海湾扇贝养殖区海水水质及扇贝体内Cu、Zn富集分析

海水水质直接影响养殖业发展及海洋产品品质,受到越来越越多关注。为了解扇贝养殖区域海水水质状况及对扇贝品质的影响,采用分期取样的方法,在莱州湾某扇贝养殖区采集表层海水样品,以非养殖区为对照,分析其pH、营养盐、COD、Cu及Zn含量。同时,采集扇贝幼体、成体,分析Cu、Zn在闭壳肌（贝柱）中蓄积。结果表明,研究区域海水中无机氮含量较高,接近0.30 mg/L,不同时间其含量和组成差异显著,10月海水中无机氮以硝态氮为主,含量极显著高于以氨态氮为主的6月(P<0.01)。不同时间,不同采样点海水中无机磷含量均小于0.02 mg/L,差异不显著。COD、Cu及Zn含量均为6月显著高于10月(P<0.05),未超出二类海水水质标准值。COD、Cu及Zn三者间呈极显著正相关(P<0.01),表明它们可能来自同一污染源。扇贝对Cu、Zn的富集能力较强,对Zn富集能力大于Cu。尽管扇贝闭壳肌中Cu、Zn含量在相关标准值之内,但Cu、Zn富集程度分别达到了1.06、0.821,所以,扇贝养殖过程中Cu、Zn等重金属在体内蓄积应引起更多关注。     

镉胁迫对两种狼尾草不同生育时期生长性能、光合作用特征及镉吸收转运差异的影响

采用盆栽法研究在不同浓度(0、5、25、50、75、100mg·kg~(-1))镉胁迫下美洲狼尾草(ML,Pennisetum americanum)和杂交狼尾草(ZL,P.americanum×P.purpureum)不同生育期的生长指标、光合作用特征,并比较两者耐镉性和对镉吸收转运差异。结果表明,1)相同生育期下,随Cd浓度的增加两种狼尾草株高先升高后降低,叶宽没有显著性变化,鲜重和干重逐渐降低;2)同一生育期,ML的叶绿素a和叶绿素b含量均高于ZL;低Cd浓度(5mg·kg~(-1)),对植株的光合指标影响不大,但Cd浓度增加后,各处理与对照相比显著下降(P0.05),高浓度Cd处理对ZL光合作用影响要大于ML;3)ML生长性能受Cd胁迫影响比ZL要小,但ZL富集系数高于ML,ML耐镉性更好,而ZL修复镉污染土壤的能力更强;4)根系是主要富集部位并且镉从根系往地上部位转移系数较低,3个生育期中幼苗期植株中Cd含量最高。     

施用污泥后石灰性土壤中铜、锌、镉的植物有效性

The toxicity of trace elements (TEs), such as copper (Cu), zinc (Zn), and cadmium (Cd), often restrict land application of sewage sludge (SS) and there was little information about soil-plant transfer of TEs in SS from field experiments in China. In this study pot and field experiments were carried out for 2 years to investigate the phytoavailability of TEs in calcareous soils amended with SS. The results of the pot experiment showed that the phytoavailability of Zn and Cu in the SS was equal to 53.4%-80.9% and 54.8%-91.1% of corresponding water-soluble metal salts, respectively. The results from the field experiment showed that the contents of total Zn, Cu, and Cd in the soils increased linearly with SS application rates. With increasing SS application rates, the contents of Zn and Cu in the wheat grains initially increased and then reached a plateau, while there was no significant change of Cd content in the maize grains. The bioconcentration factors of the metals in the grains of wheat and maize were found to be in the order of Zn > Cu > Cd, but for the straw the order was Cd > Cu > Zn. It was also found that wheat grains could accumulate more metals compared with maize grains. The results will be helpful in developing the critical loads of sewage sludge applied to calcareous soils.     

