土壤中重金属形态分析及其环境学意义

介绍了土壤重金属的形态及各种分析方法,重点说明了土壤中重金属形态分布及影响因素;讨论了影响土壤环境中重金属形态转化的因素,重金属形态与重金属在土壤中的迁移性、可给性、活性的关系,重金属污染土壤修复与重金属形态分布的关系.形态分析在一定程度上反映自然与人为作用对土壤中重金属来源的贡献,并反映重金属的生物毒性.重金属可以因形态中某一个或几个方面不同而表现出不同的毒性和环境行为.     

污染土壤重金属形态分析及其影响因素研究进展

土壤重金属形态分析是污染土壤修复的关键｡基于现阶段土壤重金属污染的研究成果,在指出土壤中重金属形态研究的必要性基础上,对土壤重金属存在的形态和分析方法进行了论述,接着着重对土壤重金属形态分布的主要影响因素进行了深入分析,最后指出本领域研究中存在的问题并提出研究展望｡为深入了解土壤重金属的赋存形态､形态分布的影响因素以及提出切实可行的重金属污染土壤修复方式提供理论指导参考｡     

湿地系统中植物和土壤在治理重金属污染中的作用

重金属污染环境的治理是目前环境工程的核心课题。湿地作为水陆相互作用形成的独特生态系统,在重金属污染治理中的作用倍受关注。对湿地植物、土壤在治理重金属污染中所起的关键作用及其机理做一综述,并对治理重金属污染的湿地构建提出几点建议。     

硫对土壤重金属形态转化及植物有效性的影响研究进展

生源要素硫在土壤中的化学循环不仅会直接影响土壤重金属元素的环境行为,也可通过调控植物根际微环境间接影响植物对重金属元素的吸收累积.土壤中的硫被植物根吸收后在植株中合成的有机硫化合物如植物螯合素(PCs)和金属硫蛋白(MTs)可与重金属形成毒性较低的络合物,构成植物重金属解毒的重要机制之一.我国部分土壤缺硫现象严重,为保证作物高质高产,硫肥的使用逐渐被重视,而硫与重金属的交互作用机制也逐渐成为研究热点.本文综合相关研究,介绍了硫在土壤中的生物化学转化,探讨了土壤硫的化学转化对土壤重金属形态转化及植物有效性的影响,并对今后硫在土壤重金属控制的应用提出展望.
     

外源氮输入对闽江河口芦苇湿地土壤磷形态赋存特征的影响

河口湿地是响应全球气候变化和人类活动最为敏感的生态系统之一，是外源氮的一个重要"汇"，其对于生源元素循环过程可产生深刻的影响。在当前闽江河口区氮负荷增强背景下，探讨外源氮输入对湿地土壤磷形态赋存及其关键转化过程具有重要意义。为此，选择闽江河口鳝鱼滩的芦苇湿地为研究对象，基于野外原位氮输入模拟试验，研究了不同氮输入水平（N_Nt，对照处理；N_Lt，低氮处理；N_Mt，中氮处理；N_Ht，高氮处理）对湿地土壤磷形态赋存特征的影响。结果表明，外源氮输入不但增加了湿地土壤的TP含量，而且改变了其土层分布特征。除N_Mt与N_Nt处理下的TP含量相当外，N_Lt和N_Ht处理下的全磷（TP）含量相比N_Nt处理分别增加了3.5%和4.4%。氮输入整体上增加了湿地土壤的活性磷和闭蓄态磷含量，但降低了中等活性磷含量。相比N_Nt处理，N_Mt和N_Ht处理下的活性磷含量分别增加了6.5%和12.6%，而N_Lt、N_Mt和N_Ht处理下的闭蓄态磷含量分别增加了3.3%、3.9%和7.0%。中等活性磷在N_Mt处理下的降幅尤为明显，其值相比N_Nt处理降低了6.7%。不同氮处理下湿地土壤以闭蓄态磷占比最高（51.8%-54.1%），中等活性磷次之（38.1%-41.2%），活性磷最低（7.0%-7.9%）。不同氮处理下的各形态磷占比以HCl-P_i、Residual-P、NaOH-P_o和NaOH-P_i较高，Sonic-P_o和NaHCO₃-P_i次之，而NaHCO₃-P_o、Resin-P和Sonic-P_i较低。研究发现，氮输入主要通过改变土壤养分及酸碱状况来进一步影响土壤中各形态磷的赋存。其中，N_Mt和N_Ht处理下活性磷含量的增加主要与Resin-P和NaHCO₃-P_o有关，N_Lt、N_Mt和N_Ht处理下闭蓄态磷含量的增加主要与Residual-P有关，而N_Mt处理下中等活性磷的显著降低主要与NaOH-P_i和Sonic-P_o有关。     

