release upon organic matter decomposition.Arsenate and arsenite concentration versus depth profiles indicate a rapid (but incomplete in a thermodynamic sense) response to the oxic—anoxic interface. The arsenate/ arsenite concentration ratio is 15/1 in the oxic region of the water column and 1/12 in the anoxic zone. Arsenate—arsenite interconversion occurs at a depth shallower than ferric-ferrous but deeper than MnO2 —Mn2+ interconversions.Measurements of arsenite oxidation rates at near-ambient arsenite concentrations and temperatures using an 74As3+ radioactive tracer technique indicate that arsenite oxidation is initially ten times faster in seawater taken from the manganese-rich particulate layer at 165 m depth than in seawater collected near the surface at 50 m depth. Addition of antibiotics to seawater from 165 m depth initially suppressed the rate of arsenite oxidation, indicating that it may be partially microbially mediated. 相似文献
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黄海两种典型硅藻的磷胁迫生理研究 总被引：6，自引：0，他引：6
在实验室批次培养条件下,研究黄海两种浮游植物优势种玛氏骨条藻(Skeletonema marinoi)和旋链角毛藻(Chaetoceros curvisetus)在低磷条件下的生长特性、环境中不同形态磷浓度的变化以及磷饥饿状态下浮游植物的营养吸收动力学和碱性磷酸酶动力学。结果表明,玛氏骨条藻在磷胁迫情况下可利用自身较高的吸收速率和较小的细胞体积有效摄取环境中的无机磷快速生长并取得优势,而旋链角毛藻在无机磷的利用上并无优势,其比玛氏骨条藻需要更多的细胞颗粒磷去维持细胞活性,而且更容易诱导碱性磷酸酶分解利用有机磷,推测在有机磷丰富的环境下旋链角毛藻会在二者竞争中取得优势。这些生理特性有可能是二者在黄海季节性水华发生过程中大量存在的原因。 相似文献
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The sea as a source of atmospheric phosphorus 总被引：1，自引：0，他引：1
The geochemical fractionation of phosphorus on the drop produced by bubbles bursting in seawater has been studied using a field sampling system called the Bubble Interfacial Microlayer Sampler (BIMS). The droplets from bursting bubbles were collected on filter samples in Narragansett Bay, Rhode Island during the summer of 1975. Phosphorus was found to be fractionated by the bubble-bursting process. The enrichment factor ranged from 4 to 170. Enrichment was found to increase with decreasing phosphorus concentration at 20 cm depth while it decreases with increasing wind velocity. Enrichment was independent of bubbling depth. Together these facts suggest that the sea-surface microlayer is the source of the phosphorus on the ejected drops. Organic phosphorus on the filter samples was found to be enriched relative to surface-water phosphorus by factors of 100–200, while reactive phosphorus was enriched by factors of only 6–8. This suggests that surface-active organic phosphorus compounds are the source phosphorus in the microlayer.The organic phosphorus content of samples of atmospheric particulates collected over the phosphate-rich upwelling waters near the Peru coast was found to correlate significantly with sea-salt sodium. Enrichments calculated using the average phosphorus concentration of the surface water in this area agree well with the results of the BIMS study. Thus it appears that phosphorus fractionation does occur in nature and may be important in supplying this nutrient to some coastal regions of the world. 相似文献
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厦门潮间带沉积物磷、铁和硫的时空分布及磷释放风险研究 总被引：2，自引：1，他引：2
为了解潮间带沉积物中铁和硫的氧化还原过程以及上覆水缺氧等对磷再活化和释放的影响,选择厦门翔安海岸带,应用原位、高分辨采样技术,对沉积物、孔隙水以及上覆水进行为期1 a的连续采样和监测。结果表明:上覆海水缺氧和磷含量超标较为严重,二者在多数月份分别低于2 mg/L和高于0.06 mg/L;在垂向剖面上,孔隙水中溶解活性磷含量同溶解铁含量变化规律一致,而薄膜扩散梯度技术有效态磷和有效态硫含量在局部硫高值区分布一致,表明磷的钝化和再活化主要受控于铁,局部受控于硫的氧化还原过程;在季度变化上,孔隙水中溶解活性磷同上覆水中溶解活性磷含量比较一致,归因于缺氧的沉积环境有利于溶解活性磷的跨界面交换,而多种环境因素的叠加,影响着溶解活性磷和膜扩散梯度技术有效态磷的时空变化;表层孔隙水中磷含量梯度不显著,即磷的释放风险不大,但环境因素的变化极易触发内源磷的释放。 相似文献
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广西近海营养盐的时空分布特征 总被引：2，自引：1，他引：1