Fate and plant uptake of persistent organic pollutants in soil

Many persistent organic pollutants (POPs), notably hexachlorocyclohexanes (HCHs), chlorinated cyclodienes, and dichlorodiphenyltrichloroethanes (DDTs), remain in Japanese farming soils, more than 40 years after their use as insecticides was prohibited. In recent years, residues of chlorinated cyclodienes in cucurbit fruits have become a problem. But, though HCHs and DDTs have been staying in the soil, residues of these chemicals in crops have not been a problem. So we compared the fates of HCHs (α-, β-, γ-HCHs), chlorinated cyclodienes (dieldrin, endrin, heptachlor exo-epoxide), and DDTs (DDE, dichlorodiphenyldichloroethylene; DDD, dichlorodiphenyldichloroethane) in soil and investigated their uptake by several non-cucurbits and cucurbits. As for the fate of POPs in soil, not only the total concentrations but also the concentrations in soil solution as bioavailable POPs were determined. The half-lives of total β-HCH and DDTs in soil were the longest, and α- and γ-HCHs the shortest. On the other hand, the half-lives of bioavailable POPs ranged from 1/3 to 1/20 of those of total POPs. The ratio of the half-lives of bioavailable POPs to those of total POPs decreased in the order of HCHs > chlorinated cyclodienes > DDTs. Because hydrophobic chemicals were adsorbed strongly to the soil, the bioavailable POPs in soil are controlled by their hydrophobicity, indicated by the values of log K _OW (K _OW: n-octanol-water partition coefficient). The shoot concentrations of chlorinated cyclodienes and DDTs were higher in cucurbits than in non-cucurbits. However, among POP insecticides, HCHs did not show clear differences. As for the root concentrations, all tested POPs were higher in cucurbits than in non-cucurbits. Through the determination of POPs in soil solution, we could compare the abilities of plants to take up the chemicals using soil solution bioconcentration factors (BCF_SS). The values of BCF_SS increased with the magnitude of log K _OW, in the order of HCHs < chlorinated cyclodienes < DDTs. In addition, BCF_SS did not show marked differences among isomers or chemicals with similar structure. Therefore, plant uptake ability was influenced mainly by log K _OW. After being applied to agricultural land, α- and γ-HCHs seemed to disappear quickly, β-HCH persisted longer but the uptake in roots was low because of the low log K _OW, and DDTs also persisted longer but the bioavailability decreased rapidly in the soil because of their high log K _OW. Chlorinated cyclodienes have remained in the soil and have remained available, because they are less likely than HCHs (except β-HCH) to disappear and less likely than DDTs to become adsorbed to the soil. In addition, their higher log K _OW than that of HCHs makes them more easily taken up by roots. However, shoot concentrations were high only in cucurbits, for which they remain a problem in Japan.     

氧化乐果对斑马鱼的毒性作用及生物富集性研究

为研究斑马鱼(Danio rerio)作为有机磷农药指示生物的可能性,以斑马鱼为实验对象,采用半静态法,研究浓度为0、2.5、5.0、7.5、10.0 mg/L的氧化乐果对斑马鱼体内蛋白质含量及乙酰胆碱酯酶(Ach E)和过氧化物酶(POD)活性的影响及其对0、2、4、6、8、10 mg/L氧化乐果7 d的富集系数(即BCF7 d),探究氧化乐果对斑马鱼的毒性作用及其生物富集性。结果显示,氧化乐果对斑马鱼的96 h半数致死浓度(LC50)为31.57 mg/L,在1~100mg/L之间,属于高毒药物;蛋白质含量总体表现为先升高、再下降的趋势;Ach E活性受到抑制,总体表现为下降趋势;POD活性表现为诱导-抑制效应;BCF7 d随浓度的增加而减小,为1.54~5.80,且BCF7 d随Ach E活性的降低而降低,毒性作用越大,斑马鱼对氧化乐果的富集作用越弱。研究表明,蛋白质含量和乙酰胆碱酯酶活性与氧化乐果浓度有显著的剂量-效应关系,斑马鱼可以作为有机磷农药污染的指示生物。     

Variation of Cd concentration in various rice cultivars and derivation of cadmium toxicity thresholds for paddy soil by species-sensitivity distribution

It is imperative to derive an appropriate cadmium(Cd) health risk toxicity threshold for paddy soils to ensure the Cd concentration of rice grains meet the food safety standard. In this study, 20 rice cultivars from the main rice producing areas in China were selected, and a pot-experiment was conducted to investigate transformation of Cd in paddy soil-rice system with 0(CK), 0.3 mg kg–1(T1) and 0.6 mg kg–1(T2) Cd treatments in greenhouse. The results showed that Cd concentrations of rice grains existed significant difference(P0.05) in 20 rice cultivars under the same Cd level in soil. The Cd concentrations of rice grains of the CK, T1 and T2 treatments were in the range of 0.143–0.202, 0.128–0.458 and 0.332–0.806 mg kg–1, respectively. Marked differences of the ratios of Cd concentration for soil to rice grain(BCFs) and transfer factors(TFs, root to grain and straw to grain) among the tested cultivars were observed in this study. The bioconcentration factors(BCFgrain) and TFs of the 20 rice cultivars were 0.300–1.112 and 0.342–0.817, respectively. The TFs of Cd from straw to grain ranged from 0.366 to 1.71, with significant differences among these 20 rice cultivars. The bioconcentration factors(BCFgrain) and TFs among the 20 rice cultivars ranged from 0.300–1.112 and 0.342–0.817, respectively. The species-sensitivity distribution(SSD) of Cd sensitivity of the rice species could be fitted well with Burr-III(R2=0.987) based on the data of BCFs. The toxicity threshold of Cd derived from SSD for the paddy soil was 0.507 mg kg–1 in the present study.     

水生植物修复重金属污染水体研究进展

利用水生植物的根、茎、叶富集水体中的重金属具有很好的经济和生态效益.文中综述了水体重金属污染的来源及危害, 阐述了水生植物修复水体重金属污染的机理, 并比较植物的富集能力, 提出影响水生植物修复重金属污染水体的因素包括温度、pH值和重金属离子间的交互作用等, 总结分析了当前研究中存在的问题, 以期为相关研究提供信息和参考.     