闽江河口互花米草入侵湿地土壤无机硫赋存形态及其影响因素

选择闽江河口鳝鱼滩的互花米草湿地为研究对象,基于时空互代法,探讨了不同互花米草入侵年限（SA1： 5-6 年;SA2： 8-10 年;SA3： 12-14年）湿地土壤的无机硫赋存形态及其主要影响因素。结果表明,随着互花米草入侵年限的增加,湿地土壤的水溶性硫（H₂O-S）含量整体呈增加趋势,而吸附性硫（Adsorbed-S）、盐酸可溶性硫（HCl-Soluble-S）和盐酸挥发性硫（HCl-Volatile-S）含量整体均呈降低趋势。相对于SA1,SA2、SA3土壤的H₂O-S含量分别增加了10.02%和2.68%,而其Adsorbed-S、HCl-Soluble-S和HCl-Volatile-S含量分别降低了9.02%、10.95%、7.57%和15.61%、32.89%、15.14%。湿地土壤的总无机硫（TIS）含量、TIS储量及其占全硫（TS）储量的比例均随互花米草入侵年限的增加而降低,且这种降低主要取决于Adsorbed-S、HCl-Soluble-S和HCl-Volatile-S的贡献。此外,随着互花米草入侵年限的增加,影响湿地土壤不同形态无机硫赋存的环境因子均发生了较大变化,其中土壤颗粒组成、EC和pH的改变对无机硫赋存形态的影响最为明显。研究发现,随着互花米草入侵年限的增加以及该区对互花米草定期刈割活动的进行,湿地土壤无机硫养分可能将继续降低并逐渐趋于缺乏状态,长期而言将减弱互花米草自身的入侵能力。     

节节草生长对铜尾矿砂重金属形态转化和土壤酶活性的影响

通过盆栽模拟栽培试验,研究了节节草生长对铜尾矿砂重金属形态转化和土壤酶活性的影响。结果表明,节节草生长显著提高了尾矿砂中有机物结合态重金属比例(P0.01),降低了交换态和残渣态重金属比例(P0.05)。土壤过氧化氢酶、脲酶、多酚氧化酶和蔗糖酶活性均随着节节草的生长而不同程度的升高,其中过氧化氢酶和脲酶活性均与植物生长时间呈显著正相关(r过氧化氢酶=0.911,P0.05;r脲酶=0.957,P0.01),多酚氧化酶和蔗糖酶活性在植物生长旺盛期达到峰值,分别是对照组的2.40和2.02倍,随后迅速下降;而磷酸酶活性却显著下降(r磷酸酶=-0.923,P0.05)。土壤酶活性与节节草地下部分干重的相关性大于地上部分;且与土壤有机物结合态重金属的含量呈显著正相关,与交换态和残渣态重金属含量呈显著负相关。节节草生长不仅促进了铜尾矿砂重金属朝螯合态方面转化,有效降低重金属的生物有效性,同时还显著地改善了铜尾矿砂的基质环境和土壤肥力。因此,节节草在铜尾矿废弃地恢复实践中具有较大的应用潜力。     