利用2006～2007年4个航次的大面调查数据,分析讨论了广西近海4个季节营养盐的时空分布变化特征。结果表明,该海域在春、夏、秋三季,活性硅酸盐和溶解无机氮分布趋势是近岸高,远岸低,由北向南呈梯度快速递减,高值区主要出现在廉州湾、铁山港和茅尾海三个区域;夏季磷酸盐在雷州半岛与涠洲岛之间出现高值;冬季3类营养盐在调查海区内分布均匀且为一年最低值。对该海区营养盐结构分析表明,硅在该海区过剩,溶解无机氮基本能满足浮游植物的生长需要,但在春季溶解无机氮和磷浓度都较低,属于寡营养型;夏季该海区磷浓度充足,在秋冬两季磷为该海区的限制性元素。 相似文献
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Replicate portions of a Delaware salt marsh were enclosed in cylindrical microcosms and exposed to elevated levels of inorganic arsenic (arsenate). All biotic and abiotic components in dosed cylinders rapidly incorporated arsenic. Spartina blades showed the greatest arsenic enrichment, with dosed plants incorporating arsenic concentrations an order of magnitude higher than controls. Spartina detritus and sediments also exhibited greatly elevated arsenic concentrations. Virtually all of the arsenic was incorporated into plant tissue or strongly sorbed to cell surfaces. Thus, elevated arsenic concentrations in estuarine waters will be reflected in living and non-living components of a salt marsh ecosystem, implying that increased arsenic will be available to organisms within the marsh ecosystem. 相似文献
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采集九龙江河口表层和柱状沉积物样品,对表层沉积物中总砷、不同形态砷和其他重金属元素、有机质含量以及粒径等参数进行测定.分析了柱状沉积物中总砷和各形态砷的含量,结合沉积速率和响应因子,探讨总砷的污染累计特征.结果表明：（1）沉积物中检出的形态砷是As3＋和As5＋,未检出有机砷.（2）表层沉积物中总砷含量范围为10.03～11.29μg/g,河端总砷含量为11.28μg/g,高于海端总砷含量10.42μg/g.As3＋的含量范围为0.84～1.08μg/g,As5＋的含量范围为6.87～8.99μg/g;As5＋含量表现为河端（8.63μg/g）高于海端（7.31μg/g）,As3＋则不明显.（3）有机质含量是影响本区域表层沉积物中砷及其他重金属含量分布的重要因素,粒径与砷及其他重金属显著相关性不强,影响较小.（4）柱状沉积物中总砷含量范围为9.15～13.61μg/g,随深度的变化不明显,人为污染程度较轻.（5）柱状沉积物中As3＋含量介于2.45～5.35μg/g之间,As5＋含量范围为5.58～11.77μg/g,二者含量随深度的增加而降低. 相似文献
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The conservative potential of arsenic in the relatively pristine waters of Galway Bay, an estuarine system in the west of Ireland, is examined through the inter-seasonal variations in the distribution of its total, hydride and non-hydride fractions. The arsenic concentrations in Galway Bay and local fresh water sources at all seasons were lower than what is considered the natural seawater concentration of 2 μg L−1 (27 nM). The effects of physical mixing, biological uptake and regeneration of arsenic on its distribution are considered. The degree of biological uptake and regeneration of the element are determined by a first order speciation between total arsenic (a small part of which should be of organic origin) and hydride arsenic (mostly of inorganic origin). The structural similarity of arsenic species to phosphate in seawater causes arsenic to be taken up by biota, which then have to detoxify it, so results are presented against phosphate to determine the degree of biological transformation of arsenic at different seasons. An in-house, batch type system of hydride generation coupled to electro-thermal atomic absorption spectrometry is used for the analysis of arsenic; this is preceded by UV-digestion prior to the measurement of total arsenic. Results show only a small association of arsenic with phosphate but a near linear, positive distribution pattern between arsenic and salinity in Galway Bay (R2 ∼ 0.6), which is reproducible among seasons, indicating that in this environment the biological uptake of arsenic is likely to be a much slower process than the physical mixing of the water masses. 相似文献
