| In order to learn the heavy metal content characteristics of karst caves fish and water in Libo Guizhou,therefore,some typical karst caves were selected,and in August 2018,went to Libo County for cave selection and sample collection,A total of 6 caves and cave water samples were selected,and 8 cave fishes were counted,98 samples were taken.The sample size of each cave fish was 3-24.which are Sinocyclocheilus longibarbatus and Sinocyclocheilus macrolepis,Parasilurus cochinchinensis,Carassius auratus,Sinocrossocheilus microstomatus,Hemibarbus maculatus,Misgurnus anguillicaudatus,and Monopterus albus.Investigation and laboratory processing work were carried out.The preliminary study of the paper discussed the content characteristics of eight heavy metals?Cr,As,Cd,Pb,Zn,Cu,Ni,Hg?in cave water and fish,and some conventional physical and chemical factors?NO3-N,NH3-N,DO,CODMn,TN,TP,Chl-a,turbidity?,while analyzing the biomagnification of heavy metals in cave fish,and using the US Environmental Protection Agency's recommended health risk assessment model.The risk of human health hazards in cave waters and heavy metals in fish.The main results of the paper are as follows:?1?The conventional physical and chemical factors of the water bodies of the six karst caves in Libo did not exceed the national groundwater quality standards?GBT-14848-2017?and the surface water quality standards?GB-3838-2002?.At the average level,the content of 8heavy metals in the cave water is:Cr?4.48×10-44 mg/L?>As(2.88×10-4mg/L)>Zn(2.42×10-4mg/L)>Ni(2.39×10-4mg/L)>Cu(2.00×10-4mg/L)>Cd(1.29×10-5mg/L)>Hg(1.08×10-5mg/L)>Pb(2.36×10-6mg/L),which did not exceed the Class I standard limits in the National Groundwater Quality Standard?GBT-14848-2017?.It is indicated that the conventional physical and chemical factors and heavy metals of the six cave water bodies are at low levels.?2?At the average level,the content of each heavy metal in 8 cave fish is:Zn?141.16 mg/kg?>Cu?9.58 mg/kg?>Cr?2.81 mg/kg?>Ni?1.26 mg/kg?>Cd?1.12mg/kg?>As?1.02 mg/kg?>Pb?0.69 mg/kg?>Hg?0.16 mg/kg?.According to the limit values of heavy metals in aquatic products in national standards?GB2762-2005?and?NY5073-2006?,the eight heavy metals in the cave fish species and tissue level showed that all the heavy metals except Cu had exceeded the standard.In addition,from the level of cave fish age group,the content of heavy metals decreased with age in Xiaokouhua carp and carp,and increased with age in the long-term carp and carp,most significant with age.The heavy metals are Zn and Cu.At the non-average level,the over-standard rate of Zn in the carp was 54.01%,and the over-standard rate of Cd in the visceral viscera was 37.8%,and the heavy metal Cd exceeded the standard.Principal component and correlation analysis showed that there was a strong positive correlation between heavy metals Cr,As,Cd,Pb,Cu and Ni,indicating that their distribution in cave fish was similar,or they might have the same source.In addition,both Cr and Pb were significantly negatively correlated with age,Pb was significantly negatively correlated with age;Cd and Hg were significantly positively correlated with body weight;only Cd was significantly positively correlated with body length.?3?The range of?13C in 8 kinds of cave fish samples was-28.98‰?-24.43‰,while the range of?15N was 9.63‰?13.86‰.Except for Monopterus albus,it is carnivorous than omnivorous?partial plant?,and?13C is expressed as Sinocyclocheilus longibarbatus?-24.43‰?with a partial animal diet,and?15N is carnivorous.The Parasilurus cochinchinensis?13.86‰?is the highest,while the?13C and?15N are the lowest of the Carassius auratus?-27.33‰?and?10.68‰?.The results of regression analysis showed that only Pb showed an increasing trend with the increase of food chain level,while heavy metals Cr,As,Cd,Zn,Cu,Ni and Hg all showed a trend of decreasing with the increase of food chain level,all heavy metals.The correlation between the content and?15N was not significant.?4?The health risk of heavy metals in the waters of six caves in Libo are Cr>As>Cd>Cu>Hg>Ni>Pb>Zn,children are significantly higher than adults,and the risk level of chemical carcinogens is lower than that of non-chemistry.Carcinogens are 5 to 6 orders of magnitude higher,Cr has the greatest contribution to total risk,and the contribution rate is as high as 80.68%.In the spatial distribution,the risk value of Cr in the water body is the highest.At the same time,in both groups,only Cr and As were higher than the acceptable risk levels of the Swedish Environmental Protection Agency,the Netherlands Ministry of Construction and Environmental Protection and the Royal Society(1x10-6),and the remaining heavy metals did not exceed the risk levels recommended by other agencies.?5?The health risk assessment results of cave fish in the study area showed that the THQ of heavy metals Cr,Cd,Pb and Zn were all less than 1,and the THQ of Cu was greater than 1.The THQ of other heavy metals was greater than 1 in some fishes,and the performance was Cu?2.900?>As?1.100?>Hg?0.479?>Cd?0.234?>Zn?0.207?>Pb?0.0099?>Cr?0.000953?;in addition,all fish have TTHQ greater than 1,and TTHQ of carnivorous fish Higher than omnivorous.The contribution rate of Cu and As to total risk TTHQ?44.81%?79.86%?and?12.66%?27.93%?were the highest,and the THQ average values of Cu and As were both greater than1,so Cu and As were the main risk elements. |
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