Can liming reduce barium uptake by agricultural plants grown on sandy soil?

Uptake of barium (Ba) from soil by vascular plants varies among species. Despite the toxicity of soluble Ba compounds to plants, research on mechanisms controlling Ba uptake from natural soils is scarce. This study investigated the treatment effect of lime (CaCO₃) added to a sandy soil containing a total of 500 mg Ba kg^?1 on uptake and interspecies distribution of Ba in legumes and other cultivated food and feed plants. Nine species of grasses, vegetables, herbs, and legumes were cultivated under controlled conditions in a greenhouse experiment. The plants were harvested at maturity or flowering, dried, milled, and digested with nitric acid using the microwave technique prior to ICP‐MS analysis. All plant species acquired Ba from the soil in considerable amounts, probably due to low Ba adsorption potential of the sandy soil. Shoot tissue concentrations ranged from about 100 (grass) to 600 mg Ba kg^?1 (legume) and root concentrations from about 100 (tuber vegetable) to 700 mg kg^?1 (legume). Vicia cracca L. (bird vetch) showed an accumulation capacity due to high shoot concentrations of Ba compared to the other species. Higher yield accompanied by a potential dilution effect can partly explain why Trifolium repens L. (white clover), Pisum sativum ssp. arvénse L. (gray pea) and Hordeum vulgare L. (barley) did not display the highest Ba concentrations, but showed the highest Ba uptake from soil. High plant uptake of calcium (Ca) also seemed to enhance Ba uptake, by legumes in particular. However, liming reduced shoot Ba concentrations, particularly of species with low affinity for Ca. The risk of Ba accumulation thus raises toxicity concerns when forage legumes are cultivated in soils containing elevated concentrations of Ba.     

水分管理和施用石灰对水稻镉吸收与运移的影响

通过田间试验,研究了间歇灌溉和全生育期淹水2种水分管理结合水稻分蘖期施用石灰对不同水稻生育期的土壤和水稻各组织中Cd分布与运移的影响。研究结果表明,全生育淹水和施用石灰均能升高土壤p H值,降低土壤中有效态Cd含量;施用石灰能降低土壤中酸可提取态Cd所占比例而残渣态所占比例增加。在全生育期淹水条件下施用石灰有利于改善土壤性状并提高土壤中Fe质量百分含量。与不施用石灰相比,在间歇灌溉条件下,施用石灰处理的糙米中Cd质量分数从0.86 mg/kg降低到0.56 mg/kg,而在全生育期淹水条件下,施用石灰处理的糙米中Cd质量分数从0.77 mg/kg降低到0.34 mg/kg;无论间歇灌溉还是全淹水处理条件下,施用石灰均增加了水稻总生物量。施用石灰后,在灌浆期,水稻茎叶中Cd的富集系数显著降低(P0.05);在成熟期,根和稻米中Cd的富集系数显著降低(P0.05);在全生育期淹水条件下,成熟期水稻根到茎叶转运系数和茎叶到米中转运系数均显著降低(P0.05)。水稻糙米中Cd含量与土壤中有效态Cd含量、水稻地上部Cd累积量呈显著正相关,与土壤p H值呈显著负相关。上述研究结果表明,施用石灰能够显著降低稻田土壤中Cd的生物有效性;采用全生育期淹水结合在分蘖期施用石灰是降低稻米中Cd含量有效措施且不会导致水稻减产。     

地肤对硼的耐受及富集能力研究

为了考察地肤对硼的耐受及富集能力,开展了溶液培养试验。将溶液硼浓度设置为0(对照)、10、20、30、40、80、120 mg·L~(-1),考察了硼胁迫对地肤植株生长、硼积累和细胞酶活性的影响。结果表明:地肤在溶液硼浓度为30 mg·L~(-1)以下能够正常生长。溶液硼浓度超过30 mg·L~(-1)后,随着溶液硼浓度的增加、地肤的生物量显著降低。当硼浓度达到120 mg·L~(-1)时,根、茎、叶生物量分别比对照降低了56.0%、72.2%和71.4%。随着溶液硼浓度的增加,地肤根、茎、叶中的硼浓度均显著增加,在120 mg·L~(-1)时,地肤体内硼浓度可达4000 mg·kg~(-1)。经计算,地肤地上部和根部的BCF和TF值均大于1,地上部的BCF甚至大于20,表现出较强的硼富集能力。随着硼浓度的增加,地肤体内SOD和POD的浓度呈现先增加后降低的趋势,CAT的浓度呈现增加的趋势,表现出较好的抗氧化防御机制。综上所述,地肤在硼胁迫下有较好的抗氧化防御机制,其对高浓度硼具有较强的耐受和富集能力,可以作为高硼土壤植物修复的候选物种。