哈尼梯田湿地土壤不同形态磷的时空分布特征

磷是湿地和农业生态系统中的重要元素之一,其中土壤磷形态的迁移转化广受关注。以哈尼梯田湿地为例,分别在哈尼梯田湿地的水稻生长期、收获期和休闲期,采集湿地不同海拔（梯田区上部、中部和下部）和不同深度的土壤（0-20 cm,20-40 cm,40-60 cm,60-80 cm）进行磷形态分析,研究了哈尼梯田湿地土壤中不同形态磷的时空分布规律和影响因素。结果表明：（1）哈尼梯田湿地土壤中总磷（TP）含量均值为318.74 mg/kg,在水稻收获期含量最高,无机磷（IP）含量均值在水稻休闲期最高（85.95 mg/kg）,湿地土壤磷总体呈缺乏状态。（2）受外源磷输入影响,铁铝结合态磷（NaOH-P）占无机磷比重最大,且季节差异性显著（P<0.05）;而钙结合态磷（HCl-P）在各季节无显著差异（P>0.05）,这与湿地生态环境和地质背景有关。（3）哈尼梯田湿地对磷的迁移有截留作用,表现为各形态磷含量总体呈现在上部梯田湿地较高,并随海拔的降低而降低;不同形态磷含量在20-40 cm土层富集。（4）除HCl-P外,其余形态磷与土壤粒径在不同土层表现为负相关;不同土层TP和有机磷（OP）与pH值呈正相关;土壤总有机碳（TOC）与不同形态磷在收获期呈显著负相关（P<0.05）。研究表明了哈尼梯田湿地立体空间结构和人为活动能影响湿地生态系统中磷的分布与迁移循环,该结论可为梯田湿地的可持续发展提供参考。     

重金属污染土壤的湿地生物修复技术

生物修复技术是近年来发展起来的一种有前途的污染治理技术,重金属的湿地植物稳定技术和植物萃取技术等植物修复技术是一研究热点;同时,针对微生物对重金属的生物积累、生物转化及生物修复作一分析,重金属的生物修复生理机制及其提高富集效率的条件作一综述,以期推动国内这一国际热点领域的研究。     

强还原过程对设施菜地土壤重金属形态转化的影响

设施菜地由于污水灌溉、粪肥施用等导致重金属污染.本文通过土柱淹水同时添加玉米秸秆培养和后期通水淋洗,研究强还原法对设施土壤重金属(Cd、Cu、Pb和Zn)形态转化的影响.结果表明: 强还原处理使土壤pH显著降低,玉米秸秆处理变化更显著;土壤氧化还原电位(Eh)迅速下降至-280 mV左右.玉米秸秆处理可以促进土壤中Cd、Cu、Pb和Zn活化,第9天土壤中有机物及硫化物结合态和残渣态Cd、Cu、Pb和Zn含量比重下降;至15 d培养结束,土壤中4种重金属含量较对照分别减少18.1%、19.0%、16.1%和15.7%.玉米秸秆处理可以增加土壤中Cd和Zn的溶出量,但是Cu的溶出量减少;胶体结合态Cd和Pb含量较对照增加、Cu较对照显著减少、Zn没有显著变化.强还原可以引起设施土壤重金属活化,提高蔬菜积累重金属的风险,而且其随土壤水分的运移可能导致水体的污染.     

Accumulation of Heavy Metals in Water,Sediments and Wetland Plants of Kizilirmak Delta (Samsun,Turkey)

In this study, concentrations of heavy metals (Fe, Mn, Ni, Co, Zn, Cu, and Pb) were measured in water bodies including streams, bottom sediments and various wetland plants of K?z?l?rmak Delta. K?z?l?rmak Delta is one of the largest and the most important natural wetlands in Turkey and has been protected by Ramsar convention since 1993. The heavy metal concentrations in water were found lower than that of national standards for protected lakes and reserves. In bottom sediments and wetland plants, however, the accumulated amounts of different heavy metals varied in the following order: Fe>Mn>Zn>Ni>Co>Cu>Pb, and Fe>Mn>Zn>Ni>Co respectively. Heavy metal uptake of Hydrocharis morsus-ranae and Myriophyllum verticillatum plants among others were found far above the toxic levels and they might be used as bio-indicators and heavy metal accumulators in polluted natural areas.     