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River water quality, particularly in lowland catchments, is a matter of concern to the New Zealand public. We assessed river water quality and biological state and trends using data from more than 900 monitoring sites. Parallel state and trend analyses were carried out using all sites and a subset of lowland river sites. Median water-quality state in urban and pastoral land-cover classes was poorer than in exotic forest and natural land-cover classes, and lowland sites in the urban and pastoral classes had the poorest water quality. Nutrient and Escherichia coli concentrations increased and visual clarity and Macroinvertebrate Community Index scores decreased as proportions of catchments in high-intensity agricultural and urban land cover increased. Ten-year trends (2004–2013) indicated recent improvements in ammoniacal nitrogen, dissolved reactive phosphorus and total phosphorus in the pastoral and urban classes, possibly reflecting improved land management. In contrast, trends in nitrate-nitrogen in the exotic forest and cool-dry/pastoral classes indicated worsening conditions. 相似文献
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With the rising cost of oil the electric power generating companies are turning to coal as a fuel source. Large amounts of fly ash are produced as a by product of coal combustion. This fly ash must then be disposed of, with the oceans being considered an alternative to land fill disposal. This research investigated the sorptive behavior of the surface-associated arsenic and utilized the results to project arsenic's impact on the water column during the ocean disposal of fly ash.Several acid digests were investigated to determine an effective method of arsenic recovery from fly ash. Of these, the HCl digest was the most effective technique, yielding 100% arsenic recoveries from fly-ash particles. The arsenic content of the fly ashes studied varied from 69 ± 11 μg g−1 to 323 ± 24 μg g−1, reflecting differences in the arsenic content of the source coal. In both seawater and freshwater there is an increase in arsenic desorption with increasing pH. The greatest release of arsenic occurred at pH 12 with generally over 80% of the surface arsenic released.Fly ash in contact with seawater and freshwater can exhibit either acidic or alkaline tendencies depending upon the soluble elemental composition on the surface of the flyash particle. The acidic ashes were shown to leach a greater percentage of arsenic (16.9%) than the more alkaline ashes (8.2%). During these leaching studies in seawater, arsenic was found to leach in both the pentavalent and trivalent oxidation state. The pentavalent state was predominant, comprising 77% of the arsenic initially desorbed.The dissolution in seawater of arsenic was utilized to assess the possible impact of the ocean disposal of fly ash. Based upon these data it appears that the natural levels of arsenic in the water column would not be significantly increased. Further research is needed on the fate of fly-ash particles in marine sediments. 相似文献
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R. A. Hoare 《新西兰海洋与淡水研究杂志》2013,47(3-4):339-349
This paper gives the data and methods used to calculate the nitrogen and phosphorus loads of the Ngongotaha Stream, near Rotorua, New Zealand. The variations in concentration with time and with flow rate are given in some detail, as examples of what may happen in other streams of the central volcanic plateau, and a novel way to define a flow‐concentration curve is described. Nitrate, ammonia, dissolved reactive phosphorus (DRP), total phosphorus (TP), and total Kjeldahl nitrogen (TKN) concentrations were measured, and mean concentrations in 1976 base flow were found to be 527, 25, 32, 48, and 162 mg m‐3 respectively. Nitrate concentrations showed seasonal