Heavy metal contamination and health risk assessment in soil-rice system near Xinqiao mine in Tongling city,Anhui province,China

In this study, paddy soil and rice grain samples were collected from the vicinity around the Xinqiao mine in Tongling, China to test for the presence of heavy metals (Cd, Ni, Cr, Cu, Zn, and Pb) in soil-rice system. Results indicated that the soil samples were primarily contaminated with Cd and Cu and followed with Zn and Pb. In rice grains, Cd, Cu, and Cr concentrations exceeded recommended guidelines. However, the regional distribution of heavy metals in rice grains and soil was inconsistent. The bioaccumulation factor of heavy metals in rice grains decreased in the order of Cd > Zn > Cu > Ni > Cr > Pb. The BAF was significantly positively correlated with TCLP-extractable metals and significantly negatively correlated with soil pH. However, the relationship between soil organic matter and the BAF in rice grains was complex. Health risk assessment through rice intake showed that hazard quotients of Cu and Cd were greater than 1 and could pose a considerable non-cancer health risk to adults and children; meanwhile, Cr, Ni, and Cd could pose an unacceptable cancer risk. The results indicated that the government must take measures to reduce heavy metal contents in paddy soil and rice.     

Heavy metal accumulation in wheat and barley: The effects of soil presence and liquid manure amendment

An experiment was undertaken to evaluate the effect of liquid manure amendment on heavy metal accumulation in wheat and barley. For this purpose, both kinds of seedlings were grown simultaneously in a Petri dish, while wheat seedlings were also grown in pots containing unpolluted agricultural soil. All of the seedlings were irrigated with one of the three prepared solutions: artificial rainwater solution, heavy metal solution and liquid manure solution containing NH₄NO₃, H₃PO₄ and KOH along with equal amounts of heavy metals as in the second solution. Twenty days later, 1 g of plant tissue was digested with the mixture of HNO₃ and H₂O₂ for ICP-OES/HG-ICP-OES analysis. The results showed that the uptake of arsenic and mercury was highest for both plants grown in a Petri dish. Furthermore, the wheat grown in a Petri dish also had a high content of nickel, cadmium and copper, while the pot-grown wheat contained high amounts of iron and manganese, probably due to the adsorption of nickel, cadmium, copper and mercury on soil phases. The lower uptake of all heavy metals was observed after the amendment of liquid manure, with the exception of manganese in wheat and mercury in all plants.     

内蒙古伊金霍洛旗红海子湿地公园鸟类种类组成及生态分布

2012年10月—2013年9月,对红海子湿地公园鸟类资源进行调查。结果表明:共发现鸟类116种,隶属于16目36科,其中,夏候鸟49种,冬候鸟9种,留鸟24种,旅鸟34种;鸟类种类和数量有所增加;依据地形地貌和植被类型,在调查区选择了湿地、林地、草地和居民区4种生境,其中,湿地鸟类多样性指数(3.042)和均匀度指数(0.687)最高,居民区多样性指数(0.599)和均匀度指数(0.227)最低,优势度指数湿地最低(0.079),居民区最高(0.766),相似性指数林地和草地最高(0.667),湿地和居民区最低(0.204);本文对该湿地主要优势鸟种与环境的关系、湿地鸟类种类和数量较前几年增加的原因进行了分析,推测出水质变化可能是导致鸟类疾病发生和死亡的原因。     

贵阳花溪区石灰土林地土壤重金属含量特征及其污染评价

选取贵阳市花溪区典型石灰土林地土壤作为研究对象,分析了林地石灰岩和土壤中7种重金属(Cu、Zn、Mn、Cd、Ni、Pb、Co)的含量特征,以贵州省土壤背景值和全国石灰(岩)土类背景值为评价标准进行林地土壤重金属污染评价和潜在生态风险评价.结果表明:林地石灰岩以Pb的平均含量(40.21mg·kg-1)最高,Zn的(5.78 mg·kg-1)最低,7种重金属平均含量高低顺序为:Pb＞Ni＞Mn＞Co＞Cu＞Cd＞Zn;林地土壤中以Mn的平均含量(451.16 mg·kg-1以上)最高,Cd的(2.87mg·kg-1以下)最低,7种重金属含量的变异系数在8.57%～63.10%之间,Zn的平均含量明显低于贵州省土壤背景值和全国石灰(岩)土类背景值,Cu、Mn、Cd、Pb、Ni、Co的平均含量高于或接近于贵州省土壤背景值和全国石灰(岩)土类背景值.Cu、Zn、Mn、Ni、Co,Ni与Pb,Cd与Pb,Cd与Co来源相同的可能性较大,而Cd与Cu、Ni,Pb与Mn、Cu、Co的来源不同;石灰土偏碱性,富含Ca、Mg元素,有利于重金属Cd、Pb的累积.单因子污染指数和多因子综合指数(内梅罗指数法)与Hakanson潜在生态危害指数的评价结果一致,林地土壤重金属综合污染指数在3.67以上,达到重污染程度,以Cd的污染指数(4.94以上)最高,污染程度最为严重,其次是Pb(1.82以上),Zn、Mn污染程度最低,林地土壤重金属潜在生态危害指数(RI)为173.75以上,为中度生态危害程度,产生最大生态危害的是Cd,其次是Pb、Ni、Co、Cu,危害程度最小的是Mn、Zn,在相同的成土母岩和人为活动影响下,无林地土壤重金属的综合污染指数和潜在生态危害指数均明显高于有林地.     

杭州西溪国家湿地公园生态旅游环境容量

综合旅游生态容量、旅游空间容量、旅游设施容量、旅游管理容量、旅游心理容量5个因素,对杭州西溪国家湿地公园的旅游环境容量进行了测算.结果表明:其旅游环境容量为4145～6450人次.d-1.本研究首次将人鸟间的合理距离应用于湿地生态容量的确定,有效地解决了在充分保证鸟类活动与栖息安全的前提下适度开发湿地旅游的问题.基于游客满意度的旅游心理容量的估算较客观地反映了旅游区(点)在规划建设和经营管理方面满足旅游者需求的程度.这种基于人鸟距离和游客满意度的综合测算方法对于湿地公园的规划和管理具有较实际的指导意义.     

基于物种落差分析的公园鸟类多样性提升设计——以湖南常德螺湾湿地公园为例

随着城市化发展,许多公园鸟类栖息环境遭受破坏,导致当前的鸟类多样性与历史上的和周边的都存在较大差异,为此,我们从项目区域的当前-周边-历史三者间在鸟类物种及其栖息地上的落差分析入手,以此确定目标物种及其栖息地,并加以归类,从而有针对性地进行相关设计。2016年5月至2017年3月在湖南常德柳叶湖螺湾湿地公园开展的鸟类多样性提升设计中,通过实地调查并结合文献查阅,记录到项目区域16种,周边79种,历史上146种鸟类,运用三者间的物种落差分析法确定主要的21种可恢复目标物种和4种栖息地类型,结合项目区域及周边空间特点,将项目区域划分为4个区域,在各区域内设计并营建相应的栖息地,再配套采用多种鸟类招引措施。至2017年3月,项目区鸟类已可实地观察到39种,并于2017年12月吸引到超过2000只的野鸭群来此越冬。以上实际效果表明,设计有效地提升了湿地公园鸟类多样性且增加了景观要素,可充分发挥生物保护功能。     