variations, and although changes occurred during floods, they were not correlated with flow rate. DRP concentrations showed little variation, except that they dropped at the peak of the largest floods. TP was strongly correlated with flow rate during floods, and TP loads could best be calculated by allowing for a curvilinear relationship between concentration and flow rate. The logarithms of the TP load carried by a flood and the peak flow rate of the flood were highly correlated (R = 0.984). The annual loads of nitrate, ammonia, DRP, TP, and TKN were estimated to be 34, 1.3, 2.9, 6.0, and 26 tonnes in 1976. 相似文献
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An automatic flow analysis system with on-line liquid nitrogen trap, hydride generation and flame-less atomic absorption spectrophotometry was presented for the determination of inorganic arsenic and antimony in seawater. The experimental conditions such as acidity of reduction reaction, the amount of sodium borohydride , the flow rate of carry gas (high purity of nitrogen) were tested and selected optimally. The limit detection of the method presented was 0. 15 ug/L for arsenic and 0. 24 μ/L for antimony . During the determination of seawater samples with levels microgram arsenic and antimony pa litre th?variation coefficient would be ±4% for arsenic and ±10% for antimony. The volume needed for one measurement was 9 mL for arsenic and 12 mL for antimony. The frequency of sample determination reached 20 times per hour for arsenic and 15 times per hour for antimony. 相似文献
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春季水华对南黄海总溶解态无机砷生物地球化学行为的影响 总被引：1，自引：0，他引：1
利用氢化物发生-原子荧光光谱法(HG-AFS)对2007年3月30日至4月23日南黄海海域总溶解态无机砷(TDIAs,[TDIAs]=[As5+]+[As3+])的含量进行了测定,其中针对水华中心区域(BM1站)进行了25h的连续观测,以探讨春季水华对有毒类金属元素砷的生物地球化学行为的影响。结果表明,TDIAs的浓度范围为7.9~22.3nmol/L,平均值为(17.8±1.9)nmol/L。TDIAs在南黄海的分布主要表现为由近岸向外海逐渐升高的趋势,最大值出现在南部海域底层海水中。近岸海域表、底层TDIAs的含量相当,而中、南部海域由于存在明显的密度跃层,表、底层TDIAs的浓度具有显著性差异。2007年3月31日至4月1日研究区域西南部受到沙尘天气和降雨的影响,表层海水中TDIAs的含量显著升高。研究区域中、南部海域在观测期间暴发了典型的黄海春季水华,通过大面观测和对重点区域的连续观测可以发现,水华期间TDIAs的分布和磷酸盐类似,与Chl a呈现出较好的负相关关系(r=0.51,P0.05,n=39)。经初步计算,浮游植物水华对10m以上表层水体中TDIAs的清除量约为2.4nmol/L,占表层保有量的15%左右。通过箱式模型计算得出黄海TDIAs的停留时间约为(18.2±8.5)a,远远低于大洋。通过对该海域砷、磷摩尔比值的计算可以发现,南黄海砷、磷摩尔比值约为大洋中的20倍左右,这可能会引起浮游生物对砷酸盐的大量吸收和转化,从而带来潜在的生态危机,需要引起足够的重视。 相似文献
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ABSTRACT National-scale analyses of land cover effects on water quality can aid in directing environmental policy. We compiled a coastal water quality database for New Zealand comprising 320 estuarine and coastal sites with records between 2013 and 2018. Previous literature had shown strong effects of agricultural and urban land cover on the quality of New Zealand’s rivers, so we examined their effects on estuaries, while controlling for marine dilution and freshwater flushing. Sites with greater freshwater influence had higher nutrient and faecal indicator bacteria concentrations, and turbidity, indicating that open coast and estuarine water quality is reduced predominantly via flows from the land. Nitrate, ammonium, total and dissolved reactive phosphorus, and water column chlorophyll-a concentrations were greater in estuaries with higher urban land cover and total phosphorus concentrations were greater with higher agricultural land cover. There was a marginally significant increase in turbidity as agricultural land cover increased. This is the first national-scale compilation and analysis of New Zealand coastal water quality data, and the first national analysis of land cover effects on water quality in New Zealand estuaries. 相似文献