Effects of biochar amendments on speciation and bioavailability of heavy metals in coal-mine-contaminated soil

An incubation experiment was executed on applying biochar as a soil remediation amendment to discuss an effect of the various addition rates on the speciation and bioavailability of heavy metals in mining-contaminated soil. The result showed that the content of Cd in soil was 9.51 times higher than the Huainan soil background values. The contents of Cu, Zn and As were 2.97, 1.60 and 1.42 times the background values, respectively, and the total contents of all heavy metals were higher than the standard values of soil environment quality GB15618-1995 set by the China Ministry of Environmental Protection. Speciation analysis indicated that Cu and Cd were mainly associated with the reducible fraction, while Zn and As were dominated by the residual fraction. After biochar was added to contaminated soil, the residual fractions of heavy metals increased, while the acid-soluble fractions reduced. According to the results of CaCl₂ extraction experiment, CaCl₂-extractable concentrations of Cu, Zn, As, and Cd were observed with a biochar dosage rate of 10%, which were 57.26%, 51.37%, 6.94% and 42.04% lower than those of control soil samples, respectively, but there were no obvious changes of CaCl₂-extractable As.     

Heavy metal tolerance and accumulation of Cd, Cr and Ni by Cannabis sativa L.

Experiments in semi-natural conditions were undertaken to assess hemp metal tolerance and its ability to accumulate cadmium, nickel and chromium. Cannabis sativa was grown in two soils, S1 and S2, containing 27, 74, 126 and 82, 115, 139 g g^–1 of Cd, Ni and Cr, respectively. After two months from germination and at ripeness, no significant alteration in plant growth or morphology was detected. On the contrary, a high hemp reactivity to heavy metal stress with an increase in phytochelatin and DNA content was observed during development, suggesting the Cannabis sativa ability to avoid cell damage by activating different molecular mechanisms. Metals were preferentially accumulated in the roots and only partially translocated to the above-ground tissues. The mean shoot Cd content was 14 and 66 g g^–1 for S1 and S2 soil, respectively. Although not negligible concentrations they were about 100 times lower than those calculated for the hyperaccumulator Thlaspi caerulescens. Similarly Ni uptake was limited if compared with that of the Ni-hyperaccumulator Alyssum murale. Chromium uptake was negligible. As expected on the base of the metal concentration detected in ripe plants, no statistically significant variation in soil metal content was detected after one crop of hemp. Nevertheless, a consistent amount (g) of Cd and Ni is expected to be extracted by 1 ha biomass of hemp (about 10 t) per year and along the time a slow restoration of deeper soil portions can be obtained by its wide root system (at least 0,5 m deep). In addition, the possibilities of growing hemp easily in different climates and using its biomass in non-food industries can make heavy metal contaminated soils productive. This means economical advantage along with a better quality of soil.     

Heavy metal contamination in water,soil, and milk of the industrial area adjacent to Swan River,Islamabad, Pakistan

Trace heavy metals such as Cr(III), Ni(II), Cd(II), Zn(II), Pb(II), and Cu(II) are hazardous pollutants and are rich in areas with high anthropogenic activities. Their concentrations were analyzed using atomic absorption spectroscopy, and it was found that their concentrations were several fold higher in downstream Swan River water samples of the Kahuta Industrial Triangle as compared to upstream. Heavy metal soil concentrations taken from the downstream site were 149% for Cr, 131% for Ni, 176% for Cd, 139% for Zn, 224% for Pb, and 182% for Cu when compared to samples from the upstream site. Quantitative analysis concluded that these metals were higher in milk samples collected from downstream as compared to the samples from upstream water-irrigated sites. The order of metal in milk was as Zn > Cr > Cu > Cd > Pb = Ni. Heavy metal contaminations may affect the drinking water quality, food chain, and ecological environment. It was also suggested that the toxicity due to such polluted water, soil, and milk are seriously dangerous to human